Comportamento de Cristais Líquidos Cromônicos em Microgotas

Prévia do material em texto

<p>Sunset Yellow Confined in Curved Geometry: A Microfluidic</p><p>Approach</p><p>Caterina Maria Tone,* Alessandra Zizzari,* Lorenza Spina, Monica Bianco, Maria Penelope De Santo,*</p><p>Valentina Arima,* Riccardo Cristoforo Barberi, and Federica Ciuchi</p><p>Cite This: Langmuir 2023, 39, 6134−6141 Read Online</p><p>ACCESS Metrics & More Article Recommendations *sı Supporting Information</p><p>ABSTRACT: The behavior of lyotropic chromonic liquid crystals (LCLCs) in</p><p>confined environments is an interesting research field that still awaits exploration,</p><p>with multiple key variables to be uncovered and understood. Microfluidics is a</p><p>highly versatile technique that allows us to confine LCLCs in micrometric spheres.</p><p>As microscale networks offer distinct interplays between the surface effects,</p><p>geometric confinement, and viscosity parameters, rich and unique interactions</p><p>emerging at the LCLC−microfluidic channel interfaces are expected. Here, we</p><p>report on the behavior of pure and chiral doped nematic Sunset Yellow (SSY)</p><p>chromonic microdroplets produced through a microfluidic flow-focusing device.</p><p>The continuous production of SSY microdroplets with controllable size gives the</p><p>possibility to systematically study their topological textures as the function of their diameters. Indeed, doped SSY microdroplets</p><p>produced via microfluidics, show topologies that are typical of common chiral thermotropic liquid crystals. Furthermore, few</p><p>droplets exhibit a peculiar texture never observed for chiral chromonic liquid crystals. Finally, the achieved precise control of the</p><p>produced LCLC microdroplets is a crucial step for technological applications in biosensing and anticounterfeiting.</p><p>■ INTRODUCTION</p><p>In recent years, thermotropic liquid crystals (LCs) have been</p><p>confined and studied in droplets and shells showing complex</p><p>topological defects strongly related to their intrinsic aniso-</p><p>tropy.1−5</p><p>Lyotropic chromonic liquid crystals are a special class of</p><p>lyotropic LCs that are formed by anisotropic assemblies of</p><p>water-soluble disk-shaped molecules that have an aromatic</p><p>core surrounded by ionic groups. Among LCLCs, there are</p><p>DNA and its bases, disodium cromoglycate (DSCG), a</p><p>commonly used drug, and sunset yellow (SSY), a dye used</p><p>in the food industry.6,7 Unlike lyotropic LCs, LCLCs do not</p><p>form micelles; rather, they stack up as linear aggregates, held</p><p>together by noncovalent interactions, which lead to a self-</p><p>assembled nematic phase or a columnar phase with a</p><p>hexagonal arrangement possessing unique optical proper-</p><p>ties.8−11 The weak interaction forces driving the self-assembled</p><p>phase formation make LCLCs highly responsive to external</p><p>stimuli (temperature, concentration, pH, ionic content, etc.)</p><p>and geometric constraints, thus conferring them distinctive</p><p>properties such as negative birefringence and a large anisotropy</p><p>in the elastic constants. Moreover, owing to biocompatibility</p><p>and anisotropic properties, LCLCs have been explored in</p><p>biological applications such as drug delivery12 and optical</p><p>biosensing13 and in technological applications.14 Curved</p><p>confinement can trigger unconventional effects on LCLCs</p><p>because their alignment direction sufficiently anchored at the</p><p>boundary will be transmitted into the bulk in the form of an</p><p>orientation field deformation. The latter leads to the</p><p>generation of new structures with controllable topological</p><p>defects or dislocations. Recently, few research groups have</p><p>studied the confinement-induced reflection symmetry breaking</p><p>of nematic LCLCs in curved geometries like tactoids,</p><p>microspheres, or cylinders.15−19 Cholesteric LCLCs confined</p><p>in microspheres have been studied as well, the chirality in some</p><p>cases is native,20 while in others, it can be induced by doping</p><p>the nematic phase with suitable molecules, for example, amino</p><p>acids.21,22 Microspheres are obtained by emulsification, i.e.,</p><p>through the mechanical agitation of a mixture based on an</p><p>immiscible matrix and the LCLC phase.23,24</p><p>Despite the large number of microspheres produced by this</p><p>method, it is not possible to achieve fine control of their size,</p><p>which plays a fundamental role in their final optical texture.</p><p>This is important for applications (i.e., anticounterfeiting or</p><p>biosensing) in which the production of precise size</p><p>distributions of microstructures with particular optical features</p><p>is the prerequisite for the correct functionality of the</p><p>device.25,26 The size control can be achieved using a</p><p>Received: January 30, 2023</p><p>Revised: April 4, 2023</p><p>Published: April 19, 2023</p><p>Articlepubs.acs.org/Langmuir</p><p>© 2023 The Authors. Published by</p><p>American Chemical Society</p><p>6134</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>D</p><p>ow</p><p>nl</p><p>oa</p><p>de</p><p>d</p><p>vi</p><p>a</p><p>U</p><p>N</p><p>IV</p><p>O</p><p>F</p><p>SA</p><p>O</p><p>P</p><p>A</p><p>U</p><p>L</p><p>O</p><p>o</p><p>n</p><p>Se</p><p>pt</p><p>em</p><p>be</p><p>r</p><p>11</p><p>, 2</p><p>02</p><p>4</p><p>at</p><p>1</p><p>7:</p><p>49</p><p>:3</p><p>2</p><p>(U</p><p>T</p><p>C</p><p>).</p><p>Se</p><p>e</p><p>ht</p><p>tp</p><p>s:</p><p>//p</p><p>ub</p><p>s.</p><p>ac</p><p>s.</p><p>or</p><p>g/</p><p>sh</p><p>ar</p><p>in</p><p>gg</p><p>ui</p><p>de</p><p>lin</p><p>es</p><p>f</p><p>or</p><p>o</p><p>pt</p><p>io</p><p>ns</p><p>o</p><p>n</p><p>ho</p><p>w</p><p>to</p><p>le</p><p>gi</p><p>tim</p><p>at</p><p>el</p><p>y</p><p>sh</p><p>ar</p><p>e</p><p>pu</p><p>bl</p><p>is</p><p>he</p><p>d</p><p>ar</p><p>tic</p><p>le</p><p>s.</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Caterina+Maria+Tone"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Alessandra+Zizzari"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Lorenza+Spina"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Monica+Bianco"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Maria+Penelope+De+Santo"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Valentina+Arima"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Valentina+Arima"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Riccardo+Cristoforo+Barberi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Federica+Ciuchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.langmuir.3c00275&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?goto=articleMetrics&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?goto=recommendations&?ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?goto=supporting-info&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=abs1&ref=pdf</p><p>https://pubs.acs.org/toc/langd5/39/17?ref=pdf</p><p>https://pubs.acs.org/toc/langd5/39/17?ref=pdf</p><p>https://pubs.acs.org/toc/langd5/39/17?ref=pdf</p><p>https://pubs.acs.org/toc/langd5/39/17?ref=pdf</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://pubs.acs.org?ref=pdf</p><p>https://pubs.acs.org?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://pubs.acs.org/Langmuir?ref=pdf</p><p>https://pubs.acs.org/Langmuir?ref=pdf</p><p>https://creativecommons.org/licenses/by/4.0/</p><p>https://creativecommons.org/licenses/by/4.0/</p><p>https://acsopenscience.org/open-access/licensing-options/</p><p>microfluidic approach by opportunely tuning the flow</p><p>conditions and surfactant concentration.