"Green" Cross-Linking of Poly(Vinyl Alcohol)-Based Nanostructured Biomaterials: From Eco-Friendly Approaches to Practical Applications.

Recently, a growing need for sustainable materials in various industries, especially biomedical, environmental, and packaging applications, has been observed. Poly(vinyl alcohol) (PVA) is a versatile and widely used polymer, valued for its biocompatibility, water solubility, and easy processing, e.g., forming nanofibers via electrospinning. As a result of cross-linking, PVA turns into a three-dimensional structure-hydrogel with unusual sorption properties and mimicry of biological tissues. However, traditional cross-linking methods often involve toxic chemicals and harsh conditions, which can limit its eco-friendly potential and raise concerns about environmental impact. "Green" cross-linking approaches, such as the use of natural cross-linkers, freeze-thawing, enzymatic processes, irradiation, heat treatment, or immersion in alcohol, offer an environmentally friendly alternative that aligns with global trends toward sustainability. These methods not only reduce the use of harmful substances but also enhance the biodegradability and safety of the materials. By reviewing and analyzing the latest advancements in "green" PVA cross-linking approaches, this review provides a comprehensive overview of current techniques, their advantages, limitations, and potential applications. The main emphasis is placed on PVA nanostructured forms and applications of PVA-based biomaterials in areas such as wound dressings, drug delivery systems, tissue engineering, biological filters, and biosensors. Moreover, this article will contribute to the broader scientific understanding of how the materials based on PVA can be optimized both in terms of "greener" and safer production, as well as adjusting the final platform properties.