Microencapsulation of capsaicin by the complex coacervation of gelatin,acacia and tannins

With gelatin and acacia as walls and capsaicin as the core substance, microcapsules were prepared through the mixing of two solutions of oppositely charged polymers and were then treated with tannins. The processing factors included the stirring rate and the types and dosages of the surfactants used in the preparation of the microcapsules. The morphology and size distribution of the microcapsules were analyzed with optical microscopy, environmental scanning electron microscopy, and laser particle size analysis. The microcapsules had a mean diameter of 20–30 μm, a maximal drug loading content of 19.84%, and an encapsulation efficiency of 88.21% with a good dispersion, even distribution, and round shape. The influence of the tannins on the morphology and structures of the microcapsules was also investigated, and their interaction mechanism was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2669–2675, 2004     

明胶/阿拉伯胶复合凝聚法制备DCOIT微胶囊

以羟乙基纤维素(HEC)为乳化剂、明胶和阿拉伯胶为壁材、4,5-二氯-2-正辛基-4-异噻唑啉-3-酮(DCOIT)芯材、甲醛为固化剂、冰醋酸(HAc)和氢氧化钠(NaOH)为pH值调节剂,采用复合凝聚法制备了DCOIT微胶囊。通过单因素试验法探讨了壁材浓度、壁芯比、反应时间、pH值、搅拌速率和乳化剂类型等对微胶囊的粒径、稳定性和包埋率等影响。结果表明:当w(壁材)=3%、壁芯比=m(壳层单体)/m(核层单体)=3、反应时间为2 h、pH≤4.5和搅拌速率为1 000 r/min时,相应DCOIT微胶囊的性能相对最佳。     

Fabrication and characterization of albumin‐acacia nanoparticles based on complex coacervation as potent nanocarrier

BACKGROUND: Bovine serum albumin (BSA) and Gum Arabic (Acacia) were used to fabricate nanoparticles (NPs) as a new nanocarrier for drug and bioactive delivery systems. Several parameters, namely pH, protein to polysaccharide ratio, ionic strength, total biopolymer concentration, temperature, agitation speed and glutaraldehyde concentration were investigated for their effect on the product preparation process. Besides fabrication, the stabilization step including heating, ultrasonicating, cross‐linking, and its effect on average size and polydispersity of NPs was examined. RESULTS: Total biopolymer concentration had no marked effect on the average size of prepared NPs although it did affect other systems produced by complex coacervation. The most effective parameters were pH, temperature and ionic strength, which affected this system (albumin‐acacia) by a complicated route. The smallest size of prepared NPs (i.e. the best product) was 108 nm, which was fabricated under the optimum condition of T = 4 °C, pH = 4.9, $Pr{:}Ps = 2$ , and Is = 0. CONCLUSION: Of the stabilization methods tested, heating gave the best results. The fabricated NPs were purified with a 0.45 µm syringe filter and analyzed by PCS, SEM, FTIR and DSC. The mechanism of complex coacervation for preparing NPs, and their use as a nanodelivery system are discussed. Copyright © 2012 Society of Chemical Industry     

复合凝聚法制备双相核材料纳米胶囊

以明胶-阿拉伯树胶为壁材,采用复合凝聚法制备了双相核材料的纳米胶囊,其内包覆改性TiO2/四氯乙烯双相分散体系。讨论了制备过程中,各参数对纳米胶囊粒径的影响,并采用扫描电镜及透射电镜观察了纳米胶囊的粒径分布及形貌。结果表明,制备的纳米胶囊囊壁光滑、均匀,具有窄的粒径分布。双相分散体系被包覆于纳米胶囊内,且TiO2纳米颗粒粒径约为50 nm。所制备的纳米胶囊平均粒径约为0.96μm,囊壁厚度约为18 nm。     

明胶-阿拉伯树胶电子墨水微胶囊表界面控制

以明胶-阿拉伯树胶为壁材,四氯乙烯为分散介质,硬脂酸改性的TiO2为显示颗粒,采用复合凝聚法制备了红白显示的电子墨水微胶囊。讨论了表面活性剂十二烷基硫酸钠(SDS)对复合凝聚相生成过程的影响,并分析了Span 80用量对微胶囊形貌的影响。结果表明,SDS与明胶间形成的复合凝聚相具有很高的表面活性。此外,Span 80体积分数为2.0%～3.0%时,制备的微胶囊囊壁光滑、均一,平均粒径约为60μm。制备的微胶囊在电场强度为2.5×106V/m时,具有良好的电场响应行为及可逆移动性。     

