Bio-dissolution process and mechanism of copper phosphate hybrid nanoflowers by Pseudomonas aeruginosa and its bacteria-toxicity in life cycle

Copper phosphate hybrid nanoflowers (HNF) have been widely used in chemical industries and wastewater treatment owing to its excellent catalytic activity and high stability. However, their fate and ecological risks have not received due attention after being discharged into natural environment. The significance of bacteria on the dissolution and fate of HNF and its toxicity to bacteria was evaluated from the perspective of its life cycle. Results showed that in the presence of Pseudomonas aeruginosa, HNF was gradually 'disassembled' into smaller nanoparticles (NPs), and then dissolved completely. More than half of the dissolution products (Cu2+) entered biological phase, and PO43- was absorbed and utilized by bacteria as a phosphorus source. The mechanisms of HNF bio-dissolution are as follows: the metabolites of bacteria dissolve HNF through complexation and acidification, in which small molecular organic acids and amino acids play an important role. Bacteria toxicity experiments of HNF in its cycle life show that HNF exhibits lower cell toxicity, but its intermediate (smaller NPs) and final dissolved products (Cu2+) exhibit stronger cytotoxicity by increasing the level of intracellular ROS and membrane permeability of bacteria. This research is helpful to provide ecological risk assessment, develop targeted applications, and rationally design future nanomaterials.