Direct quantification of cysteine and glutathione by 1H NMR based on β-cyclodextrin modified silver nanoparticles

Sulfhydryl-containing amino acids had a variety of biological functions. Herein, a method was simply set up to determine Cys and GSH with β-CD AgNPs quantitatively. The chemical shifts of Cys and GSH both moved to higher field when β-CD AgNPs were added. The reason was that the sulfhydryl groups could bind to the surface of AgNPs. In addition, the competitive effect of Cys and GSH in mixed solutions was explored via the 1 H chemical shift deviation. Peaks at 3.05 ppm and 2.93 ppm were selected as characteristic signals. This method exhibited an excellent linearity in the range of Cys and GSH in 0.1–20 mM. The detection limits of Cys and GSH were 40 μM and 14 μM, respectively. This method was successfully used to quantitatively determine Cys and GSH in human serum and urine.