An electrochemical impedimetric sensing platform based on a peptide aptamer identified by high-throughput molecular docking for sensitive l-arginine detection.

As a primary building block for protein synthesis, l-arginine (l-Arg) is also a precursor for the synthesis of important metabolites, and is involved in various physiological and pathophysiological processes. l-Arg is a potential biomarker in clinical diagnosis and nutritional status assessment, making it valuable to quantify and monitor this biomolecule. In this study, peptide aptamers that specifically interact with l-Arg were identified by high-throughput molecular docking, and the binding capacities between the synthesized peptide aptamers and l-Arg were then measured by isothermal titration calorimetry. We hypothesized that the peptide aptamer with the greatest binding capacity could be used as the recognition element in a biosensor. A chemosynthetic peptide aptamer modified with mercaptan and spacer units (thioctic acid-GGGG-FGHIHEGY) was thus used to construct label-free electrochemical impedimetric biosensors for l-Arg based on gold electrodes. The optimum biosensor showed good sensitivity to l-Arg with a linear range of 0.1 pM-0.1 mM, and the calculated limit of detection (three times the signal-to-noise ratio) was 0.01 pM. Interference studies and assays of diluted serum samples were also carried out, and satisfactory results obtained. In conclusion, a potential method of peptide aptamer screening and biosensor fabrication for detecting small biological molecules was demonstrated.