Book

Description

L-lysine is one of the essential amino acids which is obtained through diet. The normal lysine levels in a healthy human serum sample is 150 to 250 μmol/L. There is imbalance in lysine levels in certain diseased conditions and hence it could be used as a biomarker for diagnosis of various diseases. The present book describes the principles, merits and demerits of the various analytic methods for determination of lysine with special emphasis on biosensors. The fabrication of an amperometric lysine biosensor has been described, wherein nanoparticles (NPs) of lysine oxidase (LOx) are covalently immobilized onto gold electrode (AuE). The LOxNPs were prepared by desolvation method and characterized by UV Vis spectroscopy, Fourier transform infra red (FTIR) spectroscopy and transmission electron microscopy (TEM). The LOxNPs/AuE modified working electrode was studied by scanning electron microscope (SEM) and cyclic voltammetric (CV) techniques. The electrode exhibited optimum current within 3.5 s at applied potential, 0.8 V, pH 6.5 and temperature, 35°C. The sensor displayed a linear relationship between lysine concentration and current in the range 10-800 μM with a limit of detection of 10 μM. We have also described the amplification of amperometric L-lysine biosensor using L-lysine oxidase nanoparticles (LOxNPs) and graphene oxide nanoparticles (GrONPs) immobilized onto pencil graphite electrode (PGE). The biosensor showed optimum current at 0.7 V, pH 6.5, 35°C, a detection limit of 0.01 μM, response time as 3.95s and a wider linear range 0.01-1000 μM. The biosensors measured L-lysine level in biological materials.