Properties of polyelectrolyte complex films of chitosan and gelatin

A series of chitosan–gelatin complexes was prepared by varying the ratio of constituents. Differential scanning calorimetry was used to determine the amount of the different states of water. The interaction between chitosan and gelatin was checked by IR and X-ray analysis and was related to mechanical strength. The results indicate that the water take-up of a chitosan–gelatin complex is depressed by strong interactions within networks. Chitosan can improve the tensile strength of complex films, and even with high water content these can keep appropriate tensile strength and higher elongation. © 1999 Society of Chemical Industry     

明胶微胶囊化技术研究进展

本文简要地介绍了微胶囊化技术及其分类方法,微胶囊的性质和主要的应用领域。对以明胶为基础的壁材体系、利用单凝聚和复凝聚方法制备微胶囊的过程、检测分析方法和微胶囊的释放机理等作了评述,并且指出了明胶微胶囊技术中尚未解决和需要进一步探讨的问题。     

明胶与壳聚糖复凝聚过程的研究

本文研究了四种明胶与两种壳聚糖组成的体系的复凝聚过程,对于复凝聚过程的主要影响参数(pH值、配比和盐类)与体系复凝聚产率的关系进行了探讨。发现选用二价金属盐类对体系复凝聚产率的影响明显不同于一价金属盐类,少量CaCl_2(≯0.30％)的加入可提高复凝聚产率;具有高冻力的RT-52354和RT-53808两种明胶较适用于进行复凝聚;采用分子量大、脱乙酰度较低(-NH_2含量较少)的壳聚糖有利于提高复凝聚产率;并且对上述两种明胶与壳聚糖体系确定了比较适宜的复凝聚条件。     

Ethylcellulose microparticles containing chitosan and gelatin: pH-dependent release caused by complex coacervation

Ethylcellulose microparticles containing chitosan and gelatin were prepared by spray drying water-in-oil (W/O) emulsion. Water phase was chitosan:gelatin solution in distilled water, and oil phase was ethylcellulose solution in dichloromethane. FITC-dextran was included in water phase as a fluorescence dye. The maximum coacervation was observed at pH 6.0 when the ratio of chitosan to gelatin was 1:15. Microparticles containing chitosan and gelatin in the ratio showed a higher release under acidic condition (e.g. pH 4.0) and neutral condition (e.g. pH 7.0), but a lower release at pH 5.0 and pH 6.0. The complex coacervate composed of chitosan and gelatin was efficiently formed at those pHs, and the formation of coacervate would be responsible for the lower release.     

复合凝聚法制备辛硫磷微胶囊剂的研究

采用明胶－桃胶为囊材的复合凝聚方法使辛硫磷微胶囊化。研究了多种反应条件对辛硫磷微胶囊化的影响,测定了辛硫磷微胶囊剂的光解稳定性和在水中的控制释放,并进行了辛硫磷微胶囊剂与常规乳油的药效对比试验。     

Nanoencapsulation of n-Octadecane Phase Change Material in Self-Assembled Polyelectrolyte by Soft Solution Technique

Nanoencapsulation of n-octadecane phase change material was performed by facile soft solution technique. An emulsion of n-octadecane and sodium dodecyl sulfate was prepared by high intensity sonication and then mixed with 1–6 mM of poly(diallyldimethylammonium chloride) (PDDA) solution. The capsules with globular core-shell structure were obtained via self-assembly of PDDA molecules coated on the primary emulsion droplets, described as PDDA encapsulated n-octadecane (PDDA-en-Oc). Average particle size and ζ-potential of PDDA-en-Oc increased with increasing of PDDA concentration due to the different PDDA conformation and thickness of capsules' shell. The smaller diameter of PDDA-en-Oc, the faster heat releasing and absorption were obtained. However, the increasing of PDDA concentration could improve the encapsulation efficiency, resulting in an increment of latent heat quantity. The PDDA-en-Oc capsules prepared from 4 mM PDDA with ～166 nm in size possessed the maximum latent heat and encapsulation efficiency (i.e., 124.4 J/g and 58%, respectively).     

复凝聚法制备明胶/阿拉伯胶含油微胶囊工艺过程的研究

研究了复凝聚法制备含油微胶囊的工艺过程。以大豆油为囊芯材料,阿拉伯胶与明胶为璧材,研究了溶液pH值,反应温度,反应时间,壁材浓度,搅拌条件等对微胶囊产品质量的影响。发现搅拌速度对微胶囊的粒径大小和分布影响很大。最佳工艺条件为:明胶与阿拉伯胶质量比为1,浓度都为2%,pH值为4.0~4.5,搅拌速度为1500 r/min,反应温度为55℃,凝聚时间为15~20min,固化温度为10℃,固化时间60 min。     

Phase behavior of gelatin in the presence of pectin in water-acid medium

Summary Phase separation of alkaline gelatin in water-acid solutions in the presence of low etherified pectin (ED 38%) were investigated. The effects of the pectin weight fraction in pectin/gelatin mixture (q_o) as well as two conditions of complex formation, namely, mixing of the binary biopolymer-solvent systems at pH 3.5 (‘mixing conditions’), or preparation of the ternary gelatin-pectin-water systems at pH 7.5 and their subsequent acidification up to pH 3.5 (‘titration conditions’), on phase equilibrium and macrostructure of the concentrated complex phase were established using phase analysis, and optical microscopy. At q_o<0.5 the aggregative phase separation was observed in both conditions of complex formation leading to the almost complete concentration of both biopolymers in the bottom phase at q_o=0.3 (‘mixing conditions’) and at q_o=0.5 (‘titration conditions’). At q_o>0.5 unusual three phase separation took place in the ‘mixing conditions’, leading to formation of supernatant (phase 1), complex coacervate (phase 2) and concentrated pectin solution (phase 3). Possible mechanism of such phenomenon was discussed in term of segregative and aggregative phase separations.     

Controlling absorbency in gelatin networks: Preparation and characterization of alkylated,crosslinked gelatin

Gelatin is a highly abundant and relatively inexpensive protein which is used in a variety of gel applications including photography, drug delivery, microencapsulation, and food preparation. Control of network formation in gelatin may therefore provide methods of preparing protein gels tailored for specific applications. In this study, circular dichroism (CD), Raman, and nuclear magnetic resonance (NMR) spectroscopies were used to characterize ordering processes which occur in gelatin and their relationship to absorbency. Ordering of the unmodified protein, studied as a function of concentration, temperature, and time after initial preparation, correlates inversely with absorbency. Chemical modification was used to control the absorbency and solubility of the protein gels. Alkylation of gelatin using glycidyltrimethylammonium chloride causes substantial increases in water absorbency with degrees of substitution as low as 0.5%. Increases in saline swelling were observed only after additional modification of the alkylated gelatin with a nonionic polyoxyalkyleneamine crosslinking agent (Jeffamine®). Limiting the initial degree of substitution prior to crosslinking (to just below 1%) plays a key role in optimizing the absorbency and minimizing the dissolution of the gel in saline. The methods and principles used to manipulate the absorbency of gelatin may also find use for other natural protein systems. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:281–292, 1998     

Preparation and characterization of films based on crosslinked blends of gum acacia,polyvinylalcohol, and polyvinylpyrrolidone-iodine complex

In an attempt to develop iodine-release systems based on polymeric blend for biomedical applications, our research group prepared blends of gum acacia (GA), polyvinylalcohol (PVA), and polyvinylpyrrolidone-iodine (PVP-I) complex. The blends of GA/PVA and GA/PVA/PVP-I prepared from the aqueous solutions of the polymers were crosslinked with glutaraldehyde to increase the water resistance of the films and to improve their thermal and mechanical properties. The crosslinked GA/PVA and GA/PVA/PVP-I blend films were characterized by FTIR spectroscopy, DSC, and TGA. The swelling behavior of the prepared blends was investigated and crosslinked GA/PVA blend films were found to be pH sensitive. The properties of PVP-I containing blends differed from those prepared without it probably due to the formation of an intermolecular interaction between PVP-I and the hydroxy-polymers. The results indicated that after crosslinking the blends showed improvement in water resistance, thermal, and mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

