One-step coordination of metal-phenolic networks as antibacterial coatings with sustainable and controllable copper release for urinary catheter applications

Antimicrobial Phenolic Materials: From Assembly to Function

Infectious diseases pose considerable challenges to public health, particularly with the rise of multidrug-resistant pathogens that globally cause high mortality rates. These pathogens can persist on surfaces and spread in public and healthcare settings. Advances have been made in developing antimicrobial materials to reduce the transmission of pathogens, including materials composed of naturally sourced polyphenols and their derivatives, which exhibit antimicrobial potency, broad-spectrum activity, and a lower likelihood of promoting resistance. This review provides an overview of recent advances in the fabrication of antimicrobial phenolic biomaterials, where natural phenolic compounds act as active antimicrobial agents or encapsulate other antimicrobial agents (e.g., metal ions, antimicrobial peptides, natural biopolymers). Various forms of phenolic biomaterials synthesized through these two strategies, including antimicrobial particles, capsules, hydrogels, and coatings, are summarized, with a focus on their application in wound healing, bone repair and regeneration, oral health, and antimicrobial coatings for medical devices. The potential of these advanced phenolic biomaterials provides a promising therapeutic approach for combating antimicrobial-resistant infections and reducing microbial transmission.

Stable Antifouling and Antibacterial Coating Based on Assembly of Copper-Phenolic Networks

Biofilm formation on medical devices has become a worldwide issue arising from its resistance to bactericidal agents and presenting challenges to eradicating biofouling adhesion, especially in biological fluids. Metal-phenolic networks have been demonstrated as a versatile and efficient strategy to prevent biofilm formation by endowing medical devices with prolonged antifouling and antibacterial activities in a one-step surface modification. In this study, we report a simple and environmentally friendly method using coordination chemistry between copper ions (Cu2+) and dopamine-containing copolymer to fabricate metal-phenolic network-based coatings. The phenolic groups also imparted the adhesion of glycopolymer-containing dopamine residues to inorganic and organic substrates, resulting in dual antifouling and bactericidal surfaces. 2-gluconamidoethyl methacrylamide monomer (GAEMA) was first copolymerized with dopamine methacrylamide (DMA) using a free-radical polymerization process. The resulting copolymer (GAEMA-DMA), denoted as GADMA, was then mixed with copper ions in a one-step process to form the GADMA-Cu coating. The GADMA-Cu coating was hydrophilic and significantly reduced the water contact angle (WCA) and adsorption of bovine serum albumin protein even after incubation in a bovine serum albumin solution for 30 h. Moreover, the coating exhibited strong antibacterial activity against Escherichia coli and Staphylococcus aureus and was biocompatible with 99% cell viability toward normal human fibroblast (HDFa) cells. Thus, our coating shows great potential for application in medical devices.

Antibacterial and antifouling materials for urinary catheter coatings

Implantable medical devices have played a significant role in improving both medical care and patients' quality of life. Urinary Catheters (UCs) are commonly utilized as a substitute for bladder drainage and urine collection to prevent urinary retention in patients. However, bacterial colonization and biofilm formation on the catheter surface are prone to occur, leading to catheter-associated urinary tract infections (CAUTIs) and other complications. In recent years, UC coatings have garnered increasing attention. In this review, various antifouling and antibacterial materials for UC coatings are summarized and their impacts on bacterial activities are linked to potential mechanisms of action. Additionally, this review provides an in-depth understanding of the current advancements in UC coatings by presenting the advantages, limitations, notable achievements, and latest research findings. Finally, it anticipates the prospective design and development trajectories of UC coatings in this domain. This holds paramount significance in advancing medical device technology. STATEMENT OF SIGNIFICANCE: Combating catheter-associated urinary tract infections is a major healthcare challenge, and urinary catheter (UC) coatings are considered promising candidates to counter these infections. In this review, various antifouling and antibacterial materials for UCs are summarized, and their impacts on bacterial activities are linked to potential mechanisms of action. Additionally, the review provides an in-depth understanding of the current advancements in UC coatings by presenting the advantages, limitations, notable achievements, and latest research findings. This holds paramount significance in advancing medical device technology. This review not only contributes to the scientific research but also sparks interest among readerships and other researchers in the study of safer and more effective UC coatings for improved patient outcomes.

