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Ariane DENISET
Pr. Ariane DENISET-BESSEAU
Head of the AFM-IR team
Institut de Chimie Physique, Université Paris-Saclay, CNRS, Orsay, France
Abstract
In the last decade, a new instrumentation, called AFM-IR, has been developed in our team at the “Institut de Chimie-Physique” to perform IR analyses at the nanometer scale. This technique is based on the detection of the photothermal effect that occurs after IR radiation absorption in matter: it is the result of coupling an atomic force microscopy (AFM) with IR spectroscopy to perform local IR absorption measurements (Patent US11 / 803421, A. Dazzi). This combination makes it possible to identify at the nanometer scale organic molecules without using exogenous markers. The application fields range from biomedical, to polymer science, and astrochemistry.
In our team, the technique has shown its potential in the study of lipid bodies in microorganisms. This study allowed, for the first time, to carry out chemical mapping of lipid inclusions within a cell at the subcellular level. The technique also makes it possible to directly probe the composition of these inclusions by locally recording the IR absorption spectra. Nevertheless, in its initial configuration, the instrumentation has reached a limit in term of sensitivity: the size of the smallest object detectable was around 50 nm. New experimental approaches were therefore developed to overcome the technical constraints imposed by the system itself (configuration of illumination - sensitivity ...). In particular, a change of configuration allows to go down in terms of resolution and to reach tens of nanometers. This breakthrough offers new perspectives such as the study of protein fibers or nanoparticles. During the seminar, a short presentation of the technique will be done as well as the experimental constraints. Some examples will be presented to illustrate the capabilities of the AFM-IR technique.mise à jour le 26 novembre 2021
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