纳米TiO_2溶胶W/O型乳液的稳定性及其微胶囊化研究

在W/O/W复相乳液体系中,TiO2溶胶W/O型乳状液的稳定性对所制备的微胶囊形貌影响很大。以破乳率为衡量标准,借助显微镜观察,探讨了内水相含量、Span-80用量、乳化速率和乳化时间等参数对W/O型乳状液稳定性的影响。结果表明,当TiO2溶胶含量为50%(v)、Span-80体积分数为5%时,乳状液的稳定性较好,存在较优的乳化速率8000~10000 r·min-1,和乳化时间8~10 min。以聚乙烯醇(PVA)水溶液为外水相、戊二醛(GA)为交联剂,在稳定的W/O型乳状液基础上所制备的微胶囊粒径均匀,分散性好。热分析表明,微胶囊中TiO2的含量约为35%。     

初乳乳化工艺对W／O／W型复乳稳定性和药物包埋率的影响研究

研究了用两步乳化法制备W/O/W型复合乳状液的过程中,初乳制备时的乳化工艺参数(分散速度和分散时间)对复乳的稳定性和药物包埋率的影响规律.用离心分层稳定性评价复乳的稳定性,高效液相法测定胰岛素在复乳中的包埋率,初乳的黏度和粒度分布也被测定.实验结果表明,相同的配方下,初乳制备时的乳化工艺参数对复乳的稳定性没有显著影响,但对复乳的药物包埋率影响显著.主要影响规律是:乳化强度的提高使初乳的粒径减小,黏度增大,对药物的包埋率提高,但是过高的乳化强度使初乳的分散相液滴发生絮凝和聚结,初乳黏度反而降低,复乳的药物包埋率随之下降.结论:复乳的药物包埋率与初乳相的黏度呈明显的正相关关系,相关系数达到0.9137,而复乳的分层稳定性与初乳的制备工艺没有明显的关系.在本研究中使复乳的药物包埋率最高的初乳制备工艺参数为:Ultra-Turrax T25高速分散乳化器分散速度9500 r·min-1,分散时间6 min;此工艺下胰岛素的包埋率达到84.4%.     

石油醚W/O乳状液及其液膜稳定性

以破乳率为衡量标准,借助显微镜直接观察,探讨了乳状液含水量、表面活性剂用量、乳化时间、乳化强度等因素对石油醚W/O型乳状液体系稳定性的影响。在实验范围内,乳状液含水量的提高及表面活性剂用量的增加,有利于乳状液的稳定;存在较优的乳化时间20min和乳化强度4000rmin-1。选取脂肪烃、芳香烃、混合烃共6种不同油相制备乳状液,对比其稳定性的差异。此外,还初步考察了石油醚W/O/W液膜溶胀和泄漏问题,结果表明该乳状液膜泄漏率低于3.5%,表观溶胀率约为20%。     

复相乳化法制备聚乳酸/水杨酸钠微囊

以W/O/W复相乳化法,聚乳酸为壁材、水杨酸钠为芯材,制备聚乳酸/水杨酸钠微囊。聚乳酸/水杨酸钠微囊的工艺条件为:水杨酸钠溶液浓度为40 mg/mL,聚乳酸溶液浓度为25mg/mL,聚乙烯醇溶液浓度为2mg/mL,内水相水杨酸钠体积为2mL,油相聚乳酸溶液体积为10mL,外水相聚乙烯醇溶液体积为60mL,即内水相与油相比为1∶5,油相与外水相体积比为1∶6。聚乳酸/水杨酸钠微囊的包封率为75.70%。     

5-FU-PLGA复乳微球的制备及体外释放

采用乳化溶剂挥发法制备W/O/W型5-FU-PLGA复乳微球,采用单因素设计考察了第一相体积比(内水相与油相)、第二相体积比(初乳与外水相)对复乳稳定性的影响,采用正交设计考察了搅拌温度、搅拌时间、辅料浓度和有机相中载体材料浓度对微球质量的影响,并对制备条件进行优化。最适宜制备条件为:第一相体积比为1:2,第二相体积比为1:1,搅拌温度为10 ℃、搅拌时间为6 h、辅料浓度为0.5%、有机相中载体材料浓度为15%。依据最适宜条件制备的微球圆整度良好、粒径范围窄,平均粒径5.20 μm,载药量为5.34%,包封率为77.22%。体外释放试验表明微球具有明显的缓释效果,释放行为符合Higuchi模型。     

