Glycosylated stimuli responsive polyacrylamide microspheres with in-situ formed AgNPs for bacterial capture, detection and killing

Infections due to multidrug resistant bacteria are a major concern and cause for human mortality worldwide. Materials that can selectively capture, and eliminate these pathogens have turned into a priority. Development of excellent point-of-care material/system that can help in the visual detection of the captured bacterial cells in addition to their killing capability can be advantageous. In this study, we demonstrate the synthesis of a hitherto unknown glycosylated gel microspheres that can capture, kill and detect pathogenic bacteria. Silver nanoparticles (AgNPs) loaded glucose/mannose/galactose functionalized microspheres namely; PAM-Glc, PAM-Man and PAM-Gal, were synthesized by inverse emulsion polymerization. The sugar functionalities present on the microspheres interacts with the bacterial cell wall leading to capture of the cells while the antibacterial action was brought about by the AgNPs synthesized in-situ within the microspheres. The highlight of the designed system is visual indication of bacterial capture due to aggregation of gel microspheres and an indicative colour change of AgNPs. The capture kinetics of bacterial cells using PAM-Man was faster compared to PAM-Glc and PAM-Gal. Among the AgNPs loaded glyco microspheres, silver loaded mannose microspheres (Ag@PAM-Man) exhibited greater inhibition against E. coli and antibiotic resistant S. aureus cells. Bacterial cells captured by PAM-Man, exhibited pink coloration upon interaction with Resorufin β-glucuronide; suggesting the destruction of bacteria upon adhesion to microspheres. The plausible mechanistic aspects involved in the capture, detection and killing process is also discussed.