Preparation and antifouling performance evaluation of fluorine-containing amphiphilic silica nanoparticles

A Lionfish-Skin-Inspired Intrinsic Antifouling Coating for Full-Ocean-Depth up to 7730 Meters

As marine equipment advances from shallow to deep-sea environments, the demand for high-performance antifouling materials continues to increase. The lionfish, a species inhabiting both deep-sea and shallow coral reefs, prevents fouling organism adhesion via its smooth, mucus-covered skin, which contains antimicrobial peptides. Inspired by lionfish skin, this work integrates zwitterionic segments with hydration-based fouling-release properties and the furan oxime ester structure with intrinsic antibacterial activity to develop a silicone-based antifouling coating capable of operating from shallow to deep-sea environments. The coating exhibits excellent antifouling properties in shallow-water environments, completely inhibiting protein adhesion and reducing bacterial, algae adhesion by up to 33.23% and 85.23%, respectively. displays superior intrinsic bactericidal activity, achieving a 100% bactericidal rate. Field panel immersion tests confirmed the coating's effectiveness in preventing the adhesion of large shallow-water fouling organisms. After 51 days of immersion at a maximum depth of 7730 meters in the Mariana Trench, no live bacteria are detected on the coating surface, which remained in excellent condition and retained its full bactericidal efficacy. This antifouling coating presents a promising solution for marine equipment across full ocean depths adn expands applications in the marine industry.

Sonochemical Functionalization of SiO2 Nanoparticles with Citric Acid and Monoethanolamine and Its Remarkable Effect on Antibacterial Activity

Nanoparticles (NPs) are excellent antibacterial agents due to their ability to interact with microorganisms at the cellular level. However, their antimicrobial capacity can be limited by their tendency to agglomerate. Functionalizing NPs with suitable ligands improves their stability and dispersion in different media and enhances their antibacterial activity. The present work studied the functionalization of SiO2 NPs using the sonochemical method and the Influence of organic ligands on antimicrobial activity (AA). The organic ligands studied were citric acid (CA) and monoethanolamine (MEA). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the amorphous structure of SiO2 NPs and their functionalization. Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) showed that functionalization with MEA (SiO2-MEA NPs) is more favored compared to AC (SiO2-CA NPs), and the organic ligand content was 34.42% and 28.0%, respectively. Fourier-transform infrared spectroscopy (FTIR) and RAMAN spectroscopy results confirmed the functionalization of NPs through the presence of carboxyl and amino groups. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential results showed that functionalization of SiO2 NPs helped to improve their dispersion and prevent their agglomeration. Furthermore, the results of antibacterial activity against Staphylococcus aureus and Escherichia coli showed that the functionalization provided a significant improvement in the antibacterial activity (AA) of the SiO2 NPs, where the SiO2-CA NPs showed the highest activity, with a 99.99% inhibition percentage at concentrations of 200 ppm against both E. coli and S. aureus strains. The AA is maintained at high concentrations of 1200 ppm, which is essential in applications requiring high percentages of biocidal NPs, such as marine coatings.

Quaternary Ammonium Salts-Based Materials: A Review on Environmental Toxicity, Anti-Fouling Mechanisms and Applications in Marine and Water Treatment Industries

The adherence of pathogenic microorganisms to surfaces and their association to form antibiotic-resistant biofilms threatens public health and affects several industrial sectors with significant economic losses. For this reason, the medical, pharmaceutical and materials science communities are exploring more effective anti-fouling approaches. This review focuses on the anti-fouling properties, structure-activity relationships and environmental toxicity of quaternary ammonium salts (QAS) and, as a subclass, ionic liquid compounds. Greener alternatives such as QAS-based antimicrobial polymers with biocide release, non-fouling (i.e., PEG, zwitterions), fouling release (i.e., poly(dimethylsiloxanes), fluorocarbon) and contact killing properties are highlighted. We also report on dual-functional polymers and stimuli-responsive materials. Given the economic and environmental impacts of biofilms in submerged surfaces, we emphasize the importance of less explored QAS-based anti-fouling approaches in the marine industry and in developing efficient membranes for water treatment systems.

Formation of Amphiphilic Zwitterionic Thin Poly(SBMA-co-TFEMA) Brushes on Solid Surfaces for Marine Antifouling Applications

Water molecules can bind to zwitterionic polymers, such as carboxybetaine and sulfobetaine, forming strong hydration layers along the polymer chains. Such hydration layers act as a barrier to impede the attachment of marine fouling organisms; therefore, zwitterionic polymer coatings have been of considerable interest as marine antifouling coatings. However, recent studies have shown that severe adsorption of marine sediments occurs on zwitterionic-polymer-coated surfaces, resulting in the degradation of their marine antifouling performance. Therefore, a novel approach for forming amphiphilic zwitterionic polymers using zwitterionic and hydrophobic monomers is being investigated to simultaneously inhibit both sediment adsorption and marine fouling. In this study, amphiphilic zwitterionic thin polymer brushes composed of sulfobetaine methacrylate (SBMA) and trifluoroethyl methacrylate (TFEMA) were synthesized on Si/SiO2 surfaces via surface-initiated atom transfer radical polymerization. For this, a facile metal-ion-mediated method was developed for immobilizing polymerization initiators on solid substrates to subsequently form poly(SBMA-co-TFEMA) brushes on the initiator-coated substrate surface. Poly(SBMA-co-TFEMA) brushes with various SBMA/TFEMA ratios were prepared to determine the composition at which both marine diatom adhesion and sediment adsorption can be prevented effectively. The results indicate that poly(SBMA-co-TFEMA) brushes prepared with an SBMA/TFEMA ratio of 3:7 effectively inhibit both sediment adsorption and marine diatom adhesion, thereby exhibiting balanced marine antifouling properties. Thus, the findings of this study provide important insights into the design of amphiphilic marine antifouling materials.

A Comprehensive Review of Synthesis, Applications and Future Prospects for Silica Nanoparticles (SNPs)

Silica nanoparticles (SNPs) have shown great applicability potential in a number of fields like chemical, biomedical, biotechnology, agriculture, environmental remediation and even wastewater purification. With remarkably instinctive properties like mesoporous structure, high surface area, tunable pore size/diameter, biocompatibility, modifiability and polymeric hybridizability, the SNPs are growing in their applicable potential even further. These particles are shown to be non-toxic in nature, hence safe to be used in biomedical research. Moreover, the molecular mobilizability onto the internal and external surface of the particles makes them excellent carriers for biotic and non-biotic compounds. In this respect, the present study comprehensively reviews the most important and recent applications of SNPs in a number of fields along with synthetic approaches. Moreover, despite versatile contributions, the applicable potential of SNPs is still a tip of the iceberg waiting to be exploited more, hence, the last section of the review presents the future prospects containing only few of the many gaps/research extensions regarding SNPs that need to be addressed in future work.