温度敏感性壳聚糖基聚电解质载药纳米粒子的制备及表征

以天然高分子壳聚糖(CS)、羧甲基纤维素(CMC)和温度敏感性单体N-异丙基丙烯酰胺(NIPAM)为原料,通过自组装制备了温度敏感性聚电解质复合纳米粒子CS-g-PNIPAM/CMC-g-PNIPAM,并以5-氟尿嘧啶(5-FU)为模型药物研究了纳米粒子对药物的负载与可控释放性能。当CMC-g-PNIPAM与CS-g-PNIPAM的质量比为3:7时,形成的纳米粒子结构最稳定,动态光散射(DLS)测得其平均粒径为116nm,粒径分布较窄。载药纳米粒子对5-FU具有较高的载药量和包封率。在磷酸盐缓冲溶液中的释药行为表明,其累积药物释放量随pH和温度的增加而增大,表现出良好的pH与温度可控性能。     

烷基壳聚糖纳米微球的制备及其紫杉醇负载研究

在碱性条件下通过卤代烃的N-烷基取代反应制备得到烷基壳聚糖衍生物。X射线光电子能谱计算结果表明烷基取代反应主要发生在壳聚糖的氨基上。动态光散射研究表明，该衍生物在水中可自动形成粒径在10—200nm范围的纳米微粒，负载紫杉醇后微球的粒径增大，在磷酸缓冲液（pH=7．4）中体外释放研究表明，随着烷基链长的增加，紫杉醇在磷酸缓冲液中达到平衡时的浓度降低。     

组装在贵金属基底上的金纳米粒子对CO的电化学催化氧化

研究了组装在Au, Pt电极表面的金纳米粒子对CO的电化学催化氧化行为, 首次在实验上观察到较大粒径金纳米粒子(粒径＞10 nm)对CO的电催化氧化活性. 考察了金粒子表面金氧化物对粒子电催化活性的影响, 发现表面金氧化物的形成是金纳米粒子对CO具有电催化氧化活性的前提. 对于相同粒径的金纳米粒子, 随着粒子表面金氧化物量的增加,催化活性增大.     

壳聚糖修饰的Pt纳米粒子

以氯铂酸为前驱体,硼氢化钠为还原剂,壳聚糖为保护剂,通过化学还原法,在室温条件下制备了Pt纳米粒子.透射电镜(TEM)显示纳米粒子的粒径在28.5nm左右,X-射线衍射(XRD)表明纳米粒子的晶型为面心立方结构,X-光电子能谱(XPS)和红外(FTIR)证实了壳聚糖包覆在纳米粒子表面,热重分析(TGA)表明纳米粒子表面的壳聚糖含量大约为52.8％.     

AucorePtshell础纳米粒子对甲醇氧化的电催化性能研究

应用两步化学还原法制备不同厚度的AucorePtshell纳米粒子，经紫外可见光谱（UV-Vis）、透射电子显微镜（TEM）表征．该金纳米颗粒经化学还原包裹铂后平均粒径明显增大，调节金与铂的含量可获得不同包裹厚度的AucorePtshell纳米粒子．循环伏安法研究表明，粒径为70-80nm的AucorePtshell纳米粒子对甲醇的氧化具有较好的电催化活性，并且其电催化性能随着电位循环扫描次数的增加而增强．     

聚肽-壳聚糖复合体系的自组装行为研究

以聚肽、壳聚糖为原料,制备复合纳米粒子,采用透射电镜、动态激光散射仪及Zeta电位分析仪、荧光光谱仪对制备成的聚肽-壳聚糖复合体系纳米粒子的形貌、粒径、Zeta电位及临界胶束浓度等自组装行为进行表征,结果表明:聚肽-壳聚糖复合体系纳米粒子是具有壳-核结构的球型粒子;纳米粒子平均粒径为240nm,粒径分布较均匀,稳定性较好;复合体系中聚肽的临界胶束浓度为4.55×10-4mg/mL.     

