Anti-barnacle biofouling coatings for the protection of marine vessels: synthesis and progress

A comprehensive review of environment-friendly biomimetic bionic superhydrophobic surfaces

Marine fouling is a global problem that harms the ocean's ecosystem and the marine industrial sector. Traditional antifouling methods use harmful agents that damage the environment. As a result, recent research has focused on developing environmentally friendly, long-lasting, and sustainable antifouling solutions. Scientists have turned to nature for inspiration, particularly the water-repellent properties found in the microstructures of plants, insects and animals like the lotus leaf, butterfly, and shark. This review summarizes the current trends in developing superhydrophobic materials and fabrication techniques for bionic antifouling strategies. These strategies mimic the surface microstructures of various biological species, including the lotus leaf, coral tentacles, and the skins of sharks, whales, and dolphins. The review also discusses the technological applications of these biomimetic materials and the challenges associated with implementing them in the marine sector. Overall, the goal is to harness the superhydrophobicity of natural surfaces to create effective antifouling solutions.

Preparation and antifouling performance of tin-free self-polishing antifouling coatings based on side-chain suspended indole derivative structural resins

Tin-free self-polishing antifouling coatings have the highest market share since organotin self-polishing antifouling coatings have been banned. However, its high dependence on cuprous oxide was found to have caused potential harm to the environment, making it necessary to improve the functionality of the resin. In this paper, a zinc acrylate resin with side chain hanging indole derivative structure was prepared by using N-(1H-5-bromoindole-3-methylene) (BIAM) with good biological activity as functional monomer. The functional resin with good antifouling performance was selected by antibacterial and algae inhibition experiments. The results showed that when the BIAM content was 9 %, the inhibition rates of the resin on E. coli and Prymnesium parvum reached 98 % and 90 %, respectively. Tin-free self-polishing antifouling coatings were prepared using the above resins as film-forming materials. The anti-protein adsorption performance and antifouling performance of the coating were tested by anti-protein adsorption experiment and real sea hanging plate experiment. The results showed that the coating containing indole derivative structure had good anti-protein adsorption performance and antifouling performance, and the higher the BIAM content, the better the anti-protein adsorption performance and marine antifouling performance.

Proof of Concept of Natural and Synthetic Antifouling Agents in Coatings

Marine biofouling, caused by the deposition and accumulation of marine organisms on submerged surfaces, represents a huge concern for the maritime industries and also contributes to environmental pollution and health concerns. The most effective way to prevent this phenomenon is the use of biocide-based coatings which have proven to cause serious damage to marine ecosystems. Several research groups have focused on the search for new environmentally friendly antifoulants, including marine and terrestrial natural products and synthetic analogues. Some of these compounds have been incorporated into marine coatings and display interesting antifouling activities caused by the interference with the biofilm-forming species as well as by the inhibition of the settlement of macroorganisms. This review highlights the proof-of-concept studies of emerging natural or synthetic antifouling compounds in coatings, from lab-made to commercial ones, performed between 2019 and 2023 and their results in the field or in in vivo laboratorial tests.

Maternal exposure to tributyltin alters the breast milk, hormonal profile, and thyroid morphology of dams and induces sex-specific changes in neonate rat offspring

Tributyltin (TBT) is the chemical substance commonly used worldwide to prevent biofouling of vessels. Due to its ability to bioaccumulate and biomagnify, even after being banned, significant concentrations of TBT can be detected in sediment, affecting marine and human life. Although studies have shown that direct exposure to TBT alters physiological parameters in mammals, the relationship between exposure to TBT during pregnancy and lactation, considered critical windows for metabolic programming, has not been fully elucidated. Our hypothesis is that offspring whose mothers were exposed to TBT during critical stages of development may exhibit dysfunctions in endocrine-metabolic parameters. We used pregnant Wistar rats that were divided into groups and received the following treatments from gestational day 7 until the end of lactation by intragastric gavage: vehicle (ethanol 0.01%; Control), low TBT dose (100 ng/kg of body weight (bw)/day; TBT100ng) and high TBT dose (1000 ng/kg bw/day; TBT1000ng). Dams and offspring at birth and weaning (21 days old) were studied. Maternal exposure to TBT promoted dose-dependent changes in dams. The findings for adiposity, milk composition and lipid profile were more pronounced in TBT100 ng dam; however, thyroid morphology was altered in TBT1000 ng dam. Female offspring were differentially affected by the dose of exposure. At birth, females in the TBT100ng group had low body weight, lower naso-anal length (NAL), and higher plasma T4, and at weaning, females in the TBT100ng group had lower insulin and leptin levels. Females in the TBT1000ng group had lower NAL at birth and lower leptinemia and weight of white adipose tissue at weaning. Male offspring from TBT groups showed high T3 at birth, without biometric alterations at birth or weaning. Despite these findings, both sexes exhibited dose-dependent morphological changes in the thyroid gland. Thus, maternal exposure to TBT constitutes an important route of contamination for both dams and offspring.

The Role of Natural and Synthetic Flavonoids in the Prevention of Marine Biofouling

Marine biofouling is a major concern for the maritime industry, environment, and human health. Biocides which are currently used in marine coatings to prevent this phenomenon are toxic to the marine environment, and therefore a search for antifoulants with environmentally safe properties is needed. A large number of scientific papers have been published showing natural and synthetic compounds with potential to prevent the attachment of macro- and microfouling marine organisms on submerged surfaces. Flavonoids are a class of compounds which are highly present in nature, including in marine organisms, and have been found in a wide range of biological activities. Some natural and synthetic flavonoids have been evaluated over the last few years for their potential to prevent the settlement and/or the growth of marine organisms on submerged structures, thereby preventing marine biofouling. This review compiles, for the first-time, natural flavonoids as well as their synthetic analogues with attributed antifouling activity against macrofouling and microfouling marine organisms.

Research Progress of Natural Products and Their Derivatives in Marine Antifouling

With the increasing awareness of environmental protection, it is necessary to develop natural product extracts as antifouling (AF) agents for alternatives to toxic biocides or metal-based AF paints to control biofouling. This paper briefly summarizes the latest developments in the natural product extracts and their derivatives or analogues from marine microorganisms to terrestrial plants as AF agents in the last five years. Moreover, this paper discusses the structures-activity relationship of these AF compounds and expands their AF mechanisms. Inspired by the molecular structure of natural products, some derivatives or analogues of natural product extracts and some novel strategies for improving the AF activity of protective coatings have been proposed as guidance for the development of a new generation of environmentally friendly AF agents.