Simultaneous sensing of carbidopa and levodopa by a novel strategy based on dual-emission ratiometric assay of modified carbon dots.

Abstract

Rapid control of the content of Parkinson's drugs in biological fluids and pharmaceutical formulations is of great importance because changes in the concentration of these drugs affect their bioavailability and biopharmaceutical properties. Therefore, we presented a simple and convenient method for the ratiometric detection of carbidopa and levodopa for carbon dots (CDs) dual-fluorescent emission. Dual-emission CDs were prepared from chitosan using a microwave method, following which the surface was chemically modified with terephthalaldehyde. CDs had two strong well-separated peaks at 445 and 510nm. The relative measurement of carbidopa and levodopa was based on the static extinction of CDs at 445nm and increase at 510nm, respectively. The linear range for carbidopa measurement was 2.5-300nM, with a limit of detection (LOD) of 2.1nM, and a relative standard deviation (RSD) of 1.68%. Further, the linear range for levodopa measurement was equal to 3.0-400nM, with LOD and RSD% of 2.8nM and 3.5%, respectively. Also, selectivity of ratiometric sensor in the presence of interferences was investigated, which showed that the recovery of carbidopa and levodopa in serum and urine samples has changed between 96.80% and 116.24% with RSD% 0.11-0.77. CDs also provided good results for the determination of carbidopa and levodopa in real samples, and had high selectivity in the presence of possible interferences.