Nitric Oxide-Releasing Emulsion with Hyaluronic Acid and Vitamin E

Roles and current applications of S-nitrosoglutathione in anti-infective biomaterials

Bacterial infections can compromise the physical and biological functionalities of humans and pose a huge economical and psychological burden on infected patients. Nitric oxide (NO) is a broad-spectrum antimicrobial agent, whose mechanism of action is not affected by bacterial resistance. S-nitrosoglutathione (GSNO), an endogenous donor and carrier of NO, has gained increasing attention because of its potent antibacterial activity and efficient biocompatibility. Significant breakthroughs have been made in the application of GSNO in biomaterials. This review is based on the existing evidence that comprehensively summarizes the progress of antimicrobial GSNO applications focusing on their anti-infective performance, underlying antibacterial mechanisms, and application in anti-infective biomaterials. We provide an accurate overview of the roles and applications of GSNO in antibacterial biomaterials and shed new light on the avenues for future studies.

Biodegradable hyaluronic acid-based, nitric oxide-releasing nanofibers for potential wound healing applications

Nitric oxide (NO) is one of the smallest gas molecules with pharmaceutical and potential wound therapeutic effects due to its ability to regulate inflammation and eradicate bacterial infections. Recently, NO-releasing synthetic polymer-based nanofibers have become promising candidates for wound healing due to their facile functionalisation, tunable mechanical properties, and large effective surface areas. However, synthetic polymer-based nanofibers suffer from poor degradability in the physiological milieu, which restricts their use in in vivo applications. In this study, we developed biodegradable and nitric oxide-releasing nanofibers for potential wound healing applications. We synthesised dual-functionalised hyaluronic acid (HA) containing methacrylate groups and N-diazeniumdiolate (NONOate)-NO donor groups and capable of forming crosslinked, electrospun nanofibers, with an effective NO payload, through an electrospinning process and photoinitiated polymerisation. Nuclear magnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy confirmed the successful synthesis of the functionalised HA. Control over both the NO donor and HA concentrations allowed for the preparation of NO-releasing, HA-based nanofibers of varying diameters (240-490 nm), NO payloads (10-620 nmol mg^-1), maximum amounts of NO released (160-8920 ppb mg^-1), and NO release durations (1.5-20.2 h). Moreover, the NO-releasing nanofibers had good biodegradability and potential wound healing effects without any observed cytotoxicity. The biodegradable and NO-releasing HA-based nanofibers developed in this study have the potential application in wound healing.

Therapeutic Delivery of Nitric Oxide Utilizing Saccharide-Based Materials

As a gasotransmitter, nitric oxide (NO) regulates physiological pathways and demonstrates therapeutic effects such as vascular relaxation, anti-inflammation, antiplatelet, antithrombosis, antibacterial, and antiviral properties. However, gaseous NO has high reactivity and a short half-life, so NO delivery and storage are critical questions to be solved. One way is to develop stable NO donors and the other way is to enhance the delivery and storage of NO donors from biomaterials. Most of the researchers studying NO delivery and applications are using synthetic polymeric materials, and they have demonstrated significant therapeutic effects of these NO-releasing polymeric materials on cardiovascular diseases, respiratory disease, bacterial infections, etc. However, some researchers are exploring saccharide-based materials to fulfill the same tasks as their synthetic counterparts while avoiding the concerns of biocompatibility, biodegradability, and sustainability. Saccharide-based materials are abundant in nature and are biocompatible and biodegradable, with wide applications in bioengineering, drug delivery, and therapeutic disease treatments. Saccharide-based materials have been implemented with various NO donors (like S-nitrosothiols and N-diazeniumdiolates) via both chemical and physical methods to deliver NO. These NO-releasing saccharide-based materials have exhibited controlled and sustained NO release and demonstrated biomedical applications in various diseases (respiratory, Crohn's, cardiovascular, etc.), skin or wound applications, antimicrobial treatment, bone regeneration, anticoagulation, as well as agricultural and food packaging. This review aims to highlight the studies in methods and progress in developing saccharide-based NO-releasing materials and investigating their potential applications in biomedical, bioengineering, and disease treatment.

Nitric Oxide-Releasing Hyaluronic Acid as an Antibacterial Agent for Wound Therapy

Taking advantage of their respective wound-healing roles in physiology, the dual activity of hyaluronic acid (HA) and nitric oxide (NO) was combined to create a single-agent wound therapeutic. Carboxylic acid groups of HA (6 and 90 kDa) were chemically modified with a series of alkylamines via carbodiimide chemistry to provide secondary amines for subsequent N-diazeniumdiolate NO donor formation. The resulting NO-releasing HA derivatives stored 0.3-0.6 μmol NO mg^-1 and displayed diverse release kinetics (5-75 min NO-release half-lives) under physiological conditions. The 6 kDa HA with terminal primary amines and intermediate release kinetics exhibited broad-spectrum bactericidal activity against common wound pathogens, including planktonic methicillin-resistant Staphylococcus aureus as well as planktonic and biofilm-based multidrug-resistant Pseudomonas aeruginosa. The treatment of infected murine wounds with NO-releasing HA facilitated more rapid wound closure and decreased the quantity of the P. aeruginosa genetic material in the remaining wound tissue. Hyaluronidase readily degraded the HA derivatives, indicating that NO donor modification did not prohibit endogenous biodegradation pathways.