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

Abstract

Gold nanorods deserve special attention as they exhibit tunable longitudinal localized surface plasmon resonances (LSPRs). In our study, gold nanorods of the aspect ratio of 2.25 (maximum of LSPR band at 660 nm) and of controllable SiO 2 thickness in the range of 6−14 nm were mixed with pheophorbide (chlorophyll derivative) in order to create a hybrid system. Energy transfer and singlet oxygen generation were studied for different SiO 2 thicknesses of the nanorod shell. The spectral properties of the hybrid mixture were characterized, and the overlapping of the pheophorbide fluorescence and the longitudinal LSPR band of nanorods on the fluorescence emission, energy transfer, and generation of singlet oxygen were studied. Two independent approaches were used to determine the quantum yield and enhanced factor of singlet oxygen generation. For a certain thickness of the SiO 2 shell and for certain concentrations of gold nanorods, the effect of the plasmon-enhanced singlet oxygen production was observed. Moreover, the enhanced of singlet oxygen yield enhancement was correlated with the far-field optical properties of the gold nanorods. The results obtained indicate the significance of further studies of dye-photosensitizers in hybrid mixtures, taking into account the spectral overlap between dye emission and longitudinal LSPR bands as well as the character of coatings (type and thickness) and scattering yields of gold nanorods.

Development of Aminated Chitosan-Functionalized Magnetite Nanoparticles Enriched with Zinc Phthalocyanine: Detailed Photophysical and Model Cell Membrane Studies

“…The Ni 2+ complex with pheophytin a (Ni-Phea) was selected as a photocalorimetric reference for its suitable spectral properties . According to our previous studies, to maintain the mechanical properties of the medium, the mixture of Ni-Phea and the aminated chitosan-functionalized MNPs was used as a LIOAS reference sample. Ni-Phea was used at the concentration in the range of 10 –6 M, while the concentration of MNPs was 0.12 mg·mL –1 .…”

Recent Advances in Metallic Nanoparticle Assemblies for Surface-Enhanced Spectroscopy

“…There are many techniques for the functionalization of NPs, for example, via the use of receptors [ 41 ] and similar biomolecules, which are, thus, ideal candidates for biological applications. Functionalization and stabilization of nanostructures can also be performed with the use of the following chemical compounds: CTAB surfactant [ 42 , 43 ], silica dioxide [ 44 ], PEG-SH [ 45 ], titanium dioxide [ 46 ], bovine serum albumin [ 47 ], folic acid [ 48 ], polypeptides [ 49 ], oligonucleotides [ 50 ], antibodies [ 51 ], sodium citrate [ 52 ], and compounds with thiol [ 53 ]. In addition, citrate-stabilized NPs are more accessible, and it is easier for further functionalization compared to NPs functionalized with (polyvinylpyrrolidone) PVP and CTAB.…”

Current Knowledge of Silver and Gold Nanoparticles in Laboratory Research—Application, Toxicity, Cellular Uptake

“…Due to the optical properties of silver nanoparticles, they strongly interact with specific wavelengths of light, to which they have found wide use in biomedical applications, e.g., in vitro cellular imaging systems [ 21 ]. Due to their optical properties, noble metal nanoparticles can be used, for example, as an active ingredient in SPR (surface plasmon resonance) biosensors [ 22 , 23 , 24 , 25 ].…”