Nonenzymatic interference free nano-molar range detection of L-tyrosine in human serum and urine samples using carbon dots doped cerium titanate modified glassy carbon electrode

Abstract

Normally wound healing is much slower in diabetic patients. Therefore it leaves them susceptible to ulceration and subsequent infection. The concentration of L-Tyrosine (Tyr), a non-essential amino acid is found to be significantly elevated in serum and urine samples of patients with infected ulcers. In situ monitoring and early detection of Tyr levels is therefore pivotal in the timely diagnosis of infections in ulcers of diabetics. Tyr, unlike other inflammatory biomarkers, is more specific for wound related infections and is a better candidate as biomarker which necessitates researchers to design novel biosensors for the detection of infections. With this intent we have devised a sensitive biosensor system that uses a glassy carbon electrode (GCE) modified with the synthesized cerium titanate oxide doped carbon dots (CeTi2O6/CDs/GCE) for sensing Tyr in biological samples. UV–Vis. spectroscopy, FT-IR spectroscopy, XRD technique, FE-SEM, Mapping, HR-TEM, EDX and XPS analyses were used to characterize the synthesized CeTi2O6/CDs. The biosensor system was optimized after studying the effect of variables such as loading of the CeTi2O6/CDs nanocomposite, concentration of Tyr and pH of the solution. The lower detection limit of Tyr was found to be 26 nM under ideal settings where the linear variation between the oxidation peak current of Tyr and its concentration ranging from 0.01 to 230 µM. The CeTi2O6/CDs/GCE was found to be a specific, reliable and highly sensitive system for quantification of Tyr in biological samples, which paves way for early detection of onset of infection thereby preventing complications associated with diabetic foot ulcers like gangrene and sepsis that in turn leads to limb amputation.