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Curcumin loaded biocompatible polymer embedded silver nanoparticles: A 
photophysical study on new photosensitizer composite
Lakshmi Thambi a,b, Saranya Cheriyathennatt a,b, Susithra Selvam c,*, Elango Kandasamy a,b,*
a Department of Chemistry, Amrita School of Physical Sciences, Coimbatore, Amrita Vishwa Vidyapeetham, India
b Functional Materials Laboratory, Amrita School of Engineering, Coimbatore, Amrita Vishwa Vidyapeetham, India
c Department of Chemistry, Ethiraj College For Women, Ethiraj Salai, Egmore, Chennai, Tamil Nadu, India
A R T I C L E I N F O
Keywords:
Curcumin
Silver nanoparticles
Polyvinylpyrrolidone
Polyethylene glycol
Photosensitizer
A B S T R A C T
Drug delivery is a process that involves effective therapeutic delivery of drugs that we usually use in medical 
treatments like Photodynamic therapy (PDT) as adopted for cancer treatment. Polyphenyl curcumin (CUR) is one 
of the major ingredients of rhizome of turmeric. CUR is a photosensitizer molecule whose photosensitizing 
properties can be enhanced by associating it with pharmaceutical excipients like Polyvinyl pyrrolidone (PVP) 
and Polyethylene glycol (PEG). Nanoparticles have been widely used in various fields of research due to their 
unique properties. Silver nanoparticles (AgNPs) are found to have anti-proliferative properties that may increase 
the ease of drug delivery at the site of physiological action when associated with the drug molecule. The asso-
ciation of CUR with AgNP can be probable photosensitizer system, which can be used in PDT and PDD. In the 
current work, the fluorescence property of CUR was used to evaluate the AgNP-embedded CUR. The effect of PVP 
and PEG on AgNP–CUR was analyzed through photophysical studies. The results showed that there is an effective 
the solubilization and bioavailability of CUR is improvised by using PVP and PEG as well as in mixed polymer 
system. The observed fluorescence quenching in the presence of AgNPs indicates a strong interaction between 
CUR consequently reduces the CUR fluorescence. Dynamic light scattering (DLS) analysis revealed that the Z- 
average of AgNPs was 39.12 nm, which increased to 49.50 nm upon CUR addition. Zeta potential measurements 
showed a reduction from -32.38 mV (AgNPs) to -23.10 mV (CUR-AgNPs), indicating strong CUR–AgNP 
interaction.
1. Introduction
Curcumin (CUR) is the major constituent of the rhizome of turmeric 
plant, a major cooking ingredient in the Asian sub-continent. The 
polyphenol CUR is responsible for its intense yellow colour [1]. It is one 
of the major constituents of traditional Indian medicine due to its 
anti-bacterial, anti-viral, and anti-oxidative properties [2,3]. CUR is 
under great focus of pharmaceutical and biomedical research areas due 
to these special properties and numerous articles have been reported of 
its effects and it a natural dye with potential applications [4]. CUR is 
widely used as a fluorescent probe in bio-imaging, high-sensitivity 
sensing, drug delivery, and in other biomedical applications [4–7]. It 
possesses pleiotropic properties which enables to target DNA, RNA, and 
proteins within cells [8]. Apart from all these properties, CUR is a 
photosensitizer that has the ability to absorb light and transfer the en-
ergy to a substrate molecule. It can induce Type II photosensitization 
process by generation of Reactive Oxygen Species (ROS) [9]. This type of 
photosensitization is majorly used in photodynamic therapy (PDT). 
Evidences have shown that CUR efficiently sensitizes tumor cells to 
first-line chemotherapies and radiation [10]. It suppresses the expres-
sion of epidermal growth receptor and estrogen receptors, which are 
cancer-associated growth factors [8]. The major drawback of CUR 
molecule is its very low bioavailability after oral application which is 
caused by poor solubility in aqueous media [11]. It is rapidly metabo-
lized within intestine detected by nanomolar concentrations of CUR in 
the blood of humans after the application of the large dose [12]. Hence 
there is a clear need of increasing the bioavailability of this drug 
molecule.
