Marine Recombinant L-Asparaginase-MoO3 Nanocomposite as an Ecofriendly Antifouling Paint Formula

Abstract

Marine biofouling poses significant economic and environmental challenges by increasing fuel consumption, accelerating material degradation, and facilitating the spread of invasive species. Environmentally benign antifouling technologies are therefore urgently needed following restrictions on conventional biocidal coatings. In this study, recombinant L-asparaginase derived from the marine bacterium Pseudomonas otitidis EGY-NIOF-A1 was immobilized onto molybdenum trioxide nanoparticles (MoO3NPs) and evaluated as a novel eco-friendly antifouling coating additive. The recombinant enzyme exhibited an activity of 19.9 U mL-1 and a specific activity of 2.03 U mg-1. Antimicrobial assays demonstrated inhibitory activity against selected pathogenic microorganisms, while hemolysis assays confirmed the non-hemolytic nature of the free enzyme and only minor hemolytic effects following nanoparticle immobilization. Molecular docking supported plausible interactions between L-asparaginase and MoO3 through electrostatic interactions, hydrophobic interactions, hydrogen bonding, and Van der Waals forces. Antifouling performance was assessed on wood and steel panels immersed in natural seawater for up to four weeks. On wood substrates, all Asparaginase-MoO3NP formulations achieved near-complete inhibition after four weeks (99.54-99.94%), comparable to a commercial antifouling coating. On steel substrates, antifouling efficacy increased with immersion time, with the best-performing formulation achieving 75.07% inhibition compared with 47.02% for the commercial coating. Statistical modelling identified immersion time, coating formulation, substrate type, paint pH, and their interactions as significant determinants of biofouling response. These findings demonstrate that marine-derived recombinant L-asparaginase immobilized on MoO3 nanoparticles represents a promising enzyme-nanoparticle platform for sustainable antifouling coating development, while further long-term field validation and physicochemical characterization remain necessary before practical deployment.