Colorimetric and SERS dual-mode detection of GSH in human serum based on AuNPs@Cu-porphyrin MOF nanozyme

Rapid and accurate detection of glutathione content in human blood plays an important role in real-time tracking of related diseases. Currently, nanozyme-SERS combined detection mode has been proven to have excellent properties in the detection field compared to many other methods because of it combined the advantages of trace detection for SERS and efficient catalysis for nanozyme method. However, there are still existing problems in real sample detection such as quantitative detection is still difficult. In this study, gold nanoparticles (AuNPs) were synthesized in situ on the surface of two-dimensional Cu-porphyrin metal-organic framework (MOF) nanosheets to produce the AuNPs@Cu-porphyrin MOF nanozyme, which exhibited both oxidase-like activity and surface-enhanced Raman scattering (SERS) detection ability. On one hand, the intrinsic oxidase-like activity of the nanozyme could be inhibited due to the chelation of glutathione (GSH) and Cu, which thus led to the visual color change of the solution. On the other hand, the abundant Raman "hot spots" at the nanogap generated by Au NPs and the internal standard (IS) signal provided by Cu-meso-tetra (4-carboxyphenyl) porphine (Cu-TCPP) MOF improved the sensitivity and quantitative accuracy. A dual-mode signal output sensor based on the nanozyme was thus established, which could be used in the trace detection of GSH. Such a dual-mode sensor possesses excellent detection performance, with the advantage of both wide detection range from 1 to 300 μM in the colorimetric detection mode and high sensitivity of LOD with 5 nM in the SERS detection mode, and can be applied to GSH detection in actual serum samples with reliable results.