Pharmaceutical excipients like Polyvinyl pyrrolidone (PVP) and 
Polyethylene glycol (PEG) are widely used as drug delivery media by 
participating in the solubilization of drugs [13]. These are 
bio-compatible polymers that are extensively used in pharmaceutical 
* Corresponding authors.
E-mail addresses: susithra.selvam@yahoo.com (S. Selvam), k_elango@cb.amrita.edu (E. Kandasamy). 
Contents lists available at ScienceDirect
Chemical Physics Impact
journal homepage: www.sciencedirect.com/journal/chemical-physics-impact
https://doi.org/10.1016/j.chphi.2025.100929
Received 4 June 2025; Received in revised form 4 August 2025; Accepted 6 August 2025 
Chemical Physics Impact 11 (2025) 100929 
Available online 8 August 2025 
2667-0224/© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by- 
nc-nd/4.0/ ). 
https://orcid.org/0000-0002-3120-3586
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areas as co-solvents of tablets, stabilizers, co-precipitating agents of 
insoluble drugs, detoxicant of drugs and lubricants, etc [14–18]. They 
have various industrial applications, such as gelling agents for suspen-
sion polymerization, stabilizer, and fiber treating agents, paper pro-
cessing aids, adhesives, and thickening agents [19]. PVP has strong 
hydrophilicity, through which molecular adducts with many com-
pounds can be formed [20]. The presence of carboxyl group in the repeat 
unit of the polymer will increase water solubility, stability and 
bioavailability of a drug. PVP is an amorphous polymer which has a rigid 
pyrrolidone moiety and hence possesses a high glass transition tem-
perature [21] PEG was also found to remarkably increase the dissolution 
rate of insoluble drugs and hence are used as drug delivery systems 
[22–24].
The surface chemistry of nanoparticles allows it to get utilized 
heavily in various fields of science [25]. Among them the silver nano-
particles (AgNPs) have higher photodynamic efficiency, exceptional 
anti-bacterial and anti-viral properties and better biocompatibility [26,
27]. The interaction between biomolecules and nanoparticles have 
gained large attention in the field of fluorescence, surface-enhanced 
raman spectroscopy, chemical and biological sensing and other optical 
applications [28]. The anti-proliferative properties of AgNPs can in-
crease the ease of drug delivery at the site of physiological action. AgNPs 
when used along with chemotherapeutic agents was found to signifi-
cantly decline the cell viability [27,29]. Synthesis of AgNPs is carried 
out using citrate reduction method and concentration studies are carried 
out using absorption and fluorescence spectroscopy.
This research work focuses mainly on increasing the bioavailability 
of curcumin by incorporating biocompatible polymers and effectively 
increase its solubilization in aqueous media. This study is followed by 
the incorporation of AgNPs to study its interaction with curcumin 
thereby exploring its adaptability towards PDT through photophysical 
studies.
2. Materials and methods
2.1. Materials
CUR was purchased from Loba Chemie Private Limited. Silver nitrate 
was purchased from Emparta ACS, Merck Life Science PVT.LTD, India, 
and AgNps were synthesized using tri-sodium citrate and ascorbic acid 
which were purchased from SD Fine Chemicals Limited, India. PVP and 
PEG were purchasedfrom SRL Group, India. Ethanol was purchased 
from Changshu Hongsheng Co., Ltd, China. Without additional purifi-
cation, the chemicals were used. Solutions were prepared with millipore 
water.
2.2. Instrumentation and Methods
UV – visible spectra were measured using a Shimadzu 1900 Double 
beam Spectrophotometer. Fluorescence spectra were measured by the 
Agilent Cary Eclipse Fluorescence Spectrophotometer. Excitation and 
emission slit bandwidth was 5 nm. The fluorescence excitation for CUR 
was set at a wavelength of 425 nm.
