Biopolymeric Microneedles for Underwater Fish Vaccination

Over the next 30 years, with the world population continues to grow, food supplies will have to increase by 70%. Addressing challenges in food security by promoting healthy and sustainable protein sources is crucial. Aquaculture plays a vital role in meeting these requirements, and fish vaccination is integral to preventing disease spread in densely populated farming environments. However, traditional methods involving intramuscular or intraperitoneal injections require fish sedation, administration outside of water, and poses safety concerns for workers due to accidental needlestick injuries. <br/>In this work, we aim to develop an automatic system capable of precise vaccine delivery in aquaculture settings. We adapted microneedle design and fabrication for plants and mammals to meet the requirements for underwater applications. <br/>To ensure successful fish skin penetration, we have employed proteinaceous silk fibroin microneedles encapsulated with a water-proofing coating layer of food-grade natural resin. This coating layer preserves the mechanical strength of the silk fibroin microneedles in water for hours. The water-proofing coating layer prevents water absorption and swelling of silk fibroin microneedles, which could otherwise weaken their mechanical strength. The coating layer preserves the mechanical strength of silk fibroin microneedles in water for hours. <br/>Additionally, the coating layer prevents the loaded substance from prematurely releasing into the aquatic environment, ensuring controlled release after fish skin penetration. Our results demonstrate that once the microneedles pierce the fish skin, the cargo is released within hours primarily through diffusion. <br/>Our study presents a novel microneedle strategy designed specifically for precise injection and substance delivery in aquaculture, offering a promising solution for enhancing fish health, productivity, and sustainability.