A highly selective and sensitive trimethoprim sensor based on surface molecularly imprinted nanocavities coordinated polydopamine/gold nanorods-functionalized acupuncture needle microelectrode

Excessive amount of antibiotics have serious detrimental effects on the environment, making precise monitoring and removal increasingly crucial. Trimethoprim (TMP) is a typical kind of antibiotic. Herein, a novel microdetector was fabricated on the matrix of acupuncture needle (AN). The functional interface was constructed using a green electrosynthesis method, incorporating three-dimensional coral-like gold nanorods (3D-CAuNRs), polydopamine (pDA), polypyrole (pPY) and TMP molecules. Characterization was performed using electrochemistry, high-resolution SEM and elemental mapping techniques. Notably, nanocavities were formed through electropolymeric molecular imprinting, resulting in highly selective and sensitive detecting of TMP. This was attributed to the structure-complementary and configuration-suitable microenvironment, facilitating specific electron-transfer. The intrinsic properties of the microsensor were thoroughly investigated. Under optimized conditions, the sensor exhibited a wide linear range of 0.05 ∼ 50 µmol/L with a low limit detection of 0.017 µmol/L (S/N = 3) for TMP, along with high selectivity, reproducibility, and stability. Furthermore, the sensor demonstrated applicability for detecting TMP in environmental water, soil and cefalexin and trimethoprim capsules.