Scalable Aqueous-Based Process for Coating Polymer and Metal Substrates with Stable Quaternized Chitosan Antibacterial Coatings

Water-borne chitosan/CuO-GO nanocomposite as an antibacterial coating for functional leather with enhanced mechanical and thermal properties

The advancement of eco-friendly and effective antibacterial outer surfaces for medical textiles and leather products is considered important by industries and end users. Herein, positively charged chitosan (CS) and copper oxide nanoparticle-decorated negatively charged graphene oxide (CuO-GO) were assembled layer-by-layer to create an innovative nanocomposite (CS/CuO-GO) coating onto the leather surface. GO was prepared from graphite powder. Eco-friendly synthesis of CuO nanoparticles with Aloe vera leaf extract was reported and utilized to prepare the CuO-GO nanocomposite. The as-prepared materials were tested through FTIR, XRD, UV-vis spectroscopy, TEM, and DLS analyses. Different amounts of CS/CuO-GO coated leathers showed efficient antibacterial activities against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) using a "kill-release" approach. This was largely attributed to the cooperative interaction between the contact-killing of the chitosan layer, the discharge of Cu2+ ions, and the bacterial-repelling properties of the anionic GO layer. The FE-SEM analysis confirms the existence of a CuO-GO layer on the leather surface with an effect on the macroscopic level performances. The XPS analysis confirms the chemical state of the coated materials on the leather surface. Tensile, tear, and stitch tear strength increased after coating with the CS/CuO-GO nanocomposite. The WVP of the coated leather remains within the range after coating with different wt% of the CS/CuO-GO nanocomposite. The durability of the nanocomposite coating on leather surfaces was thoroughly examined through dry and wet rub fastness tests. Results clearly showed that the strong coating greatly enhanced the antibacterial effectiveness of leather against mechanical wear. The impacts of CS/CuO-GO nanocomposite coating on the leather surface hydrophilicity were evaluated using water contact angle measurements. Water-borne chitosan-based CuO-GO nanocomposite showed a good eco-friendly leather finishing system. It could extend their applications to sports and medical textiles to impart antibacterial effects.

Developing a novel antibacterial coating system for marine corrosion and fouling control

Microbial-influenced corrosion and marine biofouling have become a thorny problem restricting the effective long-term operation of marine engineering. In this study, a novel antibacterial coating system for marine corrosion and fouling control was developed to integrate and improve the antibacterial performance. The coating system was composed of an epoxy primer and a low surface energy organosilicon/polyurethane topcoat, while quaternary ammonium salt (QAS) was added as an antimicrobial agent. The primer provided excellent corrosion protection. The antifouling performance was significantly improved by the combined effect of low surface energy and antibacterial agents, resulting in an extended service life and enhanced environmental sustainability of the coating system. Furthermore, the satisfactory results of the above coating system were confirmed by 8 weeks of hanging tests in the ocean, which exhibited potential application prospects in marine engineering in the future.

Polysaccharide-based antibacterial coating technologies

To tackle antimicrobial resistance, a global threat identified by the United Nations, is a common cause of healthcare-associated infections (HAI) and is responsible for significant costs on healthcare systems, a substantial amount of research has been devoted to developing polysaccharide-based strategies that prevent bacterial attachment and biofilm formation on surfaces. Polysaccharides are essential building blocks for life and an abundant renewable resource that have attracted much attention due to their intrinsic remarkable biological potential antibacterial activities. If converted into efficient antibacterial coatings that could be applied to a broad range of surfaces and applications, polysaccharide-based coatings could have a significant potential global impact. However, the ultimate success of polysaccharide-based antibacterial materials will be determined by their potential for use in manufacturing processes that are scalable, versatile, and affordable. Therefore, in this review we focus on recent advances in polysaccharide-based antibacterial coatings from the perspective of fabrication methods. We first provide an overview of strategies for designing polysaccharide-based antimicrobial formulations and methods to assess the antibacterial properties of coatings. Recent advances on manufacturing polysaccharide-based coatings using some of the most common polysaccharides and fabrication methods are then detailed, followed by a critical comparative overview of associated challenges and opportunities for future developments. STATEMENT OF SIGNIFICANCE: Our review presents a timely perspective by being the first review in the field to focus on advances on polysaccharide-based antibacterial coatings from the perspective of fabrication methods along with an overview of strategies for designing polysaccharide-based antimicrobial formulations, methods to assess the antibacterial properties of coatings as well as a critical comparative overview of associated challenges and opportunities for future developments. Meanwhile this work is specifically targeted at an audience focused on featuring critical information and guidelines for developing polysaccharide-based coatings. Including such a complementary work in the journal could lead to further developments on polysaccharide antibacterial applications.

Recent Strategies and Future Recommendations for the Fabrication of Antimicrobial, Antibiofilm, and Antibiofouling Biomaterials

Biomaterials and biomedical devices induced life-threatening bacterial infections and other biological adverse effects such as thrombosis and fibrosis have posed a significant threat to global healthcare. Bacterial infections and adverse biological effects are often caused by the formation of microbial biofilms and the adherence of various biomacromolecules, such as platelets, proteins, fibroblasts, and immune cells, to the surfaces of biomaterials and biomedical devices. Due to the programmed interconnected networking of bacteria in microbial biofilms, they are challenging to treat and can withstand several doses of antibiotics. Additionally, antibiotics can kill bacteria but do not prevent the adsorption of biomacromolecules from physiological fluids or implanting sites, which generates a conditioning layer that promotes bacteria's reattachment, development, and eventual biofilm formation. In these viewpoints, we highlighted the magnitude of biomaterials and biomedical device-induced infections, the role of biofilm formation, and biomacromolecule adhesion in human pathogenesis. We then discussed the solutions practiced in healthcare systems for curing biomaterials and biomedical device-induced infections and their limitations. Moreover, this review comprehensively elaborated on the recent advances in designing and fabricating biomaterials and biomedical devices with these three properties: antibacterial (bacterial killing), antibiofilm (biofilm inhibition/prevention), and antibiofouling (biofouling inhibition/prevention) against microbial species and against the adhesion of other biomacromolecules. Besides we also recommended potential directions for further investigations.

