Glutathione-Functionalized Organosilicon Oxide Nanoparticles for Bioimaging and Forensics

Abstract

Herein, we report an electron beam mediated one-pot, rapid approach for the synthesis of blue light emitting organosilicon oxide nanoparticles (OSiNPs) in aqueous solution with a potential for scale-up production. Mechanistic studies based on pulse radiolysis revealed that unlike the generally believed solvated electron (e sol − ) driven process, the present synthesis proceeds through the reaction of hydroxyl radical (•OH) with the precursor molecules resulting in the formation of silane-derived radicals. Subsequently, these radicals react with each other to form OSiNPs. Compositional studies by XPS, FTIR, and Raman indicate the presence of siloxane/silicone and silica (SiO 2 ) like units as the major constituents in the NPs. XRD pattern signifies the amorphous nature of the NPs, while imaging studies revealed self-assembling of NPs (3−5 nm) into a porous structure. Notably, the NPs exhibited excitation-wavelength-dependent photoluminescence (PL) spectra, pointing to the presence of multiple emission centers with varying energy levels. The nature of these emission centers and their heterogeneous distribution was analyzed in detail through pH and absorbed dose dependent PL studies, HF treatment, fluorescence excitation spectrum, temperature dependent steady state, and time-resolved PL studies. Moreover, OSiNPs were functionalized with a biocompatible ligand, i.e., Lglutathione (L-Glu), which significantly enhanced the quantum efficiency (up to ∼25%) of emission as well as colloidal stability. These functionalized NPs (L-Glu@OSiNPs) were found to exhibit less toxicity up to a concentration of ∼0.5 mg/mL. Interestingly, the L-Glu@OSiNPs exhibited tumor selectivity (in A549 human lung cancer cells) at lower pH along with cell labeling capabilities with propensity to localize at the nucleus. Furthermore, in addition to their usage in anticounterfeiting measures, application of L-Glu@OSiNPs in fingerprinting was also demonstrated by testing on a variety of surfaces. Meanwhile, linear and reproducible PL intensity variations of OSiNPs signify highly sensitive and robust thermosensing properties of OSiNPs.

Size Tuning, Phase Stabilization, and Anticancer Efficacy of Amorphous Selenium Nanoparticles: Effect of Ion-Pair Interaction, −OH Functionalization, and Reuse of RTILs as Host Matrix

“…A control experiment was conducted wherein Se NPs were synthesized in aqueous solution in the absence of RTILs. The reaction mixture comprised a N 2 -bubbled aqueous solution of SeO 2 and tert -butanol (1 M; to quench • OH). ,,, The experimental parameters (such as absorbed dose and precursor concentration) were kept the same as in the case of experiments in the presence of RTILs. On irradiation of the reaction mixture, Se NPs were formed, as was indicated from the appearance of the red-orange color.…”

“…In this perspective, a methodology of clubbing the radiation-mediated technique with the host matrix of solvents such as room-temperature ionic liquids (RTILs) could be a promising approach. − Electron beam-induced nanomaterial synthesis is a versatile technique with several inherent advantages, such as facileness, nanocharacteristic-maneuvering parameters (such as absorbed dose and dose rate), time efficiency, scale-up potential, and not requiring any external reducing agents. − In the current work, an electron beam was used to generate reducing species, deriving nucleation that eventually leads to the formation of α-Se NPs, while RTILs played multiple roles: as a host matrix, a source of reducing species, and a stabilizer. Nonetheless, apart from the synthesis of α-Se NPs with prolonged stabilization, the main objective of the current work was to investigate the effect of the nature of cation–anion combinations (in RTILs) on the size and phase stability of α-Se NPs.…”

Facile synthesis of solid-state fluorescent organosilica nanoparticles with a photoluminescence quantum yield of 73.3% for fingerprint recognition and white-light-emitting diodes

“…3d), which are attributed to the C-O, Si-O and adsorbed free oxygen, respectively. 37,49,50 The Si 2p band can be resolved into two peaks at 101.0 and 101.8 eV (Fig. 3e), corresponding to Si-C and Si-O, respectively.…”

“…16 The peaks at B1280 cm À1 and 756 cm À1 are assigned to the stretching and bending vibrations of the Si-C bond, respectively. [35][36][37] The strong absorption peaks at B1133, 1090 and 1033 cm À1 are ascribed to the stretching vibration of Si-O-Si.…”

“…[38][39][40] The absorption at 440 cm À1 belongs to the bending vibration of Si-O-Si. 36,37,41 The peaks at 688 and 544 cm À1 are due to the stretching and bending vibrations of O-Si-O. 36,42 In the XRD pattern (Fig.…”