Antimicrobial Hybrid Coatings Combining Enhanced Biocidal Activity under Visible-Light Irradiation with Stimuli-Renewable Properties

Abstract

Hybrid, organic–inorganic, biocidal films exhibiting polishing properties were developed as effective long-lasting antimicrobial surface coatings. The films were prepared using cationically modified chitosan, synthesized by the reaction with 3-bromo-N,N,N-trimethylpropan-1-aminium bromide, to introduce permanent biocidal quaternary ammonium salt (QAS) groups along the polymer backbone and were cross-linked by a novel, pH-cleavable acetal cross-linker, which allowed polishing the hybrid coatings with the solution pH. TiO2 nanoparticles, modified with reduced graphene oxide (rGO) sheets, to narrow their band gap energy value and shift their photocatalytic activity in the visible light regime, were introduced within the polymer film to enhance its antibacterial activity. The hybrid coatings exhibited an effective biocidal activity in the dark (∼2 Log and ∼3 Log reduction for Gram-negative and Gram-positive bacteria, respectively), when only the QAS sites interacted with the bacteria membrane, and an excellent biocidal action upon visible-light irradiation (∼5 Log and ∼6 Log reduction for Gram-negative and Gram-positive bacteria, respectively) due to the synergistic antimicrobial effect of the QAS moieties and the rGO-modified TiO2 nanoparticles. The gradual decrease in the film thickness, upon immersion of the coatings in mildly basic (pH 8), neutral (pH 7), and acidic (pH 6) media, reaching 10, 20, and 70% reduction, respectively, after 60 days of immersion time, confirmed the polishing behavior of the films, whereas their effective antimicrobial action was retained. The biocompatibility of the hybrid films was verified in human cell culture studies. The proposed approach enables the facile development of highly functional coatings, combining biocompatibility and bactericidal action with a “kill and self-clean” mechanism that allows the regeneration of the outer surface of the coating leading to a strong and prolonged antimicrobial action.

Boosting the visible-light-driven photocatalytic antibacterial performance of MoS2 nanosheets by poly(3-(4-methyl-3′-thiophenoxy))propyltrimethylammonium chloride (PThM) modification

“…This situation was caused by the existence of PThM, a water-soluble cationic polymer, whose side-chain quaternary ammonium salts allowed bacteria to adsorb well on the material, and bacteria can be inactivated in the dark. 39 The results from different photocatalytic antibacterial treatment times, obtained via a planar coating method, are shown in Fig. S3, ESI † and the same results as seen in Fig.…”

Vacancy‐Modulated of CuS for Highly Antibacterial Efficiency via Photothermal/Photodynamic Synergetic Therapy

“…It has been reported that excessive ROS could lead to oxidative stress that played important role in photodynamic sterilization. [ 20 ] To explain the reason for that CuS‐T150 owns superior antibacterial efficiency, we firstly detected the ROS level inside of E. coli cells after exposure to CuS samples and laser irradiation. [ 21 ] The data from Figure a suggest that the intracellular ROS level in CuS + NIR experimental groups significantly increased compared to control group, and that in CuS‐T150 + NIR group is higher than CuS + NIR group.…”

Prospects of Synthesized Magnetic TiO2-Based Membranes for Wastewater Treatment: A Review

“…Photocatalytic membranes, which combine membrane filtration with photocatalytic degradation of organics and subsequent antibacterial treatment in a single system, have shown great prospects in water and wastewater treatment settings [12,[123][124][125][126][127]. Furthermore, membrane flux is a critical parameter for the photocatalytic membrane system, as it can be enhanced by multilayered deposition of TiO 2 nanoparticles on the membrane surface, but pore blockage can minimize water flux in some cases [20,87].…”