L-cysteine capped Fe3O4 nanoparticles-functionalized conductive carbon yarn as a flexible electrochemical biosensor for detection of L-phenylalanine

Abstract

We explore the utilization of a conductive carbon yarn (CCY) as a flexible biosensing platform with the help of L-cysteine-capped Fe3O4 nanoparticles (NPs) for amino acids, with L-Phenylalanine serving as a model analyte. The L-cys@Fe3O4 NPs are synthesized using a wet-chemical co-precipitation method, resulting in a pure cubic phase as confirmed by X-ray diffraction (XRD) analysis. The Fourier Transform Infrared (FTIR) spectroscopy confirms the functionalization of Fe3O4 NPs with L-cysteine. We used a hydrothermal technique to functionalize CCY to prepare L-cys@Fe3O4/CCY electrode. The L-cys@Fe3O4 NPs and L-cys@Fe3O4/CCY morphology are characterized using the Field Effect Scanning Electron Microscope (FESEM). Cyclic voltammetry technique is used for electrochemical detection of L-phenylalanine using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) chemistry (taken in 5 mM K4[Fe(CN)6] solution prepared with 1X PBS, pH = 7.4). The CCY-based sensor exhibits excellent linearity (R2 = 0.96) over a wide linear range from 10 μM to 100 μM, with a detection limit of 5.8 ± 0.5 μM and sensitivity of 0.02 ± 0.01 μA μM-1m−2 enabling sensitive detection of L-phenylalanine. The electrodes also exhibit excellent repeatability. We have performed a detection of L-Phe with a real sample and the analysis also suggests the applicability of the electrode. Thus, the L-cys@Fe3O4/CCY electrode demonstrates its potential as a flexible, highly efficient, and cost-effective sensing material, making it suitable for developing point-of-care biosensors.