(521f) Microfluidic Enzyme-Linked Immunosorbent Assay For Rapid Detection Of Salmonella Typhimurium In Surface Enhanced Poly(Methyl Methacrylate) Microchannels

An enzyme-linked immunosorbent assay (ELISA) was performed in a microchannel (140 micron width by 125 micron depth) on a poly(methyl methacrylate) (PMMA) microchip. The increased positive charge and amine content on poly(ethyleneimine) (PEI) treated PMMA surface greatly enhanced antibody binding on the microchip, resulting in 3-fold enhancement in the fluorescence signal. With the reduced volume in the microchannel, less sample and reagent (<5 microliter) were consumed, and the incubation time for antigen and antibody binding for the ELISA was also significantly reduced to less than 1 h in each step. Total assay time was reduced to ~2.5 h, from 13 h for ELISA in conventional microtiter plates. The microfluidic ELISA can detect as few as 30 cells of Salmonella typhimurium (with an S/N ratio >7), which is 1-3 orders more sensitive than conventional ELISA methods performed on 96-well and 384-well plates. With the reduced reagent use, enhanced sensitivity, and easy and rapid operation, this microfluidic ELISA assay provides a low-cost alternative to conventional ELISA on 96-well and 384-well plates. Further automatic processing and parallel detection of multiple foodborne pathogens can also be achieved by adopting this platform in a multichannel or microarray format. This microchip can be readily integrated with a low-cost, portable detection system for various field applications, including food safety surveillance, environmental monitoring, and diagnostics for home healthcare.