</p><p>Nowadays, advancement in microfabrication techniques of</p><p>various materials has enabled the precise design and</p><p>modulation of structural features, pressure, and boundary</p><p>conditions, with the consequent conspicuous development of</p><p>microfluidic devices applied to biological and materials</p><p>technology.27−31 Microfluidics has the unique advantages of</p><p>the continuous flow production of multifunctional materials</p><p>with accurate control of structural properties32−37 and allows</p><p>distinct interplays between the surface effects, geometric</p><p>confinement, viscosity</p><p>parameters, and interfacial phenom-</p><p>ena38 with promising applications in the LCLCs field. Recent</p><p>progress in liquid crystal microfluidics has demonstrated how</p><p>hydrodynamics, in combination with surface interactions,</p><p>geometric confinement, and flow modulation can be harnessed</p><p>to generate topological structures with potential for novel</p><p>applications.39,40 Previous works have shown that interesting</p><p>phenomena are observed by precisely tuning the flow of</p><p>nematic LCs, the confinement conditions in microchannels,</p><p>and the wettability of channel walls.41−44 On the other hand,</p><p>studies on the microfluidic generation of droplets embodying a</p><p>chromonic liquid crystal and an isotropic component are still</p><p>rare. Only a few works report on the production through</p><p>microfluidics of chromonic cholesteric droplets of cellulose</p><p>nanocrystals (CNCs)45,46 and pure SSY.47 In the last case, the</p><p>authors employed a microfluidic system that did not make use</p><p>of electromechanical injection, a crucial point for systems in</p><p>which viscosity may increase, as, for example, in the case of</p><p>chromonic materials doped with chiral moieties. To the best of</p><p>our knowledge, the control of microdroplets’ chromonic</p><p>diameter in microfluidic devices has never been reported.</p><p>In the present work, the microfluidic generation chromonic</p><p>SSY microdroplets with precise size and optical properties</p><p>obtained by tuning the flow conditions is described. We were</p><p>able to produce via microfluidics, microdroplets with rich and</p><p>unique topologies, such as those observed for the classic</p><p>nematic and cholesteric thermotropic LCs, as well as</p><p>microdroplets with topologies never observed before in chiral</p><p>chromonic droplets. Initially, a description of the strategies</p><p>used to obtain stable droplets with defined optical textures will</p><p>be provided. Then, a polarized light optical microscopy study</p><p>will be presented to gain information on the director field</p><p>configuration inside microspheres.</p><p>The production of well-defined size-dependent optical</p><p>textures is the first crucial step toward the use of chromonic</p><p>microspheres for practical applications. In particular, it has</p><p>been recently demonstrated that the optical topology of</p><p>microspheres degrades irreversibly over time due to temper-</p><p>ature.48 Degradation can be slowed down by keeping the</p><p>samples at 5 °C and can be avoided if samples are stored at</p><p>−18 °C. This paves the way for the fabrication of new</p><p>biocompatible time−temperature indicators that can be used</p><p>to monitor the cold food chain.</p><p>■ RESULTS AND DISCUSSION</p><p>The molecular formula of SSY is shown in Figure 1a. In this</p><p>work, both pure SSY solution, in the nematic and isotropic</p><p>phase, and SSY mixtures doped with trans-4-hydroxy-L-prolyne</p><p>(Trans-Hyp, see Figure 1b), which acts as a chiral agent, were</p><p>analyzed. Microdroplets of all of the solutions have been</p><p>produced by a microfluidic flow-focusing device (Figure 1d)</p><p>using a nonionic surfactant (Span80, see Figure 1c) dissolved</p><p>in the paraffin oil phase. The glass walls of the device are</p><p>covered by a silane layer that enhances the surface hydro-</p><p>phobicity, increasing the affinity of the oil phase for the walls</p><p>and decreasing that of the aqueous phase, as shown by the</p><p>water contact angle measurement of the clean and function-</p><p>alized glass substrate, reported in Table 2.</p><p>Microdroplet Production. The dispersed (aqueous)</p><p>phase was injected in the inner microchannel and then</p><p>squeezed by continuous (oil) phase flow injected by the outer</p><p>microchannel. In this geometry, the symmetric shear generated</p><p>by the continuous phase on the dispersed phase allows a highly</p><p>controlled and stable generation of droplets.36,49,50 Indeed, the</p><p>central stream of the dispersed phase becomes so narrow to</p><p>break into droplets,36,51 at different possible flow regimes</p><p>(mainly squeezing, dripping, jetting, and threading regime),52</p><p>depending on the delicate balance between the capillary</p><p>number Ca (defined as the ratio of viscous force to interfacial</p><p>tension) and the volumetric flow rate ratio (FRR) between the</p><p>outer and inner fluids.</p><p>First, we identified the flow conditions and the surfactant</p><p>amount necessary to induce the inner fluid to break into stable</p><p>droplets for a 7% wt SSY concentration, which corresponds to</p><p>Figure 1. Molecular structures of (a) SSY, (b) trans-4-hydroxy-L-proline, and (c) Span80. In (d) on the left, flow-focusing device sketch: the</p><p>continuous phase (paraffin oil) and the dispersed phase (SSY aqueous solution) were injected with programmable syringe pumps in the outer and</p><p>inner channels, respectively. The droplets were generated at the focusing zone and then collected for the SSY microspheres analysis. A picture of</p><p>the FF device used for the experiments is shown on the right.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6135</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig1&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig1&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig1&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig1&ref=pdf</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>the isotropic phase of the SSY liquid crystal solution. The</p><p>surfactants are a facet of the microfluidic technique and are not</p><p>necessary to produce LCLC droplets by mechanical shaking.24</p><p>Indeed, in the microfluidic environments, the surfactant plays a</p><p>fundamental role49 in inducing the formation of the droplets as</p><p>the surfactant molecules tend to assemble at the droplet</p><p>interface, exposing their polar heads toward the water phase</p><p>and their nonpolar tails toward the oil phase. In our setup, the</p><p>breaking of the stream into droplets for a 4% wt Span80</p><p>concentration was observed.</p><p>At this concentration, the diameter of the droplets can be</p><p>varied by tuning the flow ratios of the two fluids, in the order</p><p>of tens of μL/min for both fluids, obtaining a controlled</p><p>diameter range of tens of microns (see Figure 2). In Figure S1,</p><p>an example of the diameter distribution of isotropic droplets is</p><p>shown.</p><p>For an FRR of 2, SSY droplets presented a diameter of 50</p><p>μm with a tendency to coalesce inside the channel. When the</p><p>flow ratios increased up to 10, droplet diameters scaled around</p><p>30 μm, while for an FRR of 15, the shear forces generated at</p><p>the focusing zone allowed the formation of a narrow thread of</p><p>the inner fluid and its breakage into monodisperse droplets</p><p>with diameters much smaller than the orifice width (around 25</p><p>μm). The decrease in the droplet size with the increase in FRR</p><p>is typical of systems with low viscosity contrast of fluids.53</p><p>Furthermore, we occasionally observed a jet of small</p><p>monodisperse droplets (Figure 2c,d), already seen by Anna</p><p>et al.54 for a different liquid system. This behavior is due to the</p><p>Rayleigh plateau instability occurring when a fluid is forced to</p><p>travel rapidly through a microchannel.52,55,56 Interestingly, in</p><p>this case, the droplet downstream arrangement assumed an</p><p>“alternating pancake” configuration.57 Probably, the increased</p><p>oil fraction flowing in the microchannel and the higher</p><p>production of droplets with respect to the previous conditions</p><p>cause the build-up of pressure in the main channel, which</p><p>prevents the droplets from flowing in a single row along the</p><p>center line of the channel, thus forcing them to organize into</p><p>an alternating arrangement like a sinusoidal shape.