Highly selective and sensitive electrochemical determination of cysteine based on complexation with gold nanoparticle-modified copper-based metal organic frameworks

A gold nanoparticle-modified copper-based metal organic framework (Au NPs@Cu-BDC) was fabricated for the electrochemical determination of cysteine (Cys-SH). The nanocomposites were characterized using different techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray spectroscopy (PXRD), thermogravimetry (TGA), nitrogen adsorption-desorption isotherms, and Fourier transform infrared spectroscopy (FTIR). Formation of a new anodic peak of Cu(II)-Cys complex at +0.43 V was used to detect Cys-SH. Cyclic and square wave voltammetric studies proved that the Au NPs enhanced the conductivity of Cu-BDC. The proposed electrode exhibited a linear range of 0.0015-10.5 mu M and low detection limit of 0.0004 mu M with a good sensitivity of 0.78 +/- 0.01 mu A mu M. The as-fabricated electrode was successfully used for the estimation of Cys-SH in real samples (human plasma, urine, and saliva) with recovery % of 99-100% and RSD % of 2.7-3.6%, respectively.

Automated summary

A gold nanoparticle-modified copper-based metal organic framework was developed for the electrochemical determination of cysteine. The fabricated electrode showed excellent sensitivity, low detection limit, and accurate quantification of cysteine in real samples.