微涡流处理工艺及在造气污水处理中的应用

微涡流混凝水处理工艺通过微涡流凝聚和立体接触絮凝,充分利用混凝空间、混凝能量与絮体活性,大幅度提高了混凝反应效率。巨化合成氨厂的应用实践表明,该工艺用于造气污水处理,可明显改善出水质量,提高水循环使用率,而且投资和运行成本低。     

Microencapsulation by coacervation of poly(lactide-co-glycolide). III. Characterization of the final microspheres

This paper deals with protein microencapsulation by coacervation of poly(lactide-co-glycolide) solutions in CH₂Cl₂ induced by the addition of silicone oils of various viscosities. This coating technique proceeds along three steps: phase separation of the coating polyester, adsorption of the coacervate droplets around the protein phase, and hardening of microparticles. Size distribution, surface morphology and internal porosity of the final microspheres clearly depend on the main characteristics of the coacervate, particularly the viscosity, in a direct connection with the CH₂Cl₂ content. Indeed, the whole porosity (which may be as high as 80%), average pore size and broadness of pore size distribution decrease as the coacervate is more viscous. Hardening of the coacervate droplets is thus so fast that the organic solvent is entrapped within the polymer matrix and predetermines the internal porosity. Finally, size distribution of microspheres is bimodal in a clear relation with the coacervate viscosity. A less viscous coacervate favours smaller microspheres (within the 7–90 μm range), contaminated with a minor population of microparticles below 4 μm.     

复凝聚法制备昆虫蜕皮激素微胶囊及其性能

以明胶(GE)和阿拉伯胶(AG)为壁材,采用复凝聚法制备昆虫β-蜕皮激素微胶囊。通过正交实验获得微胶囊的最佳制备工艺条件。利用扫描电子显微镜和光学显微镜对β-蜕皮激素微胶囊形貌进行表征。研究了β-蜕皮激素微胶囊的释放行为和光稳定性。结果表明:壁材质量分数为3%,芯壁材质量比为1:1,前期pH值为4.6,后期pH值为8.0为最佳工艺条件。在此条件下,可形成壁膜光滑,大小均匀的球形微胶囊,其平均粒径大小为5μm,载药量与包覆率分别达到68.5%和63.4%。微胶囊能够明显延长蜕皮激素的释放时间及增强蜕皮激素的光稳定性。     

光甘草定微胶囊包合物制备

研究以明胶和阿拉伯胶为壁材,采用复凝聚法研究了光甘草定微胶囊的制备工艺,探讨了芯壁质量比、增溶剂使用量、乳液均质时间和搅拌速度的影响,通过正交试验确定最佳工艺条件为芯壁比为2∶1,增溶剂为0.5%,均质时间为10 min,搅拌速度为750 r/min。通过本工艺制备得到的光甘草定微胶囊包裹率可达40%,粒径分布均匀(平均粒径3.91μm),将其喷雾干燥后得到光甘草定微胶囊粉末为淡黄色,无刺激气味,可溶于丙二醇等有机溶剂。包裹后的光甘草定微胶囊,减淡了原有的棕黑颜色和刺鼻气味,可很好地用作化妆品美白添加剂。     

Preparation and characterization of microcapsules containing capsaicin

With urea‐formaldehyde (UF) resin as walls and capsaicin as core substances, microcapsules were prepared based on in situ polymerization process. The morphology and size distribution of the microcapsules were analyzed by Fourier transform infrared spectroscopy, laser particle size analyzer, and scanning electron microscopy. The microcapsulated capsaicin (MC) agents had a mean diameter of about 30–50 μm. Moreover, the thermal properties of the MC agents were measured by differential scanning calorimetry and thermogravimetric analysis. It was demonstrated that the melting point and thermal stability of the MC agents were greatly improved compared with that of the uncovered capsaicin, which were caused by the encapsulating crosslinked UF resin over the surface. The shell formation mechanism and the effects of the process conditions such as U/F ratio, shearing force, and acidification time on the particle size of the MC agents were discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010