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.

A novel, successful method of bactericidal treatment of pathogenic bacterial biofilms in vitro by laser-induced forward transfer of metallic nanoparticles from a polyethylene terephthalate polymeric substrate was suggested. Transferred nanoparticles were characterized by scanning and transmission electron microscopy, energy-dispersive X-ray and Raman spectroscopy. The antibacterial modality of the method was tested on Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas Aeruginosa) bacterial biofilms in vitro, revealing their complete destruction. The proposed simple, cost-effective and potentially mobile biofilm treatment method demonstrated its high and broad bactericidal efficiency.

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A novel approach was proposed and demonstrated to fabricate in a controllable manner alloyed colloidal Ag/Au nanoparticles with predetermined stoichiometry from thin, magnetrondeposited bilayered (Ag/Au) films of variable layer thickness by their nanosecond laser ablation in water. The optical properties of the obtained colloidal solutions were systematically analyzed, both experimentally and theoretically, indicating the alloyed character of the bimetallic nanoparticles as a monotonic 'red' spectral displacement of the localized plasmon resonance position, as well as gradual variation of its amplitude and width with increasing gold content in the bilayered films. Transmission electron microscopy and energy dispersive xray spectroscopy support the alloyed rather than fragmentary character of the bimetallic nanoparticles, with the increasing gold content resulting in an increasing average nanoparticle size. This approach appears to be highly promising for the controllable ondemand fabrication of different bi and polymetallic nanoparticles with predetermined stoichiometries.

We report the possibility of a time-resolved bacterial live/dead dynamics observation with the use of plasmonic nanospikes. Sharp nanospikes, fabricated on a 500-nm thick gold film by laser ablation with the use of 1030-nm femtosecond pulses, were tested as potential elements for antibacterial surfaces and plasmonic luminescence sensors. Staphylococcus aureus bacteria were stained by a live/dead viability kit, with the dead microorganisms acquiring the red colour, caused by the penetration of the luminescent dye propidium iodide through the damaged cell membrane. Photoluminescence was pumped by 515-nm femtosecond laser pulses with linear (Gaussian beam), circular, azimuthal and radial (Laguerre–Gaussian beam) polarizations, exciting the transverse plasmon resonance of the nanospikes and their apex lightning-rod near-field. According to the numerical electrodynamic modeling, the observed strong increase in the photoluminescence yield for radial polarization, while slightly lower for circular and azimuthal polarizations, compared with the low luminescence intensities for the linear laser polarization, was related to their different laser–nanospike coupling efficiencies.