• Journal of Pharmaceutical Investigation
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• 제20권3호
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• pp.121-127
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• 1990

Mefenamic acid has been widely used clinically as an anti-inflammatory analgesic. It has poor solubility in water $(41\;{\mu}g/ml)$ and there is the difficulty of dissolution in the mefenamic acid capsules. A study was made to investigate the effect of various surfactants on the dissolution of mefenamic acid capsules. The surfactants used were sodium lauryl sulfate (SLS), Pluronic F-68, F-77, and F-127. Mefenamic acid capsule containing surfactant showed significantly improved dissolution characteristics. The dissolution rate was fast in the order of SLS > F-77 > F-68 > F-127 in mefenamic acid capsules containing 0.2 w/w % surfactant. SLS was selected for further study on the bioavailability in rabbits. The area under the plasma concentration-time curve $(AUC_{0-24})$ of mefenamic acid capsule containing SLS was higher than one of mefenamic acid capsule not containing surfactant.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.914-916
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• 2009

Using gelatin and acacia as wall and electronic ink as core substance, microcapsules were prepared by complex coacervation to fabricate a flexible electronic paper display. In order to obtain the microcapsules in a narrow dispersed distribution, we focus on the interfacial tension between the hydrophobic electrophoretic ink and an aqueous polyelectrolyte solution, through controlling sodium dodecyl sulphate (SDS) concentration and stirring rate. The existence of anionic surfactant of SDS not only decreases the droplet diameters, but also reduces the diameter size distribution. And, as the stirring rate is increased, the average size of microcapsule is also decreased.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1729-1734
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• 2007

The electrochemical behaviors of estrone in the presence of various surfactants were examined with great details. It is found that a cationic surfactant, cetyltrimethylammonium bromide (CTAB), obviously facilitates the electro-oxidation of estrone at carbon paste electrode (CPE) from the significant peak current enhancement and the negative shift of peak potential. Additionally, chronocoulometry and electrochemical impedance spectroscopy (EIS) were also used for further investigation of the electrode process of estrone, indicating that low concentration of CTAB exhibits excellent enhancement effects on the electrochemical oxidation of estrone, greatly enhances the diffusion coefficient and the electron transfer rate. Based on this, an electrochemical method was proposed for the determination of estrone. The oxidation peak current is proportional to the concentration of estrone in the ranges over 9.0 × 10?8 - 8.0 × 10?6 mol/L, and a low detection limit of 4.0 × 10?8 mol/L was obtained for 180s accumulation at open circuit (S/N = 3). Finally, this proposed method was demonstrated using estrone tablets with good satisfaction.

• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.125-135
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• 1996

Solid lipid nanoparticles(SLN) are particulate systems for parenteral drug administration and suitable for controlled release. SLN were prepared by homogenization process. Dispersion at increased temperature (molten lipid) was performed to yield SLN loaded with lipophilic drugs. Tetracaine base, lidocaine base, prednisolone, methyltestosterone and ethinylestradiol were used as model drugs to access the loading capacity and to study the release behavior. To investigate production parameters(lipids, surfactant concentration, homogenizing rpm) in the formation of SLN, particle size was performed by laser diffraction analysis. The mean particle size of SLN with stearic acid or trilaurin was below 1 micron. By decreasing the particle size and increasing the surfactant concentration, the release rate was increased especially in the case of highly lipophilic drug loaded SLN. Methyltestosterone or ethinylestradiol loaded SLN showed a distinctly prolonged release over a few days.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.543-546
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• 2007

Herein, a new electrochemical method was described for the determination of ciprofloxacin based on the enhancement effect of an anionic surfactant: sodium dodecyl benzene sulfonate (SDBS). In pH 4.0 phosphate buffer and in the presence of 1.0 × 10-4 mol/L SDBS, ciprofloxacin yields a well-defined and sensitive oxidation peak at the carbon paste electrode (CPE). Compared with that in the absence of SDBS, the oxidation peak current of ciprofloxacin remarkably increases in the presence of SDBS. The experimental parameters, such as supporting electrolyte, concentration of SDBS, and accumulation time, were optimized for ciprofloxacin determination. The oxidation peak current is proportional to the concentration of ciprofloxacin over the range from 8.0 × 10-8 to 5.0 × 10-6 mol L-1. The detection limit is 2.0 × 10-8 mol L-1 after 2 min of accumulation. This new voltammetric method was successfully used to detect ciprofloxacin in drugs.

