Highly-Sensitive and Selective Electrochemiluminescence Biosensor for the Specific Detection ofD-alanine

A new biosensor specified for D -amino acids (DAAs) based on the electrochemiluminescence (ECL) of luminol was proposed by coupling D -amino acid oxidase (DAAO) to in situ generate coreactant with functionalized Multi-walled carbon nanotubes (F-MWCNTs) and Au-Pt alloy nanoparticles as catalysts for the ECL reaction. The stepwise fabrication process of the biosensor was characterized via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Furthermore, the Au–Pt nanostructures with different molar ratios between Au and Pt precursors were investigated by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and ECL technique, and the optimum Au/Pt ratio for ECL measurements was 1:1 with an optimized electrodeposition time at 400 s. The proposed biosensor showed excellent performance in the stereoselective recognition of D -alanine with a low detection limit of 1.67 × 10 −9 M. Hence, this paper would provide a new platform on the specific detection of D -alanine with high sensitivity, good selectivity and acceptable stability.