(168b) Biofunctional, Photodegradable Hydrogels for Discovery and Isolation of Bacteria That Drive Membrane Biofouling

Membrane biofouling is a major limitation in many biological and chemical systems; however, the mechanisms used by microorganisms to initiate and maintain biofilms on membrane surfaces are poorly understood. Understanding these underlying mechanisms is critical for the development of effective, long-term solutions to membrane biofouling. Polymer surface dissection (PSD) is a new method for characterizing biofilm formation over membrane surfaces without culturing by gently capturing early colonizers using photodegradable polyethylene glycol (PEG) hydrogels. High precision patterned UV light is used to selectively isolate targeted bacterial aggregates from fouled membranes, the DNA of which is extracted for 16S rRNA community analysis. To increase bacterial capture, PEG hydrogels formed by Michael-type addition reactions of PEG-o-NB-diacrylate and PEG-tetrathiol are functionalized with bioaffinity ligands, such as wheat germ agglutinin (WGA), using a maleimide-PEG-NHS ester crosslinker. WGA is a lectin that binds to n-acetylglucosamine in the extracellular matrix of bacterial cells without damaging the cells, making it an appropriate ligand for this application. Fluorescence microscopy was used to characterize the biofunctionalization of PEG hydrogels with and without the maleimide-PEG-NHS ester crosslinker. The addition of WGA-Alexa 594 with the crosslinker present resulted in a dramatic increase in fluorescence intensity compared to without the crosslinker present, confirming biofunctionalization of the hydrogels. Using the PSD approach with the biofunctionalized hydrogels, we were able to selectively analyze membrane-bound aggregates at the micron scale and identify early colonizers of fouled membranes at the phylum and family levels.