SPIE Journal Paper | 24 July 2024
KEYWORDS: Nanoparticles, Rhodamine B, Fluorescence, Dyes, Dye lasers, Absorption, Nanocomposites, Fluorescence spectroscopy, Emission wavelengths, Optical properties
We studied spectroscopical properties of tiny TiO2 nanoparticles (TiO2 NPs) with potential applications by the stimulation of multi-modal energy modes. Thus, nanoparticles of 2 to 4 nm sizes were modified with short modified organosilane with a fluorescent laser dye reporter. By this manner, it was covered with silanized spacer lengths of few nm with an additional protective shell. The non-modified TiO2 NPs showed high interactions between them due to their reduced sizes that afforded to homogeneous nano-patterned arrays observed by TEM. Silanized nanoparticles also afforded higher dispersible colloidal dispersion with strong interactions. As it is known, silanol groups could form strong polar and hydrogen bridges between them, but the aggregates could be easily re-dispersed just by sonication. By this manner, generation of a high-ordered nano-pattern was lost in the absence of silica shells. By dynamic light scattering, I recorded within colloidal dispersions sizes of 2 to 3 nm in presence of aqueous solvent and smaller nanoaggregates of 30 nm corresponding to decamer forms. In this context, I highlighted the possibility of managing interactions and nano-patterns controlling nano-surfaces and media. Non-labeled TiO2 NPs showed strong absorptions centered at 298.0 and 560.0 nm. Moreover, modified nanoparticles showed a constant and proportional increase of the 298.0 nm absorption band with the augmentation of the concentration. Moreover, the UV band was accompanied with a redshifted maximal absorption wavelength by the fluorophore incorporated from 553.0 to 557.0 nm. This fact was explained between an interaction between the absorption of the laser dye centered at 537 nm and the longer band by the nanoplatforms. Then, in order to evaluate their interactions in the excited state, I evaluated fluorescence lifetime decays (τ) of the free fluorophore and deposed on nanoplatforms. In addition, I evaluated the detection of the modified TiO2 nanoplatforms within in-flow cytometry (IFC). In this manner, I observed τ shortening accompanied with augmented counting of fluorescence events detected. It should be noted that in these conditions, I did not observe degradation of the fluorescent reporter. However, in absence of the modified organosilanes, I observed potential insights of fast photo-degradation under UV light irradiation. Therefore, I designed and synthesized a stable and improved tiny nano-emitter with potential use for nanophotonics, biophotonics, and nanomedicine applications. Thus, in this perspective, I discuss the development of multimodal nanoplatforms for varied functionalities and applications.
