Functionalized Fullerene as an Artificial Vector for Transfection

Gene delivery by aminofullerenes: structural requirements for efficient transfection

A series of aminofullerenes that share a common structural motif have been synthesized and subjected to a systematic investigation of structure activity relationship regarding their ability for transient transfection and cytotoxicity. DNA-binding tests indicated that any water-soluble fullerene-bearing amino group would bind to double-stranded DNA. For these molecules to be effective transfection reagents, however, they require additional structural features. First, the molecule must be capable of producing submicrometer-sized fullerene/DNA aggregates that can be internalized into mammalian cells through endocytosis. Second, the molecule must be capable of releasing DNA as the aggregates are transferred into the cytoplasm. This can be achieved in at least two ways: by loss of the DNA-binding amino groups from the fullerene core, and by transformation of the amino groups to neutral groups such as amides. The screening experiments led us to identify the best reagent, a tetrapiperidinofullerene, that can be synthesized in two steps from fullerene, piperazine, and molecular oxygen, and that is more efficient at transfection than a commonly used lipid-based transfection reagent.

A humic acid stationary phase for the high performance liquid chromatography separation of buckminsterfullerenes: theoretical and practical aspects

The influence of the mobile phase composition and column temperature on the chromatographic separation of five buckminsterfullerenes (C60, C70, C76, C78, C84) on a stationary phase based on silica gel with chemically bonded humic acid (Bonded humic acid column (BHAC)) was studied. The retention behavior of the fullerenes was measured under isocratic conditions with different mobile phase compositions, ranging from 0.05-0.70 (v/v) of toluene in cyclohexane. The column temperature was analysed in the range 35-75 degrees C. The retention factors of the five fullerenes do not depend linearly on the toluene fraction but follow a quadratic relationship. The best chromatographic conditions for baseline separation of the five fullerenes were selected. The retention of the fullerenes on the HA stationary phase was strongly affected by temperature. Positive values of thermodynamic parameters (changes of enthalpy and entropy) were due to the abnormal solubility behaviour of fullerenes in toluene in the temperature range 35-75 degrees C. The information obtained in this work makes this BHAC very simple to prepare and low cost, useful for fullerene research applications.

Multifunctionalised cationic fullerene adducts for gene transfer: design, synthesis and DNA complexation

Cationic poly-N,N-dimethylfulleropyrrolidinium derivatives have been designed and synthesised to complex plasmid DNA for gene delivery.

Distribution of nanoparticles in the see-through medaka (Oryzias latipes)

OBJECTIVE

Because the environmental fate of manufactured nanoparticles is considered an emerging environmental concern, I used water-suspended fluorescent nanoparticles (solid latex solution) to investigate the distribution of nanoparticles in the eggs and bodies of see-through medaka (Oryzias latipes).

RESULTS

Particles 39.4-42,000 nm in diameter were adsorbed to the chorion of medaka eggs and accumulated in the oil droplets; 474-nm particles had the highest bioavailability to eggs. Particles 39.4 nm in diameter shifted into the yolk and gallbladder during embryonic development. Adult medaka accumulated 39.4-nm nanoparticles mainly in the gills and intestine when exposed to a 10-mg/L nanoparticle solution. Nanoparticles were also detected in the brain, testis, liver, and blood. Concentrations of nanoparticles in the blood of male and female medaka were 16.5 and 10.5 ng/mg blood protein, respectively. These results suggest that nanoparticles are capable of penetrating the blood-brain barrier and that they eventually reach the brain. Salinity-dependent acute toxicity was observed in medaka eggs exposed for 24 hr to nanoparticles.

CONCLUSION

The bioavailability and toxicity of nanoparticles depend on environmental factors and multiple physicochemical properties. Further studies on the toxic effects of nanoparticles used in commercial products and their environmental relevance, are necessary to define the risks and benefit of nanomaterial applications.

Functional nanofibrous scaffolds for bone reconstruction

DNA compaction, encapsulation and stabilization strategies as well as a scheme for DNA chain stabilization by complex formation with modified fullerenes for gene delivery are discussed. DNA can be compacted in organic solvents and encapsulated with amphiphilic triblock copolymers. The rapid removal of the solvent mixtures by electrospinning together with a biodegradable polymer preserves the globular DNA conformation and can be used for bone reconstruction applications. Cationic fullerene surfactants can decorate and stabilize DNA coils in aqueous solution. The complex formation process is studied by static light scattering and analyzed in detail.

