Aptamer-based fluorometric determination of chloramphenicol by controlling the activity of hemin as a peroxidase mimetic

Wang, Ling-Chen; Hong, Cheng-Yi; Lin, Zheng-Zhong; Chen, Xiao-Mei; Huang, Zhi-Yong

Aptamer-based fluorometric determination of chloramphenicol by controlling the activity of hemin as a peroxidase mimetic

2020

Wang, Ling-Chen | Hong, Cheng-Yi | Lin, Zheng-Zhong | Chen, Xiao-Mei | Huang, Zhi-Yong

A method for the aptamer-based determination of chloramphenicol (CAP) was developed by exploiting the peroxidase mimicking activity of hemin. The method includes two hemin-modified DNA probes termed P1 and P2. P1, which was modified at its 5′ end with one hemin monomer, contains the CAP-binding sequence. The hybridization between P1 and P2 brings the two hemin monomers in close proximity, resulting in the formation of a hemin dimer with low peroxidase mimicking activity. The duplex structure was dehybridized in the presence of CAP. The formed hemin monomer featured a strong peroxidase mimicking activity and catalyzed the conversion of non-fluorescent tyramine into fluorescent dityramine by hydrogen peroxide. Fluorescence (with an excitation/emission maxima at 320 and 410 nm, respectively) increased linearly in the 0.1 ng mL⁻¹ to 10 ng mL⁻¹ CAP concentration range. The detection limit based on the 3σ/k criterion reached 0.07 ng mL⁻¹. The proposed assay was successfully employed for CAP detection in (spiked) honey samples with recoveries of 94.3–117.2%. Given its high sensitivity and good stability, this method shows potential in providing a platform for antibiotic detection.

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