Soraya Hosseini
University of Malaya, Malaysia
Biography
Natural food-derived peptides have attracted a great deal of interest among researchers due to the importance of a healthy diet. Parkia speciosa (stink bean), a Southeast Asian legume, is composed of medicinal chemicals which exhibit biological activities. Parkia speciosa has been reported to be anticancer, antibacterial, antioxidant, antiangiogenic and demonstrates hem-agglutinating activity. The compositional analysis of amino acids in Parkia speciosa seeds have been reported through hydrolysis using alcalase enzyme. Cyclic voltammetry (CV) using biosensor is a well-established technique with broad applications in nutrition analyses. A novel electrochemical Ag2O/CNT/ND biosensor, comprising silver-oxide, nano-diamond (ND) and carbon nanotube (CNT), has been fabricated on a copper sheet and used as the working electrode. In order to increase the stability of the biosensor, Sago, a natural biopolymer, was added to the composite. The Ag2O/CNT/ND and Ag2O/CNT/ND/Sago biosensors exhibited irreversible reaction free oxidation with reduction peaks at -1.25 and -1.16 V in 10 mM buffer phosphate solution/Parkia speciosa (pH 6.8), respectively. Amino acid biosensor was fabricated after the immobilization of L-amino acid oxidase on the Ag2O/CNT/ND/Sago electrode to estimate the level of amino acids in Parkia speciosa juice. The analysis of results suggested that the irreversible electro-chemical process was simultaneously adsorption and diffusion-controlled. The developed biosensor displayed a very good electro-catalytic activity toward the oxidation of amino acid to release H2O2 and NH3 as a result of the reaction between the active sites and the Parkia speciosa ingredient. This was also confirmed by a drop in the pH value from 6.8 to 6.55 and a change in the color of the solution from green to yellow. An increase in the charge transfer resistance at potentials higher than -1 V could be also explained by the co-formation of hydrogen peroxide (H2O2) and water on the electrode surface.