Perspectives on nanomaterial-empowered bioremediation of heavy metals by photosynthetic microorganisms

Environmental remediation of heavy metals (HMs) is a crucial aspect of sustainable development, safeguarding natural resources, biodiversity, and the delicate balance of ecosystems, all of which are critical for sustaining life on our planet. The bioremediation of HMs by unicellular phototrophs harnesses their intrinsic detoxification mechanisms, including biosorption, bioaccumulation, and biotransformation. These processes can be remarkably effective in mitigating HMs, particularly at lower contaminant concentrations, surpassing the efficacy of conventional physicochemical methods and offering greater sustainability and cost-effectiveness. Here, we explore the potential of various engineered nanomaterials to further enhance the capacity and efficiency of HM bioremediation based on photosynthetic microorganisms. The critical assessment of the interactions between nanomaterials and unicellular phototrophs emphasised the ability of tailored nanomaterials to sustain photosynthetic metabolism and the defence system of microorganisms, thereby enhancing their growth, biomass accumulation, and overall bioremediation capacity. Key factors that could shape future research efforts toward sustainable nanobioremediation of HM are discussed, and knowledge gaps in the field have been identified. This study sheds light on the potential of nanobioremediation by unicellular phototrophs as an efficient, scalable, and costeffective solution for HM removal.