Natural biological materials are formed by self-assembly processes and catalyze a myriad of reactions. Here, we report a programmable molecular assembly of designed synthetic polymers with engineered Bacillus subtilis spores. The bacterial spore-based materials possess modular mechanical and functional properties derived from the independent design and assembly of synthetic polymers and engineered spores . 

We discovered that phenylboronic acid (PBA) derivatives form tunable and reversible dynamic covalent bonds with the spore surface glycan. Spore labeling was performed using fluorescent PBA probes and monitored by fluorescence microscopy and spectroscopy. Binding affinities of PBA derivatives to spore surface glycan was controlled by aryl substituent effects. On the basis of this finding, PBA-functionalized statistical copolymers were synthesized and assembled with B. subtilis spores to afford macroscopic materials that exhibited programmable stiffness, self-healing, prolonged dry storage, and recyclability. These material properties could be examined using shear rheology, tensile testing, and NMR experiments. 

Integration of engineered spores with surface enzymes yielded reusable biocatalytic materials with exceptional operational simplicity and high benchtop stability. The reaction progress of the biocatalyses could be monitored with fluorescence specroscopy and absorption measurements, while spore leakage could be monitored by changes in solution turbidity (OD600). The use of bacterial spores as an active partner in dynamic covalent crosslinking sets our material apart from previous examples and grants control over biocontainment as well as the subsequent fate of the spores through stimuli-responsive reversal of the crosslink.

All experimental methods are briefly described in the README.md file, and fully detailed in the Supporting Information file for the paper article "Catalytic materials enabled by a programmable assembly of synthetic polymers and engineered bacterial spores".