A nanofluidic device for ultrasensitive and label-free detection of tetracycline in association with γ-cyclodextrin and GO†
Herein, an ultrasensitive and selective nanofluidic device for tetracycline (TC) was developed in association with γ-cyclodextrin and graphene oxide (GO). The assay was designed based on the change of the nanochannel surface charge due to the selective recognition ability of GO between aptamers and TC–aptamer complexes. And γ-cyclodextrin was utilized to eliminate the excess TC since the amine group molecules were inclined to be adsorbed onto the nanochannel surface and affected the adsorption efficiency of the nanochannel. In the presence of TC, TC specifically binded to the aptamer to form TC–aptamer and was separated from GO. The TC–aptamer complexes could be quantitated with conical nanochannels coated with polyethyleneimine (PEI)/Zr4+. The redundant TC was removed by γ-cyclodextrin. The detection limit of the nanofluidic device was as low as 2 ng L−1 (S/N = 3) and the linear range was 10 ng L−1 to 10 μg L−1. Moreover, the nanofluidic device provided high specificity and good recovery rates of 94.8–109.3% in natural river, tapwater and wastewater samples. The results revealed that our study provided a new rapid detection method for trace contaminant analysis.