Peptide aptamer-based polyaniline-modified amperometric biosensor for L-lysine detection in real serum samples

L-Lysine (L-Lys) quantification in serum using a novel and highly selective amperometric biosensor has been reported. In this study, an efficient, enzyme-free, and simple anti-fouling biosensor was developed based on a self-screened peptide aptamer. A glassy carbon electrode (GCE) was used to construct anti-fouling interfaces by modifying its surface with polyaniline (PANI) polymer. The peptide aptamer, Cys-Pro-Pro-Pro-Pro-Arg-Glu-Asn-Ile-Gln-Arg-Leu-Thr, was then immobilized onto this electrode via an electroactive cysteine linker and its potential in the determination of L-Lys was examined. Under optimised experimental conditions, the peptide-modified electrodes exhibited excellent anti-fouling and electrochemical sensing. The biosensor was effective in resisting biofouling in a wide range of serum samples and amino acid solutions, and its linear range for L-Lys detection ranged from 1 nM to 10 mM, with a comparatively lower detection limit (0.3 nM; S/N = 3). The anti-fouling biosensor could detect L-Lys in real serum samples, and this approach of designing peptide aptamers based low-fouling biosensors can easily be extended to the development of a bio-sensing platform system for a variety of other metabolites.