胶束增强型聚电解质胶囊的结构研究

研究了胶束增强型聚电解质(PAH/PSS和PADA/PSS)胶囊在不同溶液环境中的形貌变化,发现这种新型的胶囊具有迥异于传统聚电解质胶囊的囊壁结构;研究了二维聚电解质复合膜与模板溶解液中嵌段共聚物PS-b-PAA胶束之间的相互作用,发现胶束层可以通过静电力与聚电解质胶囊囊壁相互作用.同时,模拟模板溶出后聚电解质胶囊内部的环境条件,研究了嵌段共聚物胶束在胶囊内部的存在状态及其在透析过程中的变化规律,认为共聚物可以通过疏水作用沉积于聚电解质复合膜的内壁,并通过Ca2+离子的桥联作用稳定,也就是在聚电解质复合膜层基础上又形成了一层胶束层.即这种胶束增强型聚电解质微胶囊的囊壁是由聚电解质层和胶束层所形成的双层结构.用这种双层结构模型,我们合理解释了胶囊在高盐离子浓度下的形貌变化.     

壳聚糖基阳离子胶束用于共负载两种不同性质药物的研究

以季胺化壳聚糖-O-聚己内酯(TMC-PCL)胶束为载体,用于共负载2种不同亲疏水性质的抗肿瘤物质,阿霉素和吲哚菁绿;并研究了胶束包埋对吲哚菁绿的稳定性和光热效应的影响,以及阿霉素从胶束中的释放行为.结果表明,2种抗肿瘤物质在TMC-PCL胶束中的实际载药量均可达20％,且包封率超过85％.进一步还用MTT法评价了不同载药胶束体系对肿瘤细胞的杀灭作用,发现共负载胶束经近红外激光辐照后,对肿瘤细胞的毒性远高于单载药体系.     

聚甘油酸-g-胆固醇胶束的制备及药物释放性能研究

以甘油酸为单体,通过本体缩聚制备了水溶性生物降解高分子聚甘油酸,利用聚甘油酸侧基上的羟基固定生物相容性好的疏水性分子胆固醇,通过亲疏水作用自组装形成胶束.以形成的胶束作为载体负载抗肿瘤药物阿霉素,研究了药物的体外释放行为.将肝癌细胞HepG2与载药胶束共培养研究其体外抗肿瘤效果.研究结果表明,聚甘油酸-g-胆固醇共聚物...     

利用光化学探针技术研究长链烷烃硫酸钠水溶液中预胶束的生成

罗丹明6G与罗丹明B之间的能量转移和吖啶橙形成聚态的现象用于研究长链烷基硫酸钠(C_nH_(2n+1)OSO_3Na,n=12,14和16)在水溶液中预胶束的生成.结果表明,烷基链的长度影响这些表面活性剂形成预胶束的能力,碳数的增加使预胶束形成浓度降低.     

栓塞型新型微包纳药物控释载体的制备及性能

为了抑制药物的突释效应, 减缓药物的释放速率, 实现不同药物的空间分配及顺序释放, 采用乳化法结合高压静电液滴法, 制备了内部包埋有几丁聚糖/海藻酸钙纳米囊的聚精氨酸/几丁聚糖/海藻酸盐微包纳体系(Nano-in-micro drug delivery system, NiM). 通过荧光标记的方法证实了“微包纳”结构并考察了NiM的理化性能. 以牛血清白蛋白及氟尿嘧啶作为药物模型, 考察了聚精氨酸/几丁聚糖/海藻酸盐微包纳体系对单一蛋白类药物和负载两种药物的缓释性能并进行了动力学模型拟合. 结果表明, Ritger-Peppas模型能够较好地模拟该溶胀控释系统的药物释放过程, 与实验结果比较吻合. 同时也证明了该新型载体体系具有无突释、释放速率减缓及顺序释放的功能, 为新型药物载体体系的研究提供了新的思路.     

