ИСТИНА

Nowadays a lot of people are suffering from cancer diseases [1], so development of special bioimaging agents could be a breakthrough in oncology treatment. New approach implies a targeted impact on the tumor: directional drug delivery or different prospects of the sensitization help reduce hard consequences of chemo- and radiotherapy. Nanomaterials of porous silicon (pSi) have many useful properties for teranostics, such as biocompatibility, biodegradation, red and infrared luminescence. Due to this characteristic pSi could be detected in cancer cells or even in a whole living organism [2]. Tumors are tend to accumulate nanoparticles more active than health tissue, so pSi materials could be delivered into the tumor through the bloodstream. Bioimaging allows to trace metabolic ways of pSi and their degradation during the time. In this work porous silicon nanowires were investigated. The most popular top-down method for the synthesis of porous silicon nanowires (pSiNWs) is the metal-assisted chemical etching (MACE) of crystalline silicon (c-Si) wafers. As a catalyst in MACE, silver nanoparticles are usually used [3,4]. However, the use of bioinert gold nanoparticles (Au-NPs) here can significantly improve the performance of pSiNWs for their biomedical applications. In the presented work, arrays of pSiNWs were obtained by the MACE method, where Au NPs were used as a catalyst. The scanning electron microscopy method showed that the etching of c-Si wafers with resistivity of 1-5 mOhm*cm produces arrays of porous nanowires with 50 nm in diameter consisting of small silicon nanocrystals (nc-Si) and pores. The size of nc-Si was calculated from the Raman scattering spectra and is about 4 nm. It was shown that due to the quantum confinement effect in small silicon nanocrystals, which are present in the porous structure of pSiNWs, the excitation of effective photoluminescence (PL) with a maximum in the red region of the spectrum is possible. At the same time pSiNWs are characterized by low toxicity to cancer MCF-7 cells and the PL properties of the pSiNWs allow their usage as contrast agents for bioimaging that was demonstrated (fig.1a). Figure 1 a) pSiNWs as contrast agents for imaging of MCF-7 cells, b) Photoluminescence spectra of pSiNWs. The research is supported by Russian Science Foundation Grant No. 22-72-10062. References: [1] Siegel R.L., et al., Cancer statistics, CA. Cancer J. Clin, vol. 73, pp. 17–48 (2023). [2] Park J.-H., et al., Biodegradable luminescent porous silicon nanoparticles for in vivo applications, Nat. Mater, vol. 8, pp. 331–336 (2009). [3] Chiappini C., et. al., Biodegradable porous silicon barcode nanowires with defined geometry. Adv. Func. Mat, vol. 20, pp. 2231-2239 (2010). [4] Georgobiani, V. A., et al. "Structural and photoluminescent properties of nanowires formed by the metal-assisted chemical etching of monocrystalline silicon with different doping level." Semiconductors 49, pp. 1025-1029 (2015).