A NEW POLYMERIC IMMOBILIZER FOR ENZYMES SUITABLE FOR SPR DETECTION SCHEME

Conjugated polymers (CP) are a class of organic substances of increasing interest for their electroluminescence photoluminescence and nonlinearity properties . Some other properties of these molecules can be exploited to fix enzymes for biosensors. In this work, we investigate the immobilization property of a new class of modified polyphenil-ethynilenes (pPE). In these polymers, a glycol thioester group has been added to favour both the immobilization of enzymes and their filmability by self-assembly (SA) method. As a first glance, we choose to study the immobilization of the enzyme glucose-oxidase (GOD), responsible of the catalytic reaction of glucose, that is a well-known process and successfully applied in a wide class of glucose sensors. First, the enzymatic activity and stability of SA layers on dielectric substrates was demonstrated. Then, the behaviour of immobilized enzyme was tested in a Surface Plasmon Resonance (SPR) detection scheme as a fast and highly sensitive tool to monitor the interface enzymatic reaction. To this goal, gold-pPE/GOD multilayers were made and put in contact with a solution of glucose in water. Then, they were coupled in a Kretschmann configuration to a propagating surface plasmon by using light at 850 and 633 nm wavelengths. A well resolved angle shift was detected with both wavelengths, putting in evidence the set-on of the catalytic reaction of glucose These encouraging tests indicate that the new pPEs can be excellent and stable immobilizers of enzymes, and are able to preserve their activity. This can be combined with high resolution optical techniques as SPR to give attractive alternatives to the existing systems or for their implementation.