Use of beta-cyclodextrin as enhancer of ascorbic acid rejection in permselectivefilms for amperometric biosensor applications

Interference rejection in amperometric biosensors can be more effective introducing some modifiers during electro-deposition of permselective film. Addition of beta-cyclodextrin (?CD), a cyclic oligosaccharide composed ofseven glucose units, to the ortho-phenylendiamine (oPD) monomer were already demonstrated to provide anenhancement in ascorbic acid (AA) rejection. Here we evaluated the improvement in permselectivity of poly-eugenol and poly-magnolol films electro-polymerized in presence of different amounts of betaCD or eugenol-betaCDinclusion complex for amperometric biosensor application. Starting from Pt-Ir wire as transducer several mi-crosensors were covered with polymeric films doped with?CD-based modifiers through constant potentialamperometry. Characterization of modified polymers was achieved by scanning electron microscopy andpermselectivity analysis. Poly-magnolol film in combination with ?CD showed a worsening in permselectivitycompared to poly-magnolol alone. In contrast, the introduction of ?CD-based modifier enhanced the interferencerejection toward the archetypal interferent AA, while slightly affecting permeability toward H2O2compared tothe poly-eugenol without modifier. The AA rejection seems to be influenced by the availability of ?CD cavity aswell as film performance due to concentration of betaCD-Eugenol inclusion complex. A poly-eugenol film co-polymerized with 2 mM betaCD-eugenol inclusion complex showed a permselectivity equal to poly-orthopheny-lendiamine film (PPD), with a lower permeability to AA, likely to be related with a self-blocking mechanism.Based on these results, a biosensor for glutamate was constructed with a poly-eugenol doped with beta-CD-eugenolas permselective layer and its permselectivity, stability and lifetime were determine.