2.3. Procedure for the synthesis of AgNPs
Required quantity of silver nitrate was accurately weighed and made 
up to 10 mL solution in distilled water to prepare 0.1 M solution. An 
aqueous solution containing 0.6 mM ascorbic acid and 3 mM trisodium 
citrate was prepared by taking appropriate amount and made up to 100 
mL in distilled water. To a clean beaker, 20 mL of this mixture was added 
and maintained at pH 10 by adding few drops of 0.1 M NaOH solution 
dropwise. The solution was kept for stirring on a hot plate at 90 ◦C and 
0.2 mL of silver nitrate solution was added dropwise slowly. The colour 
changes from yellow to brown during the addition of silver nitrate and 
after 15 minutes, no further colour change was observed, indicating that 
the reaction is complete [30]. The solution is cooled and used later for 
performing the experiments. The synthesized AgNPs are characterized 
by DLS and zeta potential measurements.
2.4. Preparation of sample solutions
CUR- polymer solutions, The stock solution of CUR was prepared in 
ethanol and diluted to various concentrations by serial dilution method 
using water. Stock solutions of PVP and PEG were prepared in water. 
Different concentration of PVP and PEG (0.4 % to 3.6 % w/v) was added 
to CUR solution. Sample solutions were incubated for minimum of 2 
hours prior to the experiments.
CUR- AgNP solutions, Required concentration of the CUR was pre-
pared from the stock solution by dilution and its concentration was 
maintained constant. Synthesized AgNP solution at various concentra-
tions was introduced to the CUR solution. Before the studies, sample 
solutions were incubated for at least two hours.
CUR- polymer-AgNp solutions, Stock solution of CUR was prepared 
using ethanol. To this, PEG and PVP were added. Freshly prepared AgNP 
solution was added to the pre-formed CUR – PVP, CUR – PEG and CUR – 
PVP – PEG systems. Prior to the studies, sample solutions were incubated 
for a minimum of two hours
Fig. 1. Fluorescence spectra of CUR in different concentrations of polymers (a) CUR- PVP (b) CUR-PEG.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
2 
3. Results and discussion
3.1. Interaction of CUR with polymers
The absorption spectra of CUR at varying concentrations of PVP and 
PEG, with excitation wavelengths of 425 nm for CUR in water, 
approximately 443 nm for the CUR-PVP system, and 428 nm for the 
CUR-PEG system, are shown in Figs. S1 (a) and (b). The corresponding 
fluorescence emission spectra of the CUR-polymer systems are presented 
in Fig. 1.
A gradual increase in fluorescence intensity is observed with 
increasing concentrations of both PVP and PEG. This enhancement in 
fluorescence intensity suggests a likely interaction between CUR and the 
polymers, indicating improved solubilization of CUR within the polymer 
matrices. The plots of variation of fluorescence intensity of CUR in both 
PVP and PEG shown in Figs. 2 (a) and (b), reflecting the observations 
obtained from Fig. 2 (a) and (b).
A plot showing the variation in emission wavelength with increasing 
Fig. 2. Plot of Variation of fluorescence intensity with increase in concentration of (a) PVP (b) PEG and plot of variation of emission wavelength of CUR with increase 
in concentration of (c) PVP (d) PEG.
Fig. 3. (a) Emission spectra of Ternary system 1 (b) Emission spectra of Ternary system 2.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
3 
polymer concentration (Fig. 2 (c) and (d)) reveals that the fluorescence 
emission maximum of CUR in water is centered at 550 nm, which un-
dergoes a hypsochromic shift to the range of 530-540 nm upon addition 
of polymers. In its neutral form, CUR exists predominantly in the enol 
tautomeric form, which contributes to increased molecular rigidity. In 
aqueous solution, and in the absence of polymers, CUR is believed to 
exhibit restricted molecular rotation due to its rigid, rod-like structure. 
The addition of polymers facilitates interactions between CUR and the 
hydrophobic regions of the polymer chains, promoting more efficient 
molecular excitation. This interaction likely results in enhanced solu-
bilization and stabilization of CUR within the polymeric medium, 
leading to an increase in fluorescence intensity with rising polymer 
concentration. PVP and PEG, owing to their solubilizing and stabilizing 
capabilities, are widely used as pharmaceutical excipients, especially for 
improving the bioavailability of bulky, hydrophobic drug molecules 
such as CUR. When comparing the effects of PVP and PEG on the fluo-
rescence properties of CUR, PVP exhibits a slightly higher fluorescence 
intensity and better-defined spectral characteristics. This can be attrib-
uted to potential ability of PVP to form hydrogen bonds and encapsulate 
hydrophobic molecules like CUR more efficiently and leads to formation 
of molecular adducts, resulting in a higher degree of compatibility and 
interaction with CUR.
