Four novel Pseudomonas strains with record resistance to copper (Cu²⁺) previously isolated from ecologically diverse samples (P. lactis UKR1, P. panacis UKR2, P. veronii UKR3, and P. veronii UKR4) were tested against sonochemically synthesised copper-oxide (I) (Cu₂O) and copper-oxide (II) (CuO) nanoparticles (NPs). Nanomaterials characterisation by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the synthesis of CuO and Cu₂O NPs. CuO NPs exhibited better performance in inhibiting bacterial growth due to their heightened capacity to induce oxidative stress. The greater stability and geometrical shape of CuO NPs were disclosed as important features associated with bacterial cell toxicity. SEM and TEM images confirmed that both NPs caused membrane disruption, altered cell morphology, and pronounced membrane vesiculation, a distinctive feature of bacteria dealing with stressor factors. Finally, Cu₂O and CuO NPs effectively decreased the biofilm-forming ability of the Cu²⁺-resistant UKR strains as well as degraded pre-established biofilm, matching NPs’ antimicrobial performance. Despite the similarities in the mechanisms of action revealed by both NPs, distinctive behaviours were also detected for the different species of wild-type Pseudomonas analysed. In summary, these findings underscore the efficacy of nanotechnology-driven strategies for combating metal tolerance in bacteria.

Cork biomass (C) was grafted with antimicrobial silver phenolated-lignin nanoparticles (AgPLN) using a fast and simple sono-enzymatical process. The AgPLN-functionalised cork (C-AgPLN) exhibited potent antibacterial and antibiofilm properties against the common waterborne pathogens, Escherichia coli and Staphylococcus aureus. Its effects on bacterial cells included alterations in cell morphology and structure, as revealed by electron microscopy (SEM and TEM) and fluorescence microscopy (LIVE/DEAD staining). These effects also included increased oxidative stress (80 % and 31 % in E. coli and S. aureus, respectively), >99 % reduction in viability, a 60 % reduction in E. coli biofilm, and a 44 % reduction in S. aureus biofilm, as quantified by spectroscopic methods (ROS measurement, XTT metabolic activity test, and crystal violet staining). C-AgPLN also demonstrates anti-quorum sensing properties against both Gram-negative and Gram-positive bacteria, crucial for disrupting bacterial communication, thereby preventing biofilm formation. Further, C-AgPLN was combined with activated carbon (AC) at different proportions (1 %, 2 %, and 4 % w/w) in lab-scale packed-bed columns for the disinfection of water contaminated with E. coli or S. aureus. Columns containing 4 % w/w C-AgPLN demonstrated 100 % disinfection efficiency after 1 h of operation in recirculation mode (flow rate = 8.6 mL/min), and were reusable for up to 2 and 4 cycles without losing their disinfection capacity. Noteworthy, silver ion (Ag⁺) release was not detected in the effluent after 240 h columns operation (ICP-MS detection limit of <0.07 μg/L), confirming the environmental safety on the novel water-disinfection approach. Given that adsorption is a well-established method for advanced wastewater treatment, these results underscore the potential of nano-enabled AC-packed columns for safely and efficiently controlling the spread of water-associated pathogens.

Poly(diallyldimethylammonium chloride) (PDDA) is a cationic polymer with strong antibacterial activity, but its coating applications are hindered by limited stability and dose-dependent cytotoxicity. Nanoformulating PDDA into polymer dots (PDDA-based PDs) via hydrothermal synthesis with boric acid offers enhanced biocompatibility, stability, and antimicrobial efficacy. The synthesised PDs demonstrated potent antibacterial activity against Gram-positive (S. aureus) and Gram-negative bacteria (E. coli and P. aeruginosa) with MIC values of 0.056-0.112 mg/mL and superior biofilm inhibition capabilities. Significantly lower antimicrobial resistance development was observed, with only 4-8 fold MIC increase after 30 days compared to 128-2048 fold increase for conventional antibiotics. Sonochemical coating onto cotton fabrics achieved exceptional washing durability, retaining strong antibacterial activity even after 60 high-temperature hospital laundry cycles with log reductions of 4.72 for S. aureus, 2.31 for P. aeruginosa, and 3.26 for E. coli. The multi-targeted antimicrobial mechanism of the PDs involves ROS generation, disruption of bacterial metabolism, and physical damage to membrane integrity. The coating process was successfully upscaled using a roll-to-roll sonochemical pilot system, demonstrating industrial feasibility. PDDA-based PDs offer a promising platform for developing sustainable, wash-durable antimicrobial textiles suitable for healthcare applications.