Selection, characterization, and electrochemical biosensing application of DNA aptamers for sepiapterin

Sepiapterin reductase deficiency (SR) is a rare inborn disorder of neurotransmitter metabolism. The early diagnosis of SR disease should be achieved through the determination of the sepiapterin level in body fluids of suspected patients. Here, we report the selection, identification, and characterization of DNA aptamers against sepiapterin. The aptamer selection was achieved via the systematic evolution of ligand by the exponential enrichment technique. After ten rounds of selection, high-affinity aptamers were identified. The binding affinities of the selected aptamers were evaluated using fluorescence binding assays showing dissociation constants ranging from 37.3 to 79.0 nM. The highest affinity aptamer was then integrated into a competitive electrochemical biosensor. The biosensor achieved outstanding sensitivity with a detection limit of 0.8 pg/ml which was much lower than the reported chromatographic method for sepiapterin quantification. The aptasensor has also shown a high degree of selectivity against the closely-related compound. The aptasensor was then challenged by detecting the sepiapterin in spiked serum samples where a good recovery percentage was achieved.