Investigation of Lysine-Functionalized Dendrimers as Dichlorvos Detoxification Agents.

Lysine-containing polymers have seen broad application due to their amines' inherent ability to bind to a range of biologically relevant molecules. The synthesis of multiple generations of polyester dendrimers bearing lysine groups on their periphery is described in this report. Their hydrolytic stabilities with respect to pH and time, their toxicity to a range of cell lines, and their possible application as nano-detoxification agents of organophosphate compounds are all investigated. These zeroth-, first-, and second-generation water-soluble dendrimers have been designed to bear exactly 4, 8, and 16 lysine groups, respectively, on their dendritic periphery. Such monodisperse bioactive polymers show potential for a range of applications including drug delivery, gene delivery, heavy metal binding, and the sequestration of organic toxins. These monodisperse bioactive dendrimers were synthesized using an aliphatic ester dendritic core (prepared from pentaerythritol) and protected amino acid moieties. This library of lysine-conjugated dendrimers showed the ability to efficiently capture the pesticide dichlorvos, confirming the potential of dendrimer-based antidotes to maintain acetylcholinesterase activity in response to poisoning events.

Preparation and characterization of TiO2/HZSM-11 zeolite for photodegradation of dichlorvos in aqueous solution.

The TiO2/HZSM-11 materials were synthesized using titanium isopropoxide as a TiO2 precursor and HZSM-11 a medium pore size zeolite with high thermal and chemical resistance as support. The amount of titanium isopropoxide was varied in order to obtain TiO2 concentrations of 3, 10, 20, 30 and 50 wt% in the final material. They were characterized by a series of complementary techniques: X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (DRS), transmittance Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The surface area of the TiO2/HZSM-11 samples decreased with the increment of TiO2 loading. As result of the increment of the calcination temperature from 450 to 800°C an increase in the size of the anatase crystals was observed. However, the X-ray diffraction patterns of the solids only presented the characteristic peaks of the anatase phase. The catalytic activity of the materials in the photodegradation of Dichlorvos (DDVP) depended on the TiO2 amount the thermal treatment temperature. The sample containing 30% TiO2 calcined at 450°C showed the best catalytic performance and it can be reused without noticeable activity loss during at least four cycles. The catalytic performance was similar to that of the P25 Degussa used as a reference but its separation, recovery and reuse was easier.

Automated resolution of dichlorvos and methylparaoxon pesticide mixtures employing a Flow Injection system with an inhibition electronic tongue.

An amperometric biosensor array has been developed to resolve pesticide mixtures of dichlorvos and methylparaoxon. The biosensor array has been used in a Flow Injection system, in order to operate automatically the inhibition procedure. The sensors used were three screen-printed amperometric biosensors that incorporated three different acetylcholinesterase enzymes: the wild type from Electric eel and two different genetically modified enzymes, B1 and B394 mutants, from Drosophila melanogaster. The inhibition response triplet was modelled using an Artificial Neural Network which was trained with mixture solutions that contain dichlorvos from 10(-4) to 0.1 microM and methylparaoxon from 0.001 to 2.5 microM. This system can be considered an inhibition electronic tongue.