Fig. 4. Plot of variation (a) fluorescence intensity and (b) emission wavelength of CUR-PVP with increasing concentration of PEG. Plot of variation (a) fluorescence 
intensity and (b) emission wavelength of CUR-PEG with increasing concentration of PVP. (e) Schematic diagram of interaction of CUR with PVP and PEG.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
4 
3.2. Mixed polymer system with CUR
Other than PVP and PEG interaction individually with CUR, a mixed 
polymer system is prepared to create a ternary system with CUR to study 
their interactions. A constant concentration of CUR is made to react with 
mixed polymers in which one of the polymer concentrations is kept 
constant and the other is varied.
The absorption spectra (fig. S2) and fluorescence emission spectra 
(Fig. 3) are recorded for the ternary system at increasing concentration.
In the first ternary system, the excitation of CUR occurs at 443 nm in 
the presence of polymers, while in the second ternary system it is 
observed at 442 nm. For comparison, the excitation wavelength of CUR 
was maintained at 425 nm, consistent with the previous polymer-based 
study. From the fluorescence emission spectra of both systems, the 
emission wavelength is observed in the range of 530–540 nm, showing a 
slight blue shift relative to the native emission of CUR at 550 nm. A 
similar trend is observed in the single-polymer systems, with nearly 
identical fluorescence intensities and emission wavelengths. In both 
cases, the presence of polymers leads to effective solubilization of CUR, 
addressing its inherent limitation of poor aqueous solubility in drug 
delivery applications. Therefore, both PVP and PEG demonstrate strong 
potential as pharmaceutical excipients for formulating hydrophobic 
drug molecules like CUR.
As the concentration of PVPincreases, the fluorescence intensity of 
CUR-PVP-PEG system also increases (Fig. 4 (a)). But the emission 
wavelength decreases with increasing polymer concentration ((Fig. 4
(c)). The same trend is followed by PEG also (Fig. 4 (b) and ((Fig. 4 (d)). 
The probable association of CUR with PVP and PEG is shown in Fig. 4
(e). PVP usually forms molecular adducts with different molecules. The 
molecular complex of CUR-PVP is assumed to have intercalated with the 
alkyl chains of PEG. This kind of association might have increased the 
rate of excitation of CUR molecules which was showed up as an increase 
in fluorescence intensity in the emission spectra.
3.3. CUR-AgNP studies
The synthesis of AgNPs is carried out using ascorbic acid reduction 
method. A colour change from colourless to yellow and then changes to 
Fig. 5. (a) Absorption spectra and (b) emission spectra of CUR-AgNP. Plot of variation of (c) fluorescence intensity and (d) emission wavelength against increasing 
AgNP concentration. (e) Schematic diagram of interaction of CUR with AgNP.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
5 
reddish brown indicates the formation of nanoparticles. The formation is 
further confirmed by UV spectra. Fig. S3 represents the UV spectra of 
AgNPs in water. A broad peak is obtained at 404 nm. This broad peak is 
the SPR band corresponding to the AgNPs [31]. This peak arises from the 
interaction of the conduction electrons within the AgNPs with the 
incoming radiation [32].
3.3.1. Interaction of CUR with AgNPs
The interaction of synthesized AgNPs with CUR was studied. In this 
study, different concentration of AgNPs were made to interact with 
constant concentration of the probe in ethanolic medium. Fig. 5 illus-
trates the absorption and fluorescence spectra of CUR in ethanolic so-
lutions of AgNP.
The absorption wavelength of CUR in 4 % AgNP is 422 nm and the 
fluorescence emission spectra of CUR show a quenching in fluorescence 
with increasing concentration of AgNPs i.e., the fluorescence intensity 
decreases with increasing AgNP concentration. That means the AgNPs 
interact with CUR in such a way that the excitations of CUR molecules 
are restricted, which will eventually reduce the occurrence of emission. 
