Journal of the Society of Powder Technology, Japan

Preparation of Powders with Supercritical Fluids

Application to Macromolecular Drugs for Inhalation Therapy

Hirokazu Okamoto

2006 Volume 43 Issue 6 Pages 426-433
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.426

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Supercritical fluid is a useful medium to prepara dry tiny powders with advanced function. The powders prepared with supercritical fluid usually have a large surface area and a reduced crystallinity. This feature tends to increase the drug solubility, which is preferable especially to insoluble drugs for increasing their bioavailability. Supercritical fluid precipitation is also applicable to high molecular weight drugs. By selecting the running condition and/or additives, denaturation of proteins can be minimized. Sterilization of microorganisms and inactivation of viruses can be attained concomitantly with powder preparation in supercritical fluids.

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Particulate Design of Dry Powder Inhalation by a Novel Supercritical Freeze Granulation

Yuuki Arieda, Tomohiro Iwasaki, Satoru Watano, Daisuke Iwamoto, Kenji ...

2006 Volume 43 Issue 6 Pages 434-439
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.434

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In the particulate design for dry powder inhalation (DPI), the drug particles are required to have a good flowability in handling and dispersibility in delivering the drug to the lung in order to effectively treat pulmonary and systemic diseases. In this study, the preparation process of drug particles for DPI using a novel supercritical carbon dioxide freeze granulation based on the rapid expansion of supercritical solutions (RESS process) has been developed. When a drug dissolved into supercritical carbon dioxide is sprayed through a nozzle, frozen carbon dioxide lumps are generated due to the rapid temperature drop (i. e., Joule-Thomson effect), resulting in the granulation of fine drug particles. The granules prepared under the conditions of lower temperatures and higher pressures of supercritical carbon dioxide, in which more frozen carbon dioxide lumps are generated, have a good flowability and dispersibility because of the increased granule size and the decreased bulk density.

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Preparation of Inorganic Gd(OH)₃ Nanoparticles for Gd Neutron Capture Therapy by Using Supercritical Hydrothermal Synthesis

Takafumi Sasaki, Satoshi Ohara, Mitsuo Umetsu, Takashi Naka, Tadafumi ...

2006 Volume 43 Issue 6 Pages 440-444
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.440

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Fine Gadolinium hydroxide (Gd(OH)₃) nanoparticles with a high crystallinity for neutron capture therapy were prepared via supercritical hydrothermal synthesis. An amorphous Gd(OH)₃ suspension was pressurized to 30MPa at room temperature and rapidly heated to the reaction temperature by mixing it with supercritical water. When the reaction temperature was raised from 300 to 500°C, the particle size of Gd(OH)₃ nanoparticles with a narrow particle size distribution was decreased. In addition, the particles synthesized in the medium containing succinic acid were reduced by the capping effect, and the particle size was as small as 30nm. The tissue distribution of these Gd(OH)₃ nanoparticles was investigated by using tumor-bearing hamsters.

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Nano-Coating by Using Rapid Expansion of Supercritical Fluid Suspensions

Masahiro Ikeda, Naoya Shiki, Wei Chen, Atsushi Tsutsumi

2006 Volume 43 Issue 6 Pages 445-449
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.445

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As a method of nano-particle coating, the rapid expansion of supercritical fluid suspensions has been proposed. By using this method, stable and uniform coating of nano-particles could be achieved without agglomeration. In the present work, the effect of core particle size on the coated particles was investigated. Nano titanium dioxide particles with average particle sizes of 5, 20, 70 and 250nm were used as the core particles and paraffin as a coating material with super critical carbon dioxide as a solvent. Scanning electron microscopy and transmission electron microscopy were employed to characterize the coated nano-particles. Experimental results showed that particles with a diameter larger than 70nm were successfully coated and the coating layer was about 10nm thick. The proposed nano-coating technology has great potential for nano-particle processing.

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Microstructural Control of Wrought Magnesium Alloys with High Strength and Ductility via Powder Metallurgy Process

Katsuyoshi Kondoh

2006 Volume 43 Issue 6 Pages 450-456
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.450

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Roll compaction (RCP) process has been developed in order to produce wrought magnesium alloys with a good balance of strength and ductility via powder metallurgy. Extruded Mg alloys showed fine microstructures; a mean grain size with 1-2μm by dynamic recrystallization during RCP and hot extrusion. In applying RCP to the conventional AZ31 alloy powder, their wrought materials had superior mechanical properties of 390MPa tensile strength, 360MPa yield strength and 16% elongation at room temperature compared to the conventional ones. Its low temperature formability was also completely improved due to both refined grains and texture control by RCP process.

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DNA-based Metallic Nanostructures

Satoshi Ohara

2006 Volume 43 Issue 6 Pages 457-460
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.457

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This review reports a new method for the fabrication of ordered metallic nanostructures such as nanowire, nanogrids and nanoparticles based on the use of DNA templates. DNA has negative charge on phosphate groups, so that the DNA conformation can be attempted to mineralize metals e. g., palladium (Pd) on its atructure at a relatively high concentration of metals. We were successful in the formation of unique Pd nanoparticles by controlling reductive reaction. We showed the utilization of the Pd nanoparticles for the highly-sensitive hydrogen sensor.

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Doctoral Thesis Introduction

2006 Volume 43 Issue 6 Pages 461-463
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.461

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Report on Asia Nanoparticle Technology Symposium

[in Japanese]

2006 Volume 43 Issue 6 Pages 464
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.464

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Report of the Symposium on Functional Polymer Particles and Particle Assemblies in Pacifichem 2005, Hawaii

Hiroshi Fudouzi

2006 Volume 43 Issue 6 Pages 465-466
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.465

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Activity Report of SPTJ Research Division of Particulate Preparation and Design (2003-2004)

[in Japanese]

2006 Volume 43 Issue 6 Pages 468
Published: June 10, 2006
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.43.468

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