On-chip electrochemical measurement of beta-galactosidase expression using a microbial chip

small beta]-Galactosidase expression in a small number of Escherichia coli cells has been measured in real time with an electrochemical sensor chip. E. coli cells were embedded using collagen gel within a micropore which was microfabricated onto a chip. The activity of the expressed small beta]-galactosidase was determined using p-aminophenyl small beta]-d-galactopyranoside (PAPG) as a substrate.