Funding type: COFUND Marie Slodowska Curie Action

This project is under the Marie Skłodowska-Curie Actions (MSCA) program. There are no nationality conditions but the candidates must fulfill the MSCA mobility conditions, which means that she/he must not have stayed more than 1 year in France during the last 3 years immediately before the call deadline (31/05/2019)

Expected start date: 01/10/2019

Contacts:

Ass. Prof. Virginie MONNIER
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+33 4 72 18 62 39

Dr. Vipul Bansal, RMIT
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Websites:

• https://www.rmit.edu.au/about/our-locations-and-facilities/facilities/research-facilities/micronano-research-facility
• http://inl.cnrs.fr/en/

Collaborations/External partners :

Dr. Y. Mugnier - Laboratoire Système et Matériaux pour la Mécatronique (SYMME), Annecy, France

Domain and scientific context :

The combination of several materials on the surface of a nanoparticle is of great interest in the field of catalysis [Qin 2019]. In particular, the immobilization of gold or platinum nanocatalyzers on oxide nanoparticles allows increasing their efficiency, because oxidation reactions are preferentially achieved onto oxygen vacancies [Song 2013]. It also avoids nanocatalyzers aggregation and improves their stability. Nanozymes are hybrid nanoparticles with catalytic properties that can mimic the behaviour of natural enzymes [Walther 2018]. It was recently shown that nanozymes can be used as ultrasensitive and ultrafast biosensors able to detect target molecules with a concentration as low as 0.1 ppm and in few minutes, using aptamers as bioreceptors [Sharma 2014]. The presence of aptamers onto nanoparticles surface blocks the enzymatic oxidation. When biological target is injected, aptamers leave the surface to engage with the target and the enzymatic oxidation is restored. Using the specificity of aptamers, any kind of biological target (oligonucleotides, proteins, cells, bacteria) could be detected.

Keywords : Nanozyme, catalysis, biosensor, aptamer.

Objectives :

The objectives of the thesis will be to design new nanoparticles composed of a lithium niobate or iron oxide core with nanometric gold or platinum seeds deposited on its surface and to use them as nanozymes for the detection of several biological targets. Furthermore, to the best of our knowledge, enzymatic activities of multimaterial nanoparticles have not yet been described. It may well be that the resulting vicinity of the two nanomaterials (noble metal seeds/oxide nanoparticles) in the nanohybrids give rise to new catalytic activities or synergies by mimicking the colocalization of enzymatic activities as cells do.

Scientific hurdles :

As the thesis topic is multidisciplinary and mainly experimental, it includes several crictital points:

• The synthesis of gold or platinum seeded lithium niobate or iron oxide nanoparticles with a controlled surface density of gold seeds. Several gold seeds with various shape, size and surface chemistry will be tested. Gold and platinum seeds of spherical morphology will be compared to study the influence of metal composition.
• The functionalization of hybrid nanoparticles with selected aptamers. This point is crucial as the aptamers have to be anchored strongly enough to block the catalytic activity but loosely enough to be displaced in the presence of the targeted analyte. This will require a number of key optimisation strategies.
• The evaluation of catalytic and biosensing performances (detection threshold, sensitivity, selectivity). Biochemical enzyme kinetic studies will be performed to understand these properties.

Expected original contributions :

Nanozymes composed of gold or platinum seeds coated lithium niobate or iron oxide core were never prepared and tested as biosensors. This should bring significative progresses in the field of nanobiomedicine.

Research program and proposed scientific steps :

The PhD student will work in a first step on the chemical modification of LiNbO3 (produced by SYMME collaborator) or iron oxide nanoparticles surfaces to graft gold or platinum nanocatalyzers. To achieve this, he(she) will use different polyelectrolytes to monitor gold seeds surface density. In a second step, he(she) will select specific aptamers and adsorb them onto hybrid nanoparticles surface. At each step, the structural and surface properties of nanoparticles will be characterized at INL by Transmission Electron Microscopy (TEM), zetammetry, infrared spectroscopy and X-Ray photoelectron spectroscopy (IR). Then, the candidate will perform the biodetection of several biological targets at RMIT (oligonucleotides, proteins, cells, bacteria) and will evaluate biosensor performances (detection threshold, sensitivity, selectivity) depending on the hybrid nanoparticles structural and surface properties.

Scientific supervision:

• Description of the supervision committee : 

• The supervsion committee is composed of three members. However, as Virginie Monnier previewed to obtain her Habilitation (HDR) before the end of 2019, after that, she will be the only french supervisor, so the committee will be reduced to two members
• Integration inside the laboratories (percentage of working time inside these laboratories) : 67% at INL, 33% at RMIT

PhD funding : Co-Fund ECL/RMIT (ECLAUsion program)

Profile of the candidate :

The candidate will hold a MSc in (bio)chemistry or materials. He(she) will like experimental work and be able to work at the inferace of chemistry and biology. He(she) will not have studied in France for more than 2 years over the last 3 years.
Objectives for the valorization of the research work :
Publications in peer-review international journals (minimum 2), conferences (at least 1 in France and 1 abroad). No constraints of confidentiality except if the results could be patented.

Skills that will be developed during the PhD :

At the end of the thesis, the PhD student will have acquired skills in chemical functionalization, biochemical assays, biosensor development, etc., and will be autonomous on several microscopic characterization (TEM) and spectroscopic (IR) techniques. He(she) will also learn to valorize his work in terms of publications and patents.

Professional opportunities after the PhD:

Due to the multidisciplinarity of the techniques used and to the numerous collaborators that will interact with the PhD student, his(her) profile will be adapted for a position either in academic research or industry.

Bibliographic references about the PhD topic :

• [Qin 2019] L. Qin et al, Sci. Total Environ. 2019, 652, 93.
• [Sharma 2014] T. K. Sharma et al, Chem. Commun. 2014, 50, 15856.
• [Song 2013] W. Song et al, J. Phys. Chem. C 2013, 2, 7721.
• [Walther 2018] R. Walther et al, Angew. Chem. Int. Ed. 2018, 57, 1.