The project started with the setting up of a strategy for the preparation of usCNTs in high yield and their full characterizations. More precisely, SWCNTs were first covalently functionalized by sp3 defects (p-nitro aryl groups) using a diazonium chemistry in oleum, followed by chemical oxidation at the defect sites by hydrogen peroxide to produce ultrashort ones keeping its bright fluorescent properties. The spectroscopy characterizations (e.g. PL) have confirmed the presence of sp3 defects and the structural analysis (Atomic Force Microscopy) demonstrate that they are really shorter in length (average length of ~ 40 nm).
This multidisciplinary project also involved the design and development of an optical microscopy setup to allow for the excitation and visualization of different laser excitation wavelengths on the same imaging apparatus for multiplexed imaging. With this dedicated home-built fluorescence microscope, operating in the SWIR window, we have successfully identified and quantified the photophysical properties (photostability, brightness etc.) of usCNTs down to the single nanotube level leading to confirm that these sp3 functionalized usCNTs are bright enough to be tested on biological environment (cells or thick tissue). For that, we introduced surface bio-functionalization to couple them with an antibody (IgG) to be used as diagnostic biomarkers in cancer. We tested them on 2D cells before going into the more complex environment of liver tissue. The PL microscopic images of A431 cells (which express abnormally high levels of the Epidermal growth factor receptor/EGFr), immune-stained by this immuno-labels, clearly show marking around the membrane regions which confirms that EGFr at the membrane are immune-stained. These results were an important first step to go further into the liver cancer tissue. In parallel, we tested the accessibility of functionalized usCNTs in biological tissues. We could detect the movements of CNTs in the intricate maze of the interstitial space in brain tissue via real-time imaging technique.
The results of the project were presented in two major international conferences as well as in several scientific journals. More precisely, this work has been disseminated at the most important conferences in the field of nanoscience and low-dimensional materials (ChemOnTube and NT’23). In addition, two publications have already been published in top-class scientific journals, and at least two more are on preparation for imminent submission.
