Model-based design and optimization of a multiplexed microfluidic biochip for multi-analyte detection

Multiple enzyme assays were systematically performed for simultaneous quantification of sucrose, D-glucose and D-fructose in a single microchannel reactor. The assay was based on optical detection of the reaction product, NADH, formed through a cascade of enzymatic reactions. For design optimization of the system, a model was developed for the microfluidic flow, enzyme kinetics and mass transfer of the different species involved in the analysis. The performance of the device was then optimized using the reduced form of these models in terms of process conditions (reagents volume and flow rate) thereby facilitating biosensor development. The proposed multiplexed device increases throughput and improves user-friendliness compared to equivalent microtiter plate assays. All sugars were quantified within 2.5 min in the optimized microchip based continuous system whereas it took at least two hours in standard microtiter plate analysis. Parallelization can further improve the throughput. In addition, the amount of reagents consumed reduced drastically. For example, the amount of Hexokinase used to detect glucose in 96 well microtiter plates with a total volume of 200 muL was 21.7 ng whereas in the designed microfluidic chip it only required 4.1 ng.