The association of nanoparticles with CUR was found to increase its 
photostability and biomedical applicability [33]. Compared to conven-
tional nanoparticles, AgNPs in presence of CUR shows higher photody-
namic efficiency, selective toxicity, anti-bacterial and anti-biofilm 
activity [34,35]. The π-π* transition in the molecule is responsible for 
the strong absorption of CUR between 410-430 nm. In the fluorescence 
emission spectra, there is a minor blue shift when we add AgNP into this 
system which indicates that there is a change in the microenvironment 
of CUR [35]. This strong interaction of CUR with AgNPs has reduced its 
excitations and hence the emission that is showed up as a decrease in 
intensity (Fig. 5 (c)). Fig. 5 (d) shows as the concentration of AgNP 
increases, emission wavelength decreases. From the concentration 
versus fluorescence intensity plots, we get a better understanding of 
their variation. The quenching of fluorescence is dominating with 
increasing concentration of AgNPs in CUR. Similarly, emission wave-
length undergoes a blue shift with increasing concentration of AgNPs 
which indicates a change in microenvironment of CUR in the presence of 
AgNPs. Rather than a self-aggregation of the AgNPs, these behaviors 
indicate a strong physical interaction between CUR and the nano-
particles [30]. This suggests that CUR is getting absorbed onto the 
nanoparticle surface which will be a very strong interaction (Fig. 5 (e)).
3.3.2. Interaction of CUR with AgNPs in ethanol-water mixture
Apart from studying the interaction of CUR and AgNPs in water, we 
studied the effect of varying ethanol-water mixture keeping concentra-
tion of AgNPs as constant. Fig. 6 (a) and (b) show the absorption and 
emission spectra of CUR-AgNP in ethanol-water mixture respectively. 
The excitation wavelength (λex) of CUR in ethanol is 425 nm and shifts to 
a higher wavelength with increasing percentage of water. The absor-
bance of CUR in AgNPs decreases with increasing concentration of 
water. The absorption spectra show isosbestic points which indicates the 
existence of two or more species of CUR - AgNP in equilibrium. The 
strong absorption between 420-430 nm is due to the π-π* transitions. 
Here, the enol form of CUR is predominant which is found to be more 
stable than the keto form in normal conditions. According to the liter-
ature, a weak absorption band is shown by CUR around 260-280 nm also 
due to π-π* transition. Apart from that there is a slight transition around 
360-380 nm due to n-π* transition where the keto form undergoes 
tautomerism. The enolic form is mainly responsible for the spectral 
absorption of CUR [31].
The decreasing intensity in a water-rich medium is due to the 
Fig. 6. (a) Absorption spectra and (b) Emission spectra of CUR-AgNP-EtOH-Water. Plot of variation of (c) fluorescence intensity and (d) emission wavelength against 
increasing concentration of water.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
6 
formation of self-aggregates of CUR. The enolic form is more predomi-
nant in ethanol-rich solution, which exists in monomeric form and 
shows higher emission intensity. Hence the isosbestic point around 320- 
370 nm is assumed to be the predominant keto form in water-rich media 
where it is more stabilized by water. The isosbestic points beyond 470 
nm are due to the non-emitting self-aggregates of CUR due to the pres-
ence of water. The zeta potential values indicate that there is a strong 
interaction between CUR and AgNPs which is probably CUR getting 
absorbed onto the nanoparticle surface, because of which the zeta po-
tential values are decreasing in the presence of CUR. There is also a 
possibility of the presence of dimers in equilibrium with various 
aggregative species [35]. The plots for concentration of CUR - AgNP vs 
fluorescence intensity and emission wavelength show the variation of 
concentration of water with them. The intensity of fluorescence emis-
sion has decreased with increasing water in the solution. But there is a 
bathochromic shift in emission wavelength when the solution is 
becoming more water rich. The wavelength shifts to longer wavelengths 
as water concentration increases (Figs. 6 (c) and (d)).
