This article gives an overview of the electrochemical biosensors that incorporate genetically modified enzymes. Firstly, the improvements on the sensitivity and selectivity of biosensors that integrate mutated enzymes are summarised. Next, new trends focused on the oriented immobilisation of mutated enzymes through specific functional groups located at their surface are reviewed. Finally, the effect of enzyme mutations on the electron transfer distance and kinetics of electrochemical biosensors is described.
"A trend in biosensors is the flow-bioelectronics tongue which combines high sensitivity array of biosensors in flow systems, and chemometric tools with added advantages of possibility to miniaturise the required instrumentation with compact and portable analysis devices. In order to improve experimental parameters, current research efforts focus on the use of genetically modified enzymes with tailor-designed properties . The combination of biosensors with flow based technique offers the possibility to control the whole procedure, simplifying the sequence of steps, high sensitivity and allowing an easier optimization of the reaction conditions  .. "
[Show abstract][Hide abstract] ABSTRACT: This work presents an application of automatic flow based biosensor to detect binary (chlorpyriphos-oxon (CPO) and malaoxon (MO)) organophosphate (OP) mixtures in milk, based on artificial neural network (ANN). Genetically modified acetylcholinesterase (AChE) B394 and B4 were used as a biological recognition element for sensor development. AChE binds with OPs irreversibly, creating an anionic phosphonyl species. The enzymes were coupled on screen printed electrodes (SPEs) and inserted in a flow cell connected to the potentiostat and syringe pump. In order to model the combined response of CPO and MO, a total set of 19 mixtures were prepared using ANN. The modeling was validated with an external test of 6 milk samples spiked with CPO and MO mixtures. The spiked concentrations of CPO and MO were ranged from 5 × 10−10 to 5 × 10−12 M and 1.01 × 10−10 to 9.17 × 10−11 M, respectively. These concentrations were determined using factorial designing (FD) method and the obtained and expected recovery values in milk showed good co-relation. The average % recovery yields for CPO and MO are 109.53 and 100.66, respectively.
Sensors and Actuators B Chemical 03/2015; 208. DOI:10.1016/j.snb.2014.11.011 · 4.10 Impact Factor
"In this method the particular functional groups of the enzymes are exploited and it is possible to orient the active site of the enzyme towards the analyte. This technique requires less quantity of enzyme with specific control over the orientation . Electropolymerization is also one of the possible methods for the immobilization of the AChE enzyme in which the electric field is used for the polymerization. "
[Show abstract][Hide abstract] ABSTRACT: The exponentially growing population, with limited resources, has exerted an intense pressure on the agriculture sector. In order to achieve high productivity the use of pesticide has increased up to many folds. These pesticides contain organophosphorus (OP) toxic compounds which interfere with the proper functioning of enzyme acetylcholinesterase (AChE) and finally affect the central nervous system (CNS). So, there is a need for routine, continuous, on spot detection of OP compounds which are the main limitations associated with conventional analytical methods. AChE based enzymatic biosensors have been reported by researchers as the most promising tool for analysis of pesticide level to control toxicity and for environment conservation. The present review summarises AChE based biosensors by discussing their characteristic features in terms of fabrication, detection limit, linearity range, time of incubation, and storage stability. Use of nanoparticles in recently reported fabrication strategies has improved the efficiency of biosensors to a great extent making them more reliable and robust.
Biochemistry Research International 12/2013; 2013(7042):731501. DOI:10.1155/2013/731501
"Biosensors are based on the intimate contact between a bio-recognition element that interacts with the analyte of interest and a transducer element that converts the biorecognition event into a measurable signal. Among the different types of biosensors, the electrochemical sensors are of special interest due to the high sensitivity inherent to the electrochemical detection and the possibility to miniaturize the required instrumentation, thereby making the construction of compact and portable analysis devices possible (Campàs et al., 2009; Somerset et al., 2011). Somerset et al. (2011) reported detection limit of 0.880 nmol/L for carbaryl, 0.249 nmol/L for carbofuran and 0.111 nmol/L for methomyl using a mercaptobenzothiazole-on-gold biosensor system. "
[Show abstract][Hide abstract] ABSTRACT: The extensive use of carbamate pesticides in modern agriculture has raised serious
public concern regarding the environment and food safety. Due to their broad
spectrum of biological activity, carbamates can be used as insecticides, fungicides,
nematocides, acaracides, molluscicides sprout inhibitors or herbicides.
Contamination of fruits and vegetables may result from treatment as well as from
conditions such as improper use of pesticides, residues from preceding treatments in
the soil and cross-contamination. Sources of residues in products of animal origin
include contaminated water or feed, pesticide-treated housing, and contaminated
milk. The presence of pesticide residues is a concern for consumers because
carbamates are known to have potential harmful effects to other non-targeted
organisms than pests and diseases. The major concerns are their toxic effects such as
interfering with the reproductive systems and foetal development. In this chapter,
the more relevant contributions, of the last ten years, to the current knowledge on
several aspects regarding carbamate pesticides, such as mode of action, effects on
human health, legislation, monitoring, human exposure to carbamate residues, risk
and exposure assessment will be discussed.
The Impact of Pesticides, 1 edited by Milan Jokanović, 01/2012: chapter Carbamates: Human Exposure and Health Effects: pages 21-38; AcademyPublish.org., ISBN: 978-0-9835850-9-1
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