Fluorinated COF-based piezo-triboelectric nanocatalytic probe for SERS quantification analysis of trace metformin

This work addresses the challenge of detecting trace levels of antidiabetic drugs like metformin (Met) by developing novel surface molecular-imprinted fluorinated covalent organic framework nanocatalytic probes (MoS₂@FCOF and SNP@FCOF) leveraging the piezo-triboelectric effect. Probes were synthesized on sulfur nanoparticles (SNP) or molybdenum disulfide (MoS₂) substrates using Met as the template molecule, with 4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline, terephthalaldehyde, and 2,3,5,6-tetrafluoroterephthalaldehyde as monomers. Specific recognition of Met was achieved through spatially matched molecularly imprinted cavities engineered within the FCOF probe. It was found that the MoS₂@FCOF and SNP@FCOF probes exhibit strongly ultrasonic piezo-triboelectric nanocatalytic activity for the oxidizing 3,3',5,5'-tetramethylbenzidine (TMB) that can be monitored with surface-enhanced Raman scattering (SERS) and fluorescence (FL) techniques. The intrinsic piezo-triboelectric nanocatalytic properties were systematically investigated through slope method and slope ratio procedures. The nanocatalytic performance enhanced 2030 % by means of piezo-triboelectric hybrid nanogenerator (PTEG). Based on this strategy, a dual-mode SERS/FL method was developed for 0.02-2.0 nM and 0.05-1.8 nM Met, with detection limits of 0.008 nM and 0.016 nM respectively. This method is also applicable for the determination of biguanide drugs such as phenformin, buformin, and proguanil, with detection limits of 0.12, 0.16, and 0.23 nM, respectively. The nanoprobes demonstrated high selectivity (imprinting factor = 6.91) against 1000-fold concentration interferents, achieving satisfactory recoveries (92.1 %-107.2 %) in river water, urine and pharmaceutical formulations analysis.