3.4. Characterization of CUR - AgNPs using DLS and Zeta potential 
measurements
The DLS and zeta potential measurements of the synthesized AgNPs 
are carried out to obtain the particle size, polydispersity index, and 
stability of the colloidal system (Fig S4 – S7). From the DLS measure-
ments of AgNPs, the average diameter (Z-average) of the colloidal par-
ticles was found to be 39.12 nm and from the zeta potential 
measurements of AgNPs, it was found to be -32.38 mV. The citrate- 
reduced AgNPs usually have zeta potential values in the range -33±5 
mV for stabilized colloids in 6-8 pH range [36]. The Z-average of 
CUR-AgNP has increased to 49.50 nm. The polydispersity index is 0.354 
and that of AgNPs was 0.468. the zeta potential of CUR-AgNP solution 
has reduced to -23.1 which is much lesser than that of AgNPs, which 
means there is a strong interaction occuring between CUR and AgNPs 
[S1].
3.5. CUR-AgNP-polymer studies
The interaction of CUR with AgNPs was studied. A ternary system is 
prepared by adding the biocompatible polymer solution intothe CUR- 
AgNPs system. The absorption and fluorescence studies are carried out 
at varying concentrations of PVP and PEG (Fig 7 (a), (b) (c) and (d)).
The excitation wavelengths of all the concentrations of the polymers 
lies in between 425-435 nm. Fig. 7 (b) shows the emission spectra of 
CUR in AgNPs and varying concentrations of PVP solution. Unlike CUR 
in absence of AgNPs, the fluorescence intensity is decreasing with 
increasing concentration of polymer in constant concentration of the 
AgNPs. Without AgNPs, the intensity was increasing with the increasing 
concentration of polymers. This is due to the quenching effect of AgNPs 
that leads to the decrease in emission intensity of CUR. In case of PEG the 
same trend is being observed with a minor blue shift in the presence of 
polymer as shown in Fig. 7 (d). The emission wavelengths in the case of 
both PVP and PEG are around 530 nm with a minor blue shift in 
emission.
3.5.1. Mixed polymer system with CUR-AgNP
Apart from PVP and PEG alone, a mixed polymer system study was 
also carried out at varying concentrations of the polymers. In the first 
study, PVP concentration is kept constant and PEG concentration is 
varied and vice versa (Fig. 8 (a), (b), (c) and (d)). Absorption spectra of 
CUR in AgNP system with varying concentrations of both polymers are 
provided in Fig. 8 (a) and (c).
The excitation wavelengths were also between 425-435 nm range for 
all the concentrations. The emission wavelengths of both the ternary 
Fig. 7. (a) Absorption spectra and (b) Emission spectra of CUR-AgNP-PVP. (c) Absorption spectra and (d) Emission spectra of CUR-AgNP-PEG.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
7 
system in the presence of polymers is about 530 nm. In both the mixed 
polymer systems, the intensity was decreasing with increasing polymer 
concentration similar to single polymer systems (Fig. 8 (c)). But 
compared to the single polymer system, the decrease is found to be very 
less and the peaks are closely spaced after the addition of polymers to the 
CUR-AgNP system where AgNP concentration is constant. A gradual 
decrease is not seen in this case. A plot of emission wavelength against 
increasing PEG concentration and PVP concentration is given in Fig. 8
(d). The pre-formulation study of CUR is carried out using biocompatible 
polymers, PVP and PEG. The data obtained indicated that there is an 
increase in solubilization of CUR in presence of the polymers. AgNPs 
were synthesized using ascorbic acid reduction method. The formation 
of AgNPs was confirmed by UV-visible spectra that exhibited a broad 
absorption peak at 404 nm. The CUR-AgNP studies were carried out 
using fluorescence spectroscopy at varying concentrations of AgNPs. 
The study indicated a strong interaction between CUR and AgNPs 
resulting from the quenching of fluorescence intensity. At constant 
composition of AgNPs, varying concentration of water was added, which 
resulted in more than one isosbestic points. Varying concentrations of 
polymers separately and mixed systems were added to the CUR-AgNP 
system, which resulted in a decrease in fluorescence intensity due to 
the quenching effect of AgNPs.
4. Conclusion
The hydrophobic molecule CUR possesses a disadvantage of low 
solubility in physiological conditions, when it is used as a drug molecule. 
Among different kinds of solubilizers used for CUR, biocompatible 
polymers like PVP and PEG have proved to increase the solubility and 
bioavailability of CUR to a great extent. UV-Visible and fluorescence 
spectroscopic studies were used to assess the increase in solubilization of 
CUR in presence of the polymers. CUR forms a molecular adduct with 
PVP, while PEG intercalates within this complex. This interaction is 
attributed to a combination of hydrophobic interactions, hydrogen 
bonding, and possible encapsulation within the polymeric matrix. 
