• Polymer(Korea)
• /
• v.32 no.2
• /
• pp.143-149
• /
• 2008

We synthesized PEG-PLA (or PLGA) amphiphilic di-block copolymers, which consist of PEG as biocompatible and hydrophilic block and PLA (or PLGA) as biodegradable and hydrophobic block, by ring opening polymerization of LA in the presence of methoxy PEG as a macroinitiator. The compositions and the molecular weights of the copolymers were controlled by changing the feed ratio of LA (and GA) to PEG initiator. The di-block copolymers could self-assemble in aqueous media to form micellar structure. A hydrophobic model drug, pioglitazone, was loaded into the polymer micelle using solid dispersion and dialysis methods, and the drug-loaded micelles were characterized by AFM, DLS and HPLC measurements. The drug loading capacity and in vitro release studies were performed and evaluated under various conditions. These results indicated that the amphiphilic di-block copolymers of PEG-PLA (or PLGA) could solubilize pioglitazone by solid dispersion method and the drug release was modulated according to micellar chemical compositions.

• Journal of the Korean Chemical Society
• /
• v.56 no.2
• /
• pp.188-194
• /
• 2012

The interaction of 4-alkylbenzoic acid isomers with the micellar system of TTAB (tetradecyltrimethylammonium bromide) was studied by the UV/Vis spectrophotometric method. The solubilization constants ($K_s$) of 4-alkylbenzoic acid isomers into the TTAB micellar system and the critical micelle concentration (CMC) of TTAB have been measured with the change of temperature. Various thermodynamic parameters have been calculated and analyzed from those measurements. The results show that the values of ${\Delta}G^o{_s}$ for the solubilization of all the isomers are negative and the values of ${\Delta}H^o{_s}$ and ${\Delta}S^o{_s}$ are all positive within the measured temperature range. The effects of additives (n-butanol and NaCl) on the solubilization of 4-alkylbenzoic acid isomers have been also measured. There was a great change on the values of $K_s$ and CMC simultaneously with these additives. From these changes we can postulate that the solubilization sites of 4-alkylbenzoic acids are the core or deep palisade region of the TTAB micelle.

• Journal of the Korean Chemical Society
• /
• v.52 no.2
• /
• pp.111-117
• /
• 2008

critical micelle concentration (CMC) and the counter ion binding constant (B) in a mixed micellar state of the trimethyltetradecylammonium bromide (TTAB) with the polyoxyethylene (23) lauryl ether (Brij 35) at 25oC in water and in aqueous solutions of butanol isomers were determined as a function of 1 (the overall mole fraction of TTAB) by the use of electric conductivity method and surface tensiometer method. Various thermodynamic parameters (Xi, i, Ci, aiM, and Hmix) were calculated by means of the equations derived from the nonideal mixed micellar model. The results say that the effects of butanol isomers on the micellization of TTAB/Brij 35 mixtures have been in the order of n-butanol>iso-butanol>t-butanol> water.

• Journal of the Korean Chemical Society
• /
• v.51 no.2
• /
• pp.129-135
• /
• 2007

The critical micelle concentrations (CMC) and the counter ion binding constants (B) in a micellar state of the mixed surfactant systems of Tetradecyltrimethylammonium bromide (TTAB) with Polyoxyethylene(23) lauryl ether (Brij 35) in water were determined as a function of α1 (the overall mole fraction of TTAB) by the use of electric conductivity method and surface tensiometer method from 15 oC to 35 oC. Values of thermodynamic parameters (ΔGom, ΔHom, and ΔSom) for the micellization of TTAB/Brij 35 mixtures were calculated and analyzed from the temperature dependence of CMC values. The results say that the measured values of ΔGom are all negative at the whole measured condition but the values of ΔSom and ΔHom are positive or negative, depending on the measured temperature and α1.

