A novel mechanism is presented for immunosensor development that uses an immunological competition reaction in a vesicle system. This system consists of a suspension of reconstituted vesicles, channel agonist, protein linker to block the channels, voltage sensitive dye and analyte to be detected. In the proposed mechanism analyte serves a catalytic role as individual analytes competitively displace multiple channel linkers through association with one channel, dissociation and new associations with other channels. When one channel opens on a vesicle a permanent Nernst potential develops for that vesicle leading to fluorescence of voltage sensitive dyes. The time constant of the redistribution from linker-channel form to analyte-channel form is 0.92/k4(k4is the off-rate constant for the analyte-channel association) in the region of analyte concentrations less than 10-9M. Kinetic analyses show that several factors, including concentration of analyte or linker, number of channels per vesicle, on-rate or off-rate constant of the linker-channel and on-rate constant of analyte-channel complexes have significant effects on the minimum signal response time.
Yong-Yi, Y., Van Wie, B. J., Koch, A. R., Moffett, D. F., & Davis, W. C. (1997). Kinetic modeling and analysis of a vesicle system for immunosensor development. Biosensors and Bioelectronics, 12(2), 135–144. https://doi.org/10.1016/S0956-5663(97)87059-5