A peptide aptamer based electrochemical amperometric sensor for sensitive L-glutamate detection.

L-glutamate (L-Glu) has gained much attention owing to its contribution to the umami taste and it plays important roles in the central nervous system. Herein, an enzyme-free amperometric biosensor based on a peptide possessing an electroactive ferrocene linker as ferrocene-Gly-Gly-Gly-Gly-Ile- Pro-Val-Tyr-Cys-Gly-Leu-Ile-Gly-Gly-Gly-Gly-Lys-(CH2)4- thioctic acid self- assembled on gold electrode was designed and fabricated for specific determination of L-Glu. The biosensor was characterised via cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy and scanning electron microscopy. The biosensor showed optimum response within 200 s at 0.10 V in phosphate-buffered saline. Moreover, the biosensor exhibited excellent sensitivity and a low detection limit of 1.00 × 10-10 M. The sensitivity at an L-Glu concentration of 1.00 × 10-7 M - 1.00 × 10-3 M was 0.1572 μA/M, and that at an L-Glu concentration of 1.00 × 10-10 M - 1.00 × 10-7 M was 0.0293 μA/M. The peptide-based biosensor had excellent specificity and a wider linear range. The relative standard deviation of the L-Glu concentrations measured by the biosensor in a hundred-fold dilution of mouse serum samples was less than 5.00% compared with the high-performance liquid chromatography results, and the recovery rate of L-Glu was from 93.32% to 105.15%.