</p><p>Assured that the droplet production of SSY compound is</p><p>possible, we choose the SSY concentration at 30% wt, which is</p><p>characterized by a nematic chromonic liquid crystal phase and</p><p>an increased viscosity. In fact, to observe the stream from</p><p>breaking, we needed to add to the oily matrix an 8% wt of the</p><p>surfactant Span80. The increase in surfactant quantity is</p><p>necessary to maintain the balance between the viscous force</p><p>and the interfacial tension;58 the breaking of the streams was</p><p>observed with the flow rates of the two fluids set on μL/h for</p><p>the aqueous phase</p><p>(SSY) and μL/min for the oily phase</p><p>(paraffin oil + 8% wt Span80). An FRR in the interval 100−</p><p>117 was used to produce droplets with diameters ranging</p><p>between 10 and about 50 μm (Figure S2); no coalescence</p><p>effects were observed (Figure 3a). The same behavior was</p><p>observed for the production of SSY microdroplets when the</p><p>solution was doped with Trans-Hyp at 16% wt and 26% wt</p><p>(Figure 3b,c). The Span80 concentration was kept constant,</p><p>indicating that the addition of the chiral dopant does not affect</p><p>droplet production probably because it does not alter</p><p>significantly the equilibrium between viscosity forces and</p><p>interfacial tension.</p><p>Possible coalescence effects that could occur with time were</p><p>also studied. After microfluidic production, both pure and</p><p>chiral nematic SSY droplets were collected inside glass vials,</p><p>which were filled with the same percentage of paraffin oil and</p><p>surfactant used in the FF device. The time evolution of the</p><p>droplets was investigated by checking the vials after 24 h.</p><p>Coalescence effects have been observed only for microdroplets</p><p>of pure 7% wt SSY produced using 4% wt Span80 added to the</p><p>oily matrix (Figure 4a), while for isotropic, nematic, and chiral</p><p>nematic droplets produced using 8% wt Span80, no</p><p>coalescence effects were observed (Figure 4b). Hence, in</p><p>addition to helping the microdroplet production, the presence</p><p>of the surfactant also avoids coalescence effects, ensuring the</p><p>time stability of the emulsions.</p><p>Optical Characterization of the Microdroplets. Similar</p><p>to thermotropic LCs, the topologies observed in LCLC</p><p>microdroplets strongly depend on the droplet diameter,</p><p>anchoring condition at the boundaries, and, for chiral mixtures,</p><p>the helical pitch.2,18,59 At odds with what happens for</p><p>thermotropic LCs, controlling the director configuration inside</p><p>the microdroplets of LCLCs is a rather difficult task. However,</p><p>the vast literature on the geometrical frustration in the</p><p>thermotropics can be used to interpret the director field</p><p>configuration inside the LCLC microspheres. In this</p><p>Figure 2. Images of the FF device generating droplets of SSY 7% wt in</p><p>water (red solution injected from the inner channel of Figure 1d)</p><p>dispersed into the paraffin oil in the presence of Span80 4% wt</p><p>(flowing from the outer channel of Figure 1d). Droplets of different</p><p>sizes are produced at (a) FRR = 2, (b) FRR = 10, (c) FRR = 15, and</p><p>(d) FRR = 20.</p><p>Figure 3. Images showing droplets of (a) SSY 7% wt in water</p><p>dispersed into the paraffin oil in the presence of Span80 4% wt at FRR</p><p>= 15, (b) SSY 30% wt in water dispersed into the paraffin oil in the</p><p>presence of Span80 8% wt at FRR = 100, and (c) SSY 30% wt in</p><p>water with the addition of Trans-Hyp 26% dispersed into the paraffin</p><p>oil in the presence of Span80 8% wt at FRR = 117.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6136</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig2&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig2&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig2&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig2&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig3&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig3&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig3&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig3&ref=pdf</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>perspective, we carried out systematic polarized optical</p><p>microscopy (POM) measurements on the different micro-</p><p>droplets produced by the microfluidic device using paraffin oil</p><p>that provides planar anchoring conditions. Droplets were</p><p>imaged out of the device (after collection in a vial) at first</p><p>without polarizers to correctly estimate their diameter and then</p><p>with crossed polarizers. The observed textures were identified</p><p>by rotating the microscope plate and rotating the analyzer.</p><p>Figure 5 shows the size-dependent topologies observed in</p><p>microdroplets of pure nematic phase SSY. In general, small</p><p>droplets (10−20 μm) show a bipolar structure (BS) (Figures</p><p>5a and S3). This is the typical texture observed in the</p><p>chromonics microspheres with planar boundary condition60 in</p><p>which the director is parallel to the interface and forms two</p><p>boojums at the poles. For droplet diameters ranging between</p><p>30 and 50 μm (Figure 5b,c), a better-defined bipolar structure</p><p>was observed. In a few cases, a “concentric drop” texture is</p><p>observed, which can be related to the top view of a bipolar</p><p>texture (Figure 5d). In this configuration, the director field is</p><p>organized in concentric circles with a disclination line that</p><p>passes through the center of the drop. It is interesting to notice</p><p>that the surfactant, added to allow the production of stable</p><p>microfluidic droplets, does not affect the optical properties and</p><p>textures, thus confirming its purely interfacial role in droplet</p><p>formation.</p><p>Figure 6 shows a collection of SSY microspheres doped with</p><p>Trans-Hyp at 16% wt (Figure S4). Small droplets (10−20 μm</p><p>diameter) show bipolar configuration, as in the case of the pure</p><p>nematic phase (Figure 6a,b). The addition of the chiral dopant</p><p>is reflected in the optical texture observed in the microdroplets.</p><p>In fact, for a droplet diameter larger than 45 μm, the radial</p><p>spherical structure (RSS) develops (Figure 6c). In the RSS, the</p><p>director profile is characterized by a splay-bend distortion</p><p>inside the droplet that generates a disclination line, similar to</p><p>the so-called Frank−Pryce structure observed in thermotropic</p><p>LCs. Increasing the droplet diameter, another topology was</p><p>observed. It could be related to the diametrical spherical</p><p>structure (DSS) or the top view of the RSS (Figure 6d). The</p><p>DSS is the most symmetric structure in cholesteric droplets</p><p>with planar anchoring. It is characterized by a center ring</p><p>defect and the director field forms curved cholesteric layers</p><p>with the layer normal in the radial direction.