Amplified colorimetric detection of chloramphenicol based on gold nanoclusters and an aptamer recognition-induced three-way junction

Herein, a new colorimetric aptasensor was prepared for the ultrasensitive detection of chloramphenicol (CAP) based on gold nanoclusters (AuNCs) and an aptamer recognition-induced three-way junction (TWJ). In the presence of CAP, numerous TWJ structures were formed accompanied by the dissociation of trigger T. Then, lots of hairpins were dissociated from the AuNC surfaces, and the peroxidase-like activity of AuNCs was restored; therefore, the increased concentration of oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) generated a strong absorbance signal. The CAP concentration was proportional to the increased oxTMB level. Therefore, a new label-free colorimetric method was proposed to quantitatively detect CAP. Under optimum conditions, the proposed method exhibited two linear dynamic ranges: from 0.16 pM to 16 pM and from 0.8 nM to 0.8 μM, with a limit of detection (LOD) of 0.05 pM. Selectivity tests against other antibiotics demonstrated that the aptasensor showed an exceptional capability to specifically detect CAP. Furthermore, the effectiveness of this sensor was validated by performing recovery tests in lake water and spiked milk samples, showing recoveries of 94.38%-105.38%.