Recent advances of copper-based metal phenolic networks in biomedical applications

Metal-phenolic Networks (MPNs) are a novel class of nanomaterial developed gradually in recent years which are self-assembled by metal ions and polyphenolic ligands. Due to their environmental protection, good adhesion, and biocompatibility with green phenolic ligands, MPNs can be used as a new type of nanomaterial. They show excellent properties such as anti-inflammatory, antioxidant, antibacterial, and anticancer, and have been widely studied in the biomedical field. As one of the most common subclasses of the MPNs family, copper-based MPNs have been widely studied for drug delivery, Photodynamic Therapy (PDT), Chemo dynamic Therapy (CDT), antibacterial and anti-inflammatory, bone tissue regeneration, skin regeneration wound repair, and metal ion imaging. In this paper, the preparation strategies of different types of copper-based MPNs are reviewed. Then, the application status of copper-based MPNs in the biomedical field under different polyphenol ligands is introduced in detail. Finally, the existing problems and challenges of copper-based MPNs are discussed, as well as their future application prospects in the biomedical field.

Nanoclay Hydrogel Microspheres with a Sandwich-Like Structure for Complex Tissue Infection Treatment

Addressing complex tissue infections remains a challenging task because of the lack of effective means, and the limitations of traditional bioantimicrobial materials in single-application scenarios hinder their utility for complex infection sites. Hence, the development of a bioantimicrobial material with broad applicability and potent bactericidal activity is necessary to treat such infections. In this study, a layered lithium magnesium silicate nanoclay (LMS) is used to construct a nanobactericidal platform. This platform exhibits a sandwich-like structure, which is achieved through copper ion modification using a dopamine-mediated metallophenolic network. Moreover, the nanoclay is encapsulated within gelatin methacryloyl (GelMA) hydrogel microspheres for the treatment of complex tissue infections. The results demonstrate that the sandwich-like micro- and nanobactericidal hydrogel microspheres effectively eradicated Staphylococcus aureus (S. aureus) while exhibiting excellent biocompatibility with bone marrow-derived mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). Furthermore, the hydrogel microspheres upregulated the expression levels of osteogenic differentiation and angiogenesis-related genes in these cells. In vivo experiments validated the efficacy of sandwich-like micro- and nanobactericidal hydrogel microspheres when injected into deep infected tissues, effectively eliminating bacteria and promoting robust vascular regeneration and tissue repair. Therefore, these innovative sandwich-like micro- and nanobacteriostatic hydrogel microspheres show great potential for treating complex tissue infections.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

Medical devices such as venous catheters (VCs) and urinary catheters (UCs) are widely used in the hospital setting. However, the implantation of these devices is often accompanied by complications. About 60 to 70% of nosocomial infections (NIs) are linked to biofilms. The main complication is the ability of microorganisms to adhere to surfaces and form biofilms which protect them and help them to persist in the host. Indeed, by crossing the skin barrier, the insertion of VC inevitably allows skin flora or accidental environmental contaminants to access the underlying tissues and cause fatal complications like bloodstream infections (BSIs). In fact, 80,000 central venous catheters-BSIs (CVC-BSIs)-mainly occur in intensive care units (ICUs) with a death rate of 12 to 25%. Similarly, catheter-associated urinary tract infections (CA-UTIs) are the most commonlyhospital-acquired infections (HAIs) worldwide.These infections represent up to 40% of NIs.In this review, we present a summary of biofilm formation steps. We provide an overview of two main and important infections in clinical settings linked to medical devices, namely the catheter-asociated bloodstream infections (CA-BSIs) and catheter-associated urinary tract infections (CA-UTIs), and highlight also the most multidrug resistant bacteria implicated in these infections. Furthermore, we draw attention toseveral useful prevention strategies, and advanced antimicrobial and antifouling approaches developed to reduce bacterial colonization on catheter surfaces and the incidence of the catheter-related infections.

A review on antimicrobial strategies in mitigating biofilm-associated infections on medical implants

Biomedical implants are crucial in providing support and functionality to patients with missing or defective body parts. However, implants carry an inherent risk of bacterial infections that are biofilm-associated and lead to significant complications. These infections often result in implant failure, requiring replacement by surgical restoration. Given these complications, it is crucial to study the biofilm formation mechanism on various biomedical implants that will help prevent implant failures. Therefore, this comprehensive review explores various types of implants (e.g., dental implant, orthopedic implant, tracheal stent, breast implant, central venous catheter, cochlear implant, urinary catheter, intraocular lens, and heart valve) and medical devices (hemodialyzer and pacemaker) in use. In addition, the mechanism of biofilm formation on those implants, and their pathogenesis were discussed. Furthermore, this article critically reviews various approaches in combating implant-associated infections, with a special emphasis on novel non-antibiotic alternatives to mitigate biofilm infections.