</p><p>Figure 7 shows the POM images of SSY microspheres doped</p><p>with 26% wt of Trans-Hyp at different droplet diameters</p><p>(Figure S5). As observed for the other doped solutions, small</p><p>droplets with a diameter of about 10 μm (Figure 7a) show a</p><p>bipolar configuration, while the most interesting topologies are</p><p>observed for droplets with increasing diameters. For diameters</p><p>around 20 μm, the texture starts to become distorted in radial</p><p>concentric rings (Figure 7b). This effect is more evident in</p><p>Figure 7c in which a clear Frank−Pryce texture is shown. In</p><p>Figure 7d, we can distinguish a topology, observed only a few</p><p>times, that resembles the Lyre structure and is numerically</p><p>predicted by Sec ̌ et al.61 in cholesteric thermotropic LC</p><p>droplets. The Lyre structure, of bipolar type, has only two</p><p>surface defects positioned diametrically along one of the axes</p><p>parallel to the observation plane. This is the first experimental</p><p>observation of this kind of structure in an LCLC droplet</p><p>probably due to its metastable nature.</p><p>In Table 1, we collected schematically the director</p><p>configuration observed inside the droplets associated with</p><p>the microdroplet diameter for each LCLC solution studied in</p><p>this work. Small droplets (diameters 10−20 μm) show a</p><p>Figure 4. (a) Coalescence observed for microdroplets of pure 7% wt SSY produced using 4% wt Span80 added to the oily matrix and (b) SSY 7%</p><p>wt in water dispersed into the paraffin oil in the presence of Span80 8% wt.</p><p>Figure 5. POM images between crossed polarizers of microspheres of</p><p>pure nematic phase SSY at 30% wt. Droplet diameters are estimated</p><p>from the bright field image. Specifically, the diameter of the reported</p><p>microspheres is (a) 10 ± 1 μm; (b) 47.0 ± 1.7 μm; (c) 49.0 ± 1.2</p><p>μm; and (d) 52.0 ± 1.4 μm.</p><p>Figure 6. POM images</p><p>between crossed polarizers of microspheres of</p><p>SSY at 30% wt + 16% wt of Trans-Hyp. Droplet diameters are</p><p>estimated from the bright field image. Specifically, the diameter of the</p><p>reported microspheres is (a) 10 ± 1 μm; (b) 20.0 ± 1.8 μm; (c) 45.0</p><p>± 1.7 μm; and (d) 50.0 ± 1.5 μm.</p><p>Figure 7. POM images between crossed polarizers of microspheres of</p><p>SSY at 30% wt + 26% wt Trans-Hyp, collected according to their</p><p>dimensions. Droplet diameters are estimated from the bright field</p><p>images. Specifically, the diameter of the reported microspheres here is</p><p>(a) 10 ± 1 μm; (b) 20 ± 2 μm; (c) 50.0 ± 1.5 μm; and (d) 57.0 ±</p><p>1.6 μm.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6137</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig4&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig4&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig4&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig4&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig5&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig5&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig5&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig5&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig6&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig6&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig6&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig6&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig7&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig7&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig7&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig7&ref=pdf</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>bipolar configuration for both pure and chiral doped solutions.</p><p>The distortion increases both with the microsphere’s diameter</p><p>and the concentration of the chiral agent. Even if the material</p><p>used is a chromonic mesogen, the trend observed for the</p><p>optical textures is in agreement with the reported data in the</p><p>literature on the diameter/topology dependence in thermo-</p><p>tropic nematic and chiral LCs.</p><p>■ CONCLUSIONS</p><p>The confinement of self-assembling materials, especially chiral</p><p>liquid crystals, in spherical micro-objects with a controllable</p><p>size is crucial to obtain reproducible optical patterns that can</p><p>be used for practical applications.</p><p>Here, we report on the microfluidic production of</p><p>microspheres containing a chromonic liquid crystal, Sunset</p><p>Yellow. Exploiting and characterizing the interplay of the</p><p>interfacial phenomena, surface effects, and geometric confine-</p><p>ment, we were able to define a protocol to produce controlled</p><p>size and topology of nematic and chiral SSY microdroplets.</p><p>Studying the wettability of the channels, we identified a</p><p>functionalization of the glass device based on silanes to reduce</p><p>the interactions of the walls with the SSY phase and increase</p><p>the affinity of the oil phase for the walls, which allowed a</p><p>correct and stable flow in the flow-focusing device. The</p><p>microfluidic SSY microdroplets show unique optical top-</p><p>ologies, like the ones observed with thermotropic LC</p><p>microdroplets in planar boundary conditions. This is a relevant</p><p>achievement considering that the literature presents just a few</p><p>works on the microfluidic production of nematic SSY</p><p>chromonic microdroplets and no data are available on chiral</p><p>SSY microspheres. From a fundamental point of view, this can</p><p>help to better understand the interactions among the</p><p>supramolecular structures, studying, for example, the effect of</p><p>charged guest molecules on the optical patterns.</p><p>Doping the chromonic material with chiral amino acids has</p><p>allowed the study and production of structures and topologies</p><p>that are typically observed in cholesteric thermotropic LC</p><p>microdroplets. In chiral SSY microdroplets, a structure never</p><p>observed before and similar to that of Lyre was observed. This</p><p>is a first step toward the goal of obtaining chromonic</p><p>microspheres with homogeneous tunable optical properties,</p><p>such as reflection selectivity, which could open new</p><p>perspectives for the use of these biocompatible materials as</p><p>sensors and optical devices.</p><p>■ EXPERIMENTAL SECTION</p><p>Materials and Solution Preparations. Sunset Yellow (SSY,</p><p>Sigma-Aldrich) was used as received. At room temperature, it is a red</p><p>powder and shows a nematic phase if dissolved in water above 28% in</p><p>weight. Chirality is induced doping the SSY with a proper amount of</p><p>trans-4-Hydroxy-L-proline (Trans-Hyp) from Sigma-Aldrich. Paraffin</p><p>oil and Span80 were purchased from Sigma-Aldrich. A mixture of</p><p>paraffin oil and Span80 was used as an oil matrix in the microfluidic</p><p>device. Nonchiral SSY liquid crystal mixtures were prepared using</p><p>deionized water (18.2 MΩ cm) to make a solution of known</p><p>concentration and phase (30% wt for SSY). For chiral mixtures, we</p><p>added 16% wt and 26% wt Trans-Hyp (dissolved in water) to 30% wt</p><p>SSY.</p><p>Microfluidic Device Fabrication and Experimental Setup.</p><p>The FF droplet generator was a glass-based device with an overall</p><p>dimension of about 2.5 × 5 cm2. For the fabrication of microchannels,</p><p>commercially available B-270 glasses, covered with a 450 nm thick</p><p>chromium layer (Telic), were used as solid substrates. Hydrochloric</p><p>acid (HCl), ammonium fluoride (NH4F), and hydrofluoric acid (HF)</p><p>were purchased from Sigma-Aldrich (Taufkirchen, Germany). The</p><p>resist AZ9260 and the AZ400k developer were purchased from</p><p>MicroChemicals (Ulm, Germany). The chromium etchant solution</p><p>was purchased from Sigma-Aldrich. Photomasks were designed using</p><p>CleWin software and printed by J. D. Photo-tools Ltd. (Oldham,</p><p>Lancashire, U.K.). Fluoropolymer tubings (Tub FEP Blu 1/32 ×</p><p>0.09) were purchased from IDEX Health & Science (Germany). The</p><p>microfluidic network reported in the scheme of Figure 1 was</p><p>patterned on a B-270 glass substrate via photolithography. After the</p><p>geometry transfer, the glass substrate was etched with buffered oxide</p><p>etchant (BOE) solution by using the microwave reactor system</p><p>(Anton Paar Multiwave 3000, Labservice Analytica s.r.l., Italy) as</p><p>reported in ref 26 for obtaining a channel depth of 100 μm.