Screening of C60 crystallization using a microfluidic system

We have carried out screening of C60 crystallization using a simple liquid/liquid interfacial precipitation method in a microfluidic device. By controlling the time, temperature, and concentration, various metastable phases of C60 crystals were found, including tubes, spheres, open-ended hollow columns, stars, branches, and trees. The obtained C60 crystal shapes are similar to those of snow crystals. These findings suggest an urgent need to screen C60 crystallization for the development of fullerene C60 drugs.

Fullerene (C60) immunoconjugates: interaction of water-soluble C60 derivatives with the murine anti-gp240 melanoma antibody

The first fullerene (C60) immunoconjugates have been prepared and characterized as an initial step toward the development of fullerene immunotherapy (FIT).

Synthesis and Reactions of 2,2-[60]Fullerenoalkanoyl Chlorides

2,2-[60]Fullerenoalkanoyl chlorides (1a-d) were easily and securely prepared from the corresponding 2,2-[60]fullerenoalkanoic acids (2a-d) by the reaction with thionyl chloride in an unusual mixed solvent, CH2Cl2/dioxane. The characterization of 1a-d by 1H and 13C NMR, FT-IR, and MALDI-TOF-MASS was conducted for the first time. The 2,2-[60]fullerenoalkanoyl chlorides thus obtained were readily converted to the corresponding amides and esters in moderate to excellent yields by the condensation with amines and alcohols, respectively. Upon applying the condensation, [60]fullerene-biomolecule hybrids were easily prepared.

Design and activity of cationic fullerene derivatives as inhibitors of acetylcholinesterase

Four different regioisomers of cationic bis-N,N-dimethylfulleropyrrolidinium salts have been prepared and evaluated as inhibitors of the enzymatic activity of acetylcholinesterase. These fullerene-based derivatives were found to be noncompetitive inhibitors of acetylthiocholine hydrolysis. Molecular modelling was used to describe the possible interactions between the fullerene cage and the amino acids surrounding the cavity of the enzyme. The cationic C(60) derivatives used in this study represent a new class of molecules potentially able to modulate the enzymatic activity of acetylcholinesterase.

Development of water-soluble metallofullerenes as X-ray contrast media

Fullerenes are a new carbonic allotrope having a cage structure. We investigated whether fullerenes containing one or two atoms of heavy metals could be an X-ray contrast material with little adverse effects. One or two atoms of dysprosium (Dy), erbium (Er), gadolinium (Gd), europium (Eu) and lutetium (Lu) were encapsulated into fullerene (C(82)), which was synthesized as a polyhydroxyl form (e.g., Gd@C(82)(OH)n, n=40, Gd - fullerenols). They were dissolved in water at maximum soluble concentrations and subjected to CT number analysis. The CT numbers of the solutions were measured using a 4- or 16-row multidetector CT scanner. The CT number of the water-soluble metallofullerenes were 56.0 HU for Dy@C(82)(OH)(40), 111.5 HU for Er@C(82)(OH)(40), 58.4 HU for Gd@C(82)(OH)(40), 100.9 HU for Eu@C(82)(OH)(40) and 23.3 HU for Lu(2)@C(82)(OH)(40). The CT numbers of the metallofullerenes investigated in the present study were not high enough to be used in the clinic in place of iodinated contrast materials. However, if nanotechnology progresses in the near future, it may prove to have a possibility as an X-ray contrast material.

Fractal behavior of functionalized fullerene aggregates. I. Aggregation of two-handed tetraaminofullerene with DNA

In tris-buffered saline (TBS) with a trace of dimethylformamide (DMF), the homoaggregation process of a functionalized fullerene, the two-handed tetraaminofullerene (TH), and the heteroaggregation process (complex formation) of TH with DNA (pGL3-control plasmid) were studied dynamically by using a combination of static and dynamic laser light scattering measurements. Fractal behavior was investigated in the aggregation process of both TH homoaggregates and TH-DNA heteroaggregates. The stability of aggregates in solution depends on the molar concentration ratio R(M), defined as the molar ratio of moles of TH to moles of the DNA base pair. Higher R(M) values resulted in lower aggregate stability. The transition of the fractal dimension (Df) in TH homoaggregation by rapidly mixing 3.78 microM TH with an equal volume of the blank buffer was found to vary from a value of 1.46 to 2.02. Dynamic light scattering results revealed that, in the aggregation process, the change in the size distribution of aggregates with time could be related to a Df transition. In the Df transition region, the size distribution of homoaggregates displayed a drastic change from a single-mode distribution to a bimodal distribution, which clearly suggested a restructuring process with the formation of large aggregates. When the aggregation process finally reached equilibrium, Df = 2.02, the size of the homoaggregates had a single mode but a broad distribution. However, TH-DNA heteroaggregation showed a Df transition from 1.58 to 1.7, but over a shorter time range of less than 5 min. Then, the Df value fluctuated in the range of 1.7 and finally reached an equilibrium value of Df approximately 1.78, which was independent of molar concentration. There are two main action forces involved in the heteroaggregation process: van der Waals forces and attractive electrostatic forces, with the latter one being stronger and faster than that of the former. Therefore, a two-step action could occur in the heteroaggregation process. In the beginning of mixing, the attractive electrostatic forces dictated the aggregation process, and then van der Waals forces also got involved in the entire aggregation process. By using an initial concentration of 3.78 microM each and R(M) = 1, TH-DNA heteroaggregates showed more stable solution behavior than the homoaggregates. The lower Df value of the heteroaggregates could be related to a looser compact structure. Results from scanning electron microscopy (SEM) also disclosed the different textures between TH homoaggregates and TH-DNA heteroaggregates; the former had a more dense packing than the latter one.