多响应性聚肽共混胶束的药物控释性能

合成了聚(L-谷氨酸)-b-聚氧化丙烯-b-聚(L-谷氨酸)(PLGA-b-PPO-b-PLGA)三嵌段聚肽共聚物.通过透射电镜、激光光散射与核磁共振等方法研究了其与聚乙二醇-6-聚氧化丙烯(PEG-b-PPO)两嵌段共聚物共混体系的自组装行为,使用紫外分光光度计探讨了负载阿霉素的共混聚集体在不同环境下的释药行为.结果表明:该体系形成了以PPO为内核,PLGA和PEG为壳的共混胶束,该共混胶束的释药行为不仅具有pH和温度的响应性,并且对共混胶束的组分具有依赖性.     

荧光探针法研究PEO-PPO嵌段共聚物胶束的特性

利用十六烷基罗丹明B作为主要荧光探针，研究了水溶性嵌段共聚物PluronicF－68在水溶液中的胶束化行为．研究表明：PluronicF－68形成胶束的临界胶束浓度与温度有极大关系，随温度的升高，其CMC值急剧下降，并且温度对胶束的性质也有很大影响，温度升高可导致胶束的微观粘度增大，表现出很强的负粘－温效应，并发现引起这种负粘－温效应的主要原因是PluronicF－68分子中聚环氧乙烷（PEO）链随温度升高亲水性变差引起其收缩所致，而由聚环氧丙烷（PPO）形成的内核的微观粘度随温度的升高略有下降．     

利用光化学探针技术研究长链烷烃硫酸钠水溶液中预胶束的生成

罗丹明6G与罗丹明B之间的能量转移和吖啶橙形成聚态的现象用于研究长链烷基硫酸钠(C~nH~2~n~+~1OSO~3Na,n=12,14和16)在水溶液中预胶束的生成。结果表明,烷基链的长度影响这些表面活性剂形成预胶束的能力,碳数的增加使预胶束形成浓度降低。     

酪蛋白-g-葡聚糖接枝共聚物对溶菌酶的负载和释放

用溶菌酶作为蛋白质药物模型, 研究了天然大分子对溶菌酶的包埋和释放. 蛋白质为天然的两性聚电解质. 通过Maillard反应制备了无毒且生物相容的β-酪蛋白和葡聚糖的接枝共聚物. 利用β-酪蛋白与溶菌酶之间的静电吸引力制备了以β-酪蛋白/溶菌酶为核, 葡聚糖为壳的胶束. 胶束在低浓度条件下可以稳定存在, 在酸、碱或盐条件下解离. 释放后的溶菌酶分子具有和天然的溶菌酶分子相同的活性. 在胶束中加入Ca2+离子可以使胶束在酸性条件下的稳定性增加. 当用疏水性更强的酪蛋白和葡聚糖接枝共聚物与溶菌酶形成胶束并用Ca2+离子交联后, 胶束在酸性环境下的稳定性显著提高, 在碱性和盐条件下的稳定性也有所增加.     

新型水溶性罗丹明类荧光探针的合成及其对游离3价金属离子的识别

以罗丹明B为原料,设计合成一种新型水溶性荧光探针(L),并对其进行表征和光学性能研究.结果表明,探针L能在纯水体系(TRIS,pH=7.4)中快速识别游离M3+(Cr3+、Al3+、Fe3+)金属离子,为荧光增强型探针,具有灵敏度高、抗干扰能力强的特点.探针L对Cr3+、Al3+、Fe3+的荧光检测限分别为1.57×1...     

Synthesis of size-controlled acid-resistant hybrid calcium carbonate microparticles as templates for fabricating "micelles-enhanced" polyelectrolyte capsules by the LBL technique

Size-controlled, low-dispersed calcium carbonate microparticles were synthesized in the presence of the amphiphilic block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) by modulating the concentration of block copolymer in the reactive system. This type of hybrid microparticles have acid-resistant properties. By investigating the aggregation behaviors of PS-b-PAA micelles by transmission electron microscopy (TEM), the mechanism of hybrid calcium carbonate formation illustrated that the block copolymer served not only as "pseudonuclei" for the growth of calcium carbonate nanocrystals, but also forms the supramicelle congeries, a spherical framework, as templates for calcium carbonate nanocrystal growth into hybrid CaCO(3) particles. Moreover, this pilot study shows that the hybrid microparticle is a novel candidate as a template for fabricating multilayer polyelectrolyte capsules, in which the block copolymer is retained within the capsule interior after core removal under soft conditions. This not only facilitates the encapsulation of special materials, but also provides "micelles-enhanced" polyelectrolyte capsules.     

Matrix polyelectrolyte capsules based on polysaccharide/MnCO₃ hybrid microparticle templates

An efficient strategy for biomacromolecule encapsulation based on spontaneous deposition into polysaccharide matrix-containing capsules is introduced in this study. First, hybrid microparticles composed of manganese carbonate and ionic polysaccharides including sodium hyaluronate (HA), sodium alginate (SA) and dextran sulfate sodium (DS) with narrow size distribution were synthesized to provide monodisperse templates. Incorporation of polysaccharide into the hybrid templates was successful as verified by thermogravimetric analysis (TGA) and confocal laser scanning microscopy (CLSM). Matrix polyelectrolyte microcapsules were fabricated through layer-by-layer (LbL) self-assembly of oppositely charged polyelectrolytes (PEs) onto the hybrid particles, followed by removal of the inorganic part of the cores, leaving polysaccharide matrix inside the capsules. The loading and release properties of the matrix microcapsules were investigated using myoglobin as a model biomacromolecule. Compared to matrix-free capsules, the matrix capsules had a much higher loading capacity up to four times; the driving force is mostly due to electrostatic interactions between myoglobin and the polysaccharide matrix. From our observations, for the same kind of polysaccharide, a higher amount of polysaccharide inside the capsules usually led to better loading capacity. The release behavior of the loaded myoglobin could be readily controlled by altering the environmental pH. These matrix microcapsules may be used as efficient delivery systems for various charged water-soluble macromolecules with applications in biomedical fields.     

Encapsulation, release and applications of LbL polyelectrolyte multilayer capsules

Ever since their invention in 1998, polyelectrolyte multilayer micro- and nano-capsules have impacted various areas of biology, chemistry and physics. Here we highlight progress achieved since the millennium in the areas of encapsulation in and release from microcapsules, describe various structures including multicompartment and anisotropic constructs, and provide examples of several applications in biology. We also describe application areas such as drug delivery, intracellular trafficking, enzyme-catalyzed reactions, mechano-biology which benefited from recent developments in the area of polyelectrolyte multilayer capsules.     

Self-assembled polymer membrane capsules inflated by osmotic pressure

We fabricate and characterize capsules that are composite membranes, made of a polymer network stabilized by adsorption to colloids and inflated by osmotic pressure from internal free polyelectrolyte; here, poly-l-lysine forms the network and inflates the capsules. To assess these capsules' properties and structure, we deform capsules using microcantilevers and use finite element modeling to describe these deformations. Additional experimental tests confirm the model's validity. These capsules' resilient response to mechanical forces indicates that loading and shear should be good triggers for the release of contents via deformation. The osmotic pressure inflating these capsules has the potential to trigger release of contents via deflation in response to changes in the capsules' environment; we demonstrate addition of salt as a trigger for deflating capsules. Because these capsules have a variety of release triggers available and the technique used to fabricate them is very flexible and allows high encapsulation efficiency, these capsules have very high potential for application in many areas.     

pH‐Controlled Macromolecule Encapsulation in and Release from Polyelectrolyte Multilayer Nanocapsules

pH‐Controlled encapsulation in and release of macromolecules from polyelectrolyte capsules of a few microns in diameter is demonstrated. Capsules were prepared via alternating adsorption of the oppositely charged polymers poly(allylamine hydrochloride) and poly(styrene sulfonate) onto decomposable melamin formaldehyde cores. The capsules were open for macromolecules at pH values below 6 and closed at pH > 8.     