</p><p>Then, three holes were processed by using a microdriller (MICRO</p><p>miller MF70, Proxxon, Germany) in order to create two inlet ports</p><p>and one outlet port. The channel was then thermally bonded to a</p><p>glass top plate,62 and finally, capillary tubes were connected with the</p><p>inlet and outlet holes. After the fabrication, the internal walls of the</p><p>microchannels were functionalized with a hydrophobic coating. The</p><p>microchannels were filled with 1H,1H,2H,2H-perfluorooctyltriethox-</p><p>ysilane at a constant rate of 30 mL/min using a syringe pump (Ugo</p><p>Basile, Biological Research Apparatus, model KDS270). After</p><p>complete filling, the silane was incubated for 30 min and then</p><p>withdrawn at 150 mL/min. As the final step, the microchannel was</p><p>dried by pumping air. This procedure assures that the channel walls</p><p>are covered by the silane layer as reported in ref 63.</p><p>After functionalization, the device was used to produce the</p><p>microdroplets by injecting paraffin oil with Span80 (4% wt and 8%</p><p>wt) from the side channels and the aqueous solution of pure SSY (7%</p><p>wt and 30% wt) and chiral doped SSY 30% wt (chiral agent at 16% wt</p><p>and 26% wt) from the central inlet. The flow rates of continuous and</p><p>dispersed phases were controlled by two independent pumps (model</p><p>KDS270).</p><p>Images and videos were acquired by a NIKON mod. DS-5MC</p><p>camera with an 8 fps acquisition rate. After flowing through the</p><p>microfluidic</p><p>network, droplets were collected and analyzed on a</p><p>cleaned glass slab by an optical microscope (Nikon Eclipse Ti)</p><p>equipped with polarizers. The sizes of the droplet and image analysis</p><p>were performed through Nikon Eclipse software within the device</p><p>(Figures 2 and 3) and through ImageJ software for characterizations</p><p>out of the device (Figures 5−7).</p><p>Surface Functionalization and Contact Angle Measure-</p><p>ments. To assess the efficacy of the functionalization with the silane</p><p>in increasing the affinity of the oil phase for the device walls and</p><p>decreasing the affinity of the water phases, as well as to understand the</p><p>role of surfactant Span80 in the interactions between the oil phase and</p><p>the functionalized walls, some contact angle measurements have been</p><p>performed. For this purpose, B-270 glass substrates were treated with</p><p>the BOE solution and thermal process, by following the same</p><p>procedure used for the microfluidic device fabrication. To coat the</p><p>glass slice with a silane layer, a drop of 1H,1H,2H,2H-perfluorooctyl-</p><p>triethoxysilane was deposited on the substrates, incubated for 30 min,</p><p>and finally dried with nitrogen.64 After preparation, contact angle</p><p>(CA) measurements were acquired using the sessile drop method</p><p>with the CAM 200 instrument (KSV Instruments Ltd., Finland).</p><p>Several drops of paraffin, paraffin with Span80 (8% wt), and SSY in</p><p>Table 1. LCLCs Microdroplet Optical Textures Reported</p><p>for Each Droplet Dimension and Each Investigated Liquid</p><p>Crystal Solutiona</p><p>SSY 30%</p><p>SSY 30% + 16%</p><p>Trans-Hyp</p><p>SSY 30% + 26%</p><p>Trans-Hyp</p><p>bipolar structure,</p><p>BS</p><p>10−50 μm 10−20 μm ∼10 μm</p><p>RSS >45 μm 20 μm</p><p>DSS 50 μm 50−60 μm</p><p>Frank−Pryce 50 μm</p><p>aThe percentage of SSY and Tran-Hyp indicated in the figure are in</p><p>weight percentage (%wt).</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6138</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>water at 7% wt and 30% wt (isotropic and nematic phase) were</p><p>deposited onto different areas of bare and functionalized glass</p><p>substrates (Figure 8). The respective averages of the CA values are</p><p>reported in Table 2. The errors are calculated as standard deviations</p><p>from the average value.</p><p>The CA values on the clean and functionalized glass substrates</p><p>demonstrated that the glass walls of the device are covered by a silane</p><p>layer that enhances the surface hydrophobicity as shown by the water</p><p>contact angle measurements of the clean and functionalized glass</p><p>substrate, reported in Table 2. This fact increases the affinity of the oil</p><p>phase for the walls and decreases the affinity of both water-based</p><p>nematic (SSY 30% wt) and isotropic (SSY 7% wt) solutions. The</p><p>affinity of the paraffin oil for the functionalized walls is stronger,</p><p>implying that, when the Span80 surfactant is added, part of it is</p><p>involved in the walls/oil interaction and it is not available at the oil/</p><p>water interface of the droplets. Thus, a large amount of surfactant</p><p>must be added to compensate for the fraction subtracted by the wall/</p><p>oil interface; this can explain why the amount of surfactant we use is</p><p>double and quadruple, respectively, with respect to the typical</p><p>concentrations with a similar setup.45</p><p>■ ASSOCIATED CONTENT</p><p>*sı Supporting Information</p><p>The Supporting Information is available free of charge at</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275.</p><p>Droplets diameter as a function of the FFR. Topologies</p><p>observed in nematic and chiral chromonics (PDF)</p><p>■ AUTHOR INFORMATION</p><p>Corresponding Authors</p><p>Caterina Maria Tone − Physics Department, University of</p><p>Calabria, 87036 Arcavacata di Rende, CS, Italy; CNR-</p><p>Nanotec, c/o Physics Department, University of Calabria,</p><p>87036 Arcavacata di Rende, CS, Italy; orcid.org/0000-</p><p>0002-8340-5470; Email: caterina.tone@fis.unical.it</p><p>Alessandra Zizzari − CNR NANOTEC − Institute of</p><p>Nanotechnology, c/o Campus Ecotekne, University of Salento,</p><p>73100 Lecce, Italy; orcid.org/0000-0002-9651-7922;</p><p>Email: alessandra.zizzari@nanotec.cnr.it</p><p>Maria Penelope De Santo − Physics Department, University</p><p>of Calabria, 87036 Arcavacata di Rende, CS, Italy; CNR-</p><p>Nanotec, c/o Physics Department, University of Calabria,</p><p>87036 Arcavacata di Rende, CS, Italy; orcid.org/0000-</p><p>0001-6556-3611; Email: maria.desanto@fis.unical.it</p><p>Valentina Arima − CNR NANOTEC − Institute of</p><p>Nanotechnology, c/o Campus Ecotekne, University of Salento,</p><p>73100 Lecce, Italy; orcid.org/0000-0002-3429-8365;</p><p>Email: valentina.arima@nanotect.cnr.it</p><p>Authors</p><p>Lorenza Spina − Physics Department, University of Calabria,</p><p>87036 Arcavacata di Rende, CS, Italy; CNR-Nanotec, c/o</p><p>Physics Department, University of Calabria, 87036</p><p>Arcavacata di Rende, CS, Italy; orcid.org/0009-0007-</p><p>4194-121X</p><p>Monica Bianco − CNR NANOTEC − Institute of</p><p>Nanotechnology, c/o Campus Ecotekne, University of Salento,</p><p>73100 Lecce, Italy; orcid.org/0000-0002-1791-7232</p><p>Riccardo Cristoforo Barberi − Physics Department,</p><p>University of Calabria, 87036 Arcavacata di Rende, CS,</p><p>Italy; CNR-Nanotec, c/o Physics Department, University of</p><p>Calabria, 87036 Arcavacata di Rende, CS, Italy;</p><p>orcid.org/0000-0001-9713-1696</p><p>Federica Ciuchi − CNR-Nanotec, c/o Physics Department,</p><p>University of Calabria, 87036 Arcavacata di Rende, CS,</p><p>Italy; orcid.org/0000-0001-6898-7567</p><p>Complete contact information is available at:</p><p>https://pubs.acs.org/10.1021/acs.langmuir.3c00275</p><p>Author Contributions</p><p>M.P.D.S., F.C., and V.A. conceived the presented idea and</p><p>supervised the project. C.M.T., A.Z., and M.B. planned and</p><p>carried out the experiments. A.Z. and M.B. contributed to</p><p>microfluidic device preparation and carried out surface tension</p><p>experiments with V.A. C.M.T., A.Z., and M.B. analyzed the</p><p>data and wrote the original manuscript. L.S. helped in</p><p>analyzing and discussing the data. R.C.B. financially supported</p><p>the project. All of the authors read, contributed to the</p><p>interpretation of the results, and commented on the manu-</p><p>script.