Chemically synthesized AgNPs were incorporated with CUR system, 
both in presence and absence of the polymer. The fluorescence studies 
through quenching of intensity of CUR in presence of AgNPs reveal that 
the CUR is embedded onto the surface of AgNP. When polymers were 
added to the CUR-AgNP system, quenching of fluorescence was again 
observed. The DLS data also suggest that CUR is embedded onto the 
AgNP surface. Zeta potential measurements confirmed improved 
colloidal stability of CUR-AgNP system. This study exhibits a model 
photosensitizer composite containing CUR - AgNPs, which can have 
appreciable photodynamic efficiency and anti-proliferative properties, 
CUR was found to show better photostability and efficiency in the 
presence of AgNPs. The CUR-embedded AgNPs system were further 
stabilized by the incorporation of biocompatible polymers, resulting 
photosensitizer composite that serves as a potential model for CUR drug 
delivery. The polymers provided steric stabilization and enhanced 
biocompatibility by forming a hydrophilic barrier around the 
CUR–AgNP complex, effectively reducing aggregation and minimizing 
opsonization. This protective layer increases the circulation time of the 
composite in the bloodstream, thereby improving its likelihood of 
reaching target tissues. Overall, this study presents a promising model 
photosensitizer composite with enhanced solubility, stability, and 
Fig. 8. (a) Absorption spectra and (b) Emission spectra of CUR-AgNP-PVP-PEG. (c) Absorption spectra and (d) Emission spectra of CUR-AgNP-PEG-PVP.
L. Thambi et al. Chemical Physics Impact 11 (2025) 100929 
8 
potential biomedical applicability.
CRediT authorship contribution statement
Lakshmi Thambi: Writing – original draft, Methodology, Investi-
gation, Formal analysis, Data curation. Saranya Cheriyathennatt: 
Writing – original draft, Methodology, Investigation, Formal analysis, 
Data curation. Susithra Selvam: Writing – review & editing, Validation, 
Supervision, Methodology, Investigation, Conceptualization. Elango 
Kandasamy: Writing – review & editing, Validation, Supervision, 
Methodology, Investigation, Conceptualization.
Declaration of competing interest
The authors declare that they have no known competing financial 
interests or personal relationships that could have appeared to influence 
the work reported in this paper
Ethical approval
The research article does not contain any animal / human studies. 
Hence no ethical approval is required.
Funding
The authors did not receive support from any organization for the 
submitted work.
Acknowledgments
The authors gratefully acknowledge Prof. T. G. Satheesh Babu and 
the Biosensor Research Laboratory at Amrita Vishwa Vidyapeetham, 
Coimbatore, India, for providing access to the fluorescence spectrometer 
used in the fluorescence studies.
Supplementary materials
Supplementary material associated with this article can be found, in 
the online version, at doi:10.1016/j.chphi.2025.100929.
Data availability
All data generated or analysed during this study are included in this 
published article [and its supplementary information files].
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	Curcumin loaded biocompatible polymer embedded silver nanoparticles: A photophysical study on new photosensitizer composite
	1 Introduction
	2 Materials and methods
	2.1 Materials
	2.2 Instrumentation and Methods
	2.3 Procedure for the synthesis of AgNPs
	2.4 Preparation of sample solutions
	3 Results and discussion
	3.1 Interaction of CUR with polymers
	3.2 Mixed polymer system with CUR
	3.3 CUR-AgNP studies
	3.3.1 Interaction of CUR with AgNPs
	3.3.2 Interaction of CUR with AgNPs in ethanol-water mixture
	3.4 Characterization of CUR - AgNPs using DLS and Zeta potential measurements
	3.5 CUR-AgNP-polymer studies
	3.5.1 Mixed polymer system with CUR-AgNP
	4 Conclusion
	CRediT authorship contribution statement
	Declaration of competing interest
	Ethical approval
	Funding
	Acknowledgments
	Supplementary materials
	Data availability
	References