Evaluation of alternative measurement and data-processing options for enzyme-based biosensors

This paper describes an alternative measurement/data-processing approach for enzyme-based biosensors. The proposed approach, identified herein as a pseudo-equilibrium option, is designed to obtain the response corresponding to reaction of all the substrate in a small fixed volume of solution. This general approach has two important advantages relative to more conventional steady-state option. It yields constant high sensitivity over wide concentration ranges and it improves the ruggedness to changes in experimental conditions by factors of 10-fold or more relative to the steady-state option. Results obtained for an amperometric-based reactor/sensor system for glucose demonstrate constant sensitivity for glucose concentrations up to five-fold the Michaelis constant and order-of-magnitude improvements in ruggedness to changes in selected experimental variables. Regarding ruggedness, results show that the pseudo-equilibrium option is 11-, 150- and 32-fold less dependent on pH, temperature and sodium chloride concentration, respectively, than steady-state results obtained from the same data sets. Principal limitations of the implementation of the pseudo-equilibrium option reported here are the possible inconvenience of a flow system, long measurement times and more complex data-processing requirements than the steady-state option. (C) 1999 Elsevier Science B.V. All rights reserved.