Enhancing the catalytic performance of MOF-polymer@AuNP-based nanozymes for colorimetric detection of serum L-cysteine

• Published in: Analyst (London) 2023-08, Vol.148 (16), p.3785-3790
• Main Authors: Tian, Lin, Cheng, Cheng, Zhao, Zhenwen, Liu, Wei, Qi, Li
• Format: Article
• Language: English
• Subjects: Catalytic activity; Chemical bonds; Chemical reduction; Colorimetry; Composite materials; Cysteine; Dispersion; Gold; Hydrogen peroxide; Metal-organic frameworks; Nanoparticles; Oxidation; Pepsin; Peroxidase; Polymers; Reagents
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/d3an00917c

The dispersion of gold nanoparticles (AuNPs) on a metal-organic framework (MOF) surface greatly affects the catalytic activity of the material. However, regulating the catalytic performance of AuNP-MOF composite-based nanozymes is a great challenge. Herein, poly(dimethylvinyloxazolinone) (PV) was chemically bonded on the surface of UiO-66-NH (U66), followed by modification of pepsin (Pep) on the PV chains. U66-PV-Pep@AuNP composite nanozymes were fabricated after the AuNPs formed with Pep as the capping and reducing reagent. Compared to Pep@AuNPs that were physically adsorbed onto the surface of U66, the U66-PV-Pep@AuNP composites exhibited superior peroxidase (POD)-mimetic activity in the oxidation of 3,3'5,5'-tetramethylbenzidine (TMB) with H O . Considering the surface dispersion uniformity and local concentration of Pep@AuNPs on the surface of the U66-PV-Pep@AuNP composites, the principle for improving the catalytic performance of the proposed nanozymes was explored. Furthermore, it was observed that the introduction of L-cysteine (L-Cys) into the U66-PV-Pep@AuNP-TMB-H O system significantly reduced its oxidation activity and faded the color, allowing the development of a highly selective and sensitive colorimetric method for L-Cys detection. The UV-vis absorption intensity of oxTMB showed a good linear relationship with the concentration of L-Cys in the range of 2.5-40.0 μM ( = 0.996), with a detection limit of 0.33 μM. The proposed protocol using U66-PV-Pep@AuNP nanozymes was applied to monitor rat serum L-Cys following intraperitoneal injection. This study paves the way for the design and construction of MOF-polymer@AuNP nanozymes for drug detection in real bio-samples.