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Y. Kuziv et al.
particularly work under single-wavelength light irradiation [2]. For this purpose, it is
perspective to combine inorganic nanostructures (PTT) and photosensitizers (PDT)
[4, 5].
Recent advancements in nanomedicine have recognized the use of Au in the
therapeutic delivery of drugs or as an agent for PTT [6]. Gold nanoparticles have
many benefits that make them suitable for the photothermal treatment of cancer.
AuNPs can be administered into the local tumor area, while minimizing non-specific
distribution, they can be activated via near-infrared (NIR) laser light, creating the
ability to penetrate deep into biological tissues, and they can be modulated to create
multifaceted cancer PTT and drug delivery systems [7].
Chlorin e6 (Ce6) is a widely used photosensitizer for PDT [8, 9] and is activated
by laser irradiation to generate highly cytotoxic reactive oxygen species, especially
singlet oxygen.
Previously, it was shown that the combination of AuNPs and Ce6 in polymer
matrix D-g-PAA was successfully used for the photodynamic anticancer therapy
with laser illumination [10].
In this study, changes of the refractive index were analyzed for the systems of
Au sol synthesized into the solutions of Dextran-graft-Polyacrylamide (D-g-PAA)
star-like copolymers in nonionic and anionic forms with and without photosensitizer
Chlorine e6 (Ce6), and for the system D-g-PAA/Ce6 without Au nanoparticles. The
polymer molecular characteristics were described in [3]. Au nanoparticles (AuNPs)
were 1.5–6 nm in size. The size of individual polymer molecule in solution was
equal to 50–60 nm. The aim of the present study was to understand the role of
photosensitizer and AuNPs in the nanocomposite which was efficiently used for
photodynamic therapy [11].
In our investigation, the laser was used with λ irr = 650 nm which is close to the
long-wavelength maximum absorption of Au nanoparticles.
It was shown that over time (t irr ) after the illumination begins, the number of
interference bands increases testifying an increase of n. After ceasing the light,
the interference pattern relaxes and the bands disappear. The interference bands are
localized only in the volume limited by the laser beam, and there is no observed diffusion of the heated solution into other parts of the cuvette. To explain the experimental
results, a phenomenological model is proposed which takes into account the features
of the molecular structure of the star-like D-g-PAA copolymer with incorporated Au
nanoparticles and photosensitizer Chlorine e6.
2 Polymer Matrix
In our investigation, a branched copolymer was used obtained by grafting polyacrylamide (PAA) chains onto dextran (M w = 7 × 10
4 , g mol
−1 ) backbone [12]
using a ceric-ion-reduce initiation method. This redox process initiates free radical
sites exclusively on the polysaccharide backbone, thus preventing the formation of
homopolymer (PAA).
Y. Kuziv et al.
particularly work under single-wavelength light irradiation [2]. For this purpose, it is
perspective to combine inorganic nanostructures (PTT) and photosensitizers (PDT)
[4, 5].
Recent advancements in nanomedicine have recognized the use of Au in the
therapeutic delivery of drugs or as an agent for PTT [6]. Gold nanoparticles have
many benefits that make them suitable for the photothermal treatment of cancer.
AuNPs can be administered into the local tumor area, while minimizing non-specific
distribution, they can be activated via near-infrared (NIR) laser light, creating the
ability to penetrate deep into biological tissues, and they can be modulated to create
multifaceted cancer PTT and drug delivery systems [7].
Chlorin e6 (Ce6) is a widely used photosensitizer for PDT [8, 9] and is activated
by laser irradiation to generate highly cytotoxic reactive oxygen species, especially
singlet oxygen.
Previously, it was shown that the combination of AuNPs and Ce6 in polymer
matrix D-g-PAA was successfully used for the photodynamic anticancer therapy
with laser illumination [10].
In this study, changes of the refractive index were analyzed for the systems of
Au sol synthesized into the solutions of Dextran-graft-Polyacrylamide (D-g-PAA)
star-like copolymers in nonionic and anionic forms with and without photosensitizer
Chlorine e6 (Ce6), and for the system D-g-PAA/Ce6 without Au nanoparticles. The
polymer molecular characteristics were described in [3]. Au nanoparticles (AuNPs)
were 1.5–6 nm in size. The size of individual polymer molecule in solution was
equal to 50–60 nm. The aim of the present study was to understand the role of
photosensitizer and AuNPs in the nanocomposite which was efficiently used for
photodynamic therapy [11].
In our investigation, the laser was used with λ irr = 650 nm which is close to the
long-wavelength maximum absorption of Au nanoparticles.
It was shown that over time (t irr ) after the illumination begins, the number of
interference bands increases testifying an increase of n. After ceasing the light,
the interference pattern relaxes and the bands disappear. The interference bands are
localized only in the volume limited by the laser beam, and there is no observed diffusion of the heated solution into other parts of the cuvette. To explain the experimental
results, a phenomenological model is proposed which takes into account the features
of the molecular structure of the star-like D-g-PAA copolymer with incorporated Au
nanoparticles and photosensitizer Chlorine e6.
2 Polymer Matrix
In our investigation, a branched copolymer was used obtained by grafting polyacrylamide (PAA) chains onto dextran (M w = 7 × 10
4 , g mol
−1 ) backbone [12]
using a ceric-ion-reduce initiation method. This redox process initiates free radical
sites exclusively on the polysaccharide backbone, thus preventing the formation of
homopolymer (PAA).