A carbon dioxide biosensor based on hemoglobin incorporated in metal supported bilayer lipid membranes (BLMs): Investigations for enhancement of response characteristics by using platelet‐activating factor

Abstract

AbstractThe present article reports the development of a novel electrochemical carbon dioxide minisenso based on hemoglobin which is incorporated into self‐assembled bilayer lipid membranes (s‐BLMs) on a metal support. The presence of carbon dioxide in solution was found to modulate the ion conductivity of BLMs containing hemoglobin, when using a lipid composition containing egg phosphatidylcholine (egg PC) and dipalmitoylphosphatidic acid (DPPA). The use of stabilized metal‐supported BLMs has allowed the electrochemical investigation of the reversibility of the response to carbon dioxide and of hemoglobin binding to lipid membranes. The effects of hemoglobin concentration, composition of BLMs in DPPA and pH on the sensitivity of the response were examined. The sensor provides the advantages of fast response times (on the order of ca. 10 s) to alterations of carbon dioxide concentration, low detection limits (ca. 0.4 × 10−6 M) and capability of analysing small sample volumes. Semisynthetic platelet‐activating factor (PAF; 1‐O‐alkyl‐2‐acetyl‐sn‐glyceryl‐3‐phosphorylcholine, AGEPC) was found to improve the response characteristics of the carbon dioxide sensor (i.e., decrease of the detection limit to nM range and increase of the dynamic range of carbon dioxide determination). The biosensor was routinely mechanically stable and functional for over 48 h. During this time it showed reproducible sensitivity and response to a given concentration of carbon dioxide in solution.