• Polymer Science and Technology
• /
• v.23 no.2
• /
• pp.185-193
• /
• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.587-588
• /
• 2011

• Journal of Pharmaceutical Investigation
• /
• v.40 no.4
• /
• pp.231-236
• /
• 2010

This study was to fabricate the porous poly(lactide-co-glycolide) (PLGA) microparticles with anthocyanin (as a model antioxidant) for pulmonary drug delivery. The highly porous PLGA microparticles were prepared by the waterin-oil-in-water ($W_1/O/W_2$) multi-emulsion method, followed by the decomposition of ammonium bicarbonate (AB) in $W_1$ phase to the base of ammonia, carbon dioxide and water vapor at $50^{\circ}C$, making a porous structure in PLGA microparticles. Herein, hyaluronate (HA), a viscous polysaccharide, was incorporated in the porous microparticles for sustained anthocyanin release. In in vitro release studies, the anthocyanin release from the porous microparticles with HA continued up to 24 hours, while the porous microparticles without HA released 80 wt.% of encapsulated anthocyanin within 2 hours. In addition, these microparticle are expected to be effectively deposited at a lung epithelium due to its high porosity (low density) and avoid alveolar macrophage's uptake in the lung due to its large particle size. We believe that this system has a great pharmaceutical potential as a long acting antioxidant for relieving the oxidative stress in chronic obstructive pulmonary disease (COPD).

• Analytical Science and Technology
• /
• v.29 no.5
• /
• pp.225-233
• /
• 2016

The chemical engrafting of polymers on particle surface, plays an important role on selective partitioning of micro/nano-particles in the separated layers of liquid media, such as aqueous two phase systems (ATPSs). Three polymers, dextran, poly (ethylene glycol) and albumin were chosen and chemically conjugated to the polystyrene (PS) magnetic microparticle surface. The attachment of long-chained polymer chains which may switch the partition behavior, can be simply performed by S_N2 substitution of various polymers having primary amine functional groups, with p-toluenesulfonyl (tosyl)-activated polystyrene magnetic micro-particles. The surface modification of microparticle was probed by infrared microscopy. The distinctive peak represents N-H stretching vibration mode for microparticles after the reaction and it is common for all three polymers examined. The locations of main peaks are similar for all micro-particles but different and distinguishable in fingerprint region.

• Macromolecular Research
• /
• v.14 no.5
• /
• pp.573-578
• /
• 2006

Three different, polymer-platinum conjugates (hydrogels, microparticles, and nanoparticles) were synthesized by complexation of cis-dichlorodiammineplatinum(II) (cisplatin) with partially succinylated glycol chitbsan (PSGC). Succinic anhydride was used as a linker to introduce cisplatin to glycol chitosan (GC). Succinylation of GC was investigated systematically as a function of the molar ratio of succinic anhydride to glucosamine, the methanol content in the reaction media, and the reaction temperature. By controlling the reaction conditions, water-soluble, partially water-soluble, and hydrogel-forming PSGCs were synthesized, and then conjugated with cisplatin. The complexation of cisplatin with water-soluble PSGC via a ligand exchange reaction of platinum from chloride to the carboxylates induced the formation of nano-sized aggregates in aqueous media. The hydrodynamic diameters of PSGC/cisplatin complex nano-aggregates, as determined by light scattering, were 180-300 nm and the critical aggregation concentrations (CACs), as determined by a fluorescence technique using pyrene as a probe, were $20-30{\mu}g/mL$. The conjugation of cisplatin with partially water-soluble PSGC, i.e., borderline between water-soluble and water-insoluble PSGC, produced micro-sized particles $<500{\mu}m$. Cisplatin-complexed PSGC hydrogels were prepared from water-insoluble PSGCs. All of the cisplatin-incorporated, polymer matrices released platinum in a sustained manner without any significant initial burst, suggesting that they may all be useful as slow release systems for cisplatin. The release rate of platinum increased with the morphology changes from hydrogel through microparticle to nanoparticle systems.

• Korean Chemical Engineering Research
• /
• v.57 no.1
• /
• pp.58-64
• /
• 2019

This study presents a novel method for preparing monodisperse polyethylene glycol diacrylate (PEGDA) microparticles in a dispensing needle based microfluidic device. The microfluidic devices are manufactured by manually assembling various off-the-shelf products without using additional equipment. In this microfluidic device, the volumetric flow rates of the dispersed phase of PEGDA solution and the continuous phase of oil are controlled to generate monodisperse PEGDA droplets. The PEGDA droplet contains photo-initiator thus it is crosslinked to microparticle by photopolymerization at the ends of the device. The particle size is easily controlled by adjusting the volume flow rate and the size of the microfluidic device. The monodispersity of the particles is calculated by a coefficient of variation of 2.57%. To demonstrate the biological applications of PEGDA particles, cells are encapsulated and observed for proliferation and viability.

• Clean Technology
• /
• v.15 no.4
• /
• pp.233-238
• /
• 2009

Supercritical fluid processes have gained great attention as a new and environmentally-benign method of preparing the microparticles of energetic materials like explosives and propellants. In this work, RDX (cyclotrimethylenetrinitramine) was selected as a target explosive. The microparticle formation of RDX using supercritical anti-solvent (SAS) recrystallization process was performed and the effect of operating variables on the size and morphology of prepared particles was observed. N,N-Dimethylformamide was used as organic solvent for dissolving the RDX. The size of the RDX particles decreased remarkably up to less than $10\;{\mu}m$ by SAS recrystallization. In the range of operating conditions of the SAS process studied in this work, the finest RDX particles were obtained at 313.15K, 150 bar, and 15wt% RDX concentration in feed solution.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.4
• /
• pp.212-230
• /
• 2001

Recent advances in recombinant DNA technology have resulted in development of many new protein drugs. Due to the unique properties of protein druges, they have to be delivered by parenteral injection Although delivery of protein drugs by other routes, such as pulmonary and nasal routes, has shown some promises, to date most protein drugs are administered by par-enteral routs. For long-term delivery of protein drugs by parenteral administration, they have been formulated into biodegradable microspheres. A number of microencapsulation methods have been developed, and the currently used microencapsulation methods are reviewed here, The microen-capsulation methods have been divided based on the method used. They are: solvent evapora-tion/extraction; phase separation (coacervation);spray drying; ionotropic gelation/polyelectrolyte complexation; interfacial polyumerization and supercritical fluid precipitation. Each method is de-scribed fro its applications, advantages, and limitations.

• Journal of Pharmaceutical Investigation
• /
• v.18 no.2
• /
• pp.55-59
• /
• 1988

The size of furosemide was reduced by the recrystallization method in order to increase the dissolution rate of the drug. Surfactants or hydrophilic polymers were used to suppress the aggregation in the crystal formation-growth process of microparticles by dispersing action. Dissolution rate of microparticles increased remarkably due to the size reduction of microparticle. The particle size decreased with increasing the concentration of the drug and the dispersing agents, i.e., surfactants or hydrophilic polymers. No polymorphic transition occurred during the microcrystallization process, but the habit of crystal formation was altered in the case of anionic surfactant.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2003.06a
• /
• pp.87-105
• /
• 2003

A new polymer technology commercialized with the name of Core Shell has been developed by Ondeo Nalco Company. Laboratory evaluations have demonstrated that Core Shell polymers produce a floc with high shear resistance, making them the flocculants of choice for modern high-speed paper machines. Core Shell polymers provide significant papermaking benefits, when used as single component or in combination with microparticles. At this time, the new program has been successfully applied on more than 60 paper and board machines across the world. Implementation of Core Shell polymers with or without a microparticle provided better and more stable retention values and improvements in paper quality, system cleanliness and machine runnability.