Sub-lethal effects of innovative anti-corrosion nanoadditives on the marine bivalve Ruditapes philippinarum

Corrosion significantly affects the maritime industry. To address this issue, corrosion inhibitors are incorporated into polymeric coatings. However, some state-of-the-art inhibitors are toxic, prone to spontaneous leaching, and interact with coating components. Accordingly, benzotriazole (BTA) and gluconate (GCN) have recently emerged as promising alternatives. Their immobilization into layered double hydroxides (LDHs) prevents direct contact with the polymeric matrix. It also allows a controlled release of BTA or GCN in response to specific stimuli (e.g., seawater, pH changes), thus providing long-lasting protection with hypothetical environmental benefits. The present study tests this hypothesis by assessing and comparing the sub-lethal effects of two novel anti-corrosion nanomaterials (Zn-Al LDH-BTA and Zn-Al LDH-GCN) and their soluble counterparts (BTA and GCN) in the edible bivalve Ruditapes philippinarum. Marine clams were exposed to sub-lethal concentrations (1.23, 11.11, and 100 mg BTA or GCN/L) of soluble and nanostructured BTA and GCN for 96 h. Subsequently, effects on health condition status, oxidative stress, neurotoxicity, and genotoxicity were assessed. Both nanoadditives (Zn-Al LDH-BTA and Zn-Al LDH-GCN) and soluble GCN caused no significant sub-lethal effects. However, exposure to soluble BTA induced GPx activity at 1.23 mg/L and DNA damage at 1.23 and 100 mg/L. This suggests that both nanoadditives are promising alternatives with high anti-corrosion performance and low ecotoxicity. GCN forms may be safer, as the biomolecule caused no sub-lethal effects in the tested species. This study presents a step forward in the development of an holistic assessment of eco-friendly anti-corrosion nanoadditives with enhanced performance.