Versatile antibacterial surface with amphiphilic quaternized chitin-based derivatives for catheter associated infection prevention

Advances in polysaccharide-based antibacterial materials

Microbial contamination is a major threat to the public health and a primary cause of food spoilage, leading to significant economic losses worldwide. Various materials have been used to combat microbes, including inorganic materials, metals and polymers. Among these, natural polymers have attracted much attention in both academic and industrial research due to their abundance, renewability, biocompatibility, biodegradability and ease of processing. Polysaccharides, such as cellulose and chitosan (chitin), are a crucial category of natural polymers. However, most polysaccharides lack inherent antibacterial activity, limiting their applications in fields like antibacterial packaging and wound dressing etc. Therefore, it is crucial to increase their antibacterial property to expand their application as green antibacterial materials. Various methods, including blending, grafting and in-situ synthesis, have been used to fabricate polysaccharide-based antibacterial materials. This review highlights the major advancements and potential of novel polysaccharide-based antibacterial materials, primarily used in antibacterial food packaging or wound dressings. Moreover, the future prospects and challenges of polysaccharide-based antibacterial materials and the incorporated antimicrobial compounds are also discussed.

Recent Progress in Antibacterial Surfaces for Implant Catheters

Catheter-related infections (CRIs) caused by hospital-acquired microbial infections lead to the failure of treatment and the increase of mortality and morbidity. Surface modifications of the implant catheters have been demonstrated to be effective approaches to improve and largely reduce the bacterial colonization and related complications. In this work, we focus on the last 5-year progress in the surface modifications of biomedical catheters to prevent CRIs. Their antibacterial strategies used for surface modifications are further divided into 5 classifications through the antimicrobial mechanisms, including active surfaces, passive surfaces, active and passive combination surfaces, stimulus-type response surfaces, and other types. Each feature and the latest advances in these abovementioned antibacterial surfaces of implant catheters are highlighted. Finally, these confronting challenges and future prospects are discussed for the antibacterial modifications of implant catheters.

Progress in chitin/chitosan and their derivatives for biomedical applications: Where we stand

Chitin and its deacetylated form, chitosan, have demonstrated remarkable versatility in the realm of biomaterials. Their exceptional biocompatibility, antibacterial properties, pro- and anticoagulant characteristics, robust antioxidant capacity, and anti-inflammatory potential make them highly sought-after in various applications. This review delves into the mechanisms underlying chitin/chitosan's biological activity and provides a comprehensive overview of their derivatives in fields such as tissue engineering, hemostasis, wound healing, drug delivery, and hemoperfusion. However, despite the wealth of studies on chitin/chitosan, there exists a notable trend of homogeneity in research, which could hinder the comprehensive development of these biomaterials. This review, taking a clinician's perspective, identifies current research gaps and medical challenges yet to be addressed, aiming to pave the way for a more sustainable future in chitin/chitosan research and application.

Dextran-Based Antibacterial Hydrogel Dressings for Accelerating Infected Wound Healing by Reducing Inflammation Levels

Infected wounds pose challenges such as exudate management, bacterial infections, and persistent inflammation, making them a significant challenge for modern dressings. To address these issues in infected wounds more effectively, aerogel-hydrogel biphase gels based on dextran are developed. The gel introduced in this study exhibits antibacterial and anti-inflammatory properties in the process of wound therapy, contributing to accelerated wound healing. The aerogel phase exhibits exceptional water-absorption capabilities, rapidly soaking up exudate from infected wound, thereby fostering a clean and hygienic wound healing microenvironment. Concurrently, the aerogel phase is enriched with hydrogen sulfide donors. Following water absorption and the formation of the hydrogel phase, it enables the sustained release of hydrogen sulfide around the wound sites. The experiments confirm that hydrogen sulfide, by promoting M2 macrophage differentiation and reducing the levels of inflammatory factors, effectively diminishes local inflammation levels at the wound site. Furthermore, the sodium copper chlorophyllin component within the hydrogel phase demonstrates effective antibacterial properties through photodynamic antimicrobial therapy, providing a viable solution to wound infection challenges.

Melt electrowritten poly-lactic acid /nanodiamond scaffolds towards wound-healing patches

Multifunctional wound dressings, enriched with biologically active agents for preventing or treating infections and promoting wound healing, along with cell delivery capability, are highly needed. To address this issue, composite scaffolds with potential in wound dressing applications were fabricated in this study. The poly-lactic acid/nanodiamonds (PLA/ND) scaffolds were first printed using melt electrowriting (MEW) and then coated with quaternized β-chitin (QβC). The NDs were well-dispersed in the printed filaments and worked as fillers and bioactive additions to PLA material. Additionally, they improved coating effectiveness due to the interaction between their negative charges (from NDs) and positive charges (from QβC). NDs not only increased the thermal stability of PLA but also benefitted cellular behavior and inhibited the growth of bacteria. Scaffolds coated with QβC increased the effect of bacteria growth inhibition and facilitated the proliferation of human dermal fibroblasts. Additionally, we have observed rapid extracellular matrix (ECM) remodeling on QβC-coated PLA/NDs scaffolds. The scaffolds provided support for cell adhesion and could serve as a valuable tool for delivering cells to chronic wound sites. The proposed PLA/ND scaffold coated with QβC holds great potential for achieving fast healing in various types of wounds.