• Journal of the Korean Chemical Society
• /
• v.41 no.1
• /
• pp.12-17
• /
• 1997

The critical micelle concentrations(CMC*) and the counterion binding constants(B) in a micellar state of the mixed surfactant systems of sodium dodecylsulfate(SDS) with sodium dodecylbenzenesulfonate(DBS) at 25℃ in pure water and in aqueous solutions of n-butanol were determined as a function of α1 (the overall mole fraction of SDS) by the use of electric conductivity method. Various thermodynamic parameters(Xi, γi, Ci, aiM, β, ΔHmix and ΔGm0 for the micellization of SDS/DBS mixtures were calculated and analyzed by means of the equations derived from the nonideal mixed micelle model. The effect of n-butanol on the mixed micellization of SDS/DBS mixtures have been measured and analyzed by comparing the values of the thermodynamic parameters in pure water with those in aqueous solutions of n-butanol(0.1 M, 0.2 M, and 0.3 M).

• Journal of the Korean Chemical Society
• /
• v.44 no.3
• /
• pp.207-211
• /
• 2000

We have studied on the determination of Ni(II) using APDC as a complexing agent in Tween80 micellar medium. The absorption spectrum of Ni(PDC)$_2$ complex in Tween80 medium was better defined and more sensitive than that in chloroform Ni(PDC)$_2$ complex was very stable at pH 7.0 and up to 100 minutes, and could be quantitatively chelated when APDC was added to over 10 times moles of Ni(II). The optimum concentration of Tween80 was 0.1%. The calibration curve of Ni(PDC)$_2$ complex with good linearity(R$^2$=0.9955) was obtained in 0.1% Tween80 medium. The detection limit and the determination limit were 0.09 ${\mu}g$/mL and 0.28 ${\mu}g$/mL, respectively. This technique was applied to the analysis of Suwon stream water samples, and about l00% of recoveries were obtained from the spiked samples. Although the formation of Ni(PDC)$_2$ complex was interfered by various metal ions, this technique could be applied to the practical determination of Ni(II).

• Journal of the Korean Chemical Society
• /
• v.44 no.3
• /
• pp.177-183
• /
• 2000

The interaction of phenoxide anion with .the mixed micelles of CTAB(Cetyl-trimethylammonium bromide) and TTAB(Tetradecyltrimethylammonium bromide) was studied by UV/Vis spectrophotometric method. The solubilization constants($K_s$) of phenoxide anion into the mixed micellar phase and the critical micellar concentrations(CMC) of those mixed surfactant systems have been measured and analyzed with the change of overall mole fraction of CTAB($\alpha_{CTAB}$) The effects of additives(n-pentanol and NaBr) on the solubilization of phenoxide anion by those mixed surfactant systems have been also measured. There was a great decrease on the values of solubilization constant and CMC with these additives. For the thermodynamic study, the dependence of $K_s$ values on temperature has been measured and various thermodynamic parameters(${\Delta}G^0_s$, ${\Delta}H^0_s$ and ${\Delta}S^0_s$) have been also calculated. The results show that all the values of ${\Delta}G^0_s$ and ${\Delta}H^0_s$ are negative within the measured temperature region but the values of ${\Delta}S^0_s$ are positive.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1994.04a
• /
• pp.169-169
• /
• 1994

항암 및 면역조절작용을 가지고 있으며 그 자체가 서방성 prodrug으로서 약효를 나타낼것으로 기대되는 ara-C와 etherphospholipid의 conjugate인 ara-CDP-DL-PCA.2Na, ara-CDP-DL-PBA.2Na, 및 ara-CDP-DL-PMA.2Na 3종의 BR-8702-2의 micellar soultion을 투여시료로 하여 제암력 평가를 실시하였다. DBA/2J 마우스(평균 체중 25g, 수컷)에 L$_{1210}$임파성 백혈병 세포를 이식한 후, 24시간 후 약물을 복강내에 투여하는 실험계 에서 400mg/kg/day, 단회투여 및 80 혹은 100mg/kg/day, 1~5일간 투여로 ILS%값이 229~543으로 우수한 제암력을 보였다. 또한 BDF$_1$ mice(15~20g)의 axillary region에 3㎣의 Lewis Lung Tumor를 피하로 이식한후 약물투여를 통한 제암효과를 관찰하였다. 100, 200, 300mg/kg/day의 단회 투여계 에서는 수명연장 효과가 없었다. 한편, 20, 40, 60mg/kg/day, 1~5일간의 투여계 에서는 ara-CDP-DL-PCA.2Na만이 효과가 있었는데 농도에 역순하여 저농도인 20mg/kg/day, 1~5일간의 투여계에서 가장 효과가 있었으며 그때의 ILS%는 32.3%였고 투여기간중의 체중변화는 거의 보이지 않았다. 한편 NICOM 370 Dynamic Light Scattering을 이용하여 투여시료로한 micellar solution의 입자도를 분석한 결과 ara-CDP-DL-PCA.2Na는 4.2nm size의 것이 99.48%를 차지하고 있었다. ara-CDP-DL-PCA.2Na의 ICR 마우스를 이용한 급성독성 시험에 있어서 경구투여에서의 LD$_{50}$값은 암,수컷 모두 5000mg/kg이상 이었고, 정맥내 투여 에서는 432mg/kg이었다. 실험과정중 생존동물의 일반적 이상소견등은 없었으나 정맥내 투여의 경우에서 체중증가 억제현상이 있었다.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.8
• /
• pp.2637-2642
• /
• 2011

