Spectral characterization of the fluorescent components present in humic substances, fulvic acid and humic acid mixed with pure benzo(a)pyrene solution.

The fate of benzo(a)pyrene (BaP), a ubiquitous contaminant reported to be persistent in the environment, is largely controlled by its interactions with the soil organic matter. In the present study, the spectral characteristics of fluorophores present in the physical fractions of the soil organic matter were investigated in the presence of pure BaP solution. After extraction of humic substances (HSs), and their fractionation into fluvic acid (FA) and humic acid (HA), two fluorescent compounds (C and C) were identified and characterized in each physical soil fraction, by means of fluorescence excitation-emission matrices (FEEMs) and Parallel Factor Analysis (PARAFAC).

Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform.

Molecularly imprinted polymer cartridges coupled to high performance liquid chromatography (HPLC-UV) for simple and rapid analysis of fenthion in olive oil.

A combination of molecular modelling and a screening of the library of non-imprinted polymers (NIPs) was used to identify acrylamide as a functional monomer with high affinity towards fenthion, organophosphate insecticide, which is frequently used in the treatment of olives. A good correlation was found between the screening tests and modelling of monomer-template interactions performed using a computational approach. Acrylamide-based molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were thermally synthesised in dimethyl formamide (porogen) using ethylene glycol dimethacrylate as a cross-linker and 1,1-azo-bis (isobutyronitrile) as an initiator.

Computational and experimental investigation of molecular imprinted polymers for selective extraction of dimethoate and its metabolite omethoate from olive oil.

This work presents the development of molecularly imprinted polymers (MIPs) for the selective extraction of dimethoate from olive oil. Computational simulations allowed selecting itaconic acid as the monomer showing the highest affinity towards dimethoate. Experimental validation confirmed modelling predictions and showed that the polymer based on IA as functional monomer and omethoate as template molecule displays the highest selectivity for the structurally similar pesticides dimethoate, omethoate and monocrotophos.

Acetylcholinesterase immobilized on magnetic beads for pesticides detection: application to olive oil analysis.

This work presents the development of bioassays and biosensors for the detection of insecticides widely used in the treatment of olive trees. The systems are based on the covalent immobilisation of acetylcholinesterase on magnetic microbeads using either colorimetry or amperometry as detection technique. The magnetic beads were immobilised on screen-printed electrodes or microtitration plates and tested using standard solutions and real samples.

Molecular imprinting solid phase extraction for selective detection of methidathion in olive oil.

A specific adsorbent for extraction of methidathion from olive oil was developed. The design of the molecularly imprinted polymer (MIP) was based on the results of the computational screening of the library of polymerisable functional monomers. MIP was prepared by thermal polymerisation using N,N'-methylene bisacrylamide (MBAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker.

Physical and chemical immobilization methods of photosynthetic materials.

Isolated photosynthetic materials have a relatively short active life time that limits their effective use. To circumvent this limitation, various immobilization techniques have been designed to improve their stability both under storage and working conditions. The immobilization methods are identified either as chemical or physical procedures depending on whether covalent bonds are established or not.

Biosensors for secondary metabolites, two case studies: ochratoxin A and microcystin.

Secondary metabolites are chemical compounds that are not directly involved in the normal growth, development or reproduction of organisms. Due to the toxicity shown by some of these compounds, their presence can represent a threat to human health. Reliable detection systems able to control their presence are required, as a tool to ensure public health.

Development of a cytochrome c-based screen-printed biosensor for the determination of the antioxidant capacity of orange juices.

This paper describes the development of an amperometric cytochrome c (cyt c)-based biosensor and its later application to the quantification of the scavenging capacity of antioxidants. The enzymatic biosensor was constructed by covalently co-immobilizing both cyt c and XOD on a mercaptoundecanol/mercaptoundecanoic acid (MU/MUA) mixed self-assembled monolayer (SAM)-modified screen-printed gold electrode. The applicability of this method was shown by analyzing the antioxidant capacity of pure substances, such as ascorbic acid and Trolox, and natural sources of antioxidants, particularly 5 orange juices.

Virtual imprinting as a tool to design efficient MIPs for photosynthesis-inhibiting herbicides.

Molecular modelling and computational screening were used to identify functional monomers capable of interacting with several different photosynthesis-inhibiting herbicides. The process involved the design of a virtual library of molecular models of functional monomers containing polymerizable residues and residues able to interact with the template through electrostatic, hydrophobic, Van der Waals forces and dipole-dipole interactions. Each of the entries in the virtual library was probed for its possible interactions with molecular models of the template molecules.

How to find effective functional monomers for effective molecularly imprinted polymers?

Molecularly imprinted polymers (MIPs) are materials mimicking biological receptors in their specific recognition of analytes. Although molecular imprinting has been around for over 30 years, recently this technology has made rapid developments. However, recent investigations have led mainly to the synthesis of new polymers imprinted for a wider range of compounds without real and better understanding of the mechanisms occurring during the polymerisation and the recognition process.

Detection of herbicide subclasses by an optical multibiosensor based on an array of photosystem II mutants.

Massive use of herbicides in agriculture over the last few decades has become a serious environmental problem. The residual concentration of these compounds frequently exceeds the maximum admissible concentration in drinking water for human consumption and is a real environmental risk for the aquatic ecosystem. Herbicides inhibiting photosynthesis via targeting photosystem II function still represent the basic means of weed control.

Stabilization of photosynthetic materials.

Isolated photosynthetic materials have a relatively short active lifetime that limits their effective use. To circumvent this limitation, various immobilization techniques have been designed to improve their stability both under storage and working conditions. The immobilization methods are identified either as chemical or physical methods.