On-surface amplification of L-glutamate using a patterned bi-enzymatic system

Abstract

We present a method for the amplification of L-glutamate directly on a surface. Our strategy is based on the surface patterning of a bi-enzymatic system consisting of glutamate oxidase (GLOD) and glutamic-pyruvate transaminase (GPT). This bi-enzymatic system amplifies L-glutamate via a recycling process. The surface chemistry on Ta2O5 was optimized for maximal enzyme loading. Enzyme activity was determined using a colormetric assay for the presence of GLOD. Co-immobilization of GLOD and GPT results in at least a doubling of the signal. Furthermore, increasing the surface concentrations of each enzyme leads to amplification levels that approach those obtained in solution. These enzymes can be patterned on substrates using a flip chip bonder for aligned microcontact printing. This bi-enzymatic system can be applied to biosensor surfaces for the in vitro detection of L-glutamate. © 2009 Springer-Verlag.