• Archives of Pharmacal Research
• /
• v.19 no.1
• /
• pp.30-35
• /
• 1996

Poly(l-lactic acid)(PLLA) microspheres loaded with ampicillin sodium (AMP-Na_, .betha.-lactam antibiotic, were prepared by a w/o/w multiple emulsion-solvent evaporation method. The amounts of each component in three phases (inner water phase, organic phase, and outer water phase) wre carefully examined in the preparation of PLLA microspheres. The stirring rate, another preparation parameter, was also investigated for study on the effect of mechanical stress on the drug loading and morphology of PLLA microspheres. Most of the preparation parameters had a great influence on the drug loading, surface morphology and size distribution of PLLA microspheres. PLLA microspheres with 15.89 w/w% drug loading were subjected to the in vitro release experimet. The release of ampicillin sodium was constant at a rate of 1.68 $mug/ml/day$ per 1 mg of microspheres for 18 days initial burst effect.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.1 no.2
• /
• pp.95-104
• /
• 2014

The objective of this study was to evaluate the cytotoxicity of poly (lactic acid) (PLA) nanoparticles. We used a water-soluble, amphiphilic phospholipid polymer, poly (2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB30W), as a stabilizer for the PLA nanoparticles. The PLA nanoparticles and PMB30W-modified PLA (PLA/PMB30W) nanoparticles were prepared by evaporating tetrahydrofuran (THF) from its aqueous solution. Precipitation of the polymers from the aqueous solution produced PLA and PLA/PMB30W nanoparticles with a size distribution of $0.4-0.5{\mu}m$. The partial coverage of PMB30W on the surface of the PLA/PMB30W nanoparticles was confirmed by X-ray photoelectron spectroscopy (XPS) and dynamic light-scattering (DLS). A high-content automated screening assay (240 random fields per group) revealed that the PLA nanoparticles induced apoptosis in a mouse macrophage-like cell line (apoptotic population: 73.9% in 0.8 mg PLA/mL), while the PLA/PMB30W nanoparticles remained relatively non-hazardous in vitro (apoptotic population: 13.8% in 0.8 mg PLA/mL). The reduction of the apoptotic population was attributed to the phosphorylcholine groups in the PMB30W bound to the surface of the nanoparticle. In conclusion, precipitation of PLA in THF aqueous solution enabled the preparation of PLA nanoparticles with similar shapes and size distribution but different surface characteristics. PMB30W was an effective stabilizer and surface modifier, which reduced the cytotoxicity of PLA nanoparticles by enabling their avoidance of the mononuclear phagocyte system.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.2
• /
• pp.158-165
• /
• 2010

Purpose: The objective of the present study was to histologically evaluate durability and bone regeneration capacity of new synthetic membranes in comparison to clinically available collagen membrane. Material and methods: To the skulls of 12 rabbits, we created 4 bone defects of 6 mm in diameter on each of them. Each of defects were covered with at least one of 5 membranes; No membrane, Collagen ($Ossix^{TM}$), PLGA, HA-coated-PLGA and HA-PLGA/PLGA. After 4, 8, 12 weeks, we cut the skulls and dyed with H-E. And then, the histologic observation was done. Results: In current study, the control group which did not use the membrane showed bone regeneration at 12 weeks and covered the bone defect partially. New bones were formed through the underneath of endocranium, and the upper defect was filled with connective tissues and fats. Collagen membrane ($Ossix^{TM}$) showed new bones after 4 weeks, and they were formed through the membrane which maintained until 12 weeks. PLGA, HA-coated-PLGA, HA-PLGA/PLGA showed bone regeneration after 4 weeks and after 8 weeks, they mostly filled defects. At 12 weeks, we could find new bones and previous bones almost look alike and also, they united well. Membranes were unnoticeable after 4 weeks and were absorbed. Conclusion: Bone formation and maturation of PLGA, HA-coated-PLGA and HA-PLGA/PLGA were faster than the control group. They showed no difference on the application of HA and after 4 weeks, they were absorbed.

• Journal of Life Science
• /
• v.31 no.9
• /
• pp.849-855
• /
• 2021

Recently, as nanotechnology has been introduced and used in various fields, the development of new drugs has been accelerating. Nanoparticles have maintained blood drug concentration for extended periods of time with a single administration of the drug. The drug can then be selectively released only at the pathological site, thereby reducing side effects to other non-pathological sites. In addition, nanoparticles can be modified for selective target sites delivery for other specific diseases, with polymers being widely used in the manufacture of these nanoparticles. Poly (D,L-lactic-co-glycolic acid ) (PLGA) is one of the most extensively developed biodegradable polymers. PLGA is widely used in drug delivery for a variety of applications. It has also been approved by the FDA as a drug delivery system and is widely applied in controlled release formulations, such as in gene therapy treatments. PLGA nanoparticles have been developed as delivery systems with high efficiency to specific cell types by using passive and active targeting methods. After the development of a drug delivery system using PLGA nanoparticles, the drug is selectively delivered to the target site, and the effective blood concentration for extended periods of time is optimized according to the disease. In this review paper, we focus on ways to improve cell-specific treatment outcomes by examining the development of astrocyte selective nanoparticles based on PLGA nanomaterials for gene therapy.

