An enzyme biosensor based on beta-galactosidase inhibition for electrochemical detection of cadmium (II) and chromium (VI)

ABSTRACT

The focus of this article is the development and optimisation of a simple, sensitive, selective biosensor for the detection of heavy metals, through inhibition of β-galactosidase (β-gal) from Aspergillus oryzae after its immobilisation on an electrochemical transducer by cross-linking with glutaraldehyde. The inhibition of β-gal by Cd(II) and Cr(VI) was demonstrated by the decrease of β-gal activity monitored by the conductometric signal. Under optimal conditions, the developed voltammetric and impedimetric biosensor, based on the specific interaction of metallic ions with beta-galactosidase that increases the electron transfer of the redox probe, presented a wide range of linearity. Detection limits of 3.12 × 10^–10 M (91.7 ng/L) were obtained, using both techniques, for Cr(VI). For Cd(II) detection limits were 2.85 × 10^–8 M (6.95 µg/L) using EIS and 3.22 × 10^–11 M (7.61 ng/L) using square wave voltammetry (SWV).

KEYWORDS:

• Electrochemical biosensors
• inhibition
• cadmium
• chromium
• β-gal
• conductometry
• CV
• EIS
• SWV

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Authors thank CAMPUS FRANCE for financial support through PHC Maghreb Project No. 14.