SnO₂ quantum dots-functionalized Ti₃C₂ MXene nanosheets for electrochemical determination of dopamine in body fluids

A novel SnO₂ quantum dots (SnO₂QDs)-functionalized Ti₃C₂ MXene nanocomposite was prepared via in situ synthesis method, resulting in well-regulated the nucleation and growth of SnO₂QDs to evenly distribute onto MXene nanosheets. Ultra-small size SnO₂QDs decorated on the surface of Ti₃C₂ MXene nanosheets can effectively prevent the restacking of MXene and remarkably increase the electroactive surface area of the electrode, which can further increase electrocatalytic activity toward dopamine. Then, an ultrasensitive electroanalytical method based on SnO₂QDs-functionalized Ti₃C₂ MXene nanocomposite for dopamine monitoring was developed, and the effects of experimental condition were investigated systematically. Under optimized conditions, the prepared sensor presented a linear dependence for dopamine in the concentration range from 0.004 to 8.0 µM with the detection limit of 2.0 nM (S/N = 3). Moreover, it selectively perceived dopamine in presence of physiological interferents in urine and serum samples with excellent linearities (correlation coefficients higher than 0.9920). The relative recoveries were in the range 97.67-105.3% and 103.0-106.8%, while the limits of quantitation were 10.12 nM and 9.62 nM in urine and serum sample, respectively, demonstrating the method suitability for dopamine sensing and being envisioned as a promising candidate for neurotransmitter monitoring in biological diagnosis.