Effects of Gold Colloids on the Photosensitization Efficiency of Silica Particles Doped with Protoporphyrin IX

Abstract

Photodynamic treatments represent a non‐invasive tool to intervene in the cell cycle, only when needed, but high excitation power is an important limitation. In this work, protoporphyrin IX (PpIX) is covalently anchored to the surface of silica particles. The hybrid colloids are prepared with different photosensitizer loadings and characterized by TEM, SEM‐EDX and spectroscopic methods. The visible excitation of the colloidal samples generates reactive oxygen species, which are quantified by use of a specific chemical scavenger agent (1,3‐diphenylisobenzofuran). The determined efficiencies depend on the PpIX loading, being higher in the sample where the aggregation is reduced. To enhance further the photosensitizing performance of silica‐PpIX samples, increasing amounts of gold nanoparticles are conjugated to the silica surface in order to exploit the antenna effect of plasmonic nanostructures. The visible excitation of silica‐PpIX systems in the presence of gold nanoparticles results in a faster and more efficient photoinduced formation of ROS species reaching a 230 % enhancement of ROS photosensitization when 1013 Au nanoparticles mL−1 (corresponding to circa 75 ppm of gold) are present. The efficiency data are discussed in terms of plasmonic enhancement of the excitation field.

Effect of Chemically Engineered Au/Ag Nanorods on the Optical and Mechanical Properties of Keratin Based Films

“…The morphology of both AuNRs and Au@AgNRs is investigated by a Philips 208 transmission electron microscope (TEM) following the same procedure described in reference (Zampini et al, 2017) operating at 80 kV of beam acceleration. For each sample, a drop of the aqueous colloidal solution was deposited on a 300 square mesh Formvar-coated copper grid.…”

Scattering-type Scanning Near-Field Optical Microscopy of Polymer-Coated Gold Nanoparticles

“…The optical properties of the synthesized colloidal samples were first investigated through a Cary 8454 UV–vis diode array spectrophotometer. Transmission electron microscope (TEM) investigations were performed using a Philips 208 transmission electron microscope (TEM) with an 80 kV beam acceleration to assess the size and morphology of the synthesized materials, according to a previously described procedure; 73 in order to have a statistically significant evaluation at least 120–150 particles for each sample have been analyzed. The particle size analysis was carried by the Nicomp Nano DLS/ZLS Systems (dynamic light scattering particle size analyzer), which allowed the determination of the hydrodynamic diameters of the colloids.…”

Photocatalytic activity of silica and silica-silver nanocolloids based on photo-induced formation of reactive oxygen species

“…Post-synthesis treatment to graft amino groups on the surface of SiO 2 NPs is performed in ethanol with a procedure described elsewhere [43], using SiO 2 NPs in concentration of 2.0 mg mL −1 and 8 µL of APTES per mL of ethanol.…”

“…The photo-induced quantum efficiency of ROS formation is determined through a widely used ROS trap, 1,3-diphenylisobenzofuran (DPBF). The data are analyzed with an already reported model [43] (see also Supporting Information). Since a white light source is adopted, instead of monochromatic irradiation, the absorbance values of the standard and the sample under investigation are integrated into the whole UV-VIS range [46].…”