Analytical Sciences

A Novel Nitrite Biosensor Based on Gold Dendrites with Egg White as Template

Yaping HE, Dawei ZHANG, Sheying DONG, and Jianbin ZHENG

Institute of Analytical Science/Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, Northwest University, Xi’an, Shaanxi 710069, P. R. China

Gold dendrites (AuD) were synthesized with egg white as the soft template and a novel nitrite (NO₂⁻) biosensor was fabricated by assembly of a myoglobin (Mb)-L-cysteamine (Cys)-AuD biological hybrid. The results of Fourier transform infrared spectra and UV-visible spectra indicated that Mb retained its original structure in the resulting Mb-Cys-AuD. Electrochemical investigation of the biosensor showed a pair of well-defined, quasi-reversible redox peaks with E_pa = −0.314 V and E_pc = −0.344 V (vs. SCE) in 0.1 M, pH 7.0 sodium phosphate buffered saline at the scan rate of 200 mV/s. The transfer rate constant (k_s) was 1.49 s⁻¹. The Mb-Cys-AuD showed a good electrochemical catalytic response for the reduction of NO₂⁻, with the linear range from 0.5 to 400 μM and the detection limit of 0.3 μM (S/N = 3). The apparent Michaelis–Menten constant (K_M^app) was estimated to be 0.2 mM. Therefore, the assembled bio-hybrid as a novel matrix opened up a further possibility for study on the design of enzymatic biosensors with potential applications.

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