</p><p>Funding</p><p>The authors wish to acknowledge PON ARS01_00401</p><p>(DEMETRA), CUP B24I20000080001 for financial support.</p><p>M.P.D.S. and L.S. acknowledge INCOMARC Project (CUP</p><p>J51B19000340005). C.M.T. acknowledges PON “Attraction</p><p>and International Mobility” R&I 2014−2020, AIM 1875705-2,</p><p>CUP H24119000450005, for financial support. A.Z., M.B., and</p><p>V.A. acknowledge financial support from the Italian Ministry of</p><p>Economic Development through the Project “GENESI” −</p><p>Development of innovative radiopharmaceuticals and bio-</p><p>Figure 8. Contact angles of the different fluids on glass and</p><p>functionalized glass.</p><p>Table 2. Contact Angle (CA) Measurements of the Fluids</p><p>Used for the Microfluidic Droplet Generation on Bare and</p><p>Functionalized Glass Substratesa</p><p>fluid</p><p>CA on glass</p><p>(deg)</p><p>CA on functionalized glass</p><p>(deg)</p><p>paraffin oil 35.46 ± 2.04 15.31 ± 0.30</p><p>paraffin oil + Span80 8% 21.84 ± 0.35 10.40 ± 0.81</p><p>SSY 30% 13.79 ± 0.68 27.85 ± 0.66</p><p>SSY 7% 7.33 ± 01.54 24.26 ± 2.16</p><p>H2O 0 30.21 ± 0.65</p><p>aThe functionalization of the glass results in a higher CA for paraffin</p><p>oil and paraffin oil + Span80 8% wt, and a lower CA for SSY (30% wt</p><p>and 7% wt) and water. The percentage of Span80 and SSY in the table</p><p>are in weight.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6139</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?goto=supporting-info</p><p>https://pubs.acs.org/doi/suppl/10.1021/acs.langmuir.3c00275/suppl_file/la3c00275_si_001.pdf</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Caterina+Maria+Tone"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0002-8340-5470</p><p>https://orcid.org/0000-0002-8340-5470</p><p>mailto:caterina.tone@fis.unical.it</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Alessandra+Zizzari"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0002-9651-7922</p><p>mailto:alessandra.zizzari@nanotec.cnr.it</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Maria+Penelope+De+Santo"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0001-6556-3611</p><p>https://orcid.org/0000-0001-6556-3611</p><p>mailto:maria.desanto@fis.unical.it</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Valentina+Arima"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0002-3429-8365</p><p>mailto:valentina.arima@nanotect.cnr.it</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Lorenza+Spina"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0009-0007-4194-121X</p><p>https://orcid.org/0009-0007-4194-121X</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Monica+Bianco"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0002-1791-7232</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Riccardo+Cristoforo+Barberi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0001-9713-1696</p><p>https://orcid.org/0000-0001-9713-1696</p><p>https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Federica+Ciuchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdf</p><p>https://orcid.org/0000-0001-6898-7567</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig8&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig8&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig8&ref=pdf</p><p>https://pubs.acs.org/doi/10.1021/acs.langmuir.3c00275?fig=fig8&ref=pdf</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>markers for the diagnosis of tumors of the male and female</p><p>reproductive apparatus.</p><p>Notes</p><p>The authors declare no competing financial interest.</p><p>■ REFERENCES</p><p>(1) Poulin, P.; Stark, H.; Lubensky, T. C.; Weitz, D. A. Novel</p><p>Colloidal Interactions in Anisotropic Fluids. Science 1997, 275, 1770.</p><p>(2) Lopez-Leon, T.; Fernandez-Nieves, A. Drops and Shells of</p><p>Liquid Crystal. Colloid Polym. Sci. 2011, 289, 345−359.</p><p>(3) Sasaki, Y.; Jampani, V. S. R.; Tanaka, C.; Sakurai, N.; Sakane, S.;</p><p>Le, K. V.; Araoka, F.; Orihara, H. Large-scale self-organization of</p><p>reconfigurable topological defect networks in nematic liquid crystals.</p><p>Nat. Commun. 2016, 7, No. 13238.</p><p>(4) Sec,̌ D.; Copar, S.; Zumer, S. Topological zoo of free-standing</p><p>knots in confined chiral nematic fluids. Nat. Commun. 2014, 5,</p><p>No. 3057.</p><p>(5) Kim, Y.-K.; Wang, X.; Mondkar, P.; Bukusoglu, E.; Abbott, N. L.</p><p>Self-reporting and self-regulating liquid crystals. Nature 2018, 557,</p><p>539.</p><p>(6) Lydon, J. Chromonic Liquid Crystal Phases. Curr. Opin. Colloid</p><p>Interface Sci. 1998, 3, 458−466.</p><p>(7) Bouligand, Y.; Livolant, F. The organization of cholesteric</p><p>spherulites. J. Phys. 1984, 45, 1899−1923.</p><p>(8) Lydon, J. Chromonic review. J. Mater. Chem. 2010, 20, 10071.</p><p>(9) Lydon, J. Chromonic liquid crystalline phases. Liq. Cryst. 2011,</p><p>38, 1663.</p><p>(10) Zhou, S. Recent progresses in lyotropic chromonic liquid</p><p>crystal research: elasticity, viscosity, defect structures, and living liquid</p><p>crystals. Liq. Cryst. Today 2018, 27, 91.</p><p>(11) Lubensky, T. C. Confined chromonics and viral membranes.</p><p>Mol. Cryst. Liq. Cryst. 2017, 646, 235.</p><p>(12) Simon, K. A.; Sejwal, P.; Falcone, E. R.; Burton, E. A.; Yang, S.;</p><p>Prashar, D.; Bandyopadhyay, D.; Narasimhan, S. K.; Varghese, N.;</p><p>Gobalasingham, N. S.; Reese, J. B.; Luk, Y-Y. Noncovalent</p><p>Polymerization and Assembly in Water Promoted by Thermodynamic</p><p>Incompatibility. J. Phys. Chem. B 2010, 114, 10357.</p><p>(13) Shiyanovskii, S. V.; Lavrentovich, O. D.; Schneider, T.;</p><p>Ishikawa, T.; Smalyukh, I. I.; Woolverton, C. J.; Niehaus, G. D.;</p><p>Doane, K. J. Lyotropic Chromonic Liquid Crystals for Biological</p><p>Sensing Applications. Mol. Cryst. Liq. Cryst. 2005, 434, 259.</p><p>(14) Guo, F.; Mukhopadhyay, A.; Sheldon, B. W.; Hurt, R. H.</p><p>Vertically Aligned Graphene Layer Arrays from Chromonic Liquid</p><p>Crystal Precursors. Adv. Mater. 2011, 23, 508.</p><p>(15) Jeong, J.; Kang, L.; Davidson, Z. S.; Collings, P. J.; Lubensky, T.</p><p>C.; Yodh, A. G. Chiral Structures from Achiral Liquid Crystals in</p><p>Cylindrical Capillaries. Proc. Natl. Acad. Sci. U.S.A. 2015, 112,</p><p>E1837−E1844.</p><p>(16) Nayani, K.; Chang, R.; Fu, J.; Ellis, P. W.; Fernandez-Nieves,</p><p>A.; Park, J. O.; Srinivasarao, M. Spontaneous emergence of chirality in</p><p>achiral lyotropic chromonic liquid crystals confined to cylinders. Nat.</p><p>Commun. 2015, 6, No. 8067.</p><p>(17) Tortora, L.; Lavrentovich, O. D. Chiral Symmetry Breaking by</p><p>Spatial Confinement in Tactoidal Droplets of Lyotropic Chromonic</p><p>Liquid Crystals. Proc. Natl. Acad. Sci. U.S.A. 2011, 108, 5163−5168.</p><p>(18) Davidson, Z. S.; Kang, L.; Jeong, J.; Still, T.; Collings, P. J.;</p><p>Lubensky, T. C.; Yodh, A. G. Chiral structures and defects of</p><p>lyotropic chromonic liquid crystals induced by saddle-splay elasticity.</p><p>Phys. Rev. E 2015, 91, No. 050501.</p><p>(19) Nayani, K.; Fua, J.; Chang, R.; Park, J. O.; Srinivasarao, M.</p><p>Using chiral tactoids as optical probes to study the aggregation</p><p>behavior of chromonics. Proc. Natl. Acad. Sci. U.S.A. 2017, 15, 3827.</p><p>(20) Lagerwall, J. P. F.; Schütz, C.; Salajkova, M.; Noh, J.; Park, J.</p><p>H.; Scalia, G.; Bergström, L. Cellulose nanocrystal-based materials:</p><p>from liquid crystal self-assembly and glass formation to multifunc-</p><p>tional thin films. NPG Asia Mater. 2014, 6, No. e80.