壳聚糖/聚丙烯酸纳米粒子对蛋白质的吸附行为

以马来酸酐改性的壳聚糖(MAH-chitosan)和丙烯酸(AA)为单体,采用反相微乳液聚合法制备了AA含量分别为77%(AA-Cs)和29%(Cs-AA)壳聚糖/聚丙烯酸复合纳米粒子。TEM结果表明,该复合纳米粒子平均粒径为125~150nm,进而研究了其对牛血红蛋白(Hb)、牛血清白蛋白(BSA)和溶菌酶(Ly)吸附和脱附行为。AA-Cs对各种蛋白的吸附量均较高;而Cs-AA对3种蛋白的吸附则具有一定选择性。AA-Cs对等电点低于脱附pH值的Hb的脱附量较大。Cs-AA粒子在较低pH值(pH=3.4)时对吸附有利,但在高pH值(pH=6.6)进行吸附时,对脱附更为有利。     

羧甲基壳聚糖磁性纳米粒子的合成及应用

通过合成油酸修饰的Fe3O4纳米粒子和羧甲基壳聚糖直接包埋油酸修饰的Fe3O4纳米粒子的两步合成法制备了羧甲基壳聚糖磁性纳米粒子。采用透射电子显微镜、傅里叶变换红外光谱、振动样品磁强计和同步热分析测试技术对制备的羧甲基壳聚糖磁性纳米粒子进行了表征。所得磁性纳米粒子呈规则球形,粒径约为10 nm;表面含羧基,且具有很好的顺磁性和稳定性。考察了羧甲基壳聚糖磁性纳米粒子对阿霉素的载药量和对阿霉素在磷酸盐缓冲溶液中的缓释性能。结果表明,磁性纳米粒子对阿霉素展示了较高的载药量(91.8 mg/g),结合了阿霉素的磁性复合物对阿霉素的缓释作用明显,说明制备的羧甲基壳聚糖磁性纳米粒子有望作为治疗肿瘤的纳米磁靶向药物输送载体。     

壳聚糖基多功能纳米药物载体的体外研究

制备了一种壳聚糖基多功能纳米药物载体系统, 并探讨了其体外释药性质. 合成了甲氨蝶呤-壳聚糖偶联物(MTX-CS), 甲氨喋呤(MTX)的取代度为6.3%; MTX-CS具有两亲性, 在水性介质中能自组装形成纳米粒子, 平均粒径为(269.5±18.3) nm, zeta电位为(25.7±0.9) mV. MTX-CS纳米粒子能有效包载抗血管生成药Combretastatin A-4(CA-4), 当药物/载体材料投料比为1∶4 时, 载药量为15.7%, 包封率为62.8%. 体外释放实验结果显示, CA-4释放较快, MTX释放缓慢, 有利于发挥2种药物的协同抗肿瘤作用.     

CoFe_2O_4纳米晶与牛血清白蛋白和牛血红蛋白的相互作用:吸附、纳米晶的团聚及蛋白构象的变化(英文)

水热制备了约10 nm的CoFe2O4纳米晶,通过Zeta电势、动态光散射(Dynamic Light Scattering,DLS)和傅立叶变换红外光谱(FTIR)技术研究了纳米晶与牛血清白蛋白(Bovine Serum Albumin,BSA)和牛血红蛋白(Hemoglobin)的相互作用。纳米晶对BSA和血红蛋白都有很强的吸附,其中对血红蛋白的吸附符合静电吸附的规律,而对BSA的吸附则不符合静电吸附的规律。在pH=5.5和7.0时纳米晶对BSA和血红蛋白的吸附容量分别达到237.9 mg·g-1和256.9 mg·g-1。DLS结果表明蛋白质能够导致纳米晶团聚。吸附BSA或血红蛋白后,纳米晶的DLS粒径由51 nm分别增大到472 nm和114 nm。CoFe2O4纳米晶还导致了蛋白质FTIR谱发生明显变化。BSA和血红蛋白的酰胺I带由于纳米晶的作用分别减少了4 cm-1和6 cm-1。     

The immobilization of antineoplastic drug cyclophosphamide in calcium alginate

IR spectroscopy and scanning electron microscopy were used for the study of formation of calcium alginate particles. The synthesis was carried out in an aqueous medium via reaction between sodium alginate and calcium chloride. It was found that calcium alginate particles with a homogeneous and dense structure were formed at concentrations 2 wt % and 0.1 M of sodium alginate and calcium chloride, respectively. Formation of calcium alginate particles in the systems containing chitosan was accompanied by the emergence of an adsorption layer of chitosan on the particle surface. The thickness of this layer increased with the enhancement of chitosan concentration. The release kinetics of cyclophosphamide from calcium alginate particles in physiological solution in vitro was investigated. The results showed that such factors as elevated temperature at the drying of calcium alginate particles, the increase in the amount of guluronate in the initial sodium alginate, and thickening of the chitosan adsorbed layer led to a significant decrease in the release rate.     

