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

Herein, the new colorimetric aptasensor was prepared for the ultrasensitive detection of chloramphenicol (CAP) based on gold nanoclusters (AuNCs) and 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 AuNCs surface 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. Thereby, the new label-free colorimetric method was proposed to quantitatively detect CAP. At 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, producing recoveries of 94.38 % - 105.38 %.