Fabrication And Biological Applications Of Photoluminescent Silica Nanomaterials

Silica, which is cheap and readily available, has drawn much attention in preparing luminescent material as the doped substrate because of their good chemical stability, thermal stability and insulating properties.Furthermore, due to their low toxicity and high loading capacity, silica has been widely used as a coating material. Dye-doped silica nanoparticles or silica coated quantum dots, for instance, has been widely used in cell imaging. These methods, however, can be time-consuming and expensive, and are commonly associated with issues like potential toxicity and dye-leaking.Therefore, the preparation of fluorescent silica materials which has the optical stability and biocompatibility without the introduction of external fluorescent group, has important significance in the field of biology and medicine.In this paper, we prepared a non-metal-doped room temperature phosphorescent silica nanomaterial via this simple sol-gel method and further optimized its preparation conditions. A preliminary study of its photoluminescent property and cytotoxicity was also performed. The controllable synthesis, spectroscopic properties, cytotoxicity and cell imaging of these nanomaterials were discussed by using photoluminescence spectra, TEM, XRD, confocal microscopy and other characterized measurements. The results demonstrated that the obtained sample is silica with diameter about 50 nm. The maximum fluorescence excitation and emission wavelengths of silica nanomaterials are 280 nm and 335 nm, and the maximum phosphorescence excitation and emission wavelengths of silica nanomaterials are 280 nm and 440 nm. The obtained silica sample possesses room-temperature phosphorescence that is stable against environmental changes. The obtained sample was stored in air at ambient conditions and its phosphorescence remained unchanged after 3 month demonstrated its long-term stability. The result of MTT and cell imaging suggested that the synthesized silica nanoparticles are feeble cytotoxicity and can be uptaken by cells at the lysosomal compartment. Therefore these nanoparticles can serve as bioprobes for cellular imaging.We further use this method to prepare luminescent magnetic nanoparticles. The silica coated magnetic nanoparticles can be granted with strong luminescence of prominent photo- and chemical stability. Through the study of uptake and intracellular localization of these materials in NCI-H446 cells, we demonstrated that such material can serve as highly photostable bioprobes and are expected to find applications in cell separation. Their room-temperature phosphorescent property is also of significant meaning for further exploring phosphorescence-based applications. This calcinations-induced luminescence shows a clear potential for wide applications in silica-based drug delivery, nanoparticle coating, and bioimaging.We also prepare the mesoporous Ti O2/Si O2 nanomaterial through the sol-gel method,using P123(which was removed by calcination) as the template, in the presence of HCl. The results demonstrated that the obtained sample is mesoporous Ti O2/Si O2 with pore diameter about 5.5nm. The maximum fluorescence excitation and emission wavelengths of silica nanomatericals are 460 nm and 510 nm, and the maximum phosphorescence excitation and emission wavelengths of silica nanomatericals are 400 nm and 535 nm. The obtained silica sample possesses room-temperature phosphorescence that is stable against environmental changes.The utility of mesoporous Ti O2/Si O2 as an intracellular carrier for anticancer drug delivery system was evaluated using weak base type anti-cancer drug doxorubicin hydrochloride(DOX) as a model anticancer drug. The drug loading and release of DOX under different ph conditions were evaluated. The release of DOX was p H dependent, with a slow release under physiological conditions, and release acceleration under acidic conditions.the ph-sensitive release pattern is conducive for the nanoparticles to play a cytotoxic effect in the tumor.Through the research work in this paper we can demonstrate that, the as prepared photoluminescent Si O2 nanomaterial obtained through the sol-gel method, due to its excellent optical properties and biological compatibility, can be used as a kind of coating material, or be prepared into mesoporous nanomaterials,which can be combined with a wide range of other functional molecular. Thus fluorescent multifunctional nanomaterial can be prepared and it will have great application in the aspect of multi-function nanomaterials preparation.