Showing papers by "En-Tang Kang published in 2020"

Antimicrobial Copper-Based Materials and Coatings: Potential Multifaceted Biomedical Applications.

Abstract: Surface contamination by microbes leads to several detrimental consequences like hospital- and device-associated infections. One measure to inhibit surface contamination is to confer the surfaces with antimicrobial properties. Copper's antimicrobial properties have been known since ancient times, and the recent resurgence in exploiting copper for application as antimicrobial materials or coatings is motivated by the growing concern about antibiotic resistance and the pressure to reduce antibiotic use. Copper, unlike silver, demonstrates rapid and high microbicidal efficacy against pathogens that are in close contact under ambient indoor conditions, which enhances its range of applicability. This review highlights the mechanisms behind copper's potent antimicrobial property, the design and fabrication of different copper-based antimicrobial materials and coatings comprising metallic copper/copper alloys, copper nanoparticles or ions, and their potential for practical applications. Finally, as the antimicrobial coatings market is expected to grow, we offer our perspectives on the implications of increased copper release into the environment and the potential ecotoxicity effects and possibility of development of resistant genes in pathogens.

Precisely Structured Nitric-Oxide-Releasing Copolymer Brush Defeats Broad-Spectrum Catheter-Associated Biofilm Infections In Vivo

Abstract: Gram-negative bacteria cannot be easily eradicated by antibiotics and are a major source of recalcitrant infections of indwelling medical devices. Among various device-associated infections, intravascular catheter infection is a leading cause of mortality. Prior approaches to surface modification, such as antibiotics impregnation, hydrophilization, unstructured NO-releasing, etc., have failed to achieve adequate infection-resistant coatings. We report a precision-structured diblock copolymer brush (H(N)-b-S) composed of a surface antifouling block of poly(sulfobetaine methacrylate) (S) and a subsurface bactericidal block (H(N)) of nitric-oxide-emitting functionalized poly(hydroxyethyl methacrylate) (H) covalently grafted from the inner and outer surfaces of a polyurethane catheter. The block copolymer architecture of the coating is important for achieving good broad-spectrum anti-biofilm activity with good biocompatibility and low fouling. The coating procedure is scalable to clinically useful catheter lengths. Only the block copolymer brush coating ((H(N)-b-S)) shows unprecedented, above 99.99%, in vitro biofilm inhibition of Gram-positive and Gram-negative bacteria, 100-fold better than previous coatings. It has negligible toxicity toward mammalian cells and excellent blood compatibility. In a murine subcutaneous infection model, it achieves >99.99% biofilm reduction of Gram-positive and Gram-negative bacteria compared with 99.99% reduction of MRSA with 5-day implantation. This precision coating is readily applicable for long-term biofilm-resistant and blood-compatible copolymer coatings covalently grafted from a wide range of medical devices.

Switchable Antimicrobial and Antifouling Coatings from Tannic Acid-Scaffolded Binary Polymer Brushes

Abstract: Surface biofouling has been a serious environmental and ecological problem for centuries. In this study, pH-sensitive poly(2-diisopropylaminoethyl methacrylate)-b-poly(2-methacryloyloxyethyl phosph...

A Simple Drop-and-Dry Approach to Grass-Like Multifunctional Nanocoating on Flexible Cotton Fabrics Using In Situ-Generated Coating Solution Comprising Titanium-Oxo Clusters and Silver Nanoparticles.

Abstract: Multifunctional nanocoatings have been of central importance in various technological fields, yet their fabrication, especially on flexible substrates, still remains a persistent challenge to date....

Potentiating anti-cancer chemotherapeutics and antimicrobials via sugar-mediated strategies

Abstract: The concept of targeted drug delivery evolved from the “magic bullet” idea put forth by Paul Ehrlich more than a century ago, whose original intention was to kill disease-causing microbes without harming the body itself. In this minireview, we highlight sugar-mediated targeted delivery strategies that capitalize on the unique metabolic features of cancer cells (the so-called Warburg effect) and bacteria to enhance the efficacy of anti-cancer chemotherapeutics and antimicrobials, respectively. The differences in metabolism between cancerous and normal cells and how the overexpression of sugar transporters in cancer cells can be capitalized for cancer therapy are first discussed. Subsequently, different designs of sugar-conjugated therapeutic agents and delivery systems are presented. Finally, we show that while targeting bacterial cell metabolism to increase antimicrobial efficacy is based on a different concept from that employed for cancer therapy, co-administration of antimicrobials with glucose and other metabolites either in the free form or conjugated to carriers can increase bacterial cell susceptibility to antimicrobial agents.

Applications and challenges of smart antibacterial coatings

Abstract: Bacterial colonization has detrimental consequences like hospital-associated infections, food spoilage, and equipment fouling. Antibacterial coatings can potentially be a solution, with “smart” coatings being an emerging area of interest. While the definition of smart coatings is broad, smart antibacterial coatings in this chapter are considered as those capable of exhibiting or altering their antibacterial activity in response to a stimulus. Such coatings are commonly investigated for application on medical devices, but they can potentially be applied in healthcare facilities, food packaging and textiles, and for water treatment and industrial equipment. Nevertheless, to translate these concepts into practical applications, several challenges have to be overcome such as the lack of appropriate stimuli in certain environments and the difficulty in designing coatings to control their antibacterial activity or maintain long-term efficacy. For medical-device applications the complex in vivo environment and the need to minimize toxicity pose additional challenges.