A target-responsive release SERS sensor for sensitive detection of tetracycline using aptamer-gated HP-UiO-66-NH2 nanochannel strategy

In this study, a target-responsive release Surface-enhanced Raman scattering (SERS) sensor was developed for sensitive detection of tetracycline (TTC) using aptamer-gated HP-UiO-66-NH2 nanochannel strategy. The hierarchically porous zirconium-based metal-organic frameworks (HP-UiO-66-NH2 MOFs) with high surface areas and the conjugated π-electron system were first synthesized and served as the nanocontainers. The methylene blue (MB) and gold nanoparticles (AuNPs) were then loaded in the pores of HP-UiO-66-NH2 as the signal probes and capping agent, respectively. Thereafter, aptamer was assembled on the surface of HP-UiO-66-NH2 based on the π-π stacking interaction. In the presence of TTC, the aptamer "molecular gate" was opened, resulting in the "cargo release" of MB and AuNPs. Hence, the amount of TTC could be determined by monitoring the change of SERS intensity of the supernatant. Under the optimal conditions, a good linear correlation between SERS intensity (886 cm-1) and TTC concentration was observed with the concentration from 0.01 to 10000 ng/mL, resulting in a relatively low detection limit of 0.01 ng/mL. Moreover, this method showed a promising practical application in spiked real samples (milk and pork) with recoveries of 93.23-108.79%, which confirmed its great potential in antibiotic detection.