Dopamine (DA) analysis is complicated by the interference from other electrochemically active endogenous compounds present in the brain, including DA precursors and metabolites and other neurotransmitters (NT). Here, we report a simple, sensitive, and selective optical fiber biosensor for in vitro detection of the DA in the presence of other NT. It is composed of a 57-mer dopamine-binding aptamer (DBA) as recognition element and nonadiabatic tapered optical fiber as a probe. Upon the addition of DA, the conformation of DBA would change from a random coil structure to a rigid tertiary structure like a pocket. The conformational change of DBA leads to the refractive index change around the tapered fiber surface. Specific recognition of DA by the aptamer allowed a selective optical detection of DA within the physiologically relevant 0–10 μM range. The sensitivity of the Apta-Biosensor for concentration of the DA in the range of 0–1 μM and 1–10 μM with correlation coefficients (R2) equal to 0.99 was 0.27 ± 0.05 and 0.08 ± 0.01 nm/μM, respectively. In addition, detection limit of the biosensor to DA in range from 0 to 1 μM and 1 to 10 μM was 37 and 125 nM, respectively. Some common interferents, such as epinephrine and ascorbic acid showed no or just a little interference in the determination of DA. In addition, the binding constant of the DA to DNA aptamer was determined.
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