Aqueous Au nanoparticles (NPs) are employed as the building blocks to construct chainlike self-assembly architectures, which greatly enhance the photothermal performance at 808 nm. Biocompatible polypyrrole (PPy) is further adopted as the package material to coat Au NP chains, producing stable photothermal agents. As a result of contributions from chainlike Au, the PPy shell, as well as the Au–PPy composite structures, the capability of photothermal transduction at 808 nm is greatly enhanced, represented by the high photothermal transduction efficiency up to 70%. Primary animal experiment proves that the current composite photothermal agents are efficient in inhibiting tumor growth under an 808 nm irradiation, showing the potentials for in vivo photothermal therapy.Keywords: nanocomposite; nanoparticle; photothermal effect; polypyrrole; self-assembly;

Carbon nanohorn/chitosan/QDs nanocomposite was prepared by covalent linkageThe nanocomposite was successfully used in the labeling of HeLa cellsThe nanocomposite was used for in vivo imaging with C. elegans as animal mode.Due to the unique optical and chemical features of quantum dots and the special structural advantages of carbon nanohorns, it is highly desirable to synthesize nanohorns/quantum dots nanocompsite which can be applied in cell labeling and in vivo imaging. Here, we report a new method which uses chitosan as connector to synthesize nanohorns/chitosan/quantum dots fluorescent nanocomposite. Further more, the synthesized nanocomposite demonstrated strong red fluorescence and had been successfully used in Hela cells labeling and in vivo imaging of Caenorhabditis elegans (C. elegans).

Photothermal therapy using inorganic nanoparticles (NPs) is a promising technique for the selective treatment of tumor cells because of their capability to convert the absorbed radiation into heat energy. Although anisotropic gold (Au) NPs present an excellent photothermal effect, the poor structural stability during storage and/or upon laser irradiation still limits their practical application as efficient photothermal agents. With the aim of improving the stability, in this work we adopted biocompatible polypyrrole (PPy) as the shell material for coating urchinlike Au NPs. The experimental results indicate that a several nanometer PPy shell is enough to maintain the structural stability of NPs. In comparison to the bare NPs, PPy-coated NPs exhibit improved structural stability toward storage, heat, pH, and laser irradiation. In addition, the thin shell of PPy also enhances the photothermal transduction efficiency (η) of PPy-coated Au NPs, resulting from the absorption of PPy in the red and near-infrared (NIR) regions. For example, the PPy-coated Au NPs with an Au core diameter of 120 nm and a PPy shell of 6.0 nm exhibit an η of 24.0% at 808 nm, which is much higher than that of bare Au NPs (η = 11.0%). As a primary attempt at photothermal therapy, the PPy-coated Au NPs with a 6.0 nm PPy shell exhibit an 80% death rate of Hela cells under 808 nm NIR laser irradiation.

Up-conversion nanoparticles (UCNPs) have exhibited great potential in biological imaging and labeling. The further development of the correlated techniques strongly depends on the stability of UCNPs in buffers and biological growth media. In this paper, Pluronic F127, a nonionic triblock copolymer of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO), is applied to coat the originally hydrophobic NaYF4:Yb,Er(Tm) UCNPs, leading to an oil-to-water phase transfer. After the phase transfer, F127-coated UCNPs are well dispersed in water with more than 43% UC luminescence preserved. Because of the nonionic nature of F127, the F127-coated UCNPs are quite stable in culture media, and exhibit excellent biocompatibility and low toxicity. The biocompatible decoration using F127 is facile and repeatable, thus facilitating the biological applications of UCNPs. As an example, the bioimaging of caenorhabditis elegans is demonstrated.

Prefibrillar amyloid aggregates of proteins are known as cytotoxic species and a common pathogenic factor for many degenerative diseases. The mechanism underlying the formation and cytotoxicity of prefibrillar aggregates is believed to be independent of the actual nature of the amyloid protein. In this study, we monitored the formation of the peptide oligomers and examined the disruptive effects of the oligomers on liposomes using the human islet amyloid polypeptide fragment hIAPP18–27 as a model peptide. We observed various morphologies of oligomers formed at different aggregation stages that precede the formation of mature amyloid fibrils. These oligomer species were sufficiently stable to maintain their structures and properties under acidic conditions. We presented the first evidence that an oligomer species with a lamellar crystalline structure and a size of about 20–60 nm in length, 8 nm in width and 1.5 nm in thickness was the most disruptive to the membrane containing the anionic component and toxic to the INS-1 cells. Our results showed that short peptides, in light of their slower fibrillation, could be used as a model system in the study of the toxic mechanism of misfolding oligomers of amyloid peptides.