肽类药物口服剂型材料及控制释放性能研究Ⅰ.壳聚糖─海藻酸盐微囊对胰岛素的控释作用

应用壳聚糖-海藻酸盐微囊技术制备了一系列胰岛素微囊，并研究了不同反应条件如海藻酸钠浓度、壳聚糖浓度、壳聚糖分子量及壳聚糖溶液pH值对微囊的胰岛素包封率及其释放性能的影响。结果表明，海藻酸钠浓度越高，微囊对胰岛素的包封率越高，在模拟小肠液中释放速率越低；壳聚糖浓度越大，微囊的胰岛素包封率及其在模拟胃液中释放率越高，在模拟肠液中释放达最大值所需时间越长；而随壳聚糖分子量减小，微囊在胃液中释放率增高；壳聚糖溶液pH值的变化对微囊的胰岛素包封率未造成明显影响。     

Physical alginate hydrogels based on hydrophobic or dual hydrophobic/ionic interactions: bead formation, structure, and stability

Hydrophobically associating alginate (AA) derivatives were prepared by covalent fixation of dodecyl or octadecyl chains onto the polysaccharide backbone (AA-C12/AA-C18). In semidilute solution, intermolecular hydrophobic interactions result in the formation of physical hydrogels, the physicochemical properties of which can be controlled through polymer concentration, hydrophobic chain content, and nonchaotropic salts such as sodium chloride. The mechanical properties of these hydrogels can then be reinforced by the addition of calcium chloride. The combination of both calcium bridges and intermolecular hydrophobic interactions leads to a decrease in the swelling ratio accompanied by an increase of elastic and viscous moduli. Beads made of hydrophobically modified alginate were obtained by dropping an aqueous solution of alginate derivative into a NaCl/CaCl2 solution. As compared to unmodified alginate beads, modified alginate particles proved to be stable in the presence of nongelling cations or calcium-sequestering agents. However, evidence is presented for a more heterogeneous structure than that of plain calcium alginate hydrogels with, in particular, an increase in the effective gel mesh size, as determined by partition and diffusion coefficient measurements.     

Formation of calcium alginate-based macroporous materials comprising chitosan and hydroxyapatite

Macroporous alginate hydrogels are prepared by the internal gelation method using crystalline saccharose. For this purpose, a sodium alginate solution containing D-glucono-δ-lactone and dispersed calcium carbonate particles was added to saccharose. Hydrolysis of D-glucono-δ-lactone gives rise to gradual acidification of the solution, which results in the decomposition of CaCO₃ with the release of calcium cations; the latter crosslink polysaccharide macromolecules via chelate complexes to cause the formation of a gel. Washing out saccharose with water results in the formation of pores separated by calcium alginate films with a thickness of smaller that 100 nm. It is shown that the proposed method can be applied to produce a composite material containing particles of hydroxyapatite, which is incorporated into implants to accelerate the repair of bone tissues. The particles are entrapped into alginate films. A cationic polysaccharide, chitosan, is additionally incorporated into the alginate materials for their reinforcement; its stabilizing action is achieved via the formation of a polyelectrolyte complex with negatively charged alginate macromolecules. Chitosan is incorporated by a new method, which consists in gradually charging the polysaccharide during the acidification of the solution as a result of D-glucono-δ-lactone hydrolysis. Materials thus prepared are characterized by different methods, including scanning electron microscopy, dynamic mechanical analysis, and porosimetry.     

Enhanced Sunscreen Effects via Layer-By-Layer Self-Assembly of Chitosan/Sodium Alginate/Calcium Chloride/EHA

The sunscreen nanocapsules were successfully synthesized by the way of layer-by-layer self-assembly using charged droplets (prepared by emulsification of LAD-30, Tween-80 and EHA (2-Ethylhexyl-4-dimethylaminobenzoate)) as templates. Chitosan/sodium alginate/calcium chloride were selected as wall materials to wrap EHA. The emulsions with the ratio of Tween-80 to EHA (1:1) were stable. A stable NEI negative emulsion can be obtained when the ratio of Tween-80 and LAD-30 was 9:1. Chitosan solutions (50 kDa, 0.25 mg/mL) and sodium alginate solutions (0.5 mg/mL) were selected to prepare nanocapsules. The nanocapsules were characterized via some physico-chemical methods. Based on the synergistic effects of the electrostatic interaction between wall materials and emulsifiers, EHA was effectively encapsulated. DLS and TEM showed that the sunscreen nanocapsules were dispersed in a spherical shape with nano-size, with the increasing number of assembly layers, the size increased from 155 nm (NEI) to 189 nm (NEII) to 201 nm (NEIII) and 205 nm after solidification. The release studies in vitro showed sustained release behavior of the nanocapsules were observed with the increase of the number of deposition layers, implying a good coating effect. The sunscreen nanocapsules could control less than 50% the release of EHA after crosslinking of calcium chloride and sodium alginate, which also could effectively avoid the stimulation of the sun protection agent on the skin.     