油包水包油型多重结构乳状液稳定性的影响因素研究

运用两步乳化法制备油包水包油(O/W/O)型多重结构乳状液,研究了乳化剂种类、乳化剂用量、相体积比和添加剂等因素对O/W/O多重结构乳状液的形成和稳定的影响。实验结果表明,O/W脂肪醇聚氧乙烯醚-21EO (S21)、聚氧乙烯-聚氧丙烯嵌段共聚物(F127)以及W/O环甲基硅氧烷(及)PEG/PPG-18/18聚二甲基硅氧烷(DC5225)的最佳质量分数均为5%;当内油相的Si-451质量分数为15%、水相的Si451质量分数为30%时是形成多重结构乳液的最佳质量分数;质量分数为2%的单甘酯(GMS)对多重结构的形成和稳定起着重要的作用;1,3-丁二醇的加入有效地提高了多重结构稳定性。     

三七皂苷R1-PLGA纳米微球的制备及优化研究

应用高分子有机化合物聚乳酸-羟基乙酸共聚物[Poly(lactide-co-glycolide),PLGA]作为成膜材料包载三七皂苷R1制备纳米微球并寻求最优制备条件。采用复乳-溶剂挥发法制备纳米微球,使用高效液相色谱仪、激光粒度分析仪,测定包封率及粒径。采用正交实验设计,对影响包封率及粒径的因素分别进行五因素四水平正交实验。在PLGA浓度10mg/m L,内水相∶油相体积比为3∶10,外水相与初乳体积比为10∶1,第一次超声乳化时间10s,第二次超声乳化时间90s的条件下制备的微球包封率最为理想。若要获得最小粒径,则优化实验条件为:PLGA浓度20mg/m L,内水相∶油相体积比为2∶5,外水相与初乳体积比为2∶1,第一次超声乳化时间10s,第二次超声乳化时间120s。以PLGA为外壳材料可制备携三七皂苷R1纳米微球,并能获得其包封率及粒径制备的最优化条件。     

流变调节剂对W/O型乳液稳定性和流变性的影响

采用均质乳化法制备了W/O型乳液,研究了高分子水溶性聚合物（黄原胶、透明质酸钠）和油相增稠剂（山嵛酸甘油酯、二甲基二硬脂基铵锂蒙脱石）对W/O型乳液稳定性和流变性的影响。实验结果表明,添加黄原胶后,W/O型乳液在不同稳定性测试条件下的稳定性均下降;添加透明质酸钠后,乳液的常温储存稳定性下降,但一定程度上提升了乳液的高温储存稳定性;山嵛酸甘油酯加入W/O型乳液体系后,常温和高温储存的稳定性均增加;二甲基二硬脂基铵锂蒙脱石添加后,乳液在不同条件下稳定性均增强。高分子水溶性聚合物加入后,内水相黏度上升,但W/O型乳液的表观黏度显著降低且线性黏弹区范围缩小,这可能是由于内水相黏度升高阻碍乳化剂分子在油/水界面的吸附;油相增稠剂的添加均增加了W/O型乳液的表观黏度和线性黏弹区范围,这可能和乳化粒子粒径降低和油/水界面能的变化有关。此外,流变调节剂加入后,乳液的滞后环面积均有不同程度的降低。     

冷冻解冻法破除液体石蜡W/O乳状液

冷冻解冻法是一种新型的破除W/O乳状液的物理破乳方法.为了揭示冷冻解冻破乳作用机制,本文以稳定性好的液体石蜡W/O乳状液为研究对象,采用差热扫描量热仪（DSC）与显微镜,研究了高黏度连续相液体石蜡体系的W/O乳状液的冷冻解冻破乳过程.结果表明：该破乳过程是一个渐进过程.当乳珠粒径均匀细小,小于5.5 μm时,乳珠在冷冻解冻循环中逐渐长大,经多次冷冻解冻后完成破乳;然而当乳珠粒径较大时,如51 μm,乳状液体系仅需单次冷冻解冻循环就可破乳较完全,破乳率超过90%.此外,乳状液含水量的增加有利于提高破乳效率.乳状液水相的凝固点受乳珠尺度的影响,但受含水量的影响不显著.当乳珠粒径较大时,水相凝固点随乳珠粒径的减小而降低;但是当乳珠粒径降至5.5 μm时,乳珠粒径的改变对其影响已不明显.     

乳状液膜法提取红土矿浸出液中镍

采用Span-80-TBP-NH3×H2O体系乳状液膜法提取红土矿浸出液中的Ni(II),研究了膜相组成、内水相试剂浓度、膜相与内水相体积比(油内比)、乳水体积比对镍离子提取效果的影响. 采用微分法测定并比较了反应的浓度级数nC和时间级数nt. 结果表明,膜相组成为Span-80:TBP:石蜡:煤油(体积比)=5:4:2:89、内水相氨水浓度为2 mol/L、油内比为1:1、乳水体积比为1:3、外水相硫酸浓度为0.3 mol/L的条件下,经过二级提取后,红土矿浸出液中Ni(II)去除率可达80%;由浓度级数(nC=1)小于时间级数(nt=2.8)可知,该过程为化学反应控制过程.     

白油W/O/W型多重乳状液的稳定性研究

以多重乳状液相对体积为衡量标准,用显微镜直接观察,探讨了乳化剂的HLB值、质量分数、亲油亲水乳化剂体积比及油水的相比等对白油W/O/W型多重乳状液体系稳定性的影响。结果表明单一乳化剂体系中适宜的制备条件:乳液中乳化剂质量分数为12.2%,V(Span80)/V(Tween80)=7.5;适合多重乳液稳定的油水相比为:第一相体积比为2.5,第二相体积比为0.2。复合乳化剂体系中适宜的制备条件:第一相乳化剂的HLB值为6.5,V(复合乳化剂)/V(Tween80)=27.5,乳液中乳化剂质量分数为9.5%。     

Mass transfer studies on multiple emulsion as a controlled mass release system

A novel type of multiple emulsions which contain a microemulsion in macrodroplets, was prepared by a two-step emulsification procedure. Mineral oil was used as the oil phase with a mixture of Aerosol OT and Span 20 as primary emulsifiers. A water-in-oil microemulsion was prepared by gradual addition of water in oil containing both these emulsifiers. This microemulsion system, when dispersed in an aqueous solution containing secondary emulsifier, produces water-in-oil-in-water (W/O/W) multiple emulsions. The release rate of solute dissolved in the internal aqueous phase was measured using the dialysis technique. A theoretical model describing the diffusion of a multiple emulsion system was developed, which predicts the half-life for 50% of the internal solute to diffuse to the external phase. Experimental results showed the stability of multiple emulsions improved significantly upon using a thermodynamically stable microemulsion as a primary emulsion and a polymeric surfactant as a secondary emulsifier. As a resull, half-life of these multiple emulsions is greater than that of conventional multiple emulsions.     

石蜡油w／o／w型多重乳液的制备及其对维生素C的包裹

以多重乳液相对体积为衡量标准,探讨了石蜡油、乳化剂、以及第一相质量分数对石蜡油w／o／w型多重乳液稳定性的影响。结果表明制备石蜡油w／o／w型多重乳液的较佳条件为：第一相中石蜡油和乳化剂Span80质量分数分别为40％和8％,第一相质量分数为65％,乳化剂Tween80质量分数为1％。采用透析-紫外分光光度法研究了该多重乳液对维生素c的包裹能力,结果表明：多重乳液可以有效包裹维生素C,包裹率达98．55％,且能缓慢释放被包裹的维生素C。     

Efficient Encapsulation of a Water-Soluble Molecule into Lipid Vesicles Using W/O/W Multiple Emulsions via Solvent Evaporation

