Biomimetic sensors

The development of highly selective chemical sensors for complex matrixes of medical, environmental, and industrial interest has been the object of greate research efforts in the last years. Recently, the use of artificial materials - molecularly imprinted polymers (MIPs) - with high recognition properties has been proposed for designing biomimetic sensors, but only a few sensor applications of MIPs based on electrosynythesized conductive polymers (MIEPs) have been reported [1-3]. 

A biomolecular system of glycoproteins derived from bacterial cell envelopes that spontaneously aggregates to form crystalline arrays in the mesoscopic range is reviewed in Chapter 9. The structure and features of these S-layers that can be applied in biotechnology, membrane biomimetics, sensors, and vaccine development are discussed. 

Haupt K. and Mosbach K., Molecularly Imprinted Polymers and Then Use in Biomimetic Sensors, Chem Rev 2000 100 2495-2504. 

Biomimetics, coordination compound applications, 7 600-601 Biomimetic sensors, 3 809-810 Biomimetic synthesis, 13 552 Biomimicry, 24 33... 

Bioresorbable polymers, 3 735-740 Bioselective adsorption, 6 387 Biosensors, 3 794-815 14 154 22 269 affinity DNA biosensors, 3 805-808 affinity immunosensors, 3 800-805 applications, 3 812-813 biomimetic sensors, 3 809-810 catalytic, 3 796-799 cellulose ester applications, 5 408 comparison with microarrays, J6 38It evolution of, 16 380-381 production by thick-film technology, 3 810-812... 

AnseU RJ, Kriz D, Mosbach K. Molecularly imprinted pol3uners for bioanalysis chromatography, binding assays and biomimetic sensors. Curr Opin Biotechnol 1996 7 89-94. 

Kriz D, Ramstrom O, Svensson A, Mosbach K. Introducing biomimetic sensors based on molecularly imprinted polymers as recognition elements. Anal Chem 1995 67 2142-2144. 

Malitesta C, Losito I, Zambonin PG. Molecularly imprinted electrosynthesized polymers new materials for biomimetic sensors. Anal Chem 1999 71 1366-1370. 

Tan YG, Nie LH, Yao SZ. A piezoelectric biomimetic sensor for aminopyrine with a molecularly imprinted polymer coating. Analyst 2001 126 664-668. 

Electrochemical biosensors [18] Here we mean biomimetic sensors, which utilize the ability of biological materials (enzymes, antibodies, etc.) to recognize specific components and to catalyze their reactions with great specificity. Many of the biosensors are electrochemical sensors, based on potentio-metric or amperometric measurements. For example, in the case of an amperometric... 

It has been demonstrated that MIPs possess recognition and binding properties close to those of antibodies and enzymes, especially in organic media, and display higher stability than their natural counterparts. These properties suggest that MIPs can be suitable as recognition elements for chemical (biomimetic) sensors or biomimetic chips. 

In spite of all their advantages, sensitivity and selectivity, bio-sensors, however, do possess disadvantages connected with thermal and timely instability, high cost of bio-receptors and the need to add substrates in the solution under analysis as signal-generating substances. Some attempts to synthesize and use as receptors chemical organic catalytic systems, which will ensure the required selectivity and response rate, have become the basis for developing enzyme-free sensors [11], or biomimetic sensors. 

K. Toko, Biomimetic Sensor Technology, Cambridge University Press, Cambridge, 2000. 

Physicochemical fundamentals of construction and action of catalase- and peroxidase-biomimetic sensors are studied. 

Figure 8.2 shows an electrochemical system - a model of a catalase-biomimetic sensor, consisting of the reference electrode (Ag/AlCl/Cl ) and biomimetic electrode. In this system, the electrochemical potential changed as a result of mimetic electrode interaction with... 

A biomimetic sensor was created with electrodes from aluminum wire (2 mm thick) and aluminum foil (size 20 X 10 X 1 mm), to which the working element was applied by two methods ... 

The change of electrode potential (E) of the catalase reaction with time was measured by a voltmeter. pH and E values for aqueous hydrogen peroxide were determined simultaneously for possible correlations between pH metric and potentiometric results of enzymatic activity of catalase-biomimetic sensors. The electrochemical unit was also equipped with a magnetic mixer. 

For the purpose of determining low hydrogen peroxide concentrations, the authors have designed the most cost-effective and simple to use potentiometric-biomimetic sensors based on immobilized catalase mimics. These sensors possess high hydrodynamic properties and the fastest speed of response. Figure 8.3 shows experimental data on catalase activity of biomimetic electrode in 0.03% aqueous H202. For the sake of comparison, catalase activities of aluminum electrode and aluminum electrode with applied adhesive are also shown. 

Biomimetic sensors, prepared from catalase adsorbed on diasorb and A1203, treated with trypsine and adhered to an aluminum electrode surface using 7.5% polyacrylamide gel of... 

Biomimetic sensors, prepared by catalase adsorption on diasorb and agarose (treated with trypsine) and adhered to an aluminum electrode surface by Pattex adhesive, displayed an abrupt decrease of the electrode potential. Sensors prepared by catalase adsorption on A1203 (without trypsine treatment) and adhesion to the aluminum electrode with Pattex adhesive displayed a high oscillation of the electrode potential, which induces extreme instability of the operation. Hence, it should be noted that sensor operation was always better in the case of enzyme treatment with trypsine. 

When the carrier is selected, aluminum oxide should be preferred, because biomimetic sensors on it display higher characteristics (Figure 8.9). Moreover, they are low in price, long lived and stable, and possess high hydrodynamic properties. 

The investigations of catalase-mimetic sensors allow continuation of studies in the field of biomimetic sensors of peroxidase type. 

The authors devoted their investigations to the development of a peroxidase-biomimetic sensor for determining trace quantities of ethyl alcohol in various solutions. In all tests the reaction system represented a mixture of microamounts of hydrogen peroxide and ethyl alcohol in an aqueous medium. The task was to determine the effect of the H202 C2H50H ratio on the detection ability of the biomimetic electrode. 

Of course, this fact outlines ways to improve the physicochemical parameters of biomimetic sensor design and, consequently, the technological modernization of biomimetic electrode preparation. As concluded from the data in Figure 8.14, the sensitivity threshold of the designed sensor is very high (10 xwt. % aqueous ethyl alcohol) [14],... 

Vesicles have demonstrated their dynamic behaviour in studies showing evidence of rapid domain formation in response to external stimuli [9], The binding of glycosidic domains to cholera toxin has been demonstrated using vesicles as biomimetic sensors [99], Protein-carbohydrate interaction has also been studied using synthetic glycolipids recently by Barboiu et al. [100] (Fig. 5). 

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