Strain Modulation in Coccolith Biomineralization: Investigating Sr Uptake Regulation via XRF Nanoimaging

Living organisms excel at orchestrating inorganic crystal growth, forming intricate mineralized structures under ambient conditions. Specifically, coccolithophores, unicellular algae, control calcite nucleation, growth and morphogenesis, producing inorganic scales termed coccoliths. Unlike abiotic calcite (Figure 1A), these biogenic crystals grow asymmetrically, challenging conventional crystal growth models. We hypothesize that coccolithophores achieve this by regulating lattice strain through incorporation of substitutional Sr during calcification. Combining Bragg CDI and XRF nanoimaging we already observed distinct strain patterns in coccolith crystals correlated with local Sr/Ca ratios. Preliminary results indicate that coccolithophores may actively regulate Sr uptake, a previously unreported biochemical process. We aim to verify this phenomenon by investigating elemental distribution across holococcoliths grown under a varying Sr concentration in the growth med