Abstract
Lipid assemblies in the form of two dimensional films have been used extensively as biosensing platforms. These films exhibit certain similarities with cell membranes, thus providing a suitable means for the immobilization of proteinaceous moieties and, further, a number of intrinsic signal amplification mechanisms. Their implementation in the detection of toxins yielded reliable and fast detectors for in field analyses of environmental and clinical samples. Some examples are presented herein, including aflatoxin and cholera toxin detection. The conditions and parameters that determine the analytical specifications of the lipid membrane sensors are discussed, advantages and technology bottlenecks are reviewed, and possible further developments are highlighted.
Highlights
Biosensors exploit the interplay between two components in order to provide useful information about a target compound: A biological moiety and a physicochemical transducer
In the case that there is a slow “channel” formation, this will result that the majority of ions will be dissipated into the bulk solution; in the case that the “channel” opening is fast, this will result in the passage of an appreciable portion of the ions through the lipid film. The former phenomena were noticed when diffusion controlled changes of the pH at one side of a bilayer lipid membranes (BLM) took place with concurrent observations of a charging current transients [1,5] while the latter phenomena were observed in the flow experiments in which the defects number varies dynamically as the pH of the carrier electrolyte solution alters; these results indicate how amplification of analytical signal of bilayer lipid membrane based transducers may be made [2]
The Tm of vesicles composed of 35% DPPA was found to be 23.6 ◦ C and did not practically change in the presence of the toxin, these results indicate that there is no adsorption of aflatoxin M1 (AFM1) onto the surface of the lipid membranes
Summary
Biosensors exploit the interplay between two components in order to provide useful information about a target compound: A biological moiety and a physicochemical transducer. The interaction between the target compound and the biological moiety (receptor) provides a biochemical signal that is readily converted into an electric signal by the transducer (electrochemical, optical, piezoelectric, calorimetric, etc.). Sophisticated techniques such as liquid chromatography (LC) provide accurate results, biosensor devices offer a much higher throughput of samples at a lower cost and with less training of personnel. A schematic lipid membrane-based transmembrane ion permeability. Figure provides a schematic of a lipid membrane-based biosensor
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