Lipid-bonded Conducting Polymer Layers for a Model Biomembrane:  Application to Superoxide Biosensors

• Published in: Analytical chemistry (Washington) Vol. 78; no. 1; pp. 52 - 60
• Main Authors: Kwon, Nak-Hyun, Rahman, Md. Aminur, Won, Mi-Sook, Shim, Yoon-Bo
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2006
• Subjects: Adenosine - analogs & derivatives; Adenosine - chemistry; Analytical chemistry; Animals; Biological and medical sciences; Biosensing Techniques; Biosensors; Biotechnology; Cardiolipins - chemistry; Chemistry; Cytochromes c - chemistry; Electrodes; Enzymes, Immobilized; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General, instrumentation; Glycerophospholipids - chemistry; Heart; Horses; Lipid Bilayers - chemistry; Lipids; Lipids - chemistry; Membranes; Membranes, Artificial; Methods. Procedures. Technologies; Models, Biological; Polymers; Polymers - chemistry; Spectrometric and optical methods; Superoxides - metabolism; Various methods and equipments; Phosphates; Monolayer; Atomic force microscopy; Scanning electron microscopy; Gold; Particle size; Oxidation reduction; Immobilization; Electron transfer; Lipids; Polymer; X ray; Chemical sensor; Bilayer; Layer thickness; Cytochrome c; Biosensor; Covalent bond; Membrane; Photoelectron spectrometry; Langmuir Blodgett layer; Redox potential; Rate constant; Quartz microbalance
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac0510080

Model biomembranes composed of poly-DATT/DGS/POPA and poly-DATT/DGS/CL were separately prepared on gold electrodes. A monolayer of 1,2-dioleoyl-sn-glycero-3-succinate (DGS) was covalently bonded onto electrochemically grown poly-(3,4-diamiono-2,2:5,2-terthiophene) (DATT) layers (thickness of ∼300 nm; particle size of ∼50 to 70 nm). The numbers of unit molecules of the poly-DATT layer and of the DGS immobilized onto the poly-DATT layers were 1.53 × 10-7 and 1.56 × 10-9 mol cm-2, respectively, using a quartz crystal microbalance technique. The lipid bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate (POPA) and cardiolipin (CL) were formed onto the poly-DATT/DGS layer using the Langmuir−Blodgett technique. The surface characterizations of each step were investigated by SEM, AFM, and XPS analyses. Cytochrome c (cyt c) was immobilized onto these model biomembranes through the charge interaction between the positive charges of cyt c and the negative charges of phosphate groups in CL or POPA lipids. At the POPA- and CL-modified biomembranes, the formal potentials of the redox couple of the immobilized cyt c were 0.22 and 0.23 V (vs Ag/AgCl), respectively. The redox reaction of the immobilized cyt c at the POPA- and CL-modified biomembranes was quasireversible, and the electron-transfer rate constants were 0.121 s-1 and 0.133 s-1, respectively. The applicability of these cyt c immobilized bioimitation membranes as the biosensors was tested for the determination of superoxide.