Highly selective and sensitive streptomycin chemiluminescence sensor based on aptamer and G-quadruplex DNAzyme modified three-dimensional graphene composite

In our work, a highly selective and sensitive streptomycin (STR) chemiluminescence (CL) sensor was successfully prepared based on aptamer and G-quadruplex DNAzyme (G-DNAzyme) modified three-dimensional graphene composite. Initially, beta-cyclodextrins and ionic liquids functionalized graphene oxide aerogel (beta-CD/IL@GOGA) was successfully prepared and characterized, in which graphene oxide aerogel (GOGA) was used as a skeleton material and provided large specific surface area, beta-CD rich in hydroxyl groups and IL containing lots of stable ions increased the biocompatibility and stability of the composite, respectively. Then, tetracycline aptamer (SApt) and G-DNAzyme was immobilized on the surface of beta-CD/IL@GOGA, consecutively. Finally, G-DNAzyme/S-Apt/beta-CD/IL@GOGA was used to construct the CL sensor for STR detection. S-Apt with specific recognition ability to its target and G-DNAzyme as a catalyst of luminol-H2O2 CL system improved the selectivity and sensitivity of the sensor, respectively. When STR existed, G-DNAzyme was released from the surface of S-Apt/beta-CD/IL@GOGA due to the specific recognition and binding ability between STR and S-Apt, catalyzing the CL reaction. The CL sensor showed the linear range of 1.4 x 10(-12) to 2.8 x 10(-9 )mol/L and detection limit of 9.2 x 10(-14) mol/L (3 delta). It was successfully used for STR detection in cucumber and milk samples.