Reactivity of Titanium Oxo Ethoxo Cluster [Ti16O16(OEt)32]. Versatile Precursor of Nanobuilding Block-Based Hybrid Materials

Oxo alcoxo metallic clusters can be employed as inorganic nanobuilding blocks to obtain well-defined organic-inorganic hybrid materials. A better understanding of the surface reactivity of the clusters should allow optimization of the elaboration of hybrid materials through a better control of the hybrid interface. The oxo alcoxo cluster Ti(16)O(16)(OEt)32 presents a shell of labile ethoxy groups that can be selectively transalcoholyzed with preservation of the titanium oxo core, leading to new oxo alcoxo clusters Ti(16)O(16)(OEt)32-x(OR)x (R: alkyl, phenyl, styrenic, etc. groups). The reactivity of the Ti(16)O(16)(OEt)32 cluster toward aliphatic and aromatic alcohols is investigated to determine both the kinetics and the number of substituted titanium atoms, which are strongly dependent on the nature of the alcohol. Characterization of the organic modification of the cluster is performed in situ by liquid (13)C NMR measurements, using the molecular structures of two new clusters, Ti(16)O(16)(OEt)28(OnPr)4 and Ti(16)O(16)(OEt)(24)(OnPr)(8) (OnPr = propoxy groups), as references. The structures of these clusters have been established using single-crystal X-ray diffraction. Moreover, a complete spectroscopic assignment of each ethoxy group is proposed after combining crystallographic data, (13)C NMR T(1) relaxation measurements, and (1)H-(1)H, (1)H-(13)C 2D NMR experiments. Finally, the cluster is functionalized with polymerizable ligands via transalcoholysis and transesterification reactions using hydroxystyrene and acetoxystyrene.

Helical Arrays of Pendant Fullerenes on Optically Active Poly(phenylacetylene)s

Novel, optically active, stereoregular poly(phenylacetylene)s bearing the bulky fullerene as the pendant were synthesized by copolymerization of an achiral phenylacetylene bearing a [60]fullerene unit with optically active phenylacetylene components in the presence of a rhodium catalyst. The C60-bound phenylacetylene was prepared by treatment of C60 with N-(4-ethynylbenzyl)glycine in a Prato reaction. The obtained copolymers exhibited induced circular dichroism (ICD) in solution both in the main-chain region and in the achiral fullerene chromophoric region, although their ICD intensities were highly dependent on the structures of the optically active phenylacetylenes and the solution temperature. These results indicate that the optically active copolymers form one-handed helical structures and that the pendant achiral fullerene groups are arranged in helical arrays with a predominant screw sense along the polymer backbone. The structures and morphology of the copolymers on solid substrates were also investigated by atomic force microscopy.

Multilayer vesicles and vesicle clusters formed by the fullerene-based surfactant C60(CH3)5K

The self-assembly behavior of a fullerene-based surfactant, C60(CH3)5K, in water was studied using a combination of static and dynamic light scattering, as well as transmission electron microscopy, and compared to that of the compound C60(C6H5)5K. Both fullerene surfactant systems spontaneously assemble into large vesicles consisting of closed spherical shells formed by bilayers, with critical aggregation concentrations (CAC) lower than 10(-6) g ml(-1). At low concentrations, the aggregate sizes of C60(CH3)5K (radius R approximately 26.8 nm) and C60(C6H5)5K (R approximately 17.0 nm) were found to be substantially different from each other, showing that the change of the substituents surrounding the polar cyclopentadienide head group makes it possible to control the size of the resulting aggregates. Furthermore, the C60(CH3)5K vesicles were found to exist in two qualitatively different types of aggregation with a critical reaggregation concentration (CRC) located at 3.30 x 10(-6) g ml(-1). Above the CRC, larger aggregates were observed (R approximately 37.6 nm), showing a more complex form of supramolecular aggregation, e.g., in terms of multi-bilayer vesicles and/or of clusters of bilayer vesicles.

