Manganese-doped g-C3N4 nanozyme-based smartphone platform for rapid L-DOPA detection in clinical samples

Levodopa (L-DOPA) is a crucial neurotransmitter utilized in the treatment of neurological disorders, particularly in Parkinson's disease, where its concentration in biological fluids serves as a key diagnostic marker. Despite its significance, current methods for L-DOPA detection often suffer from limitations such as prolonged detection times, low sensitivity and weak anti-interference. This study addresses these challenges by introducing a highly efficient and colorimetric sensor for the rapid detection of L-DOPA, utilizing manganese-doped graphitic carbon nitride (Mn-g-C 3 N 4 ) as a peroxidase-mimetic catalyst. The sensor employs 3,3′,5,5′-tetramethylbenzidine as a substrate and achieves detection within 20 s, with a linear response over the concentration ranges of 1–10 μM and 20–90 μM, and the detection limits were 0.049 μM and 0.51 μM, respectively. The method has good specificity for L-DOPA and has been successfully applied to human serum even in the presence of interference from dopamine and other amino acids. In addition, the sensor exhibits satisfactory performance in smartphone-based L-DOPA detection. The novel sensor platform offers a simple, cost-effective, and scalable solution for real-time L-DOPA monitoring, with significant potential for applications in both clinical and environmental contexts.