MOF-polymer composites with well-distributed gold nanoparticles for visual monitoring of homocysteine

The distribution of gold nanoparticles (AuNPs) on the surface of a metal-organic framework (MOF) plays a crucial role in the catalytic performance of MOF-AuNP composites. This study describes how the physical adsorption (PH@AuNPs-on-U) and chemical modification of AuNPs on the surface of UiO-66-NH2 (U) affect the composites' catalytic efficiency. After 2-vinyl-4,4-dimethyl-2-oxazolin-5-one (VD) linked to poly(N-2-hydroxypropyl methacrylamide) (PH) with U (UVD-PH), UVD-PH@AuNPs composites were constructed with PH as the capping and reducing reagent. The composites exhibited higher peroxidase (POD)-like activity than PH@AuNPs-on-U for oxidising 3,3'5,5'-tetramethylbenzidine (TMB) with H2O2. The approach demonstrated that the proposed composite-based nanozymes could significantly enhance their catalytic activity and had a highly uniform distribution of PH@AuNPs on the surface of UVD. An assay with the nanozymes for visual detection of homocysteine (Hcy) was developed, displaying a good linear relationship (R2 = 0.998) ranging from 3.34 μM to 30.0 μM and a detection of limit of 0.3 μM. Additionally, the UVD-PH@AuNPs-TMB-H2O2 system successfully monitored serum Hcy after intraperitoneal injection in rats. This study paves a new way for developing MOF-AuNPs with highly uniform surface distribution of polymer@AuNPs to boost its catalytic activity and to detect drugs in real bio-samples.

Cu-MOF@Pt 3D nanocomposites prepared by one-step wrapping method with peroxidase-like activity for colorimetric detection of glucose

As an alternative to natural enzymes, artificial enzymes based on nanomaterials have attracted a lot of attention owing to their outstanding catalytic activity and high stability as well as low cost. Cu-MOF loaded with platinum nanoparticles (labeled Cu-MOF@Pt) was prepared by simple one-step wrapping method using platinum nanoparticles, copper nitrate trihydrate and 1,3,5-tricarboxybenzene. It was confirmed that Cu-MOF@Pt exhibits peroxidase-like activity, which can quickly catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and produce blue oxidized TMB (oxTMB) in the presence of hydrogen peroxide (H₂O₂). Additionally, steady-state kinetics showed that Cu-MOF@Pt exhibits stronger appetency to TMB and H₂O₂ compared with horseradish peroxidase. Thanks to the peroxidase-like activity of Cu-MOF@Pt, a highly selective colorimetric method for glucose detection has been successfully established, the linear range is 2-15 mM (R² =0.9999) and the Limit of Detection (LOD) is 0.42 mM, with a detection range that meets clinical needs. Moreover, its good intra- and inter-assay precision and excellent stability make the results of glucose detection very reproducible. The detection performance of 90.09% was still maintained at 4 ℃ for 2 months. In conclusion, a new nanocomposite was successfully prepared and its selective detection ability for glucose was proved, which established a good basis for the clinical development of new enzymes for biosensors.

Current research progress on laccase-like nanomaterials

The first systematic review of the progress of research on the types and applications of laccase-like activity of nanomaterials is reported.