Nitrogen doped waste tea residue derived carbon dots for selective quantification of tetracycline in urine and pharmaceutical samples and yeast cell imaging application

In this work, waste tea residue, abundantly accessible, is utilized for synthesis of fluorescent carbon dots (CDs) by a simple, low cost and one step chemical oxidation method. The optical properties, surface functionality and particle size of CDs were ascertained by various techniques. The CDs exhibited excellent water solubility, optical properties, bioimaging ability etc. The fluorescence intensity of the CDs was diminished gradually with increasing concentrations of tetracycline drug owing to the inner filter effect (IFE) phenomenon. The developed fluorescent probe displayed a better linear range, excellent detection limit and interference free response to the tetracycline. This resulted in quantification of tetracycline in real sample which achieved almost 99% recoveries indicated excellent practical potential. Moreover, the CDs were used as fluorescent label for multicolour imaging of yeast cells which could open the doors for further research in biological fields.