Abstract
In the present study, we developed a novel selective molecular method for capturing zmol amounts of target antigens in femtoliter-scale volumes that is suitable for application to nanofluidic immunoassays. Our method involves antibody patterning in extended nanochannels using a photolithographic technique with vacuum ultraviolet light (VU V) and a low- temperature bonding method. The method allows for partial introduction of functional groups for antibody patterning before bonding, which is difficult in conventional processes due to the damage caused by heat and plasma. Using this extended nanofluidics method, we demonstrate for the first time the feasibility of quantitative immunochemical reactions with sample volumes smaller than that of a single cell. The volume of the constructed immunochemical reaction space was 86 fL. Analysis of the reaction rate in the femtoliter-scale reaction space indicated that the required sample volume was decreased to 810 fL, and the limit of detection was improved by 5-6 orders of magnitude, down to 3 zmol. This improvement in performance was achieved through femtoliter-scale fluid control and enabled a higher capture efficiency of near 100%. Copyright © (2013) by the Chemical and Biological Microsystems Society All rights reserved.