Abstract
The detection of chemical messenger molecules, such as neurotransmitters in nervous systems, demands high sensitivity to measure small variations, selectivity to eliminate interferences from analogues, and compliant devices to be minimally invasive to soft tissue. Here, an organic electrochemical transistor (OECT) embedded in a flexible polyimide substrate is utilized as transducer to realize a highly sensitive dopamine aptasensor. A split aptamer is tethered to a gold gate electrode and the analyte binding can be detected optionally either via an amperometric or a potentiometric transducer principle. The amperometric sensor can detect dopamine with a limit of detection of 1 μM, while the novel flexible OECT-based biosensor exhibits an ultralow detection limit down to the concentration of 0.5 fM, which is lower than all previously reported electrochemical sensors for dopamine detection. The low detection limit can be attributed to the intrinsic amplification properties of OECTs. Furthermore, a significant response to dopamine inputs among interfering analogues hallmarks the selective detection capabilities of this sensor. The high sensitivity and selectivity, as well as the flexible properties of the OECT-based aptasensor, are promising features for their integration in neuronal probes for the in vitro or in vivo detection of neurochemical signals.
Highlights
The ability to detect small-molecule neurotransmitters is crucial for understanding neuronal information processing, related neurochemical processes, and brain functions in general [1]
We found that the flexible interdigitated organic electrochemical transistor (iOECT)-based surface, and on the other hand, decrease the distance between the gold electrode and the redox group, exhibited an ultralow detection limit of 0.5 fM, which is lower than that of the corresponding which thereforesensor facilitates thepreviously charge transfer and electrochemical generates a detectable signal via At an amperometric and all reported sensorselectrochemical for dopamine detection
In the absence of dopamine, no charge transfer was observed between the aptamer and the gold electrode, even in Tris buffer containing 0.5 μM of the methylene blue-modified fragment (Figure 1a, black curve), indicating that aptamer2 freely floated in the buffer solution and no binding event between the two split aptamer parts occurred
Summary
The ability to detect small-molecule neurotransmitters is crucial for understanding neuronal information processing, related neurochemical processes, and brain functions in general [1]. As one of the most important neurotransmitters of the human central nervous system, is involved in the regulation of many behavioral responses and brain functions [2], and abnormal levels are symptomatic for several neuronal diseases, such as Parkinson’s, Alzheimer’s, Tourette’s syndrome, and schizophrenia [3]. Electrochemical approaches are versatile and promising due to their low fabrication costs, fast response, high sensitivity, and their easy miniaturization [13,14,15]. As one of the target recognition components of electrochemical sensors, has attracted plenty of attention because of its high selectivity, flexibility, high affinity [16], low cost, and easy fabrication [17]. Due to the variable distribution of dopamine concentrations in different body fluids and tissues (in the range of fM [18] to μM [19]), as well as the interference from some analogues or ascorbic acid and uric acid, which share
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