Effects of Different Functionalized Nanoplastics on the Transformation of Extracellular Antibiotic Resistance Genes in Aquatic Environments

• • PS-COOH (0.1–20 mg·L−1) promotes eARG transformation in a dose-dependent manner, increasing the environmental spread of antibiotic resistance in aquatic systems. • • Low PS-NH2 (0.1–0.5 mg·L−1) enhances transformation more strongly than PS-COOH at equal concentrations, while high PS-NH2 (1–20 mg·L−1) inhibits it, indicating a concentration-dependent dual effect. • • Promotion correlates with increased intracellular ROS, membrane permeability, and EPS protein/polysaccharide ratio, while inhibition involves ROS-induced cell lysis and plasmid aggregation. • • Both PS-COOH and low PS-NH2 stimulate biofilm formation, which can further amplify ARG dissemination in natural and engineered water systems.