Anisotropic Carbon Nanorods with Polarized Emission for Two-Photon Fluorescence Bioimaging

Project: Research

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Fluorescent carbon nanomaterials are ideal for bio-imaging because they are non-toxic, and stable in biological environments. Unfortunately, the application of carbon dots, the most prevalent form of carbon nanomaterials so far, in bioimaging is still limited by their need for blue/UV excitation which leads to autofluorescence from the surrounding cellular material, resulting in high background image noise. One attractive avenue for bio-imaging probe nanoparticles is to move from spherical carbon dots into anisotropic shapes of fluorescent carbon nanoparticles, such as carbon nanorods (CNRs). The use of such anisotropic probes can offer multiple benefits. The initial stage of this proposal will focus on developing anisotropic carbon nanorods based on our encouraging preliminary experiments. We will focus on the elucidation and control of the CNR formation mechanism, and the development of the synthesis of CNRs with controllable size and strong fluorescence over the whole visible range. This will be achieved through the use of different precursors, which take a role in templating the shape of the final nanoparticles, as well as modifying the reaction parameters to manipulate the size and also the surface modification of the CNRs. Surface modification is an important factor in controlling both the fluorescence brightness and also the biocompatibility of the CNRs. The project will furthermore focus on understanding the mechanism of the polarised emission from nanorods, where the particles are undergoing both translational and rotational diffusion (Brownian motions) in various types of fluid environments and also within biological structures. Fully understanding the emission processes from dynamic, moving anisotropic fluorescent probes where the emission and probe rotation rates overlap, will allow a detailed picture to be constructed of the biological environment in which the CNRs are embedded or the motion of moieties to which they are attached. An additional bonus of moving to anisotropic carbon particles is the fact that they may possess high two-photon absorption cross-sections, which is to be confirmed in a series of related experiments. In high contrast bio-imaging applications they can be excited by long wavelength light, even into the near IR where there is a transparency range allowing deeper penetration into biological tissues. Non-blue/UV excitation resulting in two-photon fluorescence would drastically reduce unwanted autofluorescence, providing a major benefit for bioimaging with CNRs. 


Project number9042884
Grant typeGRF
Effective start/end date1/01/20 → …