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.

Multi-shot exposure of silicon surface in air by mid-infrared (MIR, 2.5–5 microns) femtosecond laser pulses results in an initial (N_p = 2–5 shots) appearance of a bright spot with abnormally-oriented, bipolar shallow deeply-subwavelength ripples (period ∼ (0.2–0.4)λ, average trench ablation rate ∼ 10–20 nm/shot, trench depth < 100 nm), visualized by scanning confocal laser profilometry. At longer exposures (N_p = 10–20 shots), the irradiated spot becomes visibly black, exhibiting normally-oriented, almost unipolar near-wavelength ripples with ultra-deep trenches (average ablation rate ≤60 nm/shot, trench depth ∼ 400–600 nm). The observed distinct topological transition from the abnormal bipolar deeply-subwavelength ripples, formed via melt displacements, to the normal unipolar ablative near-wavelength ripples was considered to be a competitive result of the related, much stronger resonant laser coupling to the second darker, rougher near-wavelength relief, accompanied by the change in mass transfer mechanisms and strong enhancement in ablation rate per shot.

A natural diamond surface was nanopatterned in a subablative scanning mode by multiple tightly focused 515-nm, 300-fs laser pulses, resulting in regular surface metagratings (nanoripples) with a subwavelength period of Λ ∼ 100 nm, an almost undistorted crystalline structure, free from sp²-carbon, oriented perpendicular to the laser polarization, and stackable both along and normal to their stripes. In the visible-near-IR ranges (400–800 nm), these metagratings demonstrate the pronounced resonant antireflective effect in the wavelength range near ∼4Λ, while the overall specular reflectance/transmittance is considerably diminished with respect to both the simulation results and the reference diamond surface, indicating strong (∼50%) coupling/scattering of light inside the crystal. Our modeling indicates the laser wavelength-dependent plasmon-based tunability of metagrating periods, implying the corresponding tunability of their spectral response.

A novel approach was proposed and demonstrated to fabricate in a controllable manner alloyed colloidal Ag/Au nanoparticles with pre-determined stoichiometry from thin, magnetron-deposited bi-layered (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 bi-layered films. Transmission electron microscopy and energy dispersive x-ray 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 on-demand fabrication of different bi- and poly-metallic nanoparticles with pre-determined stoichiometries.