Development of microchannel devices from Low Temperature Cofired Ceramic and Screen Printed Gold for electrochemical Immunoassays

by Fakunle, Eyitayo S. O.; Aguilar, Zoraida P.; Fritsch, Ingrid

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We report a self-contained electrochem. enzyme linked immunosorbent assay in microchannel devices constructed from low temp. co-fired ceramic (LTCC) with screen-printed gold for fast and sensitive assays. Mouse IgG was the proof of concept analyte and the assay format can be modified to detect pathogens and other biol. agents. To date most microchannel immunoassays reported have been constructed on glass, silicon and polymer materials. The advantages of using multi-layer ceramics such as LTCC are the high level of integration of these materials with embedded passives, electronic circuits and three-dimensional fluid networks. The LTCC microchannel devices used for the immunoassays contain four integrated individually addressable screen-printed gold electrodes. Two of these electrodes span the entire top and bottom walls of the channel. The other two electrodes are on the sidewalls of the channel. The total channel vol. is under 0.680 L. The immunoassay components were immobilized to a specific SPG region within the microchannel using self-assembled monolayers (SAMs) of mercaptoundecanol (MUOL) covalently coupled to rat anti-mouse IgG. After the capture of mouse IgG from the sample, a secondary antibody of rat anti mouse IgG conjugated to alk. phosphatase (AP) completed the sandwich-type immunoassay. After addn. of the p-aminophenylphosphate, p-aminophenol (PAPR) is enzymic ally generated by the immobilized AP. The PAPR is electrochem. detected using the other three electrodes (as a working, counter, and pseudoreference) in the microchannel. Detection is possible within 15 s of introducing the enzyme substrate. Detection of 5 ng/mL (3.33 × 10-11M) of mouse IgG was possible.