Nanomaterials based on phosphorus dendrimers

Dendrimers constitute an increasingly important field of research in chemistry for more than 15 years. After pioneering works concerning synthesis, the interest in dendrimers is now mainly driven by their properties and applications. This Account will emphasize the properties of a special class of dendrimers, that is, phosphorus-containing dendritic macromolecules, as tools for the elaboration of nanomaterials. Indeed, these dendrimers can be considered themselves as materials, or they can be used as an intrinsic constituent of a material or as a modifier of the surface of a material. In this latter case, a fundamental work about surfaces covalently modified by dendrimers recently opened the way to the elaboration of DNA chips.

Enhancement of Water Solubility of Fullerene by Cogrinding with Mixture of Cycloamyloses, Novel Cyclic .ALPHA.-1,4-Glucans, via Solid-Solid Mechanochemical Reaction

Improvement of solubility for fullerene (C60) was studied by cogrinding with cycloamyloses using a ball mill in the solid state. Cycloamylose is a novel cyclic alpha-1,4-glucan produced from synthetic amylose by enzymatic reaction. Although sample solutions showed a pale yellow for the initial period of cogrinding with cycloamyloses and C60, the color varied to brown after 48 h. Subsequently, the solubility of C60 was improved markedly to 560 (microg/ml) at 96 h. From powder X-ray diffraction analysis, the peak intensity of crystalline C60 decreased as the cogrinding time was extended. The UV-VIS absorption spectrum of C60 shows absorption bands at 262 and 340 nm in water with cycloamyloses, and 258 and 328 nm in n-hexane. These results suggested that C60 molecules were dispersed into cycloamyloses micellar system and the red-shift of the UV-VIS spectra was due to an intermolecular interaction between C60 and cycloamyloses.

Antibacterial and antiproliferative activity of cationic fullerene derivatives

We examined the antibacterial and antiproliferative activities of alkylated C(60)-bis(N,N-dimethylpyrrolidinium iodide) derivatives. The fullerene derivatives inhibited bacteria and cancer cell growth effectively. However, the fullerene derivatives with a long alkyl chain did not show antibacterial activity.

Synthesis of Fullerene Glycoconjugates through Sulfide Connection in Aqueous Media

[reaction: see text] A thiolate/alkyl halide coupling reaction in aqueous media provides a one-step synthesis of fullerene glycoconjugates bearing five carbohydrate groups in good yield by using stoichiometric amounts of reactants, without recourse to hydroxy group protection. The sulfide-connection methodology is also useful for synthesis of simpler amphiphilic fullerene molecules, such as one bearing five carboxylic acid groups.

Respiratory chain inhibition by fullerene derivatives: hydrogen peroxide production caused by fullerene derivatives and a respiratory chain system

Fullerene is a new type of carbon allotrope. We have shown that the fullerene derivative C(60)-bis(N,N-dimethylpyrrolidinium iodide), a regio isomer mixture, inhibited Escherichia coli growth and dioxygen uptake caused by E. coli and glucose. This result indicates that the mechanism of the bacteriostatic effect is the inhibition of energy metabolism. In this study, we isolated two regio isomers of C(60)-bis(N,N-dimethylpyrrolidinium iodide) and studied their effect on E. coli growth and on respiratory chain activity. In dioxygen uptake caused by the inner-membrane and NADH, the effect of fullerene derivatives was biphasic. At low concentrations of both fullerene derivatives, dioxygen uptake was inhibited, whereas at high concentrations, it was increased. At high concentrations, consumed dioxygen was converted to H(2)O(2). An electrochemical study revealed that reduced fullerene derivatives react with dioxygen. This activity was closely related to a redox property of the isomers.

Spherical bilayer vesicles of fullerene-based surfactants in water: a laser light scattering study

The low solubility of fullerenes in aqueous solution limits their applications in biology. By appropriate substitution, the fullerenes can be transformed into stabilized anions that are water soluble and can form large aggregated structures. A laser light scattering study of the association behavior of the potassium salt of pentaphenyl fullerene (Ph5C60K) in water revealed that the hydrocarbon anions Ph5C60- associate into bilayers, forming stable spherical vesicles with an average hydrodynamic radius and a radius of gyration of about 17 nanometers at a very low critical aggregation concentration of less than 10(-7) moles per liter. The average aggregation number of associated particles in these large spherical vesicles is about 1.2 x 10(4).