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The effects of drying technique and surface pre-treatment on the cytotoxicity and dissolution rate of luminescent porous silicon quantum dots in model fluids and living cells
摘要： Tailoring of the biodegradation of photoluminescent silicon quantum dots (Si QDs) is important for their future applications in diagnostics and therapy. Here, the effect of drying and surface pretreatment on the dissolution rate of Si QDs in model liquids and living cells was studied in-vitro by a combination of photoluminescence and Raman micro-spectroscopy. Porous silicon particles were obtained by mechanical milling of electrochemically etched mesoporous silicon films, and consist of interlinked silicon nanocrystals (QDs) and pores. The samples were subjected to super-critical drying with CO2 solvent (SCD) or air drying (AD) and then annealed at 600 C for 16 hours in 1% oxygen to achieve the nano-sized Si QDs. The obtained samples were characterized by a core-shell structure with a crystalline silicon core and a SiO2 layer on the surface. The sizes of the crystalline silicon core, calculated from the Raman scaterring spectra, were about 4.5 nm for initial AD-SiQDs, and about 2 nm for initial SCD-SiQDs. Both AD-Si QDs and SCD-Si QDs exhibited visible photoluminescene (PL) properties due to quantum confinement effects. The dissolution of nanocrystals was evaluated by their PL quenching , as well as by the presence of a low-frequency shift, broadening, and decrease in the intensity of the Raman signal. The stability of AD-Si QDs and the complete dissolution of SCD-Si QDs during 24 hours of incubation with cells have been demonstrated. This might explain the apparent lower cytoxicty observed for SCD-Si QDs.
关键词： air drying,silicon quantum dots,Raman micro-spectroscopy,biodegradation,photoluminescence,super-critical drying
更新于2025-09-12 10:27:22
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X-ray irradiation effects on nuclear and membrane regions of single SH-SY5Y human neuroblastoma cells investigated by Raman micro-spectroscopy
摘要： Raman micro-spectroscopy was performed in vitro on nuclear and membrane regions of single SH-SY5Y human neuroblastoma cells after irradiation by graded X-ray doses (2, 4, 6, 8 Gy). The acquired spectra were analyzed by principal component analysis (PCA) and interval-PCA (i-PCA) methods. Biochemical changes occurring in the different regions of single cells as a consequence of the radiation exposure were observed in cells fixed immediately after the irradiation. The most relevant effects arose from the analysis of the spectra from the cell nucleus region. The observed changes were discussed in terms of the modifications in the cell cycle, resulting in an increase in the DNA-related signal, a protein rearrangement and changes in lipid and carbohydrates profiles within the nucleus. Potential markers of an apoptotic process in cell population irradiated with 6 and 8-Gy X-ray doses could have been singled out. No significant effects were found in spectra from cells fixed 24 h after the irradiation, thus suggesting the occurrence of repairing processes of the X-ray induced damage.
关键词： X-ray effects on DNA, lipids, proteins and carbohydrates,Single SH-SY5Y human cancer cells,Raman micro-spectroscopy,Cellular nucleus and membrane,Multivariate analysis
更新于2025-09-11 14:15:04