Fabrication of Integrated Dehydrogenase-Based Electrochemical Biosensors in order to detection of amino acids in biological samples

One method to detect the Phenylketonuria (PKU) disease, is the using an enzyme electrochemical biosensors that they have to be more selectivity than other biosensors. In this biosensors, different substrates are used for immobilization of enzymes and electrocatalytical structures[1]. This study describes a facile approach to the preparation of integrated dehydrogenase-based electrochemical biosensors through noncovalent attachment of an oxidized form of β-nicotinamide adenine dinucleotide (NAD+) onto graphene and graphene-based materials such as graphene oxide and graphene quantum dots with the interaction between the adenine subunit in NAD+ molecules and graphene nano-structures. With phenylalanine dehydrogenase (PDH) as a model dehydrogenasebased recognition unit, electrochemical studies reveal that phenylalanine is readily oxidized at the PDH/NAD+/GO-modified electrode without addition of NAD+ in the phosphate buffer. graphenebased materials employed here not only serve as the electronic transducer and the support to confine NAD+ cofactor onto the electrode surface, but also act as the electrocatalyst for NADH oxidation in the dehydrogenase-based electrochemical biosensors[2, 3]. Also, In this research, for the first time, the carbon ceramic electrodes will be used that they are modified with carbon structures as a substrate with high active surface to stabilize the enzyme of phenylalanine dehydrogenase and preparation of electrochemical biosensors phenylalanine amino acid with high stability and selectivity. At the PDH/NAD+/GO-based phenylalanine biosensor, the current is linear with the concentration of phenylalanine being within a concentration range from 200 to 500 μM. This study offers a facile and versatile approach to the development of integrated dehydrogenase-based electrochemical devices, such as electrochemical biosensors and biofuel cells. 306 Fig 1. Cyclic voltammograms of the enzyme electrode at scan rate of 50 mV/s, without L-phe, 0.5, 1, 2, 2.5 mM,