Nitric oxide-releasing responsive biomaterials for antimicrobial skin therapy

Nitric oxide (NO) is a key signaling molecule involved in many physiological processes including vasodilation, neurotransmission, inflammatory and antimicrobial responses. Despite its therapeutic potential, its clinical utility remains limited due to its extremely short half-life (less than 5 s), high reactivity (with oxygen radicals) and the need for precise spatiotemporal dose control. To overcome these limitations, recent advancements in biomaterials have led to the development of responsive systems capable of delivering NO in a targeted and controlled manner. These systems can respond to endogenous stimuli (such as pH changes, enzymatic activity, altered redox environment (associated with hypoxia, oxidative stress) which are key characteristics of diseased cells) or to exogenous stimuli (such as light, X-ray, ultrasound). By allowing site-specific and time-controlled NO release, these responsive biomaterials offer improved control over local NO delivery and are being evaluated predominantly in in vitro and animal models. In this review, we discuss the advances in design of NO-releasing responsive biomaterials with a particular focus on applications in antimicrobial skin therapy. This review bridges materials bioengineering and dermatology to explore the promise of NO-based therapies for tackling skin and wound care problems.