Fig. 1. Micro-niche construction by polymer/inorganic coating of live algal cells.

a Schematic illustration showing the stepwise construction of concentrically arranged PPy and CaCO₃ thin shells on the cell wall of the alga Chlorella pyrenoidosa (small yellow spheres, Fe(III) ions; black inner shell, PPy; light blue outer shell, CaCO₃). b–d TEM images of localized regions and whole cells (insets) of native (b), PPy-coated (c) and PPy/CaCO₃-coated Chlorella cells (d) showing increased electron density and granularity associated with the coatings. e UV–Vis spectra of PPy, native and PPy-coated Chlorella cells. f XRD patterns of native, PPy-coated and PPy/CaCO₃-coated algal cells; Miller indices for calcite (c) and vaterite (v) are shown. g Plot of Young’s modulus of native, PPy-coated and PPy/CaCO₃-coated Chlorella cell walls. Data are presented as mean values ± SD, error bars indicate standard deviations (n = 3, biologically independent samples). h, i Confocal fluorescence microscope images of PPy/CaCO₃-coated Chlorella cells displayed in red (h) and green (i) channels. j overlay image of h and i. Red fluorescence, intracellular chlorophyll; green fluorescence, FITC-labeled CaCO₃ shell. Scale bars: (b), 100 and 500 nm (inset); (c), 100 nm and 1 μm (inset); (d), 200 nm and 1 μm (inset); h–j 10 and 2 μm (insets). All relevant experiments were performed independently at least three times with similar results. Source data are provided as a Source Data file.