Fig. 5: Multimodal imaging and photocurrent mapping of S. elongatus and PEDOT-S/S. elongatus biocomposites.
a Schematic illustration of the multimodal imaging platform integrating a photoelectrochemical microfluidic cell with a fluorescence microscope. The setup utilizes multiple modulated lasers to enable both wide-field and focused excitation. The FTO working electrode is connected to a potentiostat for photoelectrochemical current mapping. b, c Fluorescence images of S. elongatus cells and the representative zoomed-in images of the regions indicated by dotted circles. Excitation at 405 nm, emission at 650–750 nm. d, e Fluorescence images of PEDOT-S/S. elongatus biocomposites and the representative zoomed-in images of the regions indicated by dotted circles. Each dotted area contains 15 bacteria. Scale bars indicate the magnification level. f Local current–time (J–t) profiles for bare S. elongatus (red curve) and PEDOT-S/S. elongatus biocomposites (blue curve) under a 405 nm light on-off cycle, corresponding to the regions in (c, e). g Plot of Jph as a function of bacterial count for bare S. elongatus (red data points) and PEDOT-S/S. elongatus biocomposites (blue data points). The error bars represent the standard error of the mean. For bare S. elongatus, replicates (n) of 3, 2, and 3 for bacterial numbers of 10, 15, and 26, respectively. For PEDOT-S/S. elongatus biocomposites, replicates (n) of 5, 2, 2, 11, 3, 8, 9, 5, and 4 for bacterial numbers of 3, 4, 5, 6, 8, 9, 10, 11, and 14, respectively. h Jph per cell for bare S. elongatus (red bars, n = 9) and PEDOT-S/S. elongatus biocomposites (blue bars, n = 49). Box plots show the distribution of the data: the center line indicates the median, the box bounds represent the lower to upper quartile values of the data, and the whiskers extend to the minimum and maximum values within 1.5× the interquartile range from the box. Individual data points in g, h represent both biological and technical replicates. Statistical analysis was performed using one-way ANOVA followed by Tukey’s Honestly Significant Difference (HSD) post-hoc test. All tests were two-sided, and p values were adjusted for multiple comparisons. The p-value for the comparison between bare cells and biocomposites is 0.001 (*p < 0.05, **p < 0.01).
