A new electrochemical substrate for rapid and sensitive in vivo monitoring of β-galactosidase gene expressions

Analyst. 2015 Sep 7;140(17):6040-6. doi: 10.1039/c5an01036e.

Abstract

A 4-Methoxyphenyl-β-galactopyranoside (4-MPGal) substrate incorporating 4-methoxy phenol (4-MP) as an electrochemical reporter is described for the monitoring of β-Galactosidase (β-Gal) gene expressions. β-Gal derived from Escherichia coli (E. coli) and Aspergillus oryzae (A. oryzae) were investigated, while a graphene oxide film modified electrode was employed as the transducer. The electrochemical signal of 4-MPG within 4-MPGal was masked by protecting their hydroxyl group with galactose. The externally added β-Gal triggered the deprotection through specific enzymatic hydrolysis with concomitant release of 4-MP. The apparent Km and Vmax values of 4-MPGal are determined to be 0.21 mM and 0.51 μM min(-1) mg of β-Gal(-1) (E. coli), which is consistent with the previous reports. To detect β-Gal derived from E. coli, cyclic voltammetry (CV) provides linear ranges of 12-1200 ng mL(-1) and 1.2-12 μg mL(-1) with a limit of detection (LOD) of 5 ng mL(-1), while differential pulse voltammetry (DPV) shows a linear range of 1.2-120 ng mL(-1) and LOD of 1 ng mL(-1). To detect β-Gal derived from A. oryzae, CV provides linear ranges of 0.1-100 ng mL(-1) and 0.1-1 μg mL(-1) with a LOD of 0.06 ng mL(-1), while DPV shows a linear range of 10 pg mL(-1)-10 ng mL(-1) with a LOD of 8 pg mL(-1). Moreover, we set up a platform for the real-time in vivo monitoring of β-Gal gene expressions in E. coli cultivated through microbiological culture. The developed sensing platform using 4-MPGal as a substrate is simple, rapid, sensitive, specific and advantageous over its laborious optical analogues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anisoles / chemistry
  • Aspergillus oryzae / enzymology
  • Electrochemical Techniques*
  • Electrodes
  • Enzymes, Immobilized / chemistry
  • Enzymes, Immobilized / metabolism
  • Escherichia coli / enzymology
  • Gene Expression*
  • Graphite / chemistry
  • Hydrolysis
  • Kinetics
  • Oxides / chemistry
  • Substrate Specificity
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism*

Substances

  • Anisoles
  • Enzymes, Immobilized
  • Oxides
  • mequinol
  • Graphite
  • beta-Galactosidase