Molecularly imprinted polymer based carbon dots as an optical sensor for selective detection of metronidazole

In this work, a novel selective green and eco-friendly carbon dots (CDs) were synthesized from Eucalyptus leaves as a carbon source via hydrothermal method. The CDs were used as a fluorophore in an optical sensor by joining molecularly imprinted polymers (MIPs) for the detection of metronidazole. The MIPs was prepared via reverse microemulsion method on the surface of the CDs to produce CDs@MIPs. MIPs have many advantages such as ability to recognize and bind specific target molecules, inexpensive, high stability and easy preparation. For the MIPs preparation, during the polymerization, the target molecule acts as a template to form cavities [1]. The formed molecular cavities in the polymer matrix are sites, which have similar features of physics matched with the target molecules [2]. After polymerization, the template is removed, and binding sites are exposed that are complementary to the template in size, shape, and position of the functional groups. Metronidazole (2-methyl-5-nitroimidazole-1-ethanol) is a nitroimidazole antibiotic metronidazole. It is a useful treatment of infections due to Bactericides spp. and many anaerobic bacteria. Metronidazole is one of the most commonly used drugs all over the world, one of the top 100 most prescribed drugs in the United States commonly used to treat protozoal diseases counting trichomoniasis, giardiasis [3], and central nervous system diseases [4]. Therefore, measurement of trace amount of metronidazole via sensitive, fast and selective method is very important In the suggested method, under the optimized experimental parameters such as pH, temperature, amount of CDs@MIPs and time, metronidazole could be detected with a linear dynamic range from 0.08to 1.0 ng/ml with a detection limit 0.02 ng/ml .The precision of the method for 0.27 and 8.4 ng/ml MTZ was obtained as 3.1% and 2.2% (3 replicate detection), respectively. The selectivity of the sensor was also investigated and the results showed a good selectivity due to the presence of the recognition cavities. Finally, this sensor was successfully applied to metronidazole determination in human plasma sample. This sensor has many advantages for example is green, simple and non-expensive in addition it has good figures of merits such as low detection limit and high selectivity and sensitivity.