Evaluating the adaptive mechanisms and remediation strategies of microalgae against nanoplastics

Nanoplastics (NPs) have emerged as hazardous contaminants owing to their ability to cross biological membranes, induces oxidative and genotoxic stress, and facilitate trophic transfer, increasing ecological vulnerability, underscoring the need for sustainable mitigation strategies. As the primary photosynthetic producers and foundation of aquatic food webs, microalgae constitute the first biological interface encountered by NPs and govern their environmental fate, bioavailability, and trophic transfer. Despite this ecological significance, current knowledge remains focused separately on toxicity, physiological responses or remediation potential. Henceforth, this review provides a mechanistic evaluation of microalgae NPs interactions to establish a unified framework linking NPs uptake, cellular stress responses, adaptation mechanisms, and mitigation processes. Mitigation begins through adsorption, heteroaggregation, and eco-corona formation, reducing NPs bioavailability. Upon internalisation, NPs impair photosynthesis and cellular metabolism, inducing ROS signalling, antioxidant responses, and metabolic reprogramming that promotes sequestration and detoxification. Beyond toxicity assessment, the review critically evaluates emerging evidence for NPs transformation and degradation mediated by microalgal oxidative and hydrolytic enzymes, such as esterases, lipases, oxygenases, and peroxidases. However, emerging evidence mainly supports surface deterioration and sequestration, rather than definitive mineralisation. Uncertainties regarding degradation pathways, transformation products, and their ecological significance remain a major barrier in translating algal-based NPs mitigation from laboratory to pilot scale. Furthermore, this review assesses the opportunities and limitations of omics and genetics driven strategies for enhancing phycoremediation efficiency. Finally, this review proposes a waste-to-wealth framework integrating phycoremediation of NPs, carbon sequestration, and biomass valorisation, while providing a state-of-the-art mechanistic perspective on NPs fate, transformation, and sustainable remediation.