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The supramolecular assembly of acetylsalicylic acid to a merocyanine-Zn complex translates into a photo-controllable drug delivery system. Herein, we present the synthesis and spectroscopic analysis of a three-component assembly combining a spiropyran derivative, a zinc(ii) cation, and acetylsalicylic acid. The ON/OFF system can be modulated by safe and easily affordable stimuli, for the specific delivery of more than one active compound. Our results confirm the formation of a ternary system in solution, where the behaviour is dominated by photo-induced responses, and pave the way for the use of such smart platforms for medicinal chemistry purposes.

International audience; Reduction of carbon nanohorn (CNH) aggregates with potassium naphthalenide resulted in their dismantling and individualization. Furthermore, the reduced CNHs were functionalized via addition of electrophiles.

One conventional and two related gemini surfactants have been used for the preparation of stable single-walled carbon nanotube (SWNT) aqueous dispersions. The surfactants investigated are able to disperse SWNTs at surfactant/carbon nanotube weight ratios far lower than widely used conventional surfactants. The gemini surfactants investigated demonstrated the ability to solubilize a larger amount of SWNTs with respect to the related single-tailed surfactant at concentrations far lower than their critical micellar concentrations. Their selectivity towards semiconducting SWNTs with large diameters was inferred from radial breathing mode Raman data.

The design, synthesis and complete characterization of a smart material composed of single-walled nanotubes functionalized with spiropyran-based photo switchable molecules are reported. The chemical complexity of the system requires the use of a range of complementary techniques in order to provide a complete picture of the composition and performance of the nanomaterial. Thermal gravimetric analysis ensured both the high degree of chemical functionalization and the presence of molecular switches in the nanotube sample; micro-Raman indirectly confirmed the successful oxidation of the tubes, FT-IR proved the nature of the functional groups introduced based on their characteristic stretching vibrations and atomic force microscopy demonstrated nanotube lengths of approximately 600 nm. UV–Vis–NIR absorption spectroscopy was used to evaluate the photoresponsive behaviour of the nanomaterial, and the intensity of the absorption band at 556 nm could be modulated by light-induced reversible conversion of the spiropyran molecules attached to the SWCNT from the spiro close conformation to the merocyanine open form. We were also able to provide the first example of a continuous solution based on–off switching in a spiropyran–nanotube material.

Two different lipophilic guanosine derivatives (LipoGs) have been used for the disaggregation of single walled carbon nanotubes (SWCNTs) in chloroform. UV–vis–NIR spectrophotometry, Raman spectroscopy and NIR-photoluminescence measurements as well as AFM and SEM highlight a well debundling of SWCNTs while fluorescence measurements show the adsorption of LipoGs onto SWCNT surface. The ability of LipoGs to disperse SWCNTs has been demonstrated to depend on their tendency to self-assemble into ribbon-like supramolecular structures. In turn, the super-organization of these supramolecular structures appears to control the homogeneity of the dispersion.

The 1-hexadecyl-3-vinylimidazolium bromide (hvimBr), a water-soluble long-chain imidazolium ionic liquid (IL) with surfactant properties, showed the ability to produce stable homogeneous aqueous dispersions of pristine Single-Walled Carbon Nanotubes (SWNTs). The purpose of this study is the improvement of SWNT dispersing ability by assessing the effect of different groups in position 3 of the imidazole ring. In this regard structural analogues were synthesized and, after characterization, their capability to dissolve SWNTs in water was investigated. Molecular Dynamics (MD) simulations have been performed to provide a semi-quantitative indication of the affinity of each dispersing agent toward SWNT and to attempt an explanation of the experimental results.