• KSBB Journal
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• 제13권2호
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• pp.133-140
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• 1998

Using rlFN-$\alpha$ and rhGH as the model proteins, the refolding performances of the published processes were evaluated and compared. Key engineering parameters such as the type of denaturant and this concentration, protein concentration in the refolding buffer, and pH and ionic strength of the buffer were experimentally investigated. Furthermore, the role of a co-solvent of surfactant type in aggregation reduction was also studied. Of the denaturants tested (8M urea, 6M guanidine HCI, 0.5% SDS), SDS at alkaline pH (9.5) and ambient temperature gave the highest recovery yield. The SDS process was effective in the refolding of observed where dissolution proceeded better under lower strength (10 mM) but aggregation was suppressed under higher strength (>50 mM.) When PEG-4000 and/or Tween were added as co-solvent or refolding-enhancing additive, 1.6-2 times higher yield was realized. The‘masking’of the hyrophobic patches located on the surface of the protein with the surfactant molecules was believed to be responsible for the considerable reduction in aggregation during refolding.

• Journal of Pharmaceutical Investigation
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• 제21권4호
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• pp.253-262
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• 1991

Microencapsulation of sodium ascorbate with cellulose acetate phthalate(CAP) by coacervation/ phase separation method were carried out. Various factors affecting microencapsulation, i.e., surfactant concentration. CAP concentration, stirring speed and treatment of spermaceti as a sealing agent were studied. Dissolution rate. particle size distribution, surface feature and stability test were investigated. CAP microcapsules prepared using 0.5% span 80 as a surfactant showed smooth and round surfaces. The release of sodium ascorbate was retarded by microencapsulation with CAP and by sealant treatment with spermaceti. When triturated with sodium bicarbonate, CAP microcapsules were more stable than unencapsulated sodium ascorbate under various RH conditions at $37^{\circ}C$.

• 접착 및 계면
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• 제4권1호
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• pp.35-42
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• 2003

Polystyrene nanocapsules containing octadecane as a core material were prepared by miniemulsion polymerization. The morphology and size of the nanocapsules were measured with varying the surfactant concentration, content of initiator, core/shell ratio and content of comonomer. The morphologies of the prepared nanoparticles were examined by a scanning electron microscope, a transmission electron microscope and the core material was confirmed by a differential scanning calorimeter. The particles below 70 nm in diameter were formed at a high surfactant concentration. The size of the nanoparticles was not significantly affected by the initiator content. With increasing the core/shell ratio and polar comonomer content, the particle size and its distribution were increased.

• Bulletin of the Korean Chemical Society
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• 제20권3호
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• pp.352-354
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• 1999

The spectrophotometric determination of Cu(Ⅱ) with α-(2-benzimidazolyl)-α',α"-(N-5-nitro-2-pyridylhydrazone)-toluene has been investigated. The optimum conditions of pH, stability, concentration of ligand and surfactant were evaluated. This method is a simple and sensitive method for determination of Cu(Ⅱ) and offers a selective separation of Cu(Ⅱ) from sample solution containin- I ppm below amount of Ni(Ⅱ), Co(Ⅱ), Zn(Ⅱ) and Sn(Ⅱ). Copper was determined by measuring the absorbance of Cu(Ⅱ)-BINPHT complex extracted with benzene in Brij 58 surfactant at 410 nm. Beer's law is obeyed over the concentration range 0∼2.5 μgmL-1 and the detection limit (S/N=2) is 0.06 μgmL-1. The relative standard deviation at the 0.3 μgmL-1 is 2.4% (N=7). The method was applied for the determination of Cu(Ⅱ) in various milks.

• 대한화학회지
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• 제55권3호
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• pp.335-340
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• 2011

양이온성 수용성 5, 10, 15, 20-tetrakis(N-methylpyridinium-4-yl) porphyrin (TMPyP)의 존재 하에서 음이온 계면 활성제인 sodium n-dodecyl sulfate 의 용액 특성을 전도도법, UV-vis 및 공명 빛 산란 (RLS) 분광학적 방법을 이용하여 포괄적으로 연구하였다. 그 결과에 따르면 TMPyP 농도의 증가로 SDS 용액의 임계 미셀 농도는 감소하였는데, SDS 미셀의 안정화는 미셀 표면에 존재하는 음전하의 중화 때문이다. SDS용액 내에는 자유 포르피린 단량체, 미셀에 속박된 포르피린 단량체 또는 응집체, 그리고 nonmicellar porphyrin/계면 활성제 응집체와 같은 세 종류의 TMPy종이 분명히 존재하였다. 우리의 연구 결과는 SDS가 TMPyP의 응집을 유도한다는 것을 나타내었다. 실제로 두 종류의 J-aggregations이 관찰되었는데, 하나는 미셀에 속박된 포르피린 단량체 또는 응집체였으며, 다른 하나는 nonmicellar porphyrin/계면 활성제 응집체이다. 그러나, cmc이하에서는 TMPyP가 SDS 음이온과 정전기 상호작용을 나타내었다.