Generalized Multifunctional Coating Strategies Based on Polyphenol-Amine-Inspired Chemistry and Layer-by-Layer Deposition for Blood Contact Catheters

Blood-contacting catheters play a pivotal role in contemporary medical treatments, particularly in the management of cardiovascular diseases. However, these catheters exhibit inappropriate wettability and lack antimicrobial characteristics, which often lead to catheter-related infections and thrombosis. Therefore, there is an urgent need for blood contact catheters with antimicrobial and anticoagulant properties. In this study, we employed tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) to create a stable hydrophilic coating under mild conditions. Heparin (Hep) and poly(lysine) (PL) were then modified on the TA-APTES coating surface using the layer-by-layer (LBL) technique to create a superhydrophilic TA/APTES/(LBL)4 coating on silicone rubber (SR) catheters. Leveraging the superhydrophilic nature of this coating, it can be effectively applied to blood-contacting catheters to impart antibacterial, antiprotein adsorption, and anticoagulant properties. Due to Hep's anticoagulant attributes, the activated partial thromboplastin time and thrombin time tests conducted on SR/TA-APTES/(LBL)4 catheters revealed remarkable extensions of 276 and 103%, respectively, when compared to uncoated commercial SR catheters. Furthermore, the synergistic interaction between PL and TA serves to enhance the resistance of SR/TA-APTES/(LBL)4 catheters against bacterial adherence, reducing it by up to 99.9% compared to uncoated commercial SR catheters. Remarkably, the SR/TA-APTES/(LBL)4 catheter exhibits good biocompatibility with human umbilical vein endothelial cells in culture, positioning it as a promising solution to address the current challenges associated with blood-contact catheters.

Chitinous Bioplastic Enabled by Noncovalent Assembly

Natural polymeric-based bioplastics usually lack good mechanical or processing performance. It is still challenging to achieve simultaneous improvement for these two usual trade-off features. Here, we demonstrate a full noncovalent mediated self-assembly design for simultaneously improving the chitinous bioplastic processing and mechanical properties via plane hot-pressing. Tannic acid (TA) is chosen as the noncovalent mediator to (i) increase the noncovalent cross-link intensity for obtaining the tough noncovalent network and (ii) afford the dynamic noncovalent cross-links to enable the mobility of chitin molecular chains for benefiting chitinous bioplastic nanostructure rearrangement during the shaping procedure. The multiple noncovalent mediated network (chitin-TA and chitin-chitin cross-links) and the pressure-induced orientation nanofibers structure endow the chitinous bioplastics with robust mechanical properties. The relatively weak chitin-TA noncovalent interactions serve as water mediation switches to enhance the molecular mobility for endowing the chitin/TA bioplastic with hydroplastic processing properties, rendering them readily programmable into versatile 2D/3D shapes. Moreover, the fully natural resourced chitinous bioplastic exhibits superior weld, solvent resistance, and biodegradability, enabling the potential for diverse applications. The full physical cross-linking mechanism highlights an effective design concept for balancing the trade-off of the mechanical properties and processability for the polymeric materials.

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.

Quaternary ammonium salt-modified isabgol scaffold as an antibacterial dressing to improve wound healing

Chronic wounds require suitable treatment and management strategies for proper healing. Among other causes, infection delays the healing of wounds and increases the risk of wound-related complications. In this study, an inherently antibacterial and biocompatible wound dressing is developed to enhance the healing. Chemical modification of a natural polysaccharide, Isabgol with epoxypropyltrimethylammonium chloride, renders antibacterial activity to the material. This is the first report of such chemical modification of this polymer for biomedical applications. The modified material is freeze-dried to obtain porous scaffolds. ¹³C NMR and FTIR analysis confirmed the modification of the Isabgol polymer chains with EPTMAC. SEM analysis confirmed the porous structure of the scaffold that would allow the exchange of gases and nutrients through the matrix. The material can swell up to 17 times its initial weight, allowing it to absorb wound exudates and maintain a moist environment at the wound site. Thermogravimetric analysis and compression testing showed that the scaffold has suitable thermal and mechanical properties. The material is antibacterial and can potentially prevent infections at the wound site. In vitro studies have confirmed that these scaffolds are cytocompatible and hemocompatible. These properties indicate that the EPTMAC-modified Isabgol scaffolds would be suitable for wound dressing applications.

The Construction of Alkaline Phosphatase-Responsive Biomaterial and Its Application for In Vivo Urinary Tract Infection Therapy

Urinary tract infections caused by urinary catheter implantations are becoming more serious. Therefore, the construction of a responsive antibacterial biomaterial that can not only provide biocompatible conditions, but also effectively prevent the growth and metabolism of bacteria, is urgently needed. In this work, a benzophenone-derived phosphatase light-triggered antibacterial agent is designed and synthesized, which is tethered to the biological materials using a one-step method for in vivo antibacterial therapy. This surface could kill gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). More importantly, because this material exhibited a zwitterion structure, it does not damage blood cells and tissue cells. When the bacteria interact with this surface, the initial fouling of the bacteria is reduced by zwitterion hydration. When the bacteria actively accumulate and metabolize to produce a certain amount of alkaline phosphatase, the surface immediately started the sterilization performance, and the bactericidal effect is achieved by destroying the bacterial cell membrane. In summary, an antibacterial biomaterial that shows biocompatibility with mammalian cells is successfully constructed, providing new ideas for the development of intelligent urinary catheters.