Missions

Upconverting nanoparticles (UCNPs) are lanthanide-based nanoparticles that have the ability to convert near-infrared excitation into multiple narrow emission bands spanning from UV to near-IR range. This property is a major asset as NIR excitation allows a much greater depth of penetration than visible light into materials, particularly biological samples, and causes little photobleaching. In particular, they are considered as attractive systems for energy harvesting for optoelectronics devices, bioimaging, sensing, or anti-counterfeiting devices. They have recently attracted much attention for their ability to behave as energy donors in hybrid nanoplatforms designed for biosensing applications, theranostics or photodynamic therapy.
It is therefore essential to characterize the complex energy transfer networks that govern the luminescence of these nanomaterials, in order to design optimized systems for these applications. To date, detailed photophysical studies have been carried out in solution to shed light on the complex, interleaved processes between the different partners present within UCNPs. However, the influence of the local environment must also be taken into account for the applications detailed above, and single-particle spectroscopy is proving very important in revealing the individual characteristics of UCNPs.
The aim of the research project is to probe and quantify energy transfers within Upconversion Nanoparticles (UCNPs) at the single particle level as a function of UCNP composition and architecture, in order to identify the extent to which these parameters influence resonant transfers to a peripheral energy acceptor. The study of these energy transfers will be carried out for UCNPs with a variable number and nature of activators present in the core (Tm3+, Er3+) and in the presence or absence of a shell. These UCNPs will be coated with a fluorescent polymer acting as a UCNP energy acceptor. A confocal hyperspectral imaging instrument will be used to quantitatively determine the luminescence lifetimes for the discrete emission bands of UCNPs at the single-particle scale, after µs to ms excitation in the near-IR range. This should enable us to construct a detailed mechanism for energy transfers in these organic/UCNP hybrid structures, and pave the way for finer control of the efficiency of UCNPs as nanoplatforms for the development of biosensing applications.

Activities

The candidate's activities will focus on:
- time-resolved luminescence measurements of UCNPs in solution and single particles samples;
- processing and analyzing the collected experimental data;
- the presentation of these results during progress meetings with collaborators, group meetings and conferences; writing regular reports; writing research articles.

Skills

We are looking for a highly motivated candidate who recently graduated with a Ph.D. in chemistry. His/her research should focus on upconversion nanomaterials, with a strong interest in understanding their optical and photophysical properties using time-resolved spectroscopy and microscopy methods. Experience in using these experimental methods and processing the collected data will be a real asset. Good communication skills in English (written and oral) are required.

Work Context

This project will be carried out at LASIRE laboratory (Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, UMR8516, Université de Lille), within the DyNaChem team (Dynamics, Nanoscopy and Chemometrics, https://lasir.cnrs.fr/dynachem/). The candidate will benefit from the platform of time-resolved spectroscopy and microscopy experiments installed in the laboratory, in particular a hyperspectral confocal microscope designed for the photophysical study of single UCNPs (square pulse NIR excitations at 976 and 808 nm, lifetime imaging). He/she will work in close collaboration with the project leader and may be involved in supervising student interns.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

Nothing to report