Functionalization of poly-SNS-anchored carboxylic acid with Lys and PAMAM: surface modifications for biomolecule immobilization/stabilization and bio-sensing applications

Poly(2-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) (SNS) acetic acid) was electrochemically deposited on graphite electrodes and functionalized with lysine (Lys) amino acid and poly(amidoamine) derivatives (PAMAM?G2 and PAMAM?G4) to investigate their matrix properties for biosensor applications. Glucose oxidase (GOx) was immobilized onto the modified surface as the model enzyme. X-Ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to report the surface properties of the matrices in each step of the biosensor construction. The biosensors were characterized in terms of their operational and storage stabilities and the kinetic parameters (K and I(max)). Three new glucose biosensors revealed good stability, featuring low detection limits (19.0 μM, 3.47 μM and 2.93 μM for lysine-, PAMAM?G2- and PAMAM?G4-functionalized electrodes, respectively) and prolonged the shelf lives (4, 5, and 6 weeks for Lys-, PAMAM?G2- and PAMAM?G4-modified electrodes, respectively). The proposed biosensors were tested for glucose detection on real human blood serum samples.