Lab-on-a-Chip for Field Escherichia coli Assays: Long-Term Stability of Reagents and Automatic Sampling System

Abstract

A field lab-on-a-chip system was constructed to detect mouse immunoglobulin G (mIgG; model protein target) and Escherichia coli (E. coli; model microorganism target) by using light scattering detection of particle immunoagglutination. The antibodies to these targets were conjugated to the submicron particles by covalent binding, and their long-term stability was evaluated. Antibody-conjugated particles were able to be stored in a 4 °C refrigerator for at least 4 weeks and to be lyophilized as a powder form for the storage in room temperature. The optimum antibody coverage on the particles was 50% for mIgG and 100% for E. coli in terms of assay sensitivity and long-term storage of reagents. Lab-on-a-chip device was fabricated from acrylic plate using an industrial-grade milling machine eliminating the need for photolithography and internal or external pumping. An automatic sampling system was constructed using drip emitters, such that the system can be connected to a pressurized water pipe for detecting E....