Speaker
Description
Zinc phthalocyanine (ZnPc) derivatives have many interested
properties, such as high absorption capacity in the first
near-infrared region, good reactive oxygen species (ROS) generation
efficiency, and excellent photostability [1-3]. However, ZnPc are
highly hydrophobic and tend to aggregate, which decreases their
photosensitivity. Therefore, many attempts have been made to
increase the water solubility of phthalocyanine derivatives. The
simplest approach is to conjugate hydrophilic elements, such as
sulfo, carboxyl, amino, ammonium, hydroxy and as well as
polyethylene glycol groups at peripheral and non-peripheral
positions. Recent studies highlight the potential of ZnPc to be
combined with various nanoparticles, such as Ag, Au, or different
polymers, to enhance biodistribution and photodynamic activity [1].
In this study, zinc phthalocyanine was functionalized with chitosan
surface modified gold nanoparticles and were characterized using
UV-Vis absorption spectroscopy, X-ray diffraction (XRD), zeta
potential measurements, and dynamic light scattering (DLS). The
results demonstrated that the reaction temperature plays a crucial
role in controlling the size, shape, and crystalline structure of
the gold nanoparticles (GNPs). Moreover, it was shown that chitosan
can act as a scaffold for the assembly of GNPs, which were
successfully used for ZnPc functionalization. The first optical
indication of GNP formation was a visible color change over time,
from violet to light pink. This visible color arises from the
resonant interaction of light with GNPs via surface plasmon
excitation. Since the optical spectrum of GNPs strongly depends on
their size, shape, local environment, and electronic coupling, their
formation was monitored not only visually but more accurately
through UV-Vis extinction spectroscopy, showing a characteristic
absorption maximum at 520 nm. The zeta potential was approximately
–32.25 mV, and DLS analysis revealed a mean GNP diameter of
approximately 272.2 nm. All diffraction peaks could be attributed to
the (111), (200), (220), (311), and (222) planes of a face-centered
cubic (fcc) gold crystal. Also, photophysical parameters of
chitosan-functionalized noble nanoparticles conjugated with zinc
phthalocyanine derivative will be discussed.The UV-Vis absorption
spectra of ZnPc(COOH)₄ and ZnPc(COOH)₄:AuNPs structures showed a
well-defined B-band absorption maximum at around 364 nm and only a
slight attenuation for the Q-band of ZnPc(COOH)₄:AuNPs systems
compared to the pure ZnPc. Additionally, a minor red shift in the
characteristic Q-band-of ZnPc(COOH)₄ from 700 nm to 708 nm in
ZnPc(COOH)₄ AuNPs structures was observed.
