Abstract
A biosensor consists of three fundamental components : biological component, membrane component, and transducer. A biological component also includes enzymes, antibodies, antigens, organelles, cells, and tissues. The selectivity of a biosensor normally depends on the extent of reaction specificity. While serving as a carrier for a biological component lying between itself and transducer, a membrane component can be used to immobilize the biological component and protect the transducer from interference. Moreover, a transducer can transform the involvement of a biochemical reaction into electronic signal which can be detected by instrument. This study develops the thin membrane technology immobilized with multi-enzyme. In addition, the amperometric creatinine sensors based on three kinds of enzyme ( sarcosine oxidase, creatinase, creatininase ) is adopted as our experimental model. Moreover, the electrochemical measurement is taken by the H2O2 electrode. Plasma induced grafted copolymerization of acrylic acid onto PP films was investigated in this study. The surface of chemically inert PP could be graft copolymerized with water soluble acrylic acid once being pretreated with a plasma glow discharge in N2 and then exposed to oxygen to form peroxides. The peroxides were thermally decomposed into polymeric free radicals whenever the oxidized surface was heated in the presence of monomer, but in the absence of oxygen. These polymeric radicals initiated the graft copolymerization of the acrylic acid monomer. The influence of plasma treatment power, time and graft copolymerization time upon polymerization yield were also determined. The samples were characterized by ESCA and IR. A chemical shift of C1s signal of Ar plasma treated and untreated PP films was revealed by ESCA, which also verified the presence of grafted pAA. The polyacrylic acid grafted PP was observed in this study to be a promising multi-enzyme carrier. An amperometric creatinine sensor fabricated by covered the Pt/Ag electrode with a thin layer of immobilized enzyme membrane was studied. The calibration curve for measurement of sarcosine, creatine and creatinine, the effect of pH, and the Enzymes Composition on the sensitivity, and the life time of the sensor were examined.