Nanomaterials are engineered structures with at least one dimension of 100 nanometers or less. These materials are increasingly being used for commercial purposes such as fillers, opacifiers, catalysts, semiconductors, cosmetics, microelectronics, and drug carriers. Materials in this size range may approach the length scale at which some specific physical or chemical interactions with their environment can occur. As a result, their properties differ substantially from those bulk materials of the same composition, allowing them to perform exceptional feats of conductivity, reactivity, and optical sensitivity. Possible undesirable results of these capabilities are harmful interactions with biological systems and the environment, with the potential to generate toxicity. The establishment of principles and test procedures to ensure safe manufacture and use of nanomaterials in the marketplace is urgently required and achievable.

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Toxic Potential of Materials at the Nanolevel

Sasidharan Swarnalatha Lucky,†,§ Khee Chee Soo,‡ and Yong Zhang*,†,§,∥ †NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Singapore, Singapore 117456 ‡Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Singapore 169610 Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore 117576 College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, P. R. China 321004

Nanoparticles in photodynamic therapy.

With the increased presence of nanomaterials in commercial products, a growing public debate is emerging on whether the environmental and social costs of nanotechnology outweigh its many benefits. To date, few studies have investigated the toxicological and environmental effects of direct and indirect exposure to nanomaterials and no clear guidelines exist to quantify these effects.

The potential environmental impact of engineered nanomaterials

Functional Nanomaterials for Phototherapies of Cancer

4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

Cyclosulfated fullerene derivatives were hydrolyzed in the presence of water or in aqueous NaOH solution giving polyhydroxylated fullerenes. Both sulfated precursors and hydroxylated products were characterized. 7 figs.

Efficient synthesis of polyhydroxylated fullerene derivatives via hydrolysis of polycyclosulfated precursors

We have demonstrated the high reactivity of fullerene molecules toward the electrophilic attack of the nitronium ion in the presence of nucleophilic reagents, such as aromatic carboxylic acids, under mild reaction conditions. The observed nucleophilicity of fullerenes in terms of their vulnerability to electrophilic additions in solution compensates for difficulties that have been encountered in achieving the electronic oxidation of C 60 molecules for further functionalization.

Versatile nitronium chemistry for C60 fullerene functionalization

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Photodynamic therapy with fullerenes in vivo: reality or a dream?

We have characterized and elucidated the chemical structure of fullerols, prepared from the aqueous acid reaction of C[sub 60] in the presence of sulfuric acid and nitric acid, consisting of hemiketal moieties in addition to tertiary hydroxy groups. In the aqueous reaction, a high yield of fullerols was obtained utilizing potassium nitrate as an effective precursor for generating nitric acid in situ. Evidence for the hemiketal structure is given by an observation of chemical shifts of vinyl ether carbons and ketal carbons centered at [sigma] 170.3 and 100.0, respectively, in the [sup 13]C NMR spectrum of fullerols. This structure was also substantiated by several spectroscopic methods including XPS, TGA-MS, and TGA-FTIR. Interestingly, the reversible interconversion reaction of hemiketal moieties in fullerol to the corresponding ketone upon variation of pH in aqueous solution provided conclusive results to verify the presence of hemiketal functions. This is the first observation of hemiketal functions incorporated onto the fullerene cage structure. 8 refs., 4 figs.

Evidence of hemiketals incorporated in the structure of fullerols derived from aqueous acid chemistry

Water-soluble polyhydroxylated fullerene derivatives (fullerenols) show excellent efficiency in eliminating superoxide radicals (O2–˙), generated by xanthine and xanthine oxidase, thus revealing the potential use of these compounds as novel potent free radical scavengers in biological systems.

Long Y. Chiang

Papers

Efficient synthesis of polyhydroxylated fullerene derivatives via hydrolysis of polycyclosulfated precursors

Versatile nitronium chemistry for C60 fullerene functionalization

Photodynamic therapy with fullerenes in vivo: reality or a dream?

Evidence of hemiketals incorporated in the structure of fullerols derived from aqueous acid chemistry

Free radical scavenging activity of water-soluble fullerenols