Development of Novel Nanopillar Metasurfaces for the Detection of Antimicrobial Resistance Signatures in Food Samples

The goal of this project is to develop a novel sensing platform incorporating metasurfaces and plasmonic resonance towards the identification of antimicrobial resistance (AMR) biomarkers. Rapid and sensitive detection of AMR aids in improving human health to combat microbial contaminants, especially in relation to food safety where superbugs, or bacteria resistant to antibiotics can spread between livestock and crops and into humans. Early AMR detection can also prove useful in healthcare cases such as in sepsispatients where long delays in treatment can prove fatal. Throughout the course of this project, we aim to develop new assay systems that may be customized for the detection of common and popular resistance strategies that bacteria cells employ to fight antibiotics. This work in particular will focus on resistance to beta-lactam antibiotics, one of the most widely administered categories that includes penicillin, amoxicillin, cephalexin, and many others. To achieve this broad goal, numerous objectives will be set with the intent to observe progress of the device and assay. This includes:Fabrication of a silicon nanopillar metasurface with sharp reflectance peaks/valleys at desired wavelengths. This includes control of pillar diameter, period, and height to move the sensing regime between the visible and near-IR wavelengths depending on sensing application. The sensing platform described here will be continually improved and optimized over the duration of the project.Establishing an off-chip assay for the detection of beta-lactamse, an enzyme produced in many gram-positive and gram-negative bacteria cells. This enzyme breaks down the beta-lactam ring in beta-lactam antibiotics, changing the conformational structure to disable them before disrupting cell functions. The objective will be achieved by penicillin-binding proteins on magnetic beads that will bind to antibiotics on gold nanoparticles in the absence of the enzyme. The supernatant will then be added to the metasurface described in the first objective.An on-chip variation of the enzyme detection assay will be investigated, seeing penicillin-binding proteins directly bound to the surface of the silicon nanopillar substrate for capture of intact antibiotic molecules on gold nanoparticles in the absence of the enzyme.Developing an assay for the identification of gene-mutations for the purpose of antimicrobial resistance. The mecA gene in MRSA cells will be amplified by recombinase polymerase amplification and induce trans-cleavage in CRIPSR Cas12a proteins to cleave reporter probes on gold nanoparticles. The gold nanoparticles will then be added to the silicon metasurface.Multiplex detection using a similar nanopillar metasurface that exhibits multiple reflectance peaks for identification of different AMR situations. The nanopillar metasurface may be customized to contain multiple parameter sets of pillar height, diameter, and period. This would create separate reflectance peaks that can be monitored individually while both assays described above may be run across the same metasurface but in different regions.