High Selective Parathion Voltammetric Sensor Development by Using an Acrylic Based Molecularly Imprinted Polymer-Carbon Paste Electrode

Recent Advances of Enzyme-Free Electrochemical Sensors for Flexible Electronics in the Detection of Organophosphorus Compounds: A Review

Emerging materials integrated into high performance flexible electronics to detect environmental contaminants have received extensive attention worldwide. The accurate detection of widespread organophosphorus (OP) compounds in the environment is crucial due to their high toxicity even at low concentrations, which leads to acute health concerns. Therefore, developing rapid, highly sensitive, reliable, and facile analytical sensing techniques is necessary to monitor environmental, ecological, and food safety risks. Although enzyme-based sensors have better sensitivity, their practical usage is hindered due to their low specificity and stability. Therefore, among various detection methods of OP compounds, this review article focuses on the progress made in the development of enzyme-free electrochemical sensors as an effective nostrum. Further, the novel materials used in these sensors and their properties, synthesis methodologies, sensing strategies, analytical methods, detection limits, and stability are discussed. Finally, this article summarizes potential avenues for future prospective electrochemical sensors and the current challenges of enhancing the performance, stability, and shelf life.

Molecularly imprinted polymer-based electrochemical sensors for environmental analysis

The ever-increasing presence of contaminants in environmental waters is an alarming issue, not only because of their harmful effects in the environment but also because of their risk to human health. Pharmaceuticals and pesticides, among other compounds of daily use, such as personal care products or plasticisers, are being released into water bodies. This release mainly occurs through wastewater since the treatments applied in many wastewater treatment plants are not able to completely remove these substances. Therefore, the analysis of these contaminants is essential but this is difficult due to the great variety of contaminating substances. Facing this analytical challenge, electrochemical sensing based on molecularly imprinted polymers (MIPs) has become an interesting field for environmental monitoring. Benefiting from their superior chemical and physical stability, low-cost production, high selectivity and rapid response, MIPs combined with miniaturized electrochemical transducers offer the possibility to detect target analytes in-situ. In most reports, the construction of these sensors include nanomaterials to improve their analytical characteristics, especially their sensitivity. Moreover, these sensors have been successfully applied in real water samples without the need of laborious pre-treatment steps. This review provides a general overview of electrochemical MIP-based sensors that have been reported for the detection of pharmaceuticals, pesticides, heavy metals and other contaminants in water samples in the past decade. Special attention is given to the construction of the sensors, including different functional monomers, sensing platforms and materials employed to achieve the best sensitivity. Additionally, several parameters, such as the limit of detection, the linear concentration range and the type of water samples that were analysed are compiled.

Novel Biosensors for the Rapid Detection of Toxicants in Foods

The modern environmental and food analysis requires sensitive, accurate, and rapid methods. The growing field of biosensors represents an answer to this demand. Unfortunately, most biosensor systems have been tested only on distilled water or buffered solutions, although applications to real samples are increasingly appearing in recent years. In this context, biosensors for potential food applications continue to show advances in areas such as genetic modification of enzymes and microorganisms, improvement of recognition element immobilization, and sensor interfaces. This chapter investigates the progress in the development of biosensors for the rapid detection of food toxicants for online applications. Recent progress in nanotechnology has produced affordable, mass-produced devices, and to integrate these into components and systems (including portable ones) for mass market applications for food toxicants monitoring. Sensing includes chemical and microbiological food toxicants, such as toxins, insecticides, pesticides, herbicides, microorganisms, bacteria, viruses and other microorganisms, phenolic compounds, allergens, genetically modified foods, hormones, dioxins, etc. Therefore, the state of the art of recent advances and future targets in the development of biosensors for food monitoring is summarized as follows: biosensors for food analysis will be highly sensitive, selective, rapidly responding, real time, massively parallel, with no or minimum sample preparation, and platform suited to portable and handheld nanosensors for the rapid detection of food toxicants for online uses even by nonskilled personnel.

A ferrocene/imprinted polymer nanomaterial-modified carbon paste electrode as a new generation of gate effect-based voltammetric sensor

Herein, a carbon paste electrode, concurrently incorporated with ferrocene and a molecularly imprinted polymer nanomaterial (Fc-MIP-CP electrode), is introduced as an innovative sensing platform for the detection of thiamine.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

A capacitive biosensor for ultra-trace level urea determination based on nano-sized urea-imprinted polymer receptors coated on graphite electrode surface

A novel urea biosensor based on capacitive detection was developed using nano-sized molecularly imprinted polymers (nano-MIP). The sensitive layer was created by casting a thin layer of poly (vinyl chloride) (PVC)/nano-MIP composite on a graphite electrode surface. Cyclic voltammetry and impedance spectroscopy were used to monitor the electrode surface modification. The insulating properties of the layer were studied in the presence of K3Fe(CN)6/K4Fe(CN)6 redox couple by AC impedance measurements. The proposed capacitive sensor exhibited good selectivity for urea, compared to the chemicals with high resemblance to urea. The repeatability of the senor was found to be satisfactory. Very wide dynamic linear range (1×10(-11)-1×10(-4)M) as well as an ultra-trace detection limit equal to 5 picomolar was obtained for the sensor. The relevant experiments indicated satisfactory repeatability and reproducibility for the developed sensor. The results from sample analysis confirmed the applicability of the MIP-based sensor to quantitative analysis of urea in real samples.

Preparation of parathion imprinted polymer beads and its applications in electrochemical sensing

Parathion imprinted polymer beads were prepared by free radical polymerization using parathion as template, methacrylic acid as functional monomer, divinyl benzene as cross-linking reagent and 2,2'-azobis(isobutyronitrile) as initiator. The obtained molecularly imprinted beads were characterized with transmission electron micrograph. The rebinding properties of these imprinted beads towards parathion were studied by saturation binding experiments using ultraviolet/visible spectroscopy. Effects of the template, functional monomer, cross-linking reagent and initiator on selective adsorption of parathion were investigated. The high selectivity of the imprinted beads was successfully demonstrated by their selective adsorption of free parathion from an ethanol-water (v/v=1:5) solution. In addition, the parathion imprinted beads were dispersed into dihexadecyl hydrogen phosphate solution at the concentration of 1.0 mg mL(-1). By coating this solution onto a glassy carbon electrode surface, a molecularly imprinted electrochemical sensor for parathion was obtained. The electrochemical sensor exhibited good selectivity and fast response to parathion. Under optimized experimental conditions, the peak currents were found linearly proportional to the parathion concentration in the range of 1.0×10(-7) mol L(-1) to 1.0×10(-5) mol L(-1) with a detection limit of 5.4×10(-8) mol L(-1) (S/N=3). The developed sensor was successfully employed for the determination of parathion in pear juice samples.

Preparation of molecularly imprinted polymer containing selective cavities for urea molecule and its application for urea extraction

A new molecularly imprinted polymer material having urea molecule selective cavities was introduced. Urea was properly dissolved in acetonitrile in the presence of an acidic functional monomer. Molecularly imprinted polymers with different compositions were examined and the roper formulation was selected. It was shown that the MIP had a considerable selectivity for urea in comparison to similar compounds such as thiourea and hydroxyurea. The obtained polymer was used as an adsorber for solid phase extraction (SPE) of urea in the aqueous samples. The extracted urea was determined by using a spectrophotometric method. Different parameters of SPE were optimized and the developed procedure was used for urea determination in real samples. The calibration graph of the method was linear in the range of 0.6-8.3 micromol L(-1). The detection limit was calculated to be 0.14 micromol L(-1).