Carbon dots from PEG for highly sensitive detection of levodopa†
High-intensity fluorescent carbon dots (CDs) coupled with tyrosinase (TYR) yielded hybrids, as a fluorescent probe, which were efficient, fast, stable and sensitive in the detection of levodopa (L-DOPA). The detection limit of L-DOPA was as low as 9.0 × 10−8 mol L−1 with a wide linear range from 3.17 × 10−4 mol L−1 to 3.11 × 10−7 mol L−1. The efficient selective detection of L-DOPA can be attributed to the CDs that are excellent electron acceptors/donors and exhibit high adsorption capacity of H+. It is worth mentioning that TYR does not require modification and immobilization, and the test results could be read as soon as the probe–sample incubation was completed. Moreover, the test results are comparable to those of the present clinical fluorescence and high performance liquid chromatography (HPLC) methods. Our experimental results indicated that CDs possess great potential in the development of various enzyme-based biosensors.