New Polymeric Films with Antibacterial Activity Obtained by UV-induced Copolymerization of Acryloyloxyalkyltriethylammonium Salts with 2-Hydroethyl Methacrylate.

New polymeric films with antibacterial activity have been prepared, by simple UV-induced copolymerization of readily available ω-(acryloyloxy)-N,N,N-triethylalcan-1-aminium bromides (or acryloyloxyalkyltriethylammonium bromides, AATEABs) with commercially available 2-hydroethyl methacrylate (HEMA), at different relative amounts. In particular, the antibacterial activity of polymeric films derived from 11-(acryloyloxy)-N,N,N-triethylundecan-1-aminium bromide (or acryloyloxyundecyltriethylammonium bromide, AUTEAB; bearing a C-11 alkyl chain linker between the acrylate polymerization function and the quaternary ammonium moiety) and 12-(acryloyloxy)-N,N,N-triethyldodecan-1-aminium bromide (or acryloyldodecyltriethylammonium bromide, ADTEB, bearing a C-12 alkyl chain linker) has been assessed against Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus cells. The results obtained have shown a clear concentration-dependent activity against both bacterial strains, the films obtained from homopolymerization of pure AUTEAB and ADTEAB being the most effective. Moreover, ADTEAB-based films showed a higher antibacterial activity with respect to the AUTEAB-based ones. Interestingly, however, both types of films presented a significant activity not only toward Gram-positive S. aureus, but also toward Gram-negative E. Coli cells.

Thermo-Plasmonic Killing of Escherichia coli TG1 Bacteria.

Plasmonic photo-thermal therapy (PPTT) is a minimally invasive, drug-free, therapy based on the properties of noble metal nanoparticles, able to convert a bio-transparent electromagnetic radiation into heat. PPTT has been used against cancer and other diseases. Herein, we demonstrate an antimicrobial methodology based on the properties of gold nanorods (GNRs). Under a resonant laser irradiation GNRs become highly efficient light to heat nano-converters extremely useful for PPTT applications. The concept here is to assess the antimicrobial effect of easy to synthesize, suitably purified, water-dispersible GNRs on Escherichia coli bacteria. A control on the GNRs concentration used for the process has been demonstrated critical in order to rule out cytotoxic effects on the cells, and still to be able to generate, under a near infrared illumination, an adequate amount of heat suited to increase the temperature up to ≈50 °C in about 5 min. Viability experiments evidenced that the proposed system accomplished a killing efficiency suitable to reducing the Escherichia coli population of about 2 log CFU (colony-forming unit).