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Bifunctional Fluorescence Aptasensor Based on Target-Induced Strand Displacement Enables Simultaneous Detection of
M A Hagir Omer1,2, Meng Li1, Xiaolin Yang1
1Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P.R. China.
Abstract:
Simultaneous detection of dopamine (DA) and serotonin (5-HT) provides useful information in the early diagnosis of neurological diseases. However, existing approaches have to be conducted in centralized laboratories with assay complexity. Herein, we developed a bifunctional fluorescence aptasensor based on target-induced strand displacement, which enables the simultaneous detection of DA and 5-HT in multiple body fluids. Cy5/FAM-tagged aptamers were first hybridized with a Dabcyl-quenched complementary strand ss-DNA1-(Dabcyl)2 to form a low fluorescence background complex Cy5-ds-DNA-(Dabcyl)2-FAM. Upon target binding (DA/5-HT), the tagged aptamers were selectively displaced, restoring Cy5 (red) and FAM (green) fluorescence upon excitation with 600 and 465 nm, respectively. The aptasensor exhibits high sensitivity, with a limit of detection of 0.3 nM for DA and 0.5 nM for 5-HT in solution. Good recovery in artificial cerebrospinal fluid and urine and results consistent with those of high-performance liquid chromatography (HPLC) were achieved. With the success in solution-based detection, we further transferred the aptasensor onto glass fiber paper (GFP) to develop a paper-based aptasensor. Good recovery in tears and urine and results matching those of HPLC were also obtained. This simple and bifunctional fluorescence aptasensor offers a promising point-of-care platform for the detection of multiple neurotransmitters in diverse body fluids.
