Cyanide ion minisensor based on methemoglobin incorporated in metal supported self-assembled bilayer lipid membranes and modified with platelet-activating factor

The present paper reports the development of an electrochemical minisensor for the detection of cyanide ions based on methemoglobin, which is incorporated into self-assembled bilayer lipid membranes (s-BLMs) on a metal support. The presence of cyanide in solution was found to modulate the ion permeability of BLMs containing methemoglobin, when using a lipid composition containing egg phosphatidylcholine (egg PC) and semisynthetic platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, AGEPC). The cyanide ion sensor exhibited good mechanical stability and longevity (routinely over 48 h) and constant sensitivity and response to a given concentration of cyanide ion in solution. Incorporation of hemoglobin or methemoglobin into s-BLMs was examined, and methemoglobin was found to provide lower (by five-fold) detection limit for cyanide ion determination. The effects of protein concentration and composition of BLMs on sensitivity of response were examined. Selectivity studies of cyanide detection were done in the presence of oxygen, carbon monoxide and dioxide, and other anions. The present cyanide ion sensor based on thin lipid film technology provides advantages of fast response times (in the order of 10 s) to alterations of cyanide ion concentration, low detection limits (ca. 4.9 nM, 0.317 μg l−1), and the capability of analyzing small volumes of samples. Furthermore, a device can now simply and reliably be fabricated at low cost, and therefore can be used as a disposable sensor.