</p><p>(21) Lee, H.; Labes, M. M. Helical Twisting Power of Amino Acids</p><p>in a Nematic Lyophase. Mol. Cryst. Liq. Cryst. 1984, 108, 125.</p><p>(22) Shirai, T.; Shuai, M.; Nakamura, K.; Yamaguchi, A.; Naka, Y.;</p><p>Sasaki, T.; Clark, N. A.; Le, K. V. Chiral Lyotropic Chromonic Liquid</p><p>Crystals Composed of Disodium Cromoglycate Doped with Water-</p><p>Soluble Chiral Additives. Soft Matter 2018, 14, 1511−1516.</p><p>(23) Pellegrino, C.; De Santo, M. P.; Spina, L.; Ciuchi, F. Induced</p><p>chiral chromonics confined in micrometric droplets. Adv. Funct.</p><p>Mater. 2021, 31, No. 2010394.</p><p>(24) Spina, L.; De Santo, M. P.; Tone, C. M.; Pisani, M.; Vita, F.;</p><p>Barberi, R.; Ciuchi, F. Intercalation or external binding: How to</p><p>torque chromonic Sunset Yellow. J. Mol. Liq. 2022, 359, No. 119265.</p><p>(25) Capocefalo, A.; Quintiero, E.; Bianco, M.; Zizzari, A.; Gentilini,</p><p>S.; Conti, C.; Arima, V.; Viola, I.; Ghofraniha, N. Random Laser</p><p>Spectral Fingerprinting of Lithographed Microstructures. Adv. Mater.</p><p>Technol. 2021, 6, No. 2001037.</p><p>(26) Noh, J. H.; Liang, H-L.; Drevensek-Olenik, I.; Lagerwall, J. P. F.</p><p>Tuneable multicoloured patterns from photonic cross-communication</p><p>between cholesteric liquid crystal droplets. J. Mater. Chem. C 2014, 2,</p><p>806.</p><p>(27) Whitesides, G. M. The origins and the future of microfluidics.</p><p>Nature 2006, 442, 368.</p><p>(28) Zizzari, A.; Bianco, M.; Perrone, E.; Manera, M. G.; Cellamare,</p><p>S.; Ferorelli, S.; Purgatorio, R.; Scilimati, A.; Tolomeo, A.; Dimiccoli,</p><p>V.; Rella, R.; Arima, V. Microfluidic pervaporation of ethanol from</p><p>radiopharmaceutical formulations. Chem. Eng. Process. − Process</p><p>Intensif. 2019, 141, No. 107539.</p><p>(29) Zacheo, A.; Quarta, A.; Zizzari, A.; Monteduro, A. G.;</p><p>Maruccio, G.; Arima, V.; Gigli, G. One step preparation of quantum</p><p>dot-embedded lipid nanovesicles by a microfluidic device. RCS Adv.</p><p>2015, 5, 98576.</p><p>(30) Zizzari, A.; Arima, V.; Zacheo, A.; Pascali, G.; Salvadori, P. A.;</p><p>Perrone, E.; Mangiullo, D.; Rinaldi, R. Fabrication of SU-8</p><p>microreactors for radiopharmaceutical production. Microelectron.</p><p>Eng. 2011, 88, 1664.</p><p>(31) Liu, Y.; Cheng, Y.; Zhao, C.; Wang, H.; Zhao, Y. Nanomotor-</p><p>derived porous biomedical particles from droplet microfluidics. Adv.</p><p>Sci. 2022, 9, No. 2104272.</p><p>(32) Shang, L.; Cheng, Y.; Zhao, Y. J. Emerging Droplet</p><p>Microfluidics. Chem. Rev. 2017, 117, 7964.</p><p>(33) Wang, W.; Zhang, M. J.; Chu, L. Functional Polymeric</p><p>Microparticles Engineered from Controllable Microfluidic Emulsions.</p><p>Acc. Chem. Res. 2014, 47, 373.</p><p>(34) Shah, R. K.; Shum, H. C.; Rowat, A. C.; et al. Designer</p><p>Emulsions Using Microfluidics. Mater. Today 2008, 11, 18.</p><p>(35) Chu, L. Y.; Utada, A. S.; Shah, R. K.; Kim, J.-W.; Weitz, D. A.</p><p>Controllable Monodisperse Multiple Emulsions. Angew. Chem., Int.</p><p>Ed. 2007, 46, 8970.</p><p>(36) Teh, S-Y.; Lin, R.; Hung, L-H.; Lee, A. P. Droplet microfluidics.</p><p>Lab Chip 2008, 8, 198.</p><p>(37) Cai, Q.-W.; Ju, X.-J.; Zhang, S.-Y.; Chen, Z.-H.; Hu, J.-Q.;</p><p>Zhang, L.-P.; Xie, R.; Wang, W.; Liu, Z.; Chu, L.-Y. Controllable</p><p>Fabrication of Functional Microhelices with Droplet Microfluidics.</p><p>ACS Appl. Mater. Interfaces 2019, 11, 46241.</p><p>(38) Lathia, R.; Nampoothiri, K. N.; Sagar, N.; Bansal, S.; CD</p><p>Modak, C. D.; Sen, P. Advances in Microscale Droplet Generation</p><p>and Manipulation in Microscale Droplet Generation and Manipu-</p><p>lation. Langmuir 2023, 39, 2461−2482.</p><p>(39) Lee, H. G.; Munir, S.; Park, S. Y. Cholesteric Liquid Crystal</p><p>Droplets for Biosensors. ACS Appl. Mater. Interfaces 2016, 8, 26407−</p><p>26417.</p><p>(40) Chen, H.-Q.; Wang, X.-Y.; Bisoyi, H. K.; Chen, L.-J.; Li, Q.</p><p>Liquid Crystals in Curved Confined Geometries: Microfluidics Bring</p><p>New Capabilities for Photonic Applications and Beyond. Langmuir</p><p>2021, 37, 3789−3807.</p><p>(41) Sengupta, A.; Tkalec, U.; Bahr, C. A. Nematic textures in</p><p>microfluidics environment. Soft Matter 2011, 7, 6542.</p><p>(42) Sengupta, A.; Pieper, C.; Enderlein, J.; Bahra, C.; Herminghaus,</p><p>S. Flow of a nematogen past a cylindrical micro-pillar. Soft Matter</p><p>2013, 9, 1937.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6140</p><p>https://doi.org/10.1126/science.275.5307.1770</p><p>https://doi.org/10.1126/science.275.5307.1770</p><p>https://doi.org/10.1007/s00396-010-2367-7</p><p>https://doi.org/10.1007/s00396-010-2367-7</p><p>https://doi.org/10.1038/ncomms13238</p><p>https://doi.org/10.1038/ncomms13238</p><p>https://doi.org/10.1038/ncomms4057</p><p>https://doi.org/10.1038/ncomms4057</p><p>https://doi.org/10.1038/s41586-018-0098-y</p><p>https://doi.org/10.1016/S1359-0294(98)80019-8</p><p>https://doi.org/10.1051/jphys:0198400450120189900</p><p>https://doi.org/10.1051/jphys:0198400450120189900</p><p>https://doi.org/10.1039/b926374h</p><p>https://doi.org/10.1080/02678292.2011.614720</p><p>https://doi.org/10.1080/1358314X.2018.1570593</p><p>https://doi.org/10.1080/1358314X.2018.1570593</p><p>https://doi.org/10.1080/1358314X.2018.1570593</p><p>https://doi.org/10.1080/15421406.2017.1288010</p><p>https://doi.org/10.1021/jp103143x?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/jp103143x?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/jp103143x?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1080/15421400590957288</p><p>https://doi.org/10.1080/15421400590957288</p><p>https://doi.org/10.1002/adma.201003158</p><p>https://doi.org/10.1002/adma.201003158</p><p>https://doi.org/10.1073/pnas.1423220112</p><p>https://doi.org/10.1073/pnas.1423220112</p><p>https://doi.org/10.1038/ncomms9067</p><p>https://doi.org/10.1038/ncomms9067</p><p>https://doi.org/10.1073/pnas.1100087108</p><p>https://doi.org/10.1073/pnas.1100087108</p><p>https://doi.org/10.1073/pnas.1100087108</p><p>https://doi.org/10.1103/PhysRevE.91.050501</p><p>https://doi.org/10.1103/PhysRevE.91.050501</p><p>https://doi.org/10.1073/pnas.1614620114</p><p>https://doi.org/10.1073/pnas.1614620114</p><p>https://doi.org/10.1038/am.2013.69</p><p>https://doi.org/10.1038/am.2013.69</p><p>https://doi.org/10.1038/am.2013.69</p><p>https://doi.org/10.1080/00268948408072102</p><p>https://doi.org/10.1080/00268948408072102</p><p>https://doi.org/10.1039/C7SM02262J</p><p>https://doi.org/10.1039/C7SM02262J</p><p>https://doi.org/10.1039/C7SM02262J</p><p>https://doi.org/10.1002/adfm.202010394</p><p>https://doi.org/10.1002/adfm.202010394</p><p>https://doi.org/10.1016/j.molliq.2022.119265</p><p>https://doi.org/10.1016/j.molliq.2022.119265</p><p>https://doi.org/10.1002/admt.202001037</p><p>https://doi.org/10.1002/admt.202001037</p><p>https://doi.org/10.1039/C3TC32055C</p><p>https://doi.org/10.1039/C3TC32055C</p><p>https://doi.org/10.1038/nature05058</p><p>https://doi.org/10.1016/j.cep.2019.107539</p><p>https://doi.org/10.1016/j.cep.2019.107539</p><p>https://doi.org/10.1039/C5RA18862H</p><p>https://doi.org/10.1039/C5RA18862H</p><p>https://doi.org/10.1016/j.mee.2010.12.059</p><p>https://doi.org/10.1016/j.mee.2010.12.059</p><p>https://doi.org/10.1002/advs.202104272</p><p>https://doi.org/10.1002/advs.202104272</p><p>https://doi.org/10.1021/acs.chemrev.6b00848?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.chemrev.6b00848?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/ar4001263?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/ar4001263?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1016/S1369-7021(08)70053-1</p><p>https://doi.org/10.1016/S1369-7021(08)70053-1</p><p>https://doi.org/10.1002/anie.200701358</p><p>https://doi.org/10.1039/b715524g</p><p>https://doi.org/10.1021/acsami.9b17763?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acsami.9b17763?