Advances in lipid film based biosensors

© 2016 Elsevier B.V.Since first report on formation stable free standing bilayer lipid membranes (BLM) in 1962 by Mueller et al. [1] these systems became very popular in modeling various membrane processes at molecular level, such as ionic transport, ligand-receptor interactions or lipid-protein interactions. Despite of advantage of BLM in respect of variation in lipid composition and their modifications by receptors and proteins, the work with these systems was rather difficult due to their limited stability. The situation has been considerably improved by introduction of supported bilayer lipid membranes (sBLM) in 1980 by Thompson et al. [2] for possible applications in biosensors. Recent advances in stabilization of supported lipid membranes, appearance of novel nanomaterials such as carbon nanotubes has increased the number of publications on this topic. This review summarizes latest achievements in the field of biosensors utilizing sBLMs

Advances in lipid film based biosensors

© 2016 Elsevier B.V. Since first report on formation stable free standing bilayer lipid membranes (BLM) in 1962 by Mueller et al. [1] these systems became very popular in modeling various membrane processes at molecular level, such as ionic transport, ligand-receptor interactions or lipid-protein interactions. Despite of advantage of BLM in respect of variation in lipid composition and their modifications by receptors and proteins, the work with these systems was rather difficult due to their limited stability. The situation has been considerably improved by introduction of supported bilayer lipid membranes (sBLM) in 1980 by Thompson et al. [2] for possible applications in biosensors. Recent advances in stabilization of supported lipid membranes, appearance of novel nanomaterials such as carbon nanotubes has increased the number of publications on this topic. This review summarizes latest achievements in the field of biosensors utilizing sBLMs

Electrochemical aptasensor based on polycarboxylic macrocycle modified with neutral red for aflatoxin B1 detection

© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Novel electrochemical aptasensors based on glassy carbon electrodes modified with electropolymerized Neutral red and polycarboxylated macrocyclic ligands onto which the DNA aptamers were covalently attached have been developed for detection of Aflatoxin B1 (AFB1). The interaction with an analyte resulted in the decrease of the cathodic peak current of the probe measured by CV and in the increase of the electron transfer resistance determined by EIS. The limit of detection was found to be 0.1 nM for CV and 0.05 nM for EIS methods, respectively. The aptasensor makes it possible to detect AFB1 in peanuts, cashew nuts, white wine and soy sauce with a recovery of 85-100%

Acetylcholinesterase sensors based on gold electrodes modified with dendrimer and polyaniline: A comparative research

Potentiometric and amperometric enzyme sensors based on modified gold electrodes have been developed and compared in pesticide determination. PAMAM dendrimer (generation G4) stabilized with 1-hexadecanethiol was used for the immobilization of acetylcholinesterase from electric eel and choline oxidase from Alcaligenes species in the assembly of amperometric sensor. Polyaniline-doped with camphorsulfonic acid was used to obtain potentiometric response. Trichlorfon, carbofuran and eserine suppress the biosensor response due to their inhibitory effect. The detection limits of 0.003 and 200 nmol l-1 (trichlorfon), 0.04 and 6 nmol l-1 (carbofuran) and 0.1 and 700 nmol l-1 were obtained for amperometric and potentiometric sensors, respectively. The difference in the biosensor behavior and the high sensitivity of the dendrimer modified sensor to the inhibitors is due to the specific organization of protein layer at charged surface of the modifier macromolecules. © 2004 Elsevier B.V. All rights reserved

Pyrite oxidation inhibition by a cross-linked lipid coating

The effect of a diacetylene-containing phospholipid on the oxidation of pyrite, FeS(2), was investigated. Earlier work reported by our research group showed that the adsorption of l,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine on pyrite suppressed the extent of its oxidation by about 75% over a specific time period. Results presented here show that the pre-exposure to UV radiation of this lipid after sorption onto pyrite results in a 90% suppression. Attenuated total reflection (ATR) Fourier transform infra-red spectroscopy (FTIR) suggests that the UV irradiation of the lipid does not result in degradation of the adsorbed layer. It is believed that the UV exposure results in the cross-linking and polymerization of the adsorbed phospholipid into a relatively impermeable barrier that separates the pyrite from the aqueous phase. The results of this study might have implications for the protection of pyrite from oxidation in the environment

Electroanalysis may be used in the Vanillin Biotechnological Production

This study shows that electroanalysis may be used in vanillin biotechnological production. As a matter of fact, vanillin and some molecules implicated in the process like eugenol, ferulic acid, and vanillic acid may be oxidized on electrodes made of different materials (gold, platinum, glassy carbon). By a judicious choice of the electrochemical method and the experimental conditions the current intensity is directly proportional to the molecule concentrations in a range suitable for the biotechnological process. So, it is possible to imagine some analytical strategies to control some steps in the vanillin biotechnological production: by sampling in the batch reactor during the process, it is possible to determine out of line the concentration of vanillin, eugenol, ferulic acid, and vanillic acid with a gold rotating disk electrode, and low concentration of vanillin with addition of hydrazine at an amalgamated electrode. Two other possibilities consist in the introduction of electrodes directly in the batch during the process; the first one with a gold rotating disk electrode using linear sweep voltammetry and the second one requires three gold rotating disk electrodes held at different potentials for chronoamperometry. The last proposal is the use of ultramicroelectrodes in the case when stirring is not possible

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

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

Label-free and redox markers-based electrochemical aptasensors for aflatoxin M1 detection

We performed a comparative analysis of the sensitivity of aptamer-based biosensors for detection mycotoxin aflatoxin M1 (AFM1) depending on the method of immobilization of DNA aptamers and method of the detection. Label-free electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) for ferrocene labeled neutravidin layers were used for this purpose. Amino-modified DNA aptamers have been immobilized at the surface of polyamidoamine dendrimers (PAMAM) of fourth generation (G4) or biotin-modified aptamers were immobilized at the neutravidin layer chemisorbed at gold surface. In the first case the limit of detection (LOD) has been determined as 8.47 ng/L. In the second approach the LOD was similar 8.62 ng/L, which is below of allowable limits of AFM1 in milk and milk products. The aptasensors were validated in a spiked milk samples with good recovery better than 78%. Comparative analysis of the sensitivity of immuno-and aptasensors was also performed and showed comparable sensitivity. © 2018 by the authors

Study of calix[4]resorcinarene-dopamine complextion in mixed phospholipid monolayers formed at the air-water interface

We have studied the physical properties of monolayers formed by calix[4]resorcinarene and in mixtures with dipalmitoyl phosphatidylcholine (DPPC) in various molar ratios formed at the air-water interface and at presence of dopamine in water subphase by means of measurements of surface pressure and dipole potential. We showed that both calix[4]resorcinarene as well as its mixture with DPPC form stable monolayers at the water subphase. The presence of dopamine resulted in an increase of the mean molecular area and in a decrease of the compressibility modulus of the monolayers. For mixed monolayers at higher content of calix[4]resorcinarene (> 0.2 molar fraction) a deviation from ideal miscibility took place especially for monolayers in a solid state. This can be connected with formation of aggregates of calix[4] resorcinarene. Lowest miscibility and weakest interaction of dopamine with a monolayer was observed for calix[4]resorcinarene molar fraction of 0.33 in the monolayer. (c) 2006 Elsevier B.V. All rights reserved