Preparation, Properties and Mechanism of Inhomogeneous Calcium Alginate Ion Cross-linking Gel Microspheres

Inhomogeneous calcium alginate ion cross-linking gel microspheres,a novel ion absorbent,were prepared by dropping a sodium alginate solution to a calcium chloride solutioin via an electronic droplet generator.Calcium alginate microspheres have uniform particle sizes.a smooth surface and a microporous structure.The electrode probe reveals the inhomogeneous distribution of calcium ions with the highest concentration on the surface,and the lowest concentration in the cores of the spheres.As a novel ion adsorbent,calcium alginate gel microspheres have a lower limiting adsorption mass concentration,a higher enrichment capacity and a higher adsorption capacity for Pb^2 than usual ion exchange resins.The highest percentage of the adsorption is 99.79%.The limiting adsorption mass concentration is 0.0426mg/L.The adsorption capacity for Pb^2 is 644mg/g,Calcium alginate gel microspheres have a much faster ion exchange velocity than D418 chelating resin and D113 polyacrylate resin.The moving boundary model was employed to interpret the ion exchange kinetics process,which indicates that the ion exchange process is controlled by intraparticle diffusion of adsorbable ions.So the formation of inhomogeneous gel microspheres reduces the diffusion distance of adsorbable ions within the spheres and enhances the ion exchange velocity.Alginate has a higher selectivity for pb^2 than for Ca^2 and the selectivity coefficient KCa^Pb is 316. As an ion cross-linking gel,calcium alginate inhomogeneous microspheres can effectively adsorb heavy metal Pb^2 at a higher selectivity and a higher adsorption velocity.It is a novel and good ion adsorbent.     

Preparation and Characterization of a Novel Drug Delivery System: Biodegradable Nanoparticles in Thermosensitive Chitosan/Gelatin Blend Hydrogels

A novel injectable in situ gelling drug delivery system (DDS) consisting of biodegradable N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) nanoparticles and thermosensitive chitosan/gelatin blend hydrogels was developed for prolonged and sustained controlled drug release. Four different HTCC nanoparticles, prepared based on ionic process of HTCC and oppositely charged molecules such as sodium tripolyphosphate, sodium alginate and carboxymethyl chitosan, were incorporated physically into thermosensitive chitosan/gelatin blend solutions to form the novel DDSs. Resulting DDSs interior morphology was evaluated by scanning electron microscopy. The effect of nanoparticles composition on both the gel process and the gel strength was investigated from which possible hydrogel formation mechanisms were inferred. Finally, bovine serum albumin (BSA), used as a model protein drug, was loaded into four different HTCC nanoparticles to examine and compare the effects of controlled release of these novel DDSs. The results showed that BSA could be sustained and released from these novel DDSs and the release rate was affected by the properties of nanoparticle: the slower BSA release rate was observed from DDS containing nanoparticles with a positive charge than with a negative charge. The described injectable drug delivery systems might have great potential application for local and sustained delivery of protein drugs.     

O-羧甲基壳聚糖纳米微粒制备及对Ni~(2+)吸附研究

将壳聚糖与氯乙酸反应,通过控制反应条件制备了取代度为0.71的O-羧甲基壳聚糖,将改性后的O-羧甲基壳聚糖与多聚磷酸钠反应,制备了粒径分布在370-710nm的O-羧甲基壳聚糖纳米微粒,透射电镜观察表明该微粒呈球状,平均粒径为450nm.在此基础上研究了O-羧甲基壳聚糖纳米微粒对工业电镀镍废水Ni~(2+)吸附性能,考察了溶液pH、Ni~(2+)起始浓度、平衡吸附时间、粒径等因素的影响,结果表明:O-羧甲基壳聚糖微粒最佳吸附条件是Ni~(2+)溶液pH为8.0、Ni~(2+)溶液起始浓度为33.28mg/ml、平衡吸附时间为0.5h、粒径较小的O-羧甲基壳聚糖纳米微粒对Ni~(2+)的吸附量要大于粒径较大的吸附量.     

Preparation of chitosan nanoparticles by spray drying,and their antibacterial activity

Chitosan nanoparticles were prepared from chitosan of different molecular weight by spray drying. The morphology of the particles was characterized by SEM, and size distribution and zeta potential were determined. The effects of chitosan solution concentration, molecular weight of chitosan, and size of the spray dryer nozzles on average size, size distribution and zeta potential of chitosan nanoparticles were investigated. The effects of chitosan nanoparticles and chitosan nanoparticles–amoxicillin complex on Staphylococcus aureus were also tested. The results showed that the average size of chitosan nanