Now showing 1 - 2 of 2
  • Publication
    Multimodal Microscopy Distinguishes Extracellular Aggregation and Cellular Uptake of Single-Walled Carbon Nanohorns
    The low toxicity, high surface area, and ease of functionalisation of carbon nanohorns (CNH) makes them attractive systems for cellular imaging, diagnostics and therapeutics. However, challenges remain for the biomedical translation of these and other nanomaterials. A significant task is tuning the surface chemistry to achieve optimal cellular interactions. Herein, we combine real-time fluorescent imaging of nanoparticle cellular uptake and real-time differential interference contrast (DIC) imaging of extracellular media to monitor a) nanoparticle/nanoparticle and b) nanoparticle/cell interactions for CNHs covalently modified with an OFF/ON near-IR dye, the fluorescence of which is switched OFF in extracellular environments and triggered upon cellular internalisation. CHN samples modified with different loadings of the hydrophobic dye are taken as a simple model of drug-loaded nanoparticle systems. The punctate fluorescence suggests the CNHs are delivered to lysosomes and other vesicles of the endocytic pathway. DIC imaging highlights the competition that exists for many particle types, between extracellular aggregation and cellular internalization, the efficiency of which would be dependent upon the amount of fluorophore loading. The results of this study illustrate how complementary real-time imaging methods together with physicochemical characterisation can be used to address the challenges involved in optimising nanoparticle/cell interactions for biomedical applications.
      403Scopus© Citations 6
  • Publication
    Cellular Uptake Mediated Off/On Responsive Near-Infrared Fluorescent Nanoparticles
    Fluorescence imaging, utilizing molecular fluorophores, often acts as a central tool for the investigation of fundamental biological processes and offers huge future potential for human imaging coupled to therapeutic procedures. An often encountered limitation with fluorescence imaging is the difficulty in discriminating nonspecific background fluorophore emission from a fluorophore localized at a specific region of interest. This limits imaging to individual time points at which background fluorescence has been minimized. It would be of significant advantage if the fluorescence output could be modulated from off to on in response to specific biological events as this would permit imaging of such events in real time without background interference. Here we report our approach to achieve this for the most fundamental of cellular processes, i.e. endocytosis. We describe a new near-infrared off to on fluorescence switchable nanoparticle construct that is capable of switching its fluorescence on following cellular uptake but remains switched off in extracellular environments. This permits continuous real-time imaging of the uptake process as extracellular particles are nonfluorescent. The principles behind the fluorescence off/on switch can be understood by encapsulation of particles in cellular organelles which effect a microenvironmental change establishing a fluorescence signal. © 2011 American Chemical Society.
      235Scopus© Citations 64