Time-resolved fluorescence anisotropy measurements of the adsorption of Rhodamine-B and a labelled polyelectrolyte onto colloidal silica

 The application of time-resolved fluorescence anisotropy measurements (TRAMS) to the investigation of the adsorption of the dye Rhodamine B and a Rhodamine B-labelled cationic polyelectrolyte onto colloidal silica (Ludox) is described. For Rhodamine B the time-resolved fluorescence anisotropy behavior observed can be interpreted using a model consisting of fluorophores with two distinct fluorescence decay lifetimes and two rotational correlation times corresponding to the fluorophore free in solution and bound to the Ludox. Details of the binding obtained from a global analysis of the data are reported. Restricted motion of the fluorescently labelled polyelectrolyte is also observ-ed on adsorption. The considerations for the general application of TRAMS for monitoring adsorption behavior are discussed. Received: 8 July 1998 Accepted: 10 August 1998     

Encapsulation of proteinase K in PELA ultrafine fibers by emulsion electrospinning: preparation and in vitro evaluation

The aims of this study were to encapsulate water-soluble bioactive agents into biodegradable hydrophobic polymers via emulsion electrospinning for drug delivery and tissue engineering applications and propose a simple and facile method to evaluate the bioactivity of the encapsulated protein. Proteinase K was selected as a model protein to be incorporated into poly(ethylene glycol)-poly(l-lactide) (PELA) ultrafine fibers. Core–shell structured fibers with single core or multi-core were observed. In vitro release study showed that after a burst release at the early stage, a sustained release was achieved, indicating that proteinase K was incorporated inside ultrathin fibers successfully. Results of in vitro incubation in Tris–HCl buffer at pH?8.6 and 37?°C revealed that electrospun PELA membranes containing proteinase K (PELA-P) showed obvious morphological changes, large mass loss, and slight decreases in melting temperature, melting enthalpy and relative molecular mass in 7 days. Additionally, a significant drop in pH value of the buffer after incubation of the PELA-P membrane was also observed. These findings clearly showed that encapsulation of water-soluble bioactive agents inside hydrophobic polymers could be achieved by emulsion electrospinning without compromising their bioactivity.     

PLA/PEG/PLA三嵌段共聚物载药纳米胶囊的制备及表征

用于药物控释体系的微胶束具有实心微球结构,药物分子主要吸附于微球表面,极易脱落,在释药初期有明显的突释效应;而微胶囊的药物主要集中于囊心部分,药物通过扩散作用以及高分子膜的降解而逐渐释放到环境中,因而更有利于药物分子平稳、缓慢地释放．对于自然界中能够自发形成微胶囊的小分子材料,其分子中往往具有一个较小的亲水部分和一个相对较大的憎水部分,     

A general strategy for one-step fabrication of biocompatible microcapsules with controlled active release

Fabrication of biocompatible core-shell microcapsules in a controllable and scalable manner remains an important but challenging task.Here,we develop a one-step microfluidic approach for the highthroughput production of biocompatible microcapsules,which utilizes single emulsions as templates and controls the precipitation of biocompatible polymer at the water/oil interface.The facile method enables the loading of various oils in the core and the enhancement of polymer shell strength by polyelectrolyte coating.The resulting microcapsules have the advantages of controllability,scalability,biocompatibility,high encapsulation efficiency and high loading capacity.The core-shell microcapsules are ideal delivery vehicles for programmable active release and various controlled release mechanisms are demonstrated,including burst release by vigorous shaking,pH-triggered release for targeted intestinal release and sustained release of perfume over a long period of time.The utility of our technique paves the way for practical applications of core-shell microcapsules.     

Microcontainers with electrochemically reversible permeability

The present study demonstrates a novel application of polyelectrolyte microcapsules as microcontainers with electrochemically reversible flux of redox active materials into and out of the capsule volume. Incorporation of the capsules inside the conducting polymer (polypyrrole) film results in a new composite electrode combining electrocatalytic and conducting properties of the polypyrrole with the storage and release properties of the capsules. This electrode, if loaded with electrochemical fuels, can possess electrochemically controlled switching between "open/closed" states of the capsule shell and be of practical interest for a new type of chemically rechargeable batteries or fuel cells. A special explanation for the potential depending loading and unloading of the capsule inner volume may be related to the fact that the polyelectrolyte capsules experience a potential gradient in the polypyrrole matrix within which the polyions of the shell can be moved.