Design of DMAP functionalized MoS2-GO hybrid for targeted visual detection of dopamine: a step towards chromogenic substrate free point of care testing

Abstract

Abnormal release of DA, a crucial neurotransmitter, can cause serious neurological disorders such as Parkinson's and Alzheimer's disease. Thus, sensitive DA detection becomes critical for the investigation of physiological functions and disease diagnosis. Specific DA quantification in real samples is a tedious task due to the presence of analogous neurotransmitters. Therefore, aiming at on-site selective monitoring of DA, a high-performance colorimetric probe has been designed using a DMAP-modified MoS2-GO hybrid for highly selective visual detection of DA, especially for POC testing. The efficient DA recognition can be attributed to the large surface area with potentially active sites for greater electron transport and oxidation ability owing to the synergistic effect of MoS2 and GO. The hybrid has been modified with DMAP, which allows extremely selective and specific DA recognition against potential interferents, especially other neurotransmitters. The proposed mechanism relies on the attachment of DA to the hybrid surface, facilitating the oxidation and complexation processes that induce aggregation causing instant color change. The designed colorimetric method can recognize DA in neutral medium at room temperature without any reagents or supplementary operations. A good linear relationship was observed between the absorbance of the hybrid and DA concentrations in the range 1–100 μM, with a low detection limit of 0.17 μM. Furthermore, the applicability of the present approach was also verified by the analysis of DA in human serum samples and proved to be promising for sequential DA detection in biological samples with good precision and accuracy. From a POC perspective, easy-to-use paper-based test strips were prepared for visual recognition of DA in just 3 min. Results indicate that the designed DA assay provides a powerful, low-cost, convenient, and reagentless colorimetric platform for instant and highly selective DA detection in aqueous solution, strips, and human serum that is predicted to find extended applications in the fields of biosensing, clinical diagnosis, and in-vitro disease monitoring.