Electrochemical biosensors in the assay of antibiotics

Certain antibiotics such as amphotericin B and nystatin are known to interact selectively with cholesterol in bilayer lipid membranes, resulting in changes in the transmembrane electrical properties. The possibilities for use of this effect in selective trace organic analysis are demonstrated by experiments performed with a simple electrical circuit incorporating a conventional research pH meter. Transmembrane resistance-based responses correlate with aqueous antibiotic concentration and are rapid and reversible. The limit of detection of the technique is approximately 10^-9 M of stimulant.