INnovative chemIcal sensors for enanTioselective detectIon of chiral pOllutants

Project Information

INITIO

Grant agreement ID: 828779

DOI

10.3030/828779

Project closed

EC signature date 17 December 2018

Start date 1 January 2019

End date 31 December 2022

Funded under

• EXCELLENT SCIENCE - Future and Emerging Technologies (FET)

Total cost

€ 2 929 901,25

EU contribution

€ 2 929 901,25

Coordinated by

UNIVERSITA DEGLI STUDI DI ROMA TOR VERGATA
Italy

Periodic Reporting for period 2 - INITIO (INnovative chemIcal sensors for enanTioselective detectIon of chiral pOllutants)

Reporting period: 2020-01-01 to 2022-12-31

Summary of the context and overall objectives of the project

A chiral species is a single molecule or molecular assembly that cannot be superimposed with its mirror image. Chiral molecules are consequently present as two stereoisomers, called enantiomers. On a daily basis, chiral molecules are conventionally used and produced by pharmaceutical, food, agrochemical, perfume, and cosmetics industries. As a result, chiral waste becomes an extremely important issue at present. Chiral compounds can be ecologically hazardous, due to their high biological activity, creating a global pollution problem. It is of note, that enantiomers have a different impact on living organisms making it extremely important to differentiate these stereoisomers, which is extremely a difficult and challenging task and usually requires highly specific and costly instruments. Yet, the stereoisomerism of contaminants is presently not considered in detail.
In this context, developing portable chemical sensors devices that are reliable, sensitive and rapid, capable of fast, simple and real-time in situ and on site analysis for sensing and discrimination of chiral molecules presents an attractive breakthrough target compared to existing standard instrumental methods.
However, the stereoselective detection of the chiral substances with chemical sensors is an arduous task, because, in contrast to chromatography or electrophoresis, sensors rely on a single binding event and the highly efficient discrimination of the receptor is an important prerequisite.
The main objective of the INITIO research project is the development of chemical sensors able to recognize chiral substances based on rationally designed sensing materials, to fill the existing gap between the production of enantioselective receptors and the realization of macroscopic devices. The success of the INITIO project opens the way to a further potential application of the developed devices for chiral pollutants removal, allowing prompt remedial procedures in an unprecedented environmental “theranostic” approach.
Further prospects in this field will include not only smart and cost-effective detection of chiral pollutants but subsequent recycling and utilization of chiral waste to produce useful enantiopure intermediates and compounds to be used in chemical, pharmaceutical, agrochemical and other industries.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the INITIO project, the following research activities have been carried out to achieve the steps necessary for the development of chiral chemical sensors:
• A first goal was the definition of synthetic protocols for the preparation of a series of chiral receptors belonging to the two typologies reported in the proposal: porphyrins and hemicucurbiturils. Hybrid receptors have also been obtained by supramolecular aggregation of porphyrin and hemicucurbituril derivatives, opening the way for a simple preparation protocol for chiral receptors, where the binding properties are in charge of the porphyrin sub unit, while hemicucurbituril imparts the chiral features.
• Parallel to the preparation of the molecular receptors, the second goal has been the preparation of chiral nanostructures, based on metal oxides. The aim was to use these nanostructured materials as support for the grafting of receptors. In a first system, the nanostructured oxide was formed by chiral helices of SiO2, obtained by using chiral tartrate aggregates as template. Once the hybrid helices were formed, they have been grafted with functionalized achiral porphyrinoid derivatives (porphyrins and corroles). A second tested system is represented by ZnO nanoparticles, in this case functionalized with chiral porphyrin derivatives; also in this case the chiral properties are retained in the hybrid materials.
• The binding properties towards chosen model analytes of some of the receptors developed have been studied in solution.
• The crystallization and solid state structure determination of chiral hemicucurbiturils and porphyrins has been carried out.
• The optimization of the deposition protocols of the receptors onto the transducers surfaces, which are quartz crystal microbalances (QCM) for gas phase sensors and transparent slides for optical transduction.
A simple protocol by drop casting of a solution containing porphyrins derivatives and chiral hemicucurbiturils has been pointed out. Remarkably chiral films produced combining different metalloporphyrins with hemicucurbituril enantiomers showed different enantioselective properties of the sensors, opening the way to the possibility of easily obtaining a large library of enantioselective receptors.
• Other than the reported research activities, different dissemination activities have been performed by the project consortium members, including the organization of a conference (Chirality), a school (Lecce), talks at conferences and publication of several scientific articles (38). A flyer reporting the project aims has also been published and distributed during these conferences. A video presenting the INITIO concepts and results has been realized by professionals and posted in the YouTube channel and linked to the project website.
• Several press releases were published as listed in the project web site.
• All the Deliverables and Milestones have been achieved and posted on the EU portal.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The INITIO project aim is to develop efficient chemical sensors able to perform chiral recognition.
To reach this goal, the main aims of the project are: a) the development of novel molecular receptors, b) integration of the receptors with different nanostructures and characterization their solid state organization, c) deposition of the structures onto transducer surfaces, d) testing and validation of the new chemical sensor devices with enantiomeric pairs of model analytes.
In the four years project important insights related to these fundamental steps have been pursued. A wide library of chiral receptors has been obtained and a series of hybrid inorganic/organic nanostructures has been investigated. The solid state organization of some receptors has also been characterized, also in the presence of target chiral analyte, in order to obtain fundamental insights on their sensing mechanism.
The introduction of the sensor array concept to the challenging task of the stereoselective detection of chiral substances with chemical sensors is an important breakthrough to respect the state of the art. The usual approach related to the development of chemical probes able to perform a differential binding of chiral species is limited in scope, possible only for a single target analyte or even for a single enantiomer of the chiral pair. In the INITIO project we demonstrate the advantages offered by the introduction of a cross-sensitive array, able to recognize the chemical compounds, and to obtain the desired recognition of their chiral identity, by using the differential binding of enantiomers in the same way of Circular Dichroism, which uses the different absorption of polarized light. This approach allows the possibility to exploit the sensor array for different chiral compounds, filling the existing gap between the production of enantioselective receptors and the realization of macroscopic devices.
The success of this approach open the way to the realization of field-capable devices, able to monitor an important class of emerging pollutants. The realization of such devices represents an important breakthrough in the monitoring of chiral pollutants.

Project presentation