Competitive Adsorption Mechanisms Of Mycotoxin at the Interface “Liquid-Solid” – CAMOMILS

CAMOMILS focuses in particular on the ochratoxin A present in wines. .
Detoxification can be achieved through various processes, more or less effective, selective and cost-effective. The process studied here is carried out by adsorption on lamellar solids. The materials are selected to make the best use of the physicochemical properties of the toxic molecules, in particular the hydrophilic / hydrophobic character, the steric hindrance, the charge, the nature of the active sites. Montmorillonite clays and organomodified double lamellar hydroxides were selected for the first part of the project.
A «surface science« approach is carried out in situ in order to target the specific study of the solid / liquid interface where the adsorption mechanisms take place. Interactions between molecules, solvent (ethanol / water mixtures), competitive species and solid are studied in order to know the main parameters that make it possible to optimize selective trapping. The selectivity in multi-component medium is explored in order to better simulate real systems and to be able to detoxify without modifying the organoleptic properties of the beverages.
A nonlinear second harmonic generation device, allowing the in situ study of the interfaces of particles in solution, was developed during the first 6 months of the project. It is a remarkable experimental innovation from the point of view of physico-chemistry of interfacial systems at regional and national level. It will allow an integrated approach of the dynamic molecular processes of recognition and organization to solid-liquid interfaces which can extend over a broad application domain.

1. The first axis of work is chemical materials and systems.
• It includes the supply of Ochratoxin A from a fungus strain of the genus Apsergillus. After 6 months of effort, production of OTA by mushroom cultivation was considered unprofitable. Supply is now available from Sigma Aldrich as provided in the project in this case. Currently work is also being carried out on the quercetin molecule. It is a flavonoid also present in wine (potentially in competition), cheap. Its properties approximate that of OTA (comparison by DFT calculation).
• The selection and synthesis of HDL-based lamellar materials was carried out (hydrophobic functionalized anion exchanger). These modulable solids allow adaptation to the properties of the molecules studied during the experiments. Electrostatic and hydrophobic properties were evaluated.
• Finally, several techniques have been used to study the effectiveness of the adsorbent material vis-à-vis molecules of interest, especially DFT for the theoretical study of the molecule in different solvents. Measurements of UVvis and non-linear optical spectrometry are currently underway for quercetin. Particular attention has been paid to the solvation (water / alcohol mixture) of the molecules.
2. The second axis concerns the introduction of an measuring device in non-linear optics : plane surface second harmonic generation, hyper-Rayleigh Scattering , second harmonic scattering, two photon fluorescence.
• A design and installation of a non-linear optical set up was carried out, in conjunction with the development of a computer program managing the control of the set up for measurements. The built-in measuring device was tested and validated on model chemical systems before moving to more complex applications. This assembly was finalized in the first 6 months of the project. It was very quickly validated by chromophore adsorption tests on latex particles.
• The assembly is currently used on the systems of interest of the project.

Several tracking axes were highlighted for the second period of the project.
• The project will be based on the study of lamellar materials: HDL and clays and will open on the use of zeolites at the end of the period. HDL will be functionalized by intercalation of hydrophobic species containing benzene rings (SDBS) in order to increase the affinity for fat-soluble molecules. The use of cationic clay, not originally foreseen, has been favored and appears to be successful. Montmorillonite, hydrophilic cationic exchanger comes from a partnership with a laboratory in Poitiers.
• The OTA will be obtained commercially and used at the end of the project when the protocols are validated. Currently a work is being carried out on the molecule quercetin. It is a flavonoid also present in wine (potentially in competition), cheap and whose properties closely resemble the OTA (comparison by DFT calculation).
• Fluorescence measurements with 1 and 2 photons will complement the panel of studies with the hypothesis that the toxin may be in complexed form in wine. Studies are currently being conducted on interactions with amino acids of proteins, sugars or cell wall components, such as proline, alginate, pectin and surfactant SDS.

Journal of Physical Chemistry Part C, Just accepted June 2017, «Adsorbed Dyes Onto Nanoparticles: Large Wavelength Dependence in Second Harmonic Scattering«, Authors: Gassin, Pierre-Marie; Bellini, Sarah; Zajac, Jerzy; Martin-Gassin, Gaelle

The CAMOMILS project, through the fundamental understanding of the mechanisms of sorption of organic molecules by solids, aims to provide ideas for designing future innovative decontamination process. This project answers to the specific needs of the food industry and implies an essential contribution to the research performed by oenological institutes. CAMOMILS focuses in particular on the mycotoxin ochratoxine A (OTA) in wine. This carcinogen toxin is increasingly encountered in France, in the context of global warming. This emerging public health problem has to be solved by proposing an integrated solution at all levels, when starting from researchers and ending by winemakers. Detoxification can be done through various methods, more or less efficient, selective and profitable. The process studied here is the OTA adsorption onto sequestering solids. Two solid materials have been selected in regard with such physical and chemical properties of the OTA such as its hydrophobicity and anionic nature. The organomodified zeolites and layered double hydroxides have been selected. A surface science approach will be conducted to focalise the "in situ" study on the interfacial area where the adsorption occurs preferentially. The interactions between the molecule and the solid will be studied in order to identify the main parameters that allow the optimisation of the toxin uptake. Thus, in the future, the objective is to provide essential information necessary for creating perfectly suited materials and processes. Selectivity in multi-component environment will be particularly explored in order to approach the real systems. The crucial challenge is to optimize the whole process while reducing changes in the organoleptic properties of wine. The CAMOMILS project is proposed to draw an integrated full picture of the OTA adsorption. This implies providing an overview of each part of the problematics. To reach this goal, the project, necessarily strongly multidisciplinary, is based on crosscutting and complementary collaborations between chemists, material scientists, and microbiologists. Each collaborator is an expert in his/her own domain and will contribute to the CAMOMILS success.. Two experimental tools particularly adapted would be used: calorimetry and optical second harmonic generation technique. A second harmonic generation device is being developed, by the coordinator, specifically for the in situ interfacial study involving solid particles in solution. From the viewpoint of physical chemistry, this represents a major experimental innovation at the national level and would be accomplished thanks to funding the CAMOMILS project. Finally, the experimental work done within the framework of the project and coupled with an adequate theoretical approach, would offer an integrated approach to dynamic molecular recognition processes at solid-liquid interfaces.