Evaluation of Green-Synthesized Nanoparticles for their Activity against Marine Fouling Bacteria: A Promising Approach for Antimicrobial Coatings

The present study aimed to synthesize nanoparticles from several crude extracts of Ulva fasciata Delile, Corallina mediterranea Areschoug, Jania rubens (Linnaeus), Pterocladiella capillacea (S.G. Gmelin), and mangrove leaves of Avicennia marina (Forsk.), mixed with composites of chitosan and iron magnet. The efficiency of these synthesized nanoparticles was screened and evaluated against marine biofilm bacteria as a potential solution to combat biofouling in marine environments. The antimicrobial potential of these biosynthesized nanoparticles was assessed under optimal conditions of concentration and pH. Various techniques, including Fourier Transform Infrared Spectroscopy (FT-IR) analysis and Transmission Electron Microscopy (TEM), were used to characterize the chemical active groups and physical properties of the nanoparticles. The findings of this study revealed that the size of all the biosynthesized nanoparticles ranged between 2.16 and 18.50nm. They demonstrated high antibacterial activity against marine fouling bacteria, suggesting a promising eco-friendly alternative for biofouling control in marine environments. The data indicated that the nanocomposites of J. rubens and C. mediterranea with chitosan were the most effective in suppressing bacterial communities, while the composites with extracts from A. marina and P. capillacea exhibited very low efficiency. For metal-centered nanoparticles, the synthesized nanocomposite of iron with J. rubens and U. fasciata showed the highest antibacterial efficiency, followed by the composite with leaves of A. marina mangrove. Nanocomposites using magnet with all the crude extracts showed lower efficiency compared to those with iron. The study also revealed that increasing the concentration of crude extracts had no significant effect on the efficiency of the nanocomposites. Additionally, shifting the pH toward an alkaline medium (pH = 9) led to a decrease in the antibacterial efficiency of the biosynthesized nanoparticles. These findings clearly demonstrate that biosynthesized nanoparticles from algae extracts combined with iron or chitosan can be developed as highly efficient antibacterial agents against biofilm-forming bacteria.