Multiwavelength excitation of photosensitizers interacting with gold nanoparticles and its impact on optical properties of their hybrid mixtures

Abstract

In a hybrid mixture of organic (dye) and inorganic (metallic nanoparticles) components, the optical properties of a dye can be easily controlled by tailoring the shape or the concentration of the noble metal nanoparticles (NPs). The influences of multiexcitation (multiwavelength excitation) of photosensitizers (pheophorbide a and hematoporphyrin) on the interactions with pegylated Au-NPs and on the photophysical parameters of the dyes are studied. Detailed, systematic fluorescence quenching studies were performed in the mixtures of different contents of Au-NPs, and interpreted together with the results of quantum singlet oxygen yield examinations. According to the results, the fluorescence of the two dyes studied was effectively quenched in the presence of Au-NPs, mainly because of the resonance energy transfer between the donor (dye) and the acceptor (Au-NPs). Stern-Volmer quenching constants were determined by a few orders of magnitude higher than those describing the photochemical quenching process. In hybrid mixtures analyzed, the mechanism of energy transfer between the donor and the acceptor was nanometal surface energy transfer. Furthermore, different behavior of the mixtures on excitation with the wavelengths from the Soret and Q bands of the dyes and with those corresponding to the surface plasmon resonance band of Au-NPs was analyzed. Moreover, for certain concentrations of Au-NPs and for certain excitation wavelengths, an increase in singlet oxygen generation was observed. The results obtained indicate the significance of further studies of photosensitizers in hybrid mixtures with NPs.

Tailoring Fluorescence and Singlet Oxygen Generation of a Chlorophyll Derivative and Gold Nanorods via a Silica Shell

“…The quantum yield of ) dissolved in EtOH. 24 The process of fluorescence quenching of Pheide versus Au-NRs@SiO 2 concentration ([Au − NRs]) can be described by the Stern−Volmer constant (K SV ) defined by the expression…”

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

“…The photosensitization efficiencies of the samples under investigation have been determined by use of DPBF, a widely used ROS trap (especially for 1 O 2 ), which strongly absorbs light at 410 nm (23 000 m −1 cm −1 at 410 nm in DMF) . The decrease of DPBF absorbance at 410 nm, as function of PS irradiation time, is due to DPBF oxidation by the formed ROS.…”

“…The values of DPBF photooxidation rates, determined in the presence of the samples under investigation ( ) or in the presence of a reference dye ( ) used as standard, enabled the determination of the ROS formation quantum yield ( ), according to Equation : …”

Activating Drugs with Sound: Mechanisms Behind Sonodynamic Therapy and the Role of Nanomedicine

“…This broad emission was also observed with the addition of ROS scavengers, specifically those acting on 1 O 2 , OH·, and O 2 – , suggesting that sonoluminescence was a result of cavitation hot spots rather than from the recombination of ROS. Noting the overlap between the peak absorbance of Hp at 411 nm and the broad sonoluminescence peak between 400 and 450 nm, the authors hypothesized activation of the sonosensitizer either through nonequilibrium energy transfer from sonochemical hotspots or by direct photoactivation from the generated light. On the basis of this study, multiple papers have investigated sonoluminescence as a mechanism of SDT action in vitro and in vivo . ,, Umemura et al.’s seminal work also illustrates the requirements needed for a PDT-like sonoluminescence pathway of SDT action to ensue: (1) a sensitizer with a high yield of intersystem crossing to generate an excited triplet state, and (2) overlap between the peak absorbance of the sensitizer and the broad emission of sonoluminescence.…”

“…Adapted with permission from Umemura et al 78 with the addition of ROS scavengers, specifically those acting on 1 O 2 , OH•, and O 2 − , suggesting that sonoluminescence was a result of cavitation hot spots rather than from the recombination of ROS. Noting the overlap between the peak absorbance of Hp at 411 nm 80 and the broad sonoluminescence peak between 400 and 450 nm, the authors hypothesized activation of the sonosensitizer either through nonequilibrium energy transfer from sonochemical hotspots or by direct photoactivation from the generated light. On the basis of this study, multiple papers have investigated sonoluminescence as a mechanism of SDT action in vitro and in vivo.…”