We developed a novel method for preparing lipid vesicles with high entrapment efficiency and controlled size using water‐in‐oil‐in‐water (W/O/W) multiple emulsions as vesicle templates. Preparation consists of three steps. First, a water‐in‐oil (W/O) emulsion containing to‐be‐entrapped hydrophilic molecules in the water phase and vesicle‐forming lipids in the oil phase was formulated by sonication. Second, this W/O emulsion was introduced into a microchannel emulsification device to prepare a W/O/W multiple emulsion. In this step, sodium caseinate was used as the external emulsifier. Finally, organic solvent in the oil phase was removed by simple evaporation under ambient conditions to afford lipid vesicles. The diameter of the prepared vesicles reflected the water droplet size of the primary W/O emulsions, indicating that vesicle size could be controlled by the primary W/O emulsification process. Furthermore, high entrapment yields for hydrophilic molecules (exceeding 80 % for calcein) were obtained. The resulting vesicles had a multilamellar vesicular structure, as confirmed by transmission electron microscopy.     

A novel method for preparing oil-in-water-in-oil type multiple emulsions using organophilic montmorillonite clay mineral

A stable formula using oil-in-water-in-oil (O/W/O) type multiple emulsions was investigated. The components consisted of hydrophilic nonionic surfactant (HCO-60), organophilic montmorillonite, and lipophilic nonionic surfactant (DIS-14). O/W/O emulsions were prepared by a double-step procedure in which an O/W emulsion was prepared in the first step, and then the O/W emulsion was “re-emulsified” in an oil phase with organophilic montmorillonite. The diameter of the innermost oil droplets decreased with increasing HCO-60 content (0.1–3%), while the viscosity showed a maximum at 1% of HCO-60, indicating that the yiel of re-emulsification is highest at this condition. Viscosity of the O/W/O emulsion increased with increasing organophilic montmorillonite and DIS-14. According to the results of a phase ratio study, viscosity and stability of the O/W/O emulsion decreased at high weight fraction of inner oil phase (0.4–0.5), indicating that the excess amount of inner oil phase is absorbed by the outer oil phase. These results revealed that the weight fraction of inner oil phase should be kept below 0.3 for a stable O/W/O emulsion. A similar study on the weight fraction of O/W phase [фO/W)/O] suggested that the O/W/O emulsion is stable at ϕ(O/W)/O=0.65–0.70.     

制备单分散含单体O/W乳液的SPG膜乳化过程

采用Shirasu多孔玻璃（SPG）膜乳化法制备了单分散含对苯二甲酰氯（TDC）单体的O/W乳液,系统地研究了SPG膜乳化过程的影响因素.实验结果表明,采用SPG膜乳化法制备单分散O/W乳液时,选择阴离子表面活性剂比考虑亲水亲油平衡（HLB）匹配更重要;增大分散相或连续相的黏度,能够改善乳液的单分散性和稳定性;随着单体浓度增加,乳液的单分散性变差,液滴的平均粒径逐渐变小.当SPG膜孔径大于1.0 μm左右时,可得到单分散的含TDC单体乳液;而当孔径小于1.0 μm左右时,水分子更容易扩散并溶解到油水界面甚至油相内部与TDC生成对苯二甲酸（TPA）,TPA积累到一定程度在油水界面上析出将膜孔堵塞,从而无法制得单分散乳液.随着乳化时间增长,乳液的平均直径逐渐变小、单分散性逐渐变差.     

Preparation of microcapsules of W/O/W emulsions containing a polysaccharide in the outer aqueous phase by spray‐drying

A water‐in‐oil‐in‐water (W/O/W) multiple emulsion containing a hydrophilic substance, 1,3,6,8‐pyrenetetrasulfonic acid tetrasodium salt (PTSA), and a wall material in its inner and outer aqueous phases, respectively, was prepared by a two‐step emulsification using a rotor/stator homogenizer, and was further homogenized with a high‐pressure homogenizer. Maltodextrin or gum arabic were used as wall materials, and olive oil was used as the oily phase. The high encapsulation efficiency for PTSA (>0.9) was realized. The emulsion was spray‐dried to produce microcapsules of W/O/W type. The efficiencies of the microcapsules prepared with maltodextrin and gum arabic were 0.82 and 0.67, respectively. Stability of the microcapsules was examined at 37 °C and 12%, 33% and 75% relative humidity. Microcapsules prepared with maltodextrin were more stable than those prepared with gum arabic.     

