Connected Pt–Fe nanoparticle catalysts with beaded network structure show both high activity and durability for oxygen reduction.

Recent advances in nanotechnology, materials science, and biotechnology have led to innovations in the field of nanomedicine. Improvements in the diagnosis and treatment of cancer are urgently needed, and it may now be possible to achieve marked improvements in both of these areas using nanomedicine. Lipid-coated nanoparticles containing diagnostic or therapeutic agents have been developed and studied for biomedical applications and provide a nanomedicine strategy with great potential. Lipid nanoparticles have cationic headgroups on their surfaces that bind anionic nucleic acids and contain hydrophobic drugs at the lipid membrane and hydrophilic drugs inside the hollow space in the interior. Moreover, researchers can design nanoparticles to work in combination with external stimuli such as magnetic field, light, and ionizing radiation, which adds further utility in biomedical applications. In this Account, we review several examples of lipid-based nanoparticles and describe their potential for cancer treatment and diagnosis. (1) The development of a lipid-based nanoparticle that included a promoter-enhancer and transcriptional activator greatly improved gene therapy. (2) The addition of a radiosensitive promoter to lipid nanoparticles was sufficient to confer radioisotope-activated expression of the genes delivered by the nanoparticles. (3) We successfully tailored lipid nanoparticle composition to increase gene transduction in scirrhous gastric cancer cells. (4) When lipophilic photosensitizing molecules were incorporated into lipid nanoparticles, those particles showed an increased photodynamic cytotoxic effect on the target cancer. (5) Coating an Fe(3)O(4) nanocrystal with lipids proved to be an efficient strategy for magnetically guided gene-silencing in tumor tissues. (6) An Fe(16)N(2)/lipid nanocomposite displayed effective magnetism and gene delivery in cancer cells. (7) Lipid-coated magnetic hollow capsules carried aqueous anticancer drugs and delivered them in response to a magnetic field. (8) Fluorescent lipid-coated and antibody-conjugated magnetic nanoparticles detected cancer-associated antigen in a microfluidic channel. We believe that the continuing development of lipid-based nanomedicine will lead to the sensitive minimally invasive treatment of cancer. Moreover, the fusion of different scientific fields is accelerating these developments, and we expect these interdisciplinary efforts to have considerable ripple effects on various fields of research.

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Crystal growth-controlled Co 3 O 4 nanoparticles were prepared to examine gas sensing properties. A cube-like, an irregular shaped, and three kinds of raspberry-type structures were observed by morphology analysis. The raspberrytype structures have an expanded lattice volume with a large oxygen deficiency area, and the cube-like structure has a contracted lattice volume as compared to the irregular shaped structure. The raspberry-type structures exhibited a higher sensor signal response than the others. A relationship between sensor properties and crystal defect was investigated, and it was revealed that the gas selectivity to a high dipole moment value of a reducing gas molecule increased with increasing oxygen deficiency area of the Co 3 O 4 nanoparticle. It was considered that the oxygen deficiency area acted as an important reaction site, which can be attributed to the selective reaction of the Co 3 O 4 nanoparticle with gas molecules.

The present Article describes the synthesis of ferromagnetic capsules approximately 330 nm in diameter with a nanometer-thick shell to apply to magnetic carriers in a magnetically guided drug delivery system. The magnetic shell of 5 nm in thickness is a nanohybrid, composed of ordered alloy FePt nanoparticles of approximately 3-4 nm in size and a polymer layer of a cationic polyelectrolyte, poly(diaryldimethylammonium chloride) (PDDA). The magnetic capsules have an excellent capacity for carrying medical drugs and genes. Surface-modified silica particles with PDDA were used as a template for the capsules. FePt nanoparticles were deposited on the PDDA-modified silica particles through a polyol method followed by dissolving the silica particles with a NaOH solution, resulting in the formation of the magnetic capsules as the final product. A three-dimensional hollow structure is maintained by the nanohybrid shell. The FePt-nanoparticles/PDDA nanohybrid shell also exhibits a ferromagnetic feature at room temperature because the FePt nanoparticles of an ordered-alloy phase are formed with the aid of PDDA despite the small size (3-4 nm).

Highly stable and active low-temperature CO oxidation catalysts without noble metals are desirable to achieve a sustainable society. While zero-dimensional to three-dimensional Co3O4 nanoparticles show high catalytic activity, simple-structured nanocrystals easily self-aggregate and become sintered during catalytic reaction. Thus, complex three-dimensional nanostructures with high stability are of considerable interest. However, the controlled synthesis of complex nanoscale shapes remains a great challenge as no synthesis theory has been established. In this study, 100 nm raspberry-shaped nanoparticles composed of 7–8 nm Co3O4 nanoparticles were synthesized by hydrothermally treating cobalt glycolate solution with sodium sulfate. Surface single nanometer-scale structures with large surface areas of 89 m2·g−1 and abundant oxygen vacancies were produced. The sulfate ions functioned as bridging ligands to promote self-assembly and suppress particle growth. The Co3O4 nano-raspberry was highly stable under catalytic tests at 350 °C and achieved nearly 100% CO conversion at room temperature. The addition of bridging ligands is an effective method to control the formation of complex but ordered three-dimensional nanostructures that possessed extreme thermal and chemical stability and exhibited high performance.

Abstract

Nano-sized FePt capsules with two types of ultrathin shell were fabricated using a template method for use in a nano-scale drug delivery system. One capsule was composed of an inorganic-organic hybrid shell of a water-soluble polymer and FePt nanoparticles, and the other capsule was composed of a network of fused FePt nanoparticles. We demonstrated that FePt nanoparticles selectively accumulated on the polymer molecules adsorbed on the template silica particles, and investigated the morphologies of the particle accumulation by changing the concentration of the polymer solution with which the template particles were treated. Capsular size was reduced from 340 to less than 90 nm by changing the size of the silica template particles, and the shell thickness was controlled by changing the amount of FePt nanoparticles adsorbed on the template particles. The hybrid shell was maintained by the connection of FePt nanoparticles and polymer molecules, and the shell thickness was 10 nm at the maximum. The FePt network shell was fabricated by hydrothermal treatment of the FePt/polymer-modified silica composite particles. The FePt network shell was produced from only the FePt alloy, and the shell thickness was 3 nm. Water-soluble anti-cancer drugs could be loaded into the hollow space of FePt network capsules, and lipid-coated FePt network capsules loaded with anti-cancer drugs showed cellular toxicity. The nano-sized capsular structure and the ultrathin shell suggest applicability as a drug carrier in magnetically guided drug delivery systems.