(36f) Selectivity of Bacterial Capture By Polydopamine-Coated Magnetic Nanoclustsers

Fast and precise identification of bacteria is essential for medical diagnostics, and for food and water quality control. Magnetic particles covered with specific surface chemistry that binds to bacteria are efficient at removing bacteria from a sample for further analysis. Herein we present a novel approach for bacterial concentration using nanoclusters of magnetic nanoparticles coated with polydopamine (pDA), a polymer known to bind aquatic mussels to surfaces, but heretofore assumed to be anti-biofouling and perhaps antimicrobial when coated on medical devices. We have discovered that 5-nm thick coating of pDA on magnetic nanoclusters (MNCs) rapidly and strongly binds to many types of bacteria, including those associated with medical infections and food and water contamination. Furthermore, the bacteria remain alive and can grow in the presence of the MNCs. We present our study of binding of several gram-positive and gram-negative bacteria to pDA-coated MNCs, including Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus mutans, E. coli, and other common infectious species. These functionalized MNCs are selective in binding various strains of bacteria. For example the binding efficiency to bacteria in a suspension ranges from 0.01 for an E. coli strain to 0.98 for S. aureus. The fraction of bacteria captured reaches a plateau that is different for various species, indicating that there are specific interactions between the pDA coating and various types of bacteria. This binding and recovery technique has immediate application in rapid capture and subsequent identification of bacteria in infected body fluids (blood, urine, cerebral spinal fluid), hospital environments, food quality assurance, and water purification.