Surface functionalization of endotracheal tubes coated with laccase-gadolinium phosphate hybrid nanoparticles for antibiofilm activity and contrasting properties

Ventilator-associated pneumonia (VAP) is a severe hospital-acquired infection that endangers patients' treatment in intensive care units (ICUs). One of the leading causes of VAP is biofilm formation on the endotracheal tube (ETT) during ventilation. This study reports a combination of laccase-gadolinium phosphate hybrid nanoparticles (laccase@GdPO4·HNPs) and enzyme mediator with an antibiofilm property coated on the surface of the ETT. The hybrid nanostructures were fabricated through a simple, rapid, and facile laccase immobilization method, resulting in efficiency and yield percentages of 82 ± 6% and 83 ± 5%, respectively. The surface of the ETT was then functionalized and coated with the constructed HNP/catechol. The layered ETT was able to reduce the surface adhesion of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by 82.1%, 84.5%, and 77.1%, respectively. The prepared ETT did not affect the viability of human lung epithelial cells L929 and A549 at concentrations of 1-5 mg mL-1. The layered ETT produced a strong computed tomography (CT) signal in comparison with iobitridol. The HNP/catechol-coated ETT exhibited a Gd3+ release of 0.45 ppm over 72 h, indicating reduced risks of cytotoxicity arising from the metal ions. In this research we develop a biofilm-resistant and contrasting agent-based ETT coated with green synthesized laccase@GdPO4·HNPs.

Multifunctional hydrogel coatings with high antimicrobial loading efficiency and pH-responsive properties for urinary catheter applications

Catheter-associated urinary tract infections are one of the most common hospital-acquired infections. Encrustation formation results from infection of urease-producing bacteria and further complicates the situation. A typical sign of the initial onset of encrustation formation is the alkalization of the urine (pH up to 9-10). However, effective antibacterial strategies with high antimicrobial loading efficiency and pH-responsiveness of antimicrobial release are still lacking. In this study, we developed a poly(sulfobetaine methacrylate)-tannic acid (polySBMA-TA) hydrogel coating, which served as a universal, efficient, and responsive carrier for antimicrobials on urinary catheters. Common antimicrobials, including poly(vinylpyrrolidone)-iodine, copper ions, and nitrofurazone were loaded into the polySBMA-TA coating in high efficiency (several fold higher than that of the polySBMA coating), via the formation of multiple non-covalent interactions between the antimicrobials and hydrogel coating. The hydrogel coatings maintained good antibacterial properties under neutral conditions. More importantly, the pH-responsive release of antibacterial agents under alkaline conditions further enhanced the antibacterial activity of the coatings, which was advantageous for killing the urease-producing bacteria and preventing encrustation. In vitro and in vivo tests confirmed that the hydrogel coating has good biocompatibility, and could effectively inhibit bacterial colonization and encrustation formation. This study offers new opportunities for the utilization of a simple and universal antimicrobial-loaded hydrogel coating with smart pH-responsive properties to combat bacterial colonization and encrustation formation in urinary catheters.

Antimicrobial Properties of a Copper/Silicone Composite Membrane Prepared Using a Two-Step Immersion Process in Iodine and Copper Sulfate Solutions

Silicone (polydimethylsiloxane) materials are widely used in various applications. Due to microbe adherence and biofilm formation at the surface of silicone materials, silicone materials must possess antibacterial properties. To achieve this, we prepared copper (Cu)−silicone composite membranes using a simple two-step process of immersion in iodine and copper sulfate solutions. Subsequent scanning electron microscopy revealed Cu nanoparticles (CuNPs) of 10 to 200 nanometers in diameter on the silicone membrane surface, which were identified as copper iodide using energy-dispersive X-ray spectroscopy. The mechanical strength of the material did not change significantly as a result of the two-step immersion treatment and the Cu/silicone membrane showed excellent antibacterial efficacy against Escherichia coli and Staphylococcus aureus, maintaining R > 2 even after a physical impact such as stomacher treatment. Additionally, the Cu ions eluted from the Cu/silicone membrane remained at very low concentrations, suggesting firm immobilization of CuNPs on the silicone membrane. This proposed antimicrobial treatment method does not require special equipment, can be performed at room temperature, and has the potential for use on silicone materials other than membranes.