Antiviral adsorption activity of porous silicon nanoparticles against different pathogenic human viruses

New viral infections, due to their rapid spread, lack of effective antiviral drugs and vaccines, kill millions of people every year. The global pandemic SARS-CoV-2 in 2019-2021 has shown that new strains of viruses can widespread very quickly, causing disease and death, with significant socio-economic consequences. Therefore, the search for new methods of combating different pathogenic viruses is an urgent task, and strategies based on nanoparticles are of significant interest. This work demonstrates the antiviral adsorption (virucidal) efficacy of nanoparticles of porous silicon (PSi NPs) against various enveloped and non-enveloped pathogenic human viruses, such as Influenza A virus, Poliovirus, Human immunodeficiency virus, West Nile virus, and Hepatitis virus. PSi NPs sized 60 nm with the average pore diameter of 2 nm and specific surface area of 200 m2/g were obtained by ball-milling of electrochemically-etched microporous silicon films. After interaction with PSi NPs, a strong suppression of the infectious activity of the virus-contaminated fluid was observed, which was manifested in a decrease in the infectious titer of all studied types of viruses by approximately 104 times, and corresponded to an inactivation of 99.99% viruses in vitro. This sorption capacity of PSi NPs is possible due to their microporous structure and huge specific surface area, which ensures efficient capture of virions, as confirmed by ELISA analysis, dynamic light scattering measurements and transmission electron microscopy images. The results obtained indicate the great potential of using PSi NPs as universal viral sorbents and disinfectants for the detection and treatment of viral diseases.

Raman Signal Enhancement Tunable by Gold-Covered Porous Silicon Films with Different Morphology

The ease of fabrication, large surface area, tunable pore size and morphology as well surface modification capabilities of a porous silicon (PSi) layer make it widely used for sensoric applications. The pore size of a PSi layer can be an important parameter when used as a matrix for creating surface-enhanced Raman scattering (SERS) surfaces. Here, we evaluated the SERS activity of PSi with pores ranging in size from meso to macro, the surface of which was coated with gold nanoparticles (Au NPs). We found that different pore diameters in the PSi layers provide different morphology of the gold coating, from an almost monolayer to 50 nm distance between nanoparticles. Methylene blue (MB) and 4-mercaptopyridine (4-MPy) were used to describe the SERS activity of obtained Au/PSi surfaces. The best Raman signal enhancement was shown when the internal diameter of torus-shaped Au NPs is around 35 nm. To understand the role of plasmonic resonances in the observed SERS spectrum, we performed electromagnetic simulations of Raman scattering intensity as a function of the internal diameter. The results of these simulations are consistent with the obtained experimental data.