Development and Characterization of a Lysine Biosensor using Lysine Oxidase Nanoparticles for Lysine Detection using Pencil Graphite Electrode

The precise detection of lysine is critical in clinical diagnostics and food safety due to its role as an essential amino acid and a biomarker in various physiological processes (Nivedita et al., 2019; Sarma & Choudhury, 2016). This study presents the development and characterization of a high-performance lysine biosensor based on lysine oxidase nanoparticles immobilized on pencil graphite electrodes (PGEs). Advanced characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical analysis (cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry), were employed to validate the sensor's design and performance (Chen & Qian, 2018; Liao & Xiao, 2016).The biosensor demonstrated a remarkable limit of detection (LOD) of 0.1 µM and a wide linear detection range spanning 0.1 µM to 1.0 mM, covering physiological and supra-physiological lysine levels (Duffy & Gillis, 2015). pH optimization revealed maximum enzymatic activity at pH 6.5, while stability tests confirmed that the sensor retained over 95% of its activity after 30 days of storage (Sharma & Byrne, 2016). The integration of lysine oxidase with a nanoparticle-modified electrode significantly enhanced sensitivity (8.2 µA/mM) and specificity, outperforming existing lysine detection technologies (Rodriguez & Fernandez, 2020).These findings establish the proposed biosensor as a cost-effective, scalable, and reliable platform for lysine monitoring in real-world applications, such as medical diagnostics and food quality control.