L-Cysteine Capped Fe3o4 Nanoparticles-Functionalized Conductive Carbon Yarn as a Flexible Electrochemical Biosensor for Detection of L-Phenylalanine

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 Lcys@Fe3O4/CCY morphology are characterized using the Field Effect Scanning Electron Microscope (FESEM). Cyclic voltammetry is used for electrochemical detection of Lphenylalanine using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and NHydroxysuccinimide (NHS) chemistry. 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-1 m-2 enabling sensitive detection of Lphenylalanine. The electrodes also exhibit excellent repeatability. Thus, the Lcys@Fe3O4/CCY electrode demonstrates its potential as a flexible, highly efficient, and costeffective sensing material, making it suitable for developing point-of-care biosensors.