Fig. 2: Bacterial respiratory chain and electrochemical tests.

a Changes in ATP synthase-related proteins after GNSs or GNSs-HA treatments at the concentration of 100 μg mL⁻¹ for 60 min; b Schematic diagram of respiratory chain changes in the GNSs treatment group; c ATP content after treatment with GNSs and GNSs-HA at the concentration of 100 μg mL⁻¹ for 60 min. Electron transfer between B. tropicus and GNSs or GNSs-HA represented by LSV curves (d), Nyquist plots (e), and CV curves (f–h). In the electrochemical tests, both GNSs and GNSs-HA were coated onto carbon fiber paper at a density of 0.5 mg cm⁻². For the GNSs+HA group, GNSs at a loading of 0.5 mg cm⁻² were applied to the carbon fiber paper, and HA was introduced into the bacterial suspension at a concentration of 1.4 μg mL⁻¹. The electrochemical tests were performed at least in triplicate with similar results. For (a, c) data are shown as mean ± SD (n = 3). Each data point represents a biologically independent replicate. P values were determined by two-sided T-test.