Quaternized chitosan as a biopolymer sanitizer for leafy vegetables: synthesis, characteristics, and traditional vs. dry nano-aerosol applications

A series of quaternary dimethyl-(alkyl)-ammonium chitosan derivatives (QACs) was synthesized and studied for physicochemical properties and bioactivity. The QACs tended to spontaneously self-assembly into nanoaggregates. Antimicrobial activity was examined in vitro on Gram-negative Escherichia coli (E. coli) and Gram-positive Listeria innocua (L. innocua) bacteria as well as phytopathogenic fungus Botrytis cinerea. The hexyl chain-substituted QAC-6 demonstrated the highest potency causing 3.0- and 4.5-log CFU mL-1 reduction of E. coli and L. innocua, respectively. QAC-6 was tested for antimicrobial activity on stainless steel coupons and fresh spinach leaves. A traditional 'wet' application (spray) and dry Engineered Water Nanostructure (EWNS) approach were used for spinach decontamination. With both approaches, significant reduction of microbial load on the treated produce was achieved. The wet application showed a greater reduction of microbial load, while the advantages of EWNS were reaching the antimicrobial effect with miniscule dose of active agent leaving treated surface visibly dry.

Preparation, Post-Modification, and Antibacterial Application of Gelatin Electrospun Membranes

Two bis(diaryldiazomethane)s substituted with amino groups are synthesized and used for the surface modification of membranes electrospun from gelatin. These membranes are then reacted with tolylene-2,4-diisocyanate to give urea-functionalized materials, so that hydrogen peroxide can be reversibly bound onto their surface. These membranes are characterized by scanning electron microscopy, XPS, differential scanning calorimeter, and tensile test to show their surface properties and bulk properties. The surface modification with amino-substituted diazomethanes and the subsequent cross-linking reaction with diisocyanates contribute to high loadings of hydrogen peroxide, and greatly increase the antibacterial activity of gelatin-derived membranes, which open a new horizon in the preparation of high loading antiseptic/antibacterial biomacromolecular surfaces and interfaces.

Emerging Chitosan-Based Films for Food Packaging Applications

Recent years have witnessed great developments in biobased polymer packaging films for the serious environmental problems caused by the petroleum-based nonbiodegradable packaging materials. Chitosan is one of the most abundant biopolymers after cellulose. Chitosan-based materials have been widely applied in various fields for their biological and physical properties of biocompatibility, biodegradability, antimicrobial ability, and easy film forming ability. Different chitosan-based films have been fabricated and applied in the field of food packaging. Most of the review papers related to chitosan-based films are focusing on antibacterial food packaging films. Along with the advances in the nanotechnology and polymer science, numerous strategies, for instance direct casting, coating, dipping, layer-by-layer assembly, and extrusion, have been employed to prepare chitosan-based films with multiple functionalities. The emerging food packaging applications of chitosan-based films as antibacterial films, barrier films, and sensing films have achieved great developments. This article comprehensively reviews recent advances in the preparation and application of engineered chitosan-based films in food packaging fields.

Transparent Copper-Loaded Chitosan/Silica Antibacterial Coatings with Long-Term Efficacy

Bacteria-contaminated inanimate surfaces within hospitals and clinics result in transmission of pathogens via direct or indirect contact, leading to increased risk of healthcare-associated infections (HAI). The use of antibacterial coatings is a potential way of reducing the bacterial burden, but many surfaces such as instrument panels and monitors necessitate the coatings to be transparent while being highly antibacterial. In this work, silica nanoparticles (SiO₂ NPs) were first grown over a layer of acrylated quaternized chitosan (AQCS) covalently immobilized on commercially available transparent poly(vinyl fluoride) (PVF) films. The SiO₂ NPs then served as nanoreservoirs for adsorption of copper ions. The coated PVF films were transparent and reduced viable bacterial count by ∼99% and 100%, when incubated with a bacteria-loaded droplet for 60 and 120 min, respectively. The killing efficacy of these coatings, after wiping 100 times, with a deionized water-wetted cloth was reduced slightly to 97-98%. The stability of these coatings can be further improved with the deposition of another layer of cationic quaternized chitosan (QCS) over the negatively charged SiO₂ NP layer, wherein the coatings maintained ∼99% killing efficacy even after 100 wipes. These coatings showed no significant toxicity to mammalian cells and, hence, can potentially be used in a clinical setting for reducing HAI.

Surface modification strategies for combating catheter-related complications: recent advances and challenges

This review summarizes the progress made in addressing bacterial colonization and other surface-related complications arising from catheter use.

B. Multifunctional nano-engineered and bio-mimicking smart superhydrophobic reticulated ABS/fumed silica composite thin films with heat-sinking applications

There are increasing requirements for engineered surfaces with distinct properties such as superhydrophobicity, self-cleaning, high thermal stability, and anti-corrosion.