A label free and rapid fluorescent method for quantitative detection of chloramphenicol (CAP) based on graphene oxide (GO) fluorescence functional G-quadruplex probe (FGP) was developed. The FGP consisted of a choramphenicol aptamer and a G-rich sequence. The aptamer was used to bind CAP and the G-quadruplex formed by G-rich sequence was employed as a signal reporter after binding to Thioflavin T (ThT). In the absence of CAP, the FGP was absorbed onto the surface of GO through π-π stacking interactions, which restrained the G-rich sequence to form a G-quadruplex structure. Thus, the fluorescent intensity of background was low. In the addition of the CAP, the aptamer part of FGP could recognize and bind CAP to form a target-FGP complex, which led to the desorption of the complex from GO. Therefore, the free G-rich sequence could form G-quadruplex structure and bind to ThT, resulting a increase in the fluorescence intensity of the solution. We observed that the fluorescence increasement of the sensing platform had a linear relationship with the concentrations of CAP in the range of 2～20 nmol/L, and the limit of detection was 1.45 nmol/L. Besides, this detection system was applied for detecting CAP in the spiked milk, the recovery rate was between 93.2%～103.3%. These results indicated that this developed method can be used to efficiently recognize CAP in real samples.

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