Among targeted delivery systems, platforms with nanosize dimensions, such as carbon nanomaterials (CNMs) and metal nanoparticles (NPs), have shown great potential in biomedical applications. They have received considerable interest in recent years, especially with respect to their potential utilization in the field of cancer diagnosis and therapy. The many functions of nanomaterials provide opportunities to use them as multimodal agents for theranostics, a combination of therapy and diagnosis. Carbon nanotubes and graphene are some of the most widely used CNMs because of their unique structural and physicochemical properties. Their high specific surface area allows for efficient drug loading and the possibility of functionalization with various bioactive molecules. In addition, CNMs are ideal platforms for the attachment of NPs. In the biomedical field, NPs have also shown tremendous potential for use in drug delivery, non-invasive tumour imaging and early detection due to their optical and magnetic properties. NP/CNM hybrids not only combine the unique properties of the NPs and CNMs but they also exhibit new properties arising from interactions between the two entities. In this review, the preparation of CNMs conjugated to different types of metal NPs and their applications in diagnosis, imaging, therapy and theranostics are presented. AbbreviationsAuNPs, gold nanoparticles; CBCs, circulating bacteria cells; CNMs, carbon nanomaterials; CNTs, carbon nanotubes; CTAB, cetyltrimethylammonium bromide; CTCs, circulating tumour cells; DOX, doxorubicin; FA, folic acid; GNCs, gold nanoclusters; GNTs, golden carbon nanotubes; GO, graphene oxide; HA, hyaluronic acid; ICP MS, inductively coupled plasma mass spectrometry; IP, IL-13-based peptide; NDs, nanodiamonds; NIR, near-infrared; NPs, nanoparticles; NRs, nanorods; MGMS, magnetic graphene-based mesoporous silica; MIONPs, magnetic iron oxide nanoparticles; MWCNTs, multi-walled carbon nanotubes; PAA, polyacrylic acid; PAT, photoacoustic tomography; PDDA, poly(diallyldimethylammonium chloride); PDT, photodynamic therapy; PE, polyelectrolyte; PEI, polyethyleneimine; PEG, poly(ethyleneglycol); PLA, poly(lactic acid); PLGA, poly(lactic-glycolic acid); PSS, poly-(sodium 4-styrenesulfonate); PTT, photothermal therapy; QDs, quantum dots; rGO, reduced graphene oxide; ROS, reactive oxygen species; SERS, surface-enhanced Raman scattering; SPIONPs, superparamagnetic iron oxide nanoparticles; SPR, surface plasmon resonance; SWCNTs, single-walled carbon nanotubes; SWNHs, single-walled carbon nanohorns; UCL, upconversion luminescence; UCNPs, upconversion nanoparticles; ZnPc, zinc phthalocyanine

Functionalization of the bis-lacunary Keggin polyoxotungstate [γ-SiW10O36]8– has been achieved with a two-step synthesis, by the covalent attachment of a 3-aminopropylsilane spacer and further linkage of the dansyl (5-dimethylamino-1-naphthalenesulfonyl-) residue. The resulting bis-decorated molecular hybrid [{{(CH3)2N}C10H6SO2NH(CH2)3Si}2O(γ-SiW10O36)]4– has been isolated and characterized in solution and in the solid state by FTIR, multinuclear NMR, ESI-MS, UV/Vis, luminescence spectroscopy, dynamic light scattering (DLS), and Scanning Electron Microscopy (SEM). The inorganic polyoxometalate provides a molecular nano-surface where the dansyl fluorophores are anchored with a tweezer-type arrangement. The merging of the organic and inorganic domains of the bis-dansylated complex dictates its fluorescence features, which are observed in the range 375–600 nm, its amphiphilic properties, and the multi-site recognition/signaling of cationic analytes due to the complementary effect of the tungsten oxide polyanionic surface. Indeed, the interplay of the appended sulfonamide moieties and of the molecular metal oxide fosters an enhanced selectivity for Cu2+ and Pb2+ ion sensing, even in the presence of potentially interfering cations such as Co2+. These latter are preferentially captured by the inorganic platform. By virtue of its hybrid nature, the title fluoroionophore evolves to supramolecular architectures and extended systems in mixed organic solvent/aqueous environment, yielding spherical vesicles and macroporous thin films. Flat polymeric membranes incorporating the hybrid fluorophore can also be obtained, suggesting the generation of heterogeneous sensing devices that integrate both filtration and separation functionalities

