Fig. 5: Chitin’s contribution to Pb²⁺ adsorption and nanomechanical characterization of yeast biomass.

a Pb²⁺ C_e after biosorption experiments with 5 mg of yeast biomass (green bar), 1.8 mg, and 5 mg of chitin (purple bars); blue dotted line represents C₀: 1000 ppb Pb²⁺. b AFM analysis of yeast cell stiffness. Box and whisker plots of the cellular spring constant (k_cell) calculated from force-extension curves acquired from yeast cells incubated with C₀ of 0, 500, and 1000 ppb Pb²⁺. Boxed region indicates upper and lower quartiles for each data set; median is indicated by the horizontal line within the box; mean is indicated by the bullet point; whiskers extend to high and low data points (n > 70 force measurements from ≥ 8 cells per condition). Asterisk indicate p < 1e-5 by single factor ANOVA test between cell groups incubated with C₀ of 0 ppb and 500 ppb, or 1000 ppb Pb²⁺. AFM deflection retrace image of yeast cells is shown in the inset (scale bar: 2 μm).