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.2c02905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.2c02905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.2c02905?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acsami.6b09624?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acsami.6b09624?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.1c00256?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.1c00256?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1039/c1sm05052d</p><p>https://doi.org/10.1039/c1sm05052d</p><p>https://doi.org/10.1039/C2SM27337C</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>(43) Sengupta, A. Topological microfluidics: present and prospects.</p><p>Liq. Cryst. Today 2015, 24, 70.</p><p>(44) Emersǐc,̌ T.; Zhang, R.; Kos, Z.; Čopar, S.; Osterman, N.; de</p><p>Pablo, J. J.; Tkalec, U. Sculpting stable structures in pure liquids. Sci.</p><p>Adv. 2019, 5, No. eaav4283.</p><p>(45) Li, Y.; Suen, J. J-Y.; Prince, E.; Larin, E. M.; Klinkova, A.;</p><p>Therien-Aubin, H.; Zuh, S.; Yang, B. M.; Helmy, A. S.; Lavrentovich,</p><p>O. D.; Kumacheva, E. Colloidal cholesteric liquid crystal in spherical</p><p>confinement. Nat. Commun. 2016, 7, No. 12520.</p><p>(46) Suzuki, T.; Li, Y.; Gevorkiana, A.; Kumacheva, E. Compound</p><p>droplets derived from a cholesteric suspension of cellulose nanocryst-</p><p>als. Soft Matter 2018, 14, 9713.</p><p>(47) Ignés-Mullol, J.; Mora, M.; Martínez-Prat, B.; Vélez-Cerón, I.;</p><p>Herrera, R. S.; Sagués, F. Stable and Metastable Patterns in</p><p>Chromonic Nematic Liquid Crystal Droplets Forced with Static and</p><p>Dynamic Magnetic Fields. Crystals 2020, 10, 138.</p><p>(48) Spina, L.; Ciuchi, F.; Tone, C. M.; Barberi, R.; De Santo, M. P.</p><p>Spherical Confinement of Chromonics: Effects of a Chiral Aminoacid.</p><p>Nanomaterials 2022, 12, 619.</p><p>(49) Milani, R.; Monogioudi, E.; Baldrighi, M.; Cavallo, G.; Arima,</p><p>V.; Marra, L.; Zizzari, A.; Rinaldi, R.; Linder, M.; Resnati, G.;</p><p>Metrangolo, P. Hydrophobin: fluorosurfactant-like properties without</p><p>fluorine. Soft Matter 2013, 9, 6505.</p><p>(50) Talebjedi, B.; Mehrizi, A. A.; Talebjedi, B.; Mohseni, S. S.;</p><p>Tasnim, N.; Hoorfar, M. Machine Learning-Aided Microdroplets</p><p>Breakup Characteristic Prediction in Flow-Focusing Microdevices by</p><p>Incorporating Variations of Cross-Flow Tilt Angles. Langmuir 2022,</p><p>38, 10465−10477.</p><p>(51) Dreyfus, R.; Tabeling, P.; Willaime, H. Ordered and Disordered</p><p>Patterns in Two-Phase Flows in Microchannels. Phys. Rev. Lett. 2003,</p><p>90, No. 144505.</p><p>(52) Yu, W.; Liu, X.; Zhao, Y.; Chen, Y. Droplet generation</p><p>hydrodynamics in the microfluidic cross-junction with different</p><p>junction angles. Chem. Eng. Sci. 2019, 203, 259.</p><p>(53) Nie, Z.; Seo, S.; Xu, S.; Lewis, P. C.; Mok, M.; Kumacheva, E.;</p><p>Whitesides, G. M.; Garstecki, P.; Stone, H. A. Emulsification in a</p><p>microfluidic flow-focusing device: effect of the viscosities of the</p><p>liquids. Microfluid. Nanofluid. 2008, 5, 585.</p><p>(54) Anna, S. L.; Bontoux, N.; Stone, H. A. Formation of dispersions</p><p>using “flow focusing” in microchannels. Appl. Phys. Lett. 2003, 82,</p><p>364.</p><p>(55) Edd, J. F.; Di Carlo, D.; Humphry, K. J.; Köster, S.; Irimia, D.;</p><p>Weitz, D. A.; Toner, M. Controlled encapsulation of single-cells into</p><p>monodisperse picolitre drops. Lab Chip 2008, 8, 1262.</p><p>(56) Rakszewska, A.; Tel, J.; Chokkalingam, V.; Huck, W. T. S. One</p><p>drop at a time: toward droplet microfluidics</p><p>as a versatile tool for</p><p>single-cell analysis. NPG Asia Mater. 2014, 6, No. e133.</p><p>(57) Vuong, S. M.; Anna, S. L. Tuning bubbly structures in</p><p>microchannels. Biomicrofluidics 2012, 6, No. 022004.</p><p>(58) Sengupta, A.; Herminghaus, S.; Bahr, C. Liquid crystal</p><p>microfluidics: surface, elastic and viscous interactions at microscales.</p><p>Liq. Cryst. Rev. 2014, 2, 73.</p><p>(59) Urbanski, M.; Reyes, C. G.; Noh, J. H.; Sharma, A.; Geng, Y.;</p><p>Jampani, V. S. R.; Lagerwall, J. P. Liquid Crystals in Micron-scale</p><p>Droplets, Shells and Fibers. J. Phys.: Condens. Matter 2017, 29,</p><p>No. 133003.</p><p>(60) Jeong, J.; Davidson, Z. S.; Collings, P. J.; Lubensky, T. C.;</p><p>Yodh, A. G. Chiral symmetry breaking and surface faceting in</p><p>chromonic liquid crystal droplets with giant elastic anisotropy. Proc.</p><p>Natl. Acad. Sci. U.S.A. 2014, 111, 1742.</p><p>(61) Sec,̌ D.; Porenta, T.; Ravnik, M.; Žumer, S. Geometrical</p><p>frustration of chiral ordering in cholesteric droplets. Soft Matter 2012,</p><p>8, 11982.</p><p>(62) Marra, L.; Fisullo, V.; Wiles, C.; Zizzari, A.; Watts, P.; Rinaldi,</p><p>R.; Arima, V. Sol−Gel Catalysts as an Efficient Tool for the Kumada-</p><p>Corriu Reaction in Continuous Flow. Sci. Adv. Mater. 2013, 5, 475.</p><p>(63) Arima, V.; Bianco, M.; Zacheo, A.; Zizzari, A.; Perrone, E.;</p><p>Marra, L.; Rinaldi, R. Fluoropolymers coatings on polydimethylsilox-</p><p>ane for retarding swelling in toluene. This Solid Films 2012, 520, 2293.</p><p>(64) Zacheo, A.; Arima, V.; Pascali, G.; Salvadori, P. A.; Zizzari, A.;</p><p>Perrone, E.; De Marco, L.; Gigli, G.; Rinaldi, R. Radioactivity</p><p>resistance evaluation of polymeric materials for application in</p><p>radiopharmaceutical production at microscale. Microfluid. Nanofluid.</p><p>2011, 11, 35.</p><p>Langmuir pubs.acs.org/Langmuir Article</p><p>https://doi.org/10.1021/acs.langmuir.3c00275</p><p>Langmuir 2023, 39, 6134−6141</p><p>6141</p><p>https://doi.org/10.1080/1358314X.2015.1039196</p><p>https://doi.org/10.1126/sciadv.aav4283</p><p>https://doi.org/10.1038/ncomms12520</p><p>https://doi.org/10.1038/ncomms12520</p><p>https://doi.org/10.1039/C8SM01716F</p><p>https://doi.org/10.1039/C8SM01716F</p><p>https://doi.org/10.1039/C8SM01716F</p><p>https://doi.org/10.3390/cryst10020138</p><p>https://doi.org/10.3390/cryst10020138</p><p>https://doi.org/10.3390/cryst10020138</p><p>https://doi.org/10.3390/nano12040619</p><p>https://doi.org/10.1039/c3sm51262b</p><p>https://doi.org/10.1039/c3sm51262b</p><p>https://doi.org/10.1021/acs.langmuir.2c01255?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.2c01255?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1021/acs.langmuir.2c01255?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p><p>https://doi.org/10.1103/PhysRevLett.90.144505</p><p>https://doi.org/10.1103/PhysRevLett.90.144505</p><p>https://doi.org/10.1016/j.ces.2019.03.082</p><p>https://doi.org/10.1016/j.ces.2019.03.082</p><p>https://doi.org/10.1016/j.ces.2019.03.082</p><p>https://doi.org/10.1007/s10404-008-0271-y</p><p>https://doi.org/10.1007/s10404-008-0271-y</p><p>https://doi.org/10.1007/s10404-008-0271-y</p><p>https://doi.org/10.1063/1.1537519</p><p>https://doi.org/10.1063/1.1537519</p><p>https://doi.org/10.1039/b805456h</p><p>https://doi.org/10.1039/b805456h</p><p>https://doi.org/10.1038/am.2014.86</p><p>https://doi.org/10.1038/am.2014.86</p><p>https://doi.org/10.1038/am.2014.86</p><p>https://doi.org/10.1063/1.3693605</p><p>https://doi.org/10.1063/1.3693605</p><p>https://doi.org/10.1080/21680396.2014.963716</p><p>https://doi.org/10.1080/21680396.2014.963716</p><p>https://doi.org/10.1088/1361-648X/aa5706</p><p>https://doi.org/10.1088/1361-648X/aa5706</p><p>https://doi.org/10.1073/pnas.1315121111</p><p>https://doi.org/10.1073/pnas.1315121111</p><p>https://doi.org/10.1039/c2sm27048j</p><p>https://doi.org/10.1039/c2sm27048j</p><p>https://doi.org/10.1166/sam.2013.1477</p><p>https://doi.org/10.1166/sam.2013.1477</p><p>https://doi.org/10.1016/j.tsf.2011.09.063</p><p>https://doi.org/10.1016/j.tsf.2011.09.063</p><p>https://doi.org/10.1007/s10404-011-0770-0</p><p>https://doi.org/10.1007/s10404-011-0770-0</p><p>https://doi.org/10.1007/s10404-011-0770-0</p><p>pubs.acs.org/Langmuir?ref=pdf</p><p>https://doi.org/10.1021/acs.langmuir.3c00275?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as</p>