Sustainable bio-functionalized epoxy coatings enabled by Vibrio alginolyticus biofilm and nutrient microspheres with real-time monitoring via Fiber Bragg grating sensors

This work investigates a sustainable approach for mitigating marine corrosion on SS400 carbon steel by employing a composite coating system integrating Vibrio alginolyticus (ATCC® 17749™) biofilm with a water-based epoxy matrix. Nutrient-loaded microspheres were incorporated into the epoxy coating to enhance bacterial adhesion and promote the in situ generation of Extracellular Polymeric Substances (EPS). Immersion tests in a seawater environment revealed that bacterial metabolism influenced local parameters—specifically increasing Dissolved Oxygen (DO) and pH while reducing Oxidation-Reduction Potential (ORP)—creating conditions favorable for passivation. Fiber Bragg Grating (FBG) sensors detected larger wavelength shifts in coatings containing nutrient microspheres, confirming the development of a thicker and more robust protective biofilm. Gravimetric analysis over 14 days showed that while treated samples exhibited surface corrosion products, they experienced significantly lower weight loss compared to sterile seawater controls. Electrochemical measurements demonstrated an increase in open-circuit and corrosion potentials, a decrease in corrosion current density, and a marked rise in charge-transfer resistance (R ct ). The system achieved a maximum corrosion inhibition efficiency of 81.97% on the second day, while Electrochemical Impedance Spectroscopy (EIS) indicated that the biofilm reached its maximum physical stability and resistance on the twelfth day. These findings highlight the potential of bio-functionalized epoxy coatings as an environmentally benign strategy for protecting marine infrastructure. • A sustainable anti-corrosion strategy is developed using Vibrio alginolyticus biofilm formation on SS400 steel. • Nutrient-loaded microsphere coatings enhance bacterial adhesion and EPS generation. • Fiber Bragg Grating (FBG) sensors enable real-time, non-destructive monitoring of corrosion dynamics. • Electrochemical analysis shows increased corrosion potential and charge transfer resistance. • The proposed system achieves a maximum corrosion inhibition efficiency of 81.97%, offering an eco-friendly solution for marine protection.