Fabrication of a capillary immunosensor in polymethyl methacrylate

A method for fabricating capillary-based immunosensors in a coupon milled from an inexpensive, commodity plastic (PMMA, plexiglass) is demonstrated. The key feature of the technique is the use of sol-gel technology to deposit a glass-like (Si [bond] OH) film on surfaces of the plastic capillary channels to facilitate antibody immobilization. The utility of this method was demonstrated in the context of continuous flow displacement immunosensors for the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). These sensors exhibited sensitivity to low microg/l RDX concentrations and peak-to-peak signal variations that were generally less than 10% for multiple injections at a single RDX concentration. The useful lifetime of the coupons in these experiments was greater than 10 h even after multiple exposures to high (1000 microg/l) RDX levels. This sensor platform has the physical characteristics needed for a portable field instrument: small, light-weight, and rugged.