Eco-Friendly Active Film and Sealant for Underwater Drug Delivery to Diseased Corals

Coral holobiont hosts several symbionts, such as algae, bacteria, archaea, fungi, and viruses. Bacteria are major regulators in maintaining holobiont homeostasis, especially in thermal or oxidative stress, with their distribution and community composition. However, not all symbiotic bacteria have solely beneficial effects on corals; some can induce dysbiosis, and others, like opportunistic strains, can leverage community dynamics to thrive and disrupt the holobiont equilibrium, inducing coral diseases. These have become a persistent threat to reefs, being more frequent and destructive to these ecosystems. To prevent catastrophic scenarios, effective technologies to treat outbreaks must be promptly implemented. We developed an eco-friendly underwater drug delivery system to efficiently treat bacterial infections in corals. This system consists of an antibiotic-loaded hydrophilic film that is applied directly onto the infected coral tissue, and a hydrophobic bio-based sealant that covers the film. The sealant ensures adhesion and prevents drug leakage into the environment. . The design was optimized to ensure monodirectional drug release to the infected coral tissue within one week of treatment, addressing the infected coral tissue and preventing environmental release. This technology successfully inhibited Vibrio coralliilyticus in vitro growth and halted the progression of tissue necrosis-like symptoms in 90% of tested corals.