Biosynthesis of superparamagnetic polymer microbeads via simple precipitation of enzymatically synthesized short-chain amylose

Here, we report a simple and non-emulsion based approach to prepare starch-based magnetic polymer beads with well-defined size, shape and dispersibility in aqueous environment through co-precipitation of enzymatically synthesized short chain amylose (SCA) and dextran-coated iron oxide nanoparticles (Dex@IONPs). The size and morphology of magnetic polymer beads (MPBs) were controlled by employing Dex@IONPs as a seeding agent. The resulting superparamagnetic amylose microbeads (SAMBs) were readily functionalized with antibody through one step reaction using a linker protein, which showed great capture efficiency (>90%) and specificity for target bacteria present in complicated food matrix. The excellent magnetic sensitivity also enabled the SAMBs readily assembled into ordered 1D arrays by external magnetic field whose structure could permanently be fixed by SCA-mediated precipitation process.