Urea biosensor, Enzyme immobilization, Conducting polymer, Polyaniline, Polyelectrolyte multilayers, Polysaccharides, Science & Technology, Life Sciences & Biomedicine, Physical Sciences, Biophysics, Biotechnology & Applied Microbiology, Chemistry, Analytical, Electrochemistry, Nanoscience & Nanotechnology, Chemistry, Science & Technology - Other Topics, NANOPOROUS ALUMINA MEMBRANES, INTEGRATED THERMAL BIOSENSOR, ELECTROINACTIVE POLYPYRROLE, PH, IMMOBILIZATION, SURFACE, SENSOR, FILMS, TRANSDUCER, PENICILLIN, Aniline Compounds, Biopolymers, Biosensing Techniques, Chitosan, Electrochemical Techniques, Enzyme Stability, Enzymes, Immobilized, Glucans, Humans, Potentiometry, Sensitivity and Specificity, Urea, Urease, 0301 Analytical Chemistry, 0903 Biomedical Engineering, 1007 Nanotechnology, Bioinformatics
A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10(-6) to 10(-1) mol L(-1) urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting.