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PhD student (M/F): Formulation and validation of polymeric sonosensitive agents for brain ultrasound therapy

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Français - Anglais

Date Limite Candidature : vendredi 20 mai 2022

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General information

Reference : UMR9011-VINLEB-003
Workplace : ORSAY
Date of publication : Friday, April 29, 2022
Scientific Responsible name : Anthony Novell
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

The research project consists in developing and characterizing formulations of sono-sensitive agents of microbubbles and nanodroplets of perfluorocarbons (PFCs) that can be activated by ultrasound in order to transiently permeabilize the blood-brain barrier and promote the penetration of drugs into the brain. In order to increase the sensitivity and stability of these agents, we propose to formulate new agents based on fluoropolymers, sensitive and stable enough to perform a longer treatment in time, thus offering the possibility to treat a larger volume of the brain. In addition, these agents will contain low-boiling PFCs (octofluoropropane, decafluorobutane) in order to facilitate their activation by ultrasound. Indeed, these PFCs in liquid phase have the advantage of being vaporizable at low acoustic pressures (a few hundred kPa) thus respecting clinical standards and patient safety. The long-term interest is to produce agents small enough (<120 nm) to cross a weakened BBB in which the drugs are incorporated (therapeutic vectors). The release of the drug is controlled by acoustic activation. Incorporating the therapeutic agent into a carrier has two advantages: (i) releasing the drug as close as possible to the pathological cells to increase its efficacy and, (ii) limiting the toxicity of the drug to the body and healthy tissues.
By taking advantage of the skills of BioMaps lab (Anthony Novell, Laurène Jourdain, Ambre Dauba, Charles Truillet) in ultrasound technology and therapy and of the Institut Galien Paris-Saclay lab (Nicolas Tsapis and Laurence Moine) in pharmaceutical formulation and physicochemical characterization, we propose an innovative strategy to improve the stability of the nanodroplets and microbubbles based on the synthesis of amphiphilic polymers bearing fluorinated chains to promote the anchoring of the polymers at the fluorine/blood interface. The first step will consist in synthesizing polymers by varying the length or the architecture of the fluorinated chains (linear or branched). The fluorinated links will be of low molar mass to ensure their good excretion and low toxicity. After characterization of the polymers, their interfacial properties will be evaluated before testing their formulation into nanodroplets and microbubbles via the formulation process mastered at BioMaps. The stability of the nanodroplets and microbubbles will be studied by dynamic light scattering or laser granulometry. These formulations will also be evaluated for their toxicity on cell cultures to ensure their safety.
The most stable and biocompatible systems will be tested from the ultrasonic point of view in the BioMaps laboratory. The second part of the work will consist in characterizing the acoustic response of these new agents and estimating their sensitivity and stability by determining the stable and inertial cavitation thresholds in the therapeutic frequency range (from 0.5 MHz to 5 MHz). The potential of these agents for therapy will then be evaluated in vitro by measuring their ability to permeabilize an endothelial cell layer (biological barrier) under the effect of ultrasound. Ultrasound parameters (frequency, amplitude, pulse duration, repetition) will be optimized in order to promote the passage of fluorescent molecules (propidium iodide) through this cell layer. Finally, the toxicity and stability in blood of these agents will be evaluated in vivo on a rodent model. Their effectiveness in opening the blood-brain barrier will be measured by quantifying the passage of Gadolinium by MRI or 18F-FDS by PET imaging. Furthermore, the safety of the ultrasound protocol will be ensured in real time by passive cavitation detection and then verified, post-processing by MRI (T2*).

Work Context

The activity will be carried out equally (50/50) within the Paris Saclay multimodal biomedical imaging laboratory (BioMaps) and the Institut Galien in Paris Saclay. These two laboratories are located a few kilometers (10 min by bus) from each other on the Orsay scientific campus (91).
BioMaps is a joint research unit of the University of Paris-Saclay and the CNRS devoted to multidisciplinary research in medical imaging and located mainly on the site of the Frédéric Joliot Hospital (CEA-SHFJ). This unit brings together nearly 120 people from various cultural backgrounds (engineers and physicists, physicians, pharmacists, biologists and chemists), whose research is based on a set of clinical and preclinical imaging platforms (MRI, ultrasound, photonic imaging). BioMaps aims at designing methods, instruments and agents for biomedical imaging of different imaging modalities and their transfer to clinical applications in neurology and cancer. Designed around biomedical imaging research in Paris-Saclay, BioMaps is a major player in medical imaging research at the Physics-Chemistry-Medicine interfaces of Paris-Saclay.
The Institut Galien Paris-Saclay (UMR CNRS 8612), founded in 1986, develops micro and nanotechnologies applied to medicine and diagnostics in the health field. The particularity of the unit is that it brings together researchers and teacher-researchers from different disciplines (chemistry, physical chemistry, galenics, analytical chemistry and biology). The research themes are organized around six teams and according to four major challenges
1- Tame the physiological barriers
2- Designing intelligent, programmable, activatable and biocompatible materials
3- Develop predictive models for the formation of new objects and their transport across biological barriers (tissue, cellular and subcellular)
4- Putting chemistry, physical chemistry and formulation at the service of diagnosis and imaging.
To address these challenges, the Institut Galien Paris-Saclay has several platforms managed by ITA/BIATSS (chromatographic analysis, cell culture, radioelement manipulation, instrumentation workshop, molecular interactions, rheology).

The PhD student who will be recruited will be placed under the hierarchical responsibility of Anthony Novell (CR CNRS BioMaps) and Nicolas Tsapis (DR CNRS Insitut Galien at Paris-Saclay).

Constraints and risks

Chemical and biological risks. Animal experimentation.

Additional Information

The PhD student will be responsible for the synthesis of fluorinated polymers, their physicochemical characterization and their formulation. He/she will then ensure the characterization of the acoustic response of these systems in vitro and in vivo. A multidisciplinary profile is therefore sought for this project: Physical chemist or general engineer with experience in physical chemistry.

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