Cascade amplification based on PEI-functionalized metal–organic framework supported gold nanoparticles/nitrogen–doped graphene quantum dots for amperometric biosensing applications

Robust and efficient multimodal catalysis platforms that possess high catalytic activity and enhanced electrical conductivity are preferred for enhancing the electrical analysis performance under a low overpotential. This report describes a function-switchable amperometric sensor for electrochemical monitoring hydrogen peroxide and glucose under relatively low overpotential based on PEI-functionalized metal–organic framework (P-MOF) supported gold nanoparticles/nitrogen-doped graphene quantum dots (AuNPs/N-GQDs) and glucose oxidase. AuNPs/N-GQDs with high peroxidase mimicking activity was anchored on the P-MOF modified electrode surface as H 2 O 2 sensors, exhibiting a high sensitivity of 134.26 μA mM −1 cm −2 and a detection limit of 3.38 μM. Subsequently, AuNPs/N-GQDs-P-MOF used as a nanocarrier for glucose oxidase (GOx) to achieve “cascade nanoreactor” amplification for glucose detection. The amplified amperometric glucose biosensor showed excellent anti-interference ability, reproducibility, and a limit of detection as low as 0.7 μM (S/N = 3) with high sensitivity of 1512.4 μA mM −1 cm −2 . In addition, the feasibility of the electrochemical biosensor for accurate and quantitative detection of glucose in human serum samples was confirmed with a recovery ranging from 93.2 to 99.3%. The strategy of combining AuNPs/N-GQDs-P-MOF and glucose oxidase for cascade catalysis in this work provides a simple yet efficient approach to prepare nanomaterial-based enzyme-mimics and enzymes hybrids with high performance, which holds great potential in biological and chemical applications of electrochemical devices and biosensing.