The presence of carboxylated carbonaceous material in nitric acid-treated single-walled carbon nanotube (SWNT) samples has recently brought renewed focus on the processes by which covalent functionalization of such materials are carried out. Using a widely reported 2-step purification/oxidation procedure, we have investigated the effect of basic treatment and solvent washing on the functionalization and final properties and behavior of SWNTs. We have demonstrated, using a number of spectroscopic techniques, that in the absence of NaOH treatment, COOH functionality is introduced directly onto SWNTs, and not only onto carbonaceous material present in the sample. Covalent functionalization of the oxidized materials was also investigated by attachment of a fluorescent probe, and ultimately, whether treated with base or solvent washed, the resulting materials are close to identical with respect to both their appearance and properties. In addition, we have demonstrated that using either of these purification/ox...

Oxidized single-walled carbon nanotubes (SWNTs) have been prepared following a widely reported two-step purification/oxidation procedure in the presence or absence of a treatment with base (NaOH). The oxidized nanotube samples washed with solvents or base appear close to identical with respect to both appearance and properties. Efficient removal of both metal and carbonaceous impurities and introduction of –COOH groups on the nanotube surface have been demonstrated by AFM, Raman and FTIR spectroscopy. Furthermore, persistence of optical properties was confirmed using UV-vis/NIR absorption and NIR photoluminescence spectroscopies.

A chemical treatment for preparing high purity selectively oxidised SWNTs while preserving optical/electronic properties of the material has been developed. Efficient removal of both metal and carbonaceous impurities has been demonstrated by AFM, TEM, Raman and absorption spectroscopy, while XPS confirmed quantitative conversion of oxidised defects to functionalisable carboxylic acid groups. Furthermore persistence of the characteristic optical properties was confirmed using absorption and NIR photoluminescence spectroscopy, thus indicating preservation of the electronic structure. This chemical treatment thus paves the way for the preparation of high purity, covalently functionalised SWNTs enhancing their potential for use in high-performance optical/electronic applications. A comparison with commonly used purification protocols that utilize nitric acid and sodium hydroxide followed by piranha solution treatments or simple solvent washing is made, highlighting the advantages of the reported method for the production of SWNT starting materials ideal for efficient chemical modifications.

Single-walled carbon nanotubes (SWNTs) are suitable for many applications in molecular imaging because of their intrinsic near-infrared (NIR) photoluminescence. Nevertheless, several important issues, such as the SWNTs low biocompatibility, still need to be overcome for the effective use of carbon nanotubes in molecular imaging. In this study, we employ a two-step oxidation procedure with the aims of (1) removing the toxic metal impurities, (2) decreasing the lengths of the tubes, and (3) introducing functional oxygenated groups on the SWNT surface to enable the future development of a multifunctional SWNT-based nanoplatform. Since the presence of defect sites on the SWNT surface is known to quench the optical properties of carbon nanotubes, we have established what effect these two chemical treatments have on the NIR photoluminescence (PL) of the tubes. Our results show that purified and oxidized SWNT samples still display structured emission features in the NIR when dispersed in surfactant aqueous solution, with a residual emission efficiency of 30%. Two-dimensional (2D) fluorescence lifetime imaging (FLIM) of aggregates of purified and oxidized SWNTs in dimethylformamide (DMF) showed an average lifetime of 1.3 and 1.2 ns, respectively. These results demonstrate the relevance of SWNT purification and oxidation in the development of novel NIR probes with reduced toxicological impact on human health and with potential for further functionalization with multiple bioactive species.

Light controllable release of antinflammatory zinc ions by a smart multifunctional material composed of spiropyrans and single walled carbon nanotubes (SWNTs) is demonstrated. The exploitation of a number of complementary characterization techniques allows the investigation of both composition and performance of the multifunctional SP/SWNT nanomaterial developed. Moreover, its suitability for potential applications in bio-systems is suggested by the effective removal of the metal catalyst and the introduction of biocompatible linkers into the SP/SWNT material. The realization of potential photo controllable SP/SWNTs based drug delivery systems (DDSs) is envisaged, where nanotubes act as intracellular carriers of light modulated receptors for bioactive agents.