Presentation - Real Time Label Free Nanoscopy Using Infra Red Absorption (LANIR), Workshop on Super Resolution and Life Sciences 2012, Romania

Foysal Khan's picture




IR microscopy is a chemical imaging technique that maps the spatial distribution of certain chemical transition which is identified by a well-established and almost universally used IR spectroscopy technique. This technique traces the chemical fingerprint of a variety of biological and nonbiological materials. It means, no chemical labelling is required for molecular identification (label-free). This is highly advantageous especially in detecting small and subtle chemical changes that can potentially have severe consequences e.g. in chemical change in the amyloid protein structure that causes Alzheimer’s disease. Breaking away from the diffraction limit of infra-red (IR) radiation in far-field microscopy has been considered impossible due to the inherent absorption of IR radiation by materials at intensities required to achieve high resolution. The best resolution offered on commercial tabletop IR microscopes is currently over 20 microns only. Even with high intensity synchrotron sources, the best resolution obtained in IR microscopy is 2-4 micron, which is still diffraction limited. Vibrational spectroscopies such as infra-red (IR) absorption, coherent anti-Stokes Raman, sumfrequency generation, stimulated Raman spectroscopy are today well established and capable of revealing the chemical structure of materials. These techniques offer diffraction limited spatial resolution, and high fidelity images can be generated. Sub-diffraction resolution for these techniques generally involves nanoscale near-field probes, and the approach remains thus suitable for surface characterization but appears unpractical in other circumstances. Here we present a conceptual framework of Infra Red Nanoscopy (IRN) that breaks away from the diffraction limit by exploiting the reversible saturation of vibrational transitions, and the experimental feasibility of the concept is rationalized. It is argued that IRN has the potential for improving the lateral resolution of IR micro-spectroscopy from the diffraction-limited current state-of-the-art down to the nanoscale. Chemical characterization and structural imaging under ambient conditions with sub-micron and nanoresolution can significantly advance our understanding of biological processes at the sub-cellular level, provide insight into early stages of diseases such as Alzheimer’s disease and lung cancer, and contribute to the improvement of therapeutic drugs and to the assessment of the real impact of nanomaterials on health and safety

Presenting Author/Speaker: George Stanciu4(speaker), Christophe Silien1, André Peremans2, Alberto Diaspro3 , , Syed A. M. Tofail1

Link: ../wsrls_2012.pdf