Screening methods biosensor-based

The current trend in analytical chemistry applied to evaluate food quality and safety leans toward user-friendly miniaturized instruments and laboratory-on-a-chip applications. The techniques applied to direct screening of colorants in a food matrix include chemical microscopy, a spatial representation of chemical information from complex aggregates inside tissue matrices, biosensor-based screening, and molec-ularly imprinted polymer-based methods that serve as chemical alternatives to the use of immunosensors. 

Gustavsson, E. and A. Stemesjo. 2004. Biosensor analysis of P-lactams in milk Comparison with microbiological, immunological, and receptor-based screening methods. J. AOAC Int. 87 614—620. 

Applications. A biotinylated GOX-based biosensor was developed based on a new electropolymerized material consisting of a pol3rp3uidyl complex of ruthenium(II) functionalized with a pyrrole group [90]. Because histidine, lysine and arginine functions also coordinate Os /Os , biosensors based on co-electrodeposited GOX, HRP, soybean peroxidase (SBP) and laccase with redox Os /Os polymer have been developed [89]. A metal chelate formed by nickel and nitrilotriacetic acid was used to modify a screen-printed electrode surface. The functionalized support allowed stable attachment of acetylcholinesterase and the resulting biosensor was used for sensitive detection of organophosphorus insecticides [91]. This method is attractive because it ensures a controlled and oriented enzyme immobilization, considerably improving the sensitivity and the detection limit. 

Biosensors based on a Clark oxygen electrode, coupled to tyrosinase immobilized by three different methods, were investigated for the determination of phenol in real matrices, such as water of various natural sources, industrial wastes and oil press. The feasibility study included direct use of the biosensors and in situ analysis. An integrated system, incorporating SPE, desorption, fractionation and biosensor detection, was validated for screening phenolic compounds in water. Two types of electrode were tested, solid graphite and CPE incorporating tyrosinase. Correct analyses were found for river water samples spiked with phenol (10 p.gL ), p-cresol (25 p.gL ) and catechol (1 A mul-... 

Study binding of 78 compounds to liposomes POPC and Avanti-blend captured on sensor chip [18]. Using an automatized SPR-based biosensor it is possible to develop a screening method to rank and characterize the binding of compoimds to captured hposomes of different properties based on binding responses, as shown in the histogram (Fig. 11b). 

Most biosensors based on AChE have the enzymes immobilized on the surface of the sensor. The inhibition reaction being irreversible, the membrane with immobilized enzyme has to be replaced after several measurements or the biosensor can be use for only one determination. Due to this fact, the researchers tried to realize pesticide biosensors with a renewable surface or disposable biosensors based on screen-printed electrodes (SPE). The screen-printing technology provides a simple, fast and inexpensive method for mass production of disposable biosensors for different biomolecules starting with glucose, lactate and finishing with environmental contaminants as pesticides (Kulys et al., 1991) and herbicides (Skladal, 1992). 

Ziyatdinova G, Labuda J (2011) Complex electrochemical and impedimetric evaluation of DNA damage by using DNA biosensor based on a carbon screen-printed electrode. Anal Methods 3(12) 2777-2782. doi 10.1039/clay05403a... 

Biosensors based on enzymes have high sensitivity and selectivity. A variety of microbial biosensors have also been developed. However, it still remains a great challenge to develop a rapid, inexpensive but sensitive method for real samples. Compared to enzymatic biosensors, development of a highly satisfactory microbial biosensor is still hampered because they suffer from long response time, low sensitivity, and poor selectivity. The trends for the development of biosensors lie in miniaturization of the devices, nanotechnology, and biotechnology. Disposable screen-printed sensors have been developed for industrial wastes or natural water. Metal nanoparticles can enhance the electron transfer between redox center in proteins and electrode surface and show promise for detection... 

Biosensors are the analytical systems, which contain sensitive biological elements and detectors. Plant cells as a possible biosensors have natural structure that determinates their high activity and stability. Criteria in the screening of the plant cells as biosensors for allelopathy should be as under (i) Reaction is fast based on the time of response, (ii) Reaction is sensitive to small doses of analysed compounds or their mixtures and (iii) Methods of detection viz., biochemical, histochemical, biophysical (in particular, spectral changes in absorbance or fluorescence) are easy in laboratory and in the field conditions. The search of biosensors in active plant species is suitable to determine the mechanisms of action of biologically active substances or external factors of the environment (Roshchina and Roshchina, 2003 Roshchina, 2004 2005 c)). 

NADH can be readily monitored electrochemically, and can be used as a simple and effective method to monitor metal ion concentrations. Such an approach has been recently utilised by Rodriguez et al. [149] for an SPCE-based biosensor for the amperometric detection of Hg2+, Cu2+, Cd2+, Zn+ and Pb2+. Devices used in this study were printed onto 250 pm thick polyester sheet. The working electrode (planar area 0.16 cm2) was fabricated from a commercially available carbon powder containing 5% rhodium plus promoters, which was made into a screen-printable paste by mixing 1 4 in 2.5% (w/v) hydroxyethyl cellulose in water. The reference electrode ink contained 15% silver chloride in silver paste. The counter electrode and basal tracks were fabricated... 

Actually, special attention is paid in the application of biosensors in environmental analysis. The high cost and slow turnaround times typically associated with the measurement of regulated pollutants clearly indicates a need for environmental screening and monitoring methods that are fast, portable and cost-effective. To meet this need, a variety of field analytical methods have been introduced. Because of their unique characteristics, however, technologies such as DNA sensors and immunosensors based on AuNPs might be exploited to fill specific niche applications in the environmental monitoring area. 

It is commonly assumed that application of these methods in sensors has started from invention of oxygen Clark electrode,2 and in biosensors from first glucose biosensor.3 At present, main sensor application of amperometric and voltammetric detections include, with wide use of oxygen Clark electrode, amperometric sensors based on modification of working electrodes with various materials, and biosensors employing practically all biorecognition species. With the very wide use of the term sensors, applications of voltammetric detections include also miniaturized screen-printed devices for stripping determinations of, e.g., heavy metal ions. 

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