• Archives of Plastic Surgery
• /
• v.44 no.3
• /
• pp.248-249
• /
• 2017

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.10a
• /
• pp.48-49
• /
• 2009

• Food Science and Preservation
• /
• v.31 no.1
• /
• pp.138-148
• /
• 2024

The production of poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA) was optimized by serial fermentation of Dendropanax morbiferus extract (DME) using Bacillus subtilis HA and Lactobacillus plantarum KS2020. The 1st alkaline fermentation was performed on 60% DME including 2% glucose and 10% monosodium ʟ-glutamate (MSG) as a precursor. The 1^st fermented DME had 57 mg% tyrosine. Consequently, the 2^nd lactic acid fermentation for 5 days increased the tyrosine content of 106 mg%. The mucilage containing γ-PGA showed a high content of 3.50% on the first day of alkaline fermentation and then increased to 4.10% after 2 days. The precursor (MSG) remaining in the 1^st fermented DME was efficiently converted to GABA by the 2^nd lactic acid fermentation in the presence of 5% skim milk, 1.5% glucose and 0.5% yeast extract, resulting in the production of 18.29 mg/mL GABA. The viable cells of lactic acid bacteria increased and indicated 9.49 log CFU/mL on the fermentation for 5 days, and the acidity of co-fermented DME indicated the highest value of 1.55%. Conclusively, the serial fermented DME has multi-functional ingredients containing γ-PGA, GABA, peptides and probiotics.

• Bulletin of the Korean Chemical Society
• /
• v.1 no.3
• /
• pp.78-82
• /
• 1980

Solutions of $Cd^{2+}$, $Co^{2+}$ and $Ni^{2+}$ were mixed with the solutions of hydroxycarboxylic acids such as salicylic, lactic and mandelic acids in the presence of cation exchange resin at room temperature. The distribution ratios of the metal ions between resin and solution were measured, using radioactive metal ions as tracer. From the observed variation of the distribution ratios with the acid anion concentrations, it was concluded that $Cd^{2+}$, $Co^{2+}$ and $Ni^{2+}$ formed the one-to-one complexes with salicylate, lactate and mandelate ions in aqueous, 20 % ethanol-water and 20 % acetone-water solutions. The results of the present study indicated that the relative stabilities of the metal-acid complexes in solution increased in the order: $Cd^{2+}$ <$Co^{2+}$ <$Ni^{2+}$ complexes. Salicylate

• Polymer(Korea)
• /
• v.29 no.2
• /
• pp.198-203
• /
• 2005

Melt extrusion foaming process for the preparation of poly(L-lactic acid) (PLLA) scaffolds was carried out and the effects of foaming conditions on the pore structure of PLLA scaffolds and their mechanical properties were investigated. The porosity and mechanical properties of fabricated scaffolds were compared with the scaffolds obtained from the salt leaching method as well. It was found that the optimum pore structure was achieved when the PLLA melt was kept in extruder for the maximum decomposition time of blowing agent. In order to maintain the proper scaffolds structure, the blowing agent content should be less than $10\;wt\%$. It can be concluded that melt extrusion foaming process allows for the production of scaffold having higher mechanical properties with reasonable pore size and open cell structure for hard tissue regeneration even though it has less porosity than scaffolds made by salt leaching process.

• Polymer(Korea)
• /
• v.29 no.4
• /
• pp.375-379
• /
• 2005

The morphology and therma]/viscoelastic characteristics were investigated for PLLA/MMT nanocomposite manufactured by incorporating inorganic nanosized silicate nanoplatelets into biodeuadable poly(l-lactic acid) (PLLA). The XRD difiactogram and TEM image may be regarded as a formation of homogeneously dispersed nanocomposites. The melting energy(${\Delta}H_m$) was increased during hydrolysis process because of increase of crystallinity. As MMT played a role of reinforcing agent, the storage modulus was increase in case of PLLA/MMT nanocomposite, it was well coincided with our previous results. From SEM image, many tiny pinholes formed by spinodal decomposition were observed on the surface, and the shape of nanocomposite was maintained during hydrolysis process. In this study, it was shown that the control of biodegradation rate, thermal/mechnical property was possibile by incorporating MMT.