Simultaneous monitoring of creatinine and urea in diversified clinical samples based on SERS-active PDMS-flower-like ZIF-67@Ag nanoparticles.

The sensitive, efficient, and simultaneous assay of creatinine and urea in different body fluid is crucial for the daily detection and treatment of chronic kidney disease. Here, we exploited a versatile composite surface enhanced Raman scattering (SERS) substrate of polydimethylsiloxane (PDMS)-flower-like ZIF-67@Ag nanoparticles (NPs) based on simple in-situ growth and ion sputtering strategies. The plasmonic Ag NPs assembled on the three-dimensional anisotropic ZIF-67 matrix, facilitating numerous resonant electromagnetic "hotspots". Furthermore, the effective photo-induced charge transfer between target molecules and the flower-like ZIF-67 provide additional chemical enhancement for the assay. Moreover, after a limit of detection as about 8.94 × 10 M was achieved for model ligand of methylene blue, the PDMS-flower-like ZIF-67@AgNPs with an optimal synergistic enhanced SERS activity was able to simultaneously monitor creatinine and urea mixed in artificial clinical samples at different concentration ratios. Significantly, the artificial clinical samples were sequentially detected by using the versatile SERS substrate under different modes of test-strip dipping for blood, hydrophilic-hydrophobic enrichment for urine, and in-situ collection for sweat, which all demonstrated reliable recovery rates. This indicated that SERS technique based on sophisticated nanocomposites has emerged as an alternative protocol to predict kidney disease.