Divacant Keggin-type polyoxotungstates [γ-XW10O36]8– with X = Si or Ge, were functionalized with chiral phosphoryl groups. The hybrid compounds [(R*PO)2(γ-XW10O36)]4– with R = N-protected aminoalkyl groups or O-protected amino acid derivatives, were isolated. The solution characterization of the products was performed by different techniques: 183W, 31P, 13C, and 1H NMR spectroscopy, electrospray ionization mass spectrometry, UV/Vis spectroscopy, and circular dichroism (CD). The experimental data confirm the covalent grafting of the organic moieties onto the polyanionic surface. A chirality transfer, from the pendant organic arm to the inorganic framework is apparent from CD studies. Multiple Cotton effects were observed in the region of charge-transfer transitions pertaining to W–O bonds. Furthermore, the 183W NMR spectra are consistent with the expected C2 symmetry, resulting from introduction of two organic stereocenters. The title complexes were used in the presence of hydrogen peroxide to perform the oxidation of methyl p-tolyl sulfide. Implications for the design of enantioselective catalysts based on these derivatives are discussed

The Keggin-type polyoxometalate [γ-SiW10O36]8− was covalently modified to obtain a bis-biotinylated conjugate able to bind avidin. Spectroscopic studies such as UV-vis, fluorimetry, circular dichroism, coupled to surface plasmon resonance technique were used to highlight the unique interplay of supramolecular interactions between the homotetrameric protein and the bis-functionalized polyanion. In particular, the dual recognition mechanism of the avidin encompasses (i) a complementary electrostatic association between the anionic surface of the polyoxotungstate and each positively charged avidin subunit and (ii) specific host-guest interactions between each biotinylated arm and a corresponding pocket on the tetramer subunits. The assembly exhibits peroxidase-like reactivity and it was used in aqueous solution for L-methionine methyl ester oxidation by H2O2. The recognition phenomenon was then exploited for the preparation of layer-by-layer films, whose structural evolution was monitored in situ by ATR-FTIR spectroscopy. Finally, cell tracking studies were performed by exploiting the specific interactions with a labeled streptavidin.

A novel bis-pyrene tweezer anchored on a rigid polyoxometalate scaffold fosters a unique interplay of hydrophobic and electrostatic supramolecular interactions, to shape carbon nanostructures (CNSs)-based extended architectures.

Organic–inorganic hybrids based on polyoxometalate scaffolds(POMs) are a unique class of molecular metal-oxides featuring a composite surface, whereby the merging of complementary domains stimulates new functions and enhances performances. The interaction between the organic and inorganic components can be designed via covalent and/or non-covalent strategies, yielding novel molecular systems with key applications in catalysis and materials science. Selected examples of such a rewarding approach will be illustrated, including the synthesis of tailored POM-based catalysts, and their application in homogeneous systems and on electrocatalytic surfaces for water splitting and renewable energy production

International audienceThe assessment of the biodegradability potential of carbon nanotubes (CNTs) is a fundamental point towards their applications in materials science and biomedicine. Due to the continuous concerns about the fate of such type of nanomaterials, it is very important to understand if they can undergo degradation under certain conditions and if the morphology and structure of the nanotubes play a role in this process. For this purpose we have decided to undertake a comparative study on the enzymatic degradation of CNTs with concentric multilayers. Double-walled (DW) and multi-walled (MW) CNTs of various lengths, degrees of oxidation and functionalizations using different methods were treated with horseradish peroxidase (HRP). While all tested DWCNTs resulted resistant to the biodegradation, some of the MWCNTs were partially degraded by the enzyme. We have found that short oxidized multi-walled CNTs functionalized by amidation were reduced in length and presented a high amount of defects at the end of the period of treatment with HRP. This comparative study holds its importance in the understanding of the structural changes of different types of nanotubes towards the catalytic enzymatic degradation and will help to design safer CNTs for future applications

A divacant Keggin polyanion has been decorated with a N-heterocyclic carbene (NHC) iridium(I) organometallic complex to provide a molecular model of an Ir-based supported catalyst. The characterization of the hybrid compound has been performed by multinuclear NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, and mass spectroscopy, and the results are in agreement with a bisfunctionalization of the polyoxometalate scaffold. The resulting supported homogeneous complex has been successfully used to catalyze the transfer hydrogenation from iPrOH to benzophenone [with a turnover number (TON) of 680 and a turnover frequency (TOF) of up to 540 h–1]