Based on the host-guest molecular recognition capability of cucurbit[6]uril (CB[6]) modified on the gold surface,sensitive spectrophotometric and electrochemical methods for the detection of metformin(MET) have been developed.The molecular recognition between cucurbit[7]uril (CB[7]) or CB[6]and MET is initially demonstrated and the related recognition mechanism is further deliberated.First,CB[6]-modified gold nanoparticles (AuNPs/CB[6]) were synthesized and then characterized by ultraviolet visible light spectrum (UV-vis) and transmission electron microscopy (TEM).The aggregation of AuNPs/CB[6]prompted by MET triggered changes of color and the absorption spectrum,that explored for the visual identification and spectrophotometric determination of MET.Under the optimized detection conditions,the UV-vis spectrometry had a good linear relationship in the range of 6-700 μmol/L and the detection limit was 2 pmol/L In addition,a single-layer CB[6]-modified gold electrode (GE-CB[6]) detection system for MET was constructed.As the concentration of MET in the solution continues to increase,the charge transfer resistance (Rct) in the Nyquist diagram of the electrochemical impedance method (EIS) continues to increase.In the concentration range from 10 pmol/L to 20 nmol/L,the logarithm of the MET concen-tration has a good linear relationship with Rct,and the detection limit of this method is 1.35 pmol/L Both methods have good concentration sensitivity to MET in different concentration ranges,providing a powerful tool for the detection of MET.