Reviewing Status quo of chitosan based nanocomposites for antifouling applications

Marine biofouling remains a persistent challenge affecting the durability, efficiency and operational cost of marine structures and vessels. Conventional antifouling coatings, although effective, they are limited due to several factors, including toxicity, environmental persistence and regulatory restrictions. In this context, chitosan (CHT) and CHT-based nanocomposites have now intruded into various applications, satisfying multi-faceted requisites. What started from a humble beginning of marine shell waste transformed to chitin, transpired to CHT and diversified to multiple CHT derivatives and nanocomposites. The CHT-based coatings hold promise as eco-friendly alternatives due to their biodegradability, biocompatibility and inherent antimicrobial properties. Hence, the present review aimed to consolidate the various existing CHT based nanocomposites, and evaluated their antifouling and antibacterial efficiencies. Among the CHT-based nanocomposites, ZnO-CHT systems have demonstrated efficient antifouling with relatively lower toxicity, making them one of the most efficient and sustainable antifouling systems. In addition to the antifouling performance, the mechanisms behind the antifouling activity of the CHT-based nanocomposites were also discussed. The future recommendations based on the current challenges faced have been summarised. By consolidating the current knowledge on antifouling application of CHT-based nanocomposites, this review addresses existing knowledge gaps and provides comprehensive information and insights for future research and developments.