Enzymatic biosensor based on entrapment of D-Amino Acid Oxidase on gold nanofilm/ carbon nanotubes nanocomposite for D-Alanine determination in human serum

D-Amino Acids (DAAs) have been detected in bacterial cell wall, plants and evenvertebrates; thus, the content of these amino acids can be used to measure bacterialcontamination [1, 2]. Furthermore, amounts of DAAs in the brain are related to severalneurological and psychiatric diseases like Alzheimer [3, 4].Therefore, the sensitivemonitoring of DAAs content is necessary in medicine, foodstuff and nutritional science.sensing and determination of D-Alanine is studied by using an enzymatic biosensor whichwas constructed on the basis of D-amino acid oxidase (DAAO) immobilization by sol-gelfilm onto glassy carbon electrode surface modified with nanocomposite of gold nanofilm (AuNF) and multi walled carbon nanotubes (MWCNTs). The Au NF/MWCNT nanocompositewas prepared by applying the potentiostatic technique for electrodeposition of Au NF on theMWCNT which has been immobilized on glassy carbon electrode surface. The modifiedelectrode is investigated by scanning electron microscopy (SEM), energy dispersive X-rayspectroscopy (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry techniques.