(280k) Bioactive Block Co-Polymer Interfaces for High-Avidity Pathogen Capture and Enrichment

Authors: 
Hansen, R., Kansas State University
Lokitz, B., Oak Ridge National Laboratory
Retterer, S., Oak Ridge National Laboratory
Masigol, M., Kansas State University
Detection of microbial pathogens from environmental or clinical samples often requires pathogen isolation and enrichment from complex media. Using lectins as capture agents for this application is advantageous, as lectin-functional surfaces directly isolate microbial cells through specific binding interactions with exopolysaccharides (EPS) moieties, can be used to catch and release targeted cells, and are inexpensive relative to capture antibodies. However, lectin-based capture strategies are generally limited by inherently weak oligosaccharide binding affinities, ultimately resulting in poor capture efficiency. In this work, we have developed a block co-polymer for clustering high concentrations of lectin capture proteins together on interfaces to promote multi-valent binding interactions that drive high-avidity microbe capture. The block co-polymer poly(glycidyl methacrylate)-block-poly(vinyl dimethyl azlactone) (PGMA-b-PVDMA) was synthesized to controlled block lengths using a RAFT polymerization. This polymer is chemoselective, with epoxy groups present in GMA block that are reactive towards hydroxyl groups present at interfaces, and azlactone groups present in VDMA blocks reactive towards capture proteins. Upon surface functionalization, the length of the PVDMA block modulates the chemical reactivity of the surface, and the high densities of reactive azlactone groups resulted in the loading of capture lectins at up to 50-fold higher density compared to alternative coupling chemistries. These lectin-functional polymer interfaces were able to capture up to 43% more microbes from solution compared to control surfaces. By applying techniques in micro and nanofabrication, these polymers were patterned into microscale surface structures on silicon interfaces, allowing for identification of structures that favored the capture of single cells or of cellular aggregates of controlled size. Further optimization of these interfaces will allow for a combination of optimized microscale architecture, nanoscale roughness, and lectin density to achieve optimal bacterial pathogen isolation from food, water, or clinical samples.