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Fluorescent nanomaterials are expected to revolutionize medical diagnostic, imaging, and therapeutic tools due to their superior optical and structural properties. Their inefficient water solubility, cell permeability, biodistribution, and high toxicity, however, limit the full potential of their application. To overcome these obstacles, a water-soluble, fluorescent, cytocompatible polymer-single-walled carbon nanotube (SWNT) complex is introduced for bioimaging applications. The supramolecular complex consists of an alkylated polymer conjugated with neutral hydroxylated or charged sulfated dendronized perylene bisimides (PBIs) and SWNTs as a general immobilization platform. The polymer backbone solubilizes the SWNTs, decorates them with fluorescent PBIs, and strongly improves their cytocompatibility by wrapping around the SWNT scaffold. In photophysical measurements and biological in vitro studies, sulfated complexes exhibit superior optical properties, cellular uptake, and intracellular staining over their hydroxylated analogs. A toxicity assay confirms the highly improved cytocompatibility of the polymer-wrapped SWNTs toward surfactant-solubilized SWNTs. In microscopy studies the complexes allow for the direct imaging of the SWNTs' cellular uptake via the PBI and SWNT emission using the 1st and 2nd optical window for bioimaging. These findings render the polymer-SWNT complexes with nanometer size, dual fluorescence, multiple charges, and high cytocompatibility as valuable systems for a broad range of fluorescence bioimaging studies.

Customized polyglycerol-based surfactants incorporating different aromatic cores are used to isolate and suspend carbon nanotubes in water. Different cores yield suspension with distinct chiral species distribution. Increasing the number of the phenyl rings connecting head and tail, the dispersion of the semiconducting species becomes sharper toward the nanotubes with bigger family index.

The interaction of carbon nanotubes with the molecular dipole switch spiropyran is expected to affect the optical response of the tubes. Until now, the need of anchor groups to immobilize the switches on the tubes has hindered the experimental observation of the effects of switching on the emission behavior of the tubes. Here we present spiropyran-carbon nanotube complexes obtained by micelle swelling. This method does not require any anchor nor sophisticated chemistry to warrant close tube-switch proximity. For the first time, we observe the shifts predicted theoretically and their effect on the tubes' excitation and emission energies.

We exploited a non-covalent approach based on π-stacking interactions to address the formation of hybrids between pyrene-functionalized gold nanoparticles (PyAuNPs) and reduced graphene oxide (RGO), in which the former are distributed homogeneously on the surface of the latter with a high degree of coverage. We used water soluble PyAuNPs of two different average dimensions, namely 2 and 8 nm, in which the pendant pyrene moieties were introduced within a mixed monolayer with a choline derivative. The combination with RGO originates highly insoluble materials, in which microscopy evidences a complete adhesion of the PyAuNPs onto the carbon nanomaterial layers in a highly homogeneous fashion, with no traces of free particles, confirming the high affinity between pyrene-functionalized species and conjugated carbon nanostructure surfaces.

Covalent functionalization tailors carbon nanotubes for a wide range of applications in varying environments. Its strength and stability of attachment come at the price of degrading the carbon nanotubes sp2 network and destroying the tubes electronic and optoelectronic features. Here we present a non-destructive, covalent, gram-scale functionalization of single-walled carbon nanotubes by a new [2+1] cycloaddition. The reaction rebuilds the extended π-network, thereby retaining the outstanding quantum optoelectronic properties of carbon nanotubes, including bright light emission at high degree of functionalization (1 group per 25 carbon atoms). The conjugation method described here opens the way for advanced tailoring nanotubes as demonstrated for light-triggered reversible doping through photochromic molecular switches and nanoplasmonic gold-nanotube hybrids with enhanced infrared light emission., While covalent modification of carbon nanotubes allows their use in a wide range of applications, it often results in disruption of their optoelectronic properties. Here, the authors design a cycloaddition reaction that preserves the nanotubes electronic structure.

Recently, we introduced a novel hybridization route for carbon nanotubes using gold nanoparticles, whose close proximity neatly enhances their radiative emission. Here we investigate the mechanisms behind the enhancement by monitoring the de-excitation dynamics of our π-hybrids through two-color pump-probe time-resolved spectroscopy. The de-excitation process reveals a fast component and a slow component. We find that the presence of gold prominently affects the fast processes, indicating a stronger influence of the gold nanoparticle on the intra-band non-radiative relaxation than on the inter-band recombination of the single-walled carbon nanotube. By evaluating the de-excitation times, we estimate the balance between near-field pumping and the faster metal-induced de-excitation contributions, proving the enhanced pumping to be the leading mechanism. © 2017 IOP Publishing Ltd.

Here we present our results on the optimization of a nanometallic-carbon nanotubes plasmonic hybridization process to enhance the photoluminescence quantum yield of single walled carbon nanotubes. Swelling the micelles containing the hybrids through an organic solvent improves the matching between the hybrids constituents; the optimized hybrids exhibit enhancement of the emitted photoluminescence without affecting the physical mechanisms involved in the exciton-plasmon coupling process.

Aiming to enhance the luminescence yield of carbon nanotubes, we introduce a new class of hybrid nanoplasmonic colloidal systems (π-hybrids). Nanotubes dispersed in gold nanorod colloidal suspensions yield hybrid structures exhibiting enhanced luminescence up to a factor of 20. The novelty of the proposed enhancement mechanism relies on including metal proximity effects in addition to its localized surface plasmons. This simple, robust and flexible technique enhances the luminescence of nanotubes with chiralities whose enhancement has never reported before, for example the (8,4) tube.