两步乳化法制备车用上光蜡的研究

采用两步乳化法制备出一种多重乳液型(O/W/O型)汽车上光蜡。第一步乳化分别制备水包油(O/W)型乳化蜡和乳化硅油;第二步乳化是将水包油型乳化蜡和乳化硅油与溶剂油、乳化剂、水等进行再次乳化。结果表明,最佳乳化条件为:原料蜡选择实验室制备1#氧化蜡,硅油用量为5%～10%,溶剂油为120#汽油和低芳烃溶剂油,适宜油水比介于2∶1～1∶1之间。涂在汽车表面上,不仅能清洁车面,还能产生持久的光亮效果。     

De-emulsification of 2-ethyl-1-hexanol/water emulsion using oil-wet narrow channel combined with low-speed rotation

Low-speed rotation of disc in an internal circulation of a novel de-emulsification with rotation-dise horizental contactor (RHC-D) realized de-emulsification for O/W emulsions due to repeated coalescence in oil-wet narrow channels at a low rotation speed. For three emulsions included ethanol/water/2-ethyl-1-hexanol, ethanol/water/2-ethyl-1-hexanol/SDS (Sodium Dodecyl Sulfonate) and 2-ethyl-1-hexanol/water/SDS emulsion, deemulsification ratios of oil phase could reach 1, 1 and 0.67 respectively at 170 r·min^-1, and de-emulsification ratios increased obviously after agitating 10 min. De-emulsification experiment in the seam indicated that oil droplet sizes in O/W emulsion became larger after de-emulsification. The main de-emulsification mechanism in RHCD was the coalescence of oil droplets in oil-wet narrow channels. With increase of the rotation speed, oil droplets dispersed better in the aqueous phase. However, de-emulsification effect enhanced due to the increase of the coalescence rate at a bit higher rotation speed. In addition, internal circulation made those O/W emulsions to be broken repeatedly, consequently de-emulsification ratio increased. Repeated de-emulsification through internal circulation might make continuous extraction of ethanol come true at a low rotation speed.     

Stability of vitamin A in oil-in-water-in-oil-type multiple emulsions

The stabilityof vitamin A was studied in thee different emulsions: oil-in-water (O/W), water-in-oil (W/O), and oil-in-water-in-oil (O/W/O). The stability of retinol (vitamin A alcohol) in the O/W/O emulsion was the highest among the thee types of emulsions; remaining percentages at 50°C after 4 wk in the O/W/O, W/O, and O/W emulsions were 56.9, 45.7, and 32.3, respectively. With increasing peroxide value of O/W and W/O emulsifiers, the remaining percentage of vitamin A palmitate and retinol in the emulsions decreased significantly, indicating that peroxides in the formulae accelerate the decomposition of vitamin A. Organophilic clay mineral (an oil gelling agent and a W/O emulsifier) also affected the stability of retinol; synthesized saponite was better than naturally occurring bentonite for retinol stability. The stability of retinol in the O/W/O emulsion increased with increasing inner oil phase ratio (φ_i), whereas in O/W it was unaffected by φ_i. Encapsulation percent of retinol in the O/W/O emulsion, the ratio of retinol in the inner oil phase to the total amount in the emulsion, increased with increasing φ_i. The remaining percent of retinol in the O/W/O emulsion was in excellent agreement with encapsulation percent, suggesting that retinol in the inner oil phase is more stable than that in the outer oil phase. Addition of antioxidants (tert-butylhydroxytoluene, sodium ascorbate, and EDTA) to the O/W/O emulsion improved the stability of retinol up to 77.1% at 50°C after 4 wk. We conclude that the O/W/O emulsion is a useful formula to stabilize vitamin A.