A new ultrasonic-assisted micellar extraction and cloud-point pre-concentration method was developed for the determination of major saikosaponins, namely saikosaponins -A, -C and -D, in Radix Bupleuri by high performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD). The non-ionic surfactant Genapol X-080 (oligoethylene glycol monoalkyl ether) was chosen as the extraction additive and parameters affecting the extraction efficiency were optimized. The highest yield was obtained with 10% (w/v) Genapol X-080, a liquid/solid ratio of 200:1 (mL/g) and ultrasonic-assisted extraction for 40 min. In addition, the optimum cloud-point pre-concentration was reached with 10% sodium sulfate and equilibration at $60^{\circ}C$ for 30 min. Separation was achieved on an Ascentis Express C18 column (100 ${\times}$ 4.6 mm i.d., 2.7 ${\mu}M$) using a binary mobile phase composed of 0.1% acetic acid and acetonitrile. Saikosaponins were detected by ELSD, which was operated at a $50^{\circ}C$ drift tube temperature and 3.0 bar nebulizer gas ($N_2$) pressure. The water-based solvent modified with Genapol X-080 showed better extraction efficiency compared to that of the conventional solvent methanol. Recovery of saikosaponins ranged from 93.1 to 101.9%. An environmentally-friendly extraction method was successfully applied to extract and enrich major saikosaponins in Radix Bupleuri.

• Journal of Environmental Science International
• /
• v.14 no.2
• /
• pp.241-249
• /
• 2005

This study deals with micellar effects on dephosphorylation of diphenyl-4- nitrophenylphosphate (DPNPPH), diphenyl-4-nitrophenylphosphinate (DPNPlN) and isopropylphenyl-4-nitrophenyl phosphinate (IPNPlN) mediated by $OH^\Theta$ or o-iodosobenzoate ion $(IB^\Theta)$ in aqueous and CTAX solutions. Dephosphorylation of DPNPPH, DPNPIN and IPNPIN mediated by $OH^\Theta$ or o-iodosobenzoate ion $(IB^\Theta)$ is relatively slow in aqueous solution. The reactions in CTAX micellar solutions are, however, much accelerated because CTAX micelles can accommodate both reactants in their Stem layer in which they can easily react, while hydrophilic $OH^\Theta\;(or\;IB^\Theta)$ and hydrophobic substrates are not mixed in water. Even though the concentrations $(>10^{-3}\;M)\;of\;OH^\Theta\;(or\;IB^\Theta)$ in CTAX solutions are much larger amounts than those $(6\times10^{-6}\;M)$ of substrates, the rate constants of the dephosphorylations are largely influenced by the change of concentration of the ions, which means that the reactions are not followed by the pseudo first order kinetics. In comparison to effect of the counter ions of CTAX in the reactions, CTACI is more effective on the dephosphorylation of substrates than CTABr due to easier expelling of $Cl^\Theta$ ion by $OH^\Theta\;(or\;IB^\Theta)$ ion from the micelle, because of easier solvation of $Cl^\Theta$ ion by water molecules. The reactivity of IPNPlN with $OH^\Theta\;(or\;IB^\Theta)$ is lower than that of DPNPlN. The reason seems that the 'bulky' isopropyl group of IPNPIN hinders the attack of the nucleophiles.