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Large-scale surface nanopatterning of a commercial silicon (Si) wafer in the form of regular 1D arrays of high-aspect-ratio vertical nanosheets (NSs) for antifouling and other potential promising optoelectronic, nanophotonic, and sensing applications was performed via multishot picosecond IRlaser ablation under a 5-mm-thick carbon disulfide liquid layer. Specifically, the nanopatterned surface layer demonstrates the broad ultralow mid-IR transmittance and the high content of sulfur, carbon, and even oxygen in the modified submicron-thick top layer, preventing the appearance of a Staphylococcus aureus bacterial biofilm. High-resolution transmission electron microscopy studies exhibit the anticorrelating inner versus outer surface abundance of donor sulfur versus adverse carbon and oxygen components and the amorphous structure of the sulfur-hyperdoped NSs atop their crystalline basements. These NSs indicate their appearance via the interfacial vapor/ plume bubble-mediated codeposition of Si ablation nanoplumes from the regular trenches and sulfur-containing products of carbon disulfide decomposition in the bubble. Numerical modeling indicates the nanoplasmonic origin of the Si NSs, self-limited in both the 100 nm periods and the submicron heights.

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The antibacterial properties of silicon nanoparticles with Gram-positive and Gram-negative bacteria were demonstrated. The nanoparticles were prepared with laser ablation in various liquids (distilled water, isopropyl alcohol) using a nanosecond laser. Optical and scanning electron microscopy methods were used for the sample characterization. The presence of singlet oxygen and other reactive oxygen species on the surface of the silicon nanoparticles, leading to oxidative damage to bacterial membranes and further death of the bacteria, was considered a possible mechanism of this antibacterial action.