Selective Detection of Acyclovir on Poly(L–Methionine) Membrane Coated Reduced Graphene Oxide-Based Graphite Electrode Optimized by Central Composite Design

In this study, a sensitive and facile electrochemical sensor is described to quantify the Acyclovir (ACV) in human biofluids. Firstly, a reduced graphene oxide (rGO) thin film was electrodeposited on a pencil graphite electrode (PGE). Then, a thin polymer film of L-methionine (L-Met) was electropolymerized on the rGO-coated PGE to prepare P-L-Met/rGO/PGE. Various techniques characterized the morphology and electrochemical response of the modified electrode. Furthermore, the central composite design (CCD) methodology was used as an experimental design strategy to optimize the sensor response's useful variables. The P-L-Met/rGO/PGE presented better quantity and stability for the ACV compared to that of bare PGE. The effective surface area of the P-L-Met/rGO/PGE (0.217 cm
²
, which is 3.2 times more than the unmodified PGE), electron transfer coefficient (α = 0.3) and the transferred electron number in the rate-determining step (n
_α
= 2) for the ACV catalysis were also evaluated. Using P-L-Met amplified catalytic activity and stability of rGO on the PGE surface and improved the separation of analyte signal from other spices. Furthermore, the ACV was determined in the presence of the guanine (GU), adenine (AD), ascorbic acid (AA), epinephrine (EP) and acetaminophen (ACT) without interference. The sensor response to the ACV was linear in two ranges of 0.044-2.98 μM and 2.98-29.1 μM with a limit of detection of 30 nM. Besides, the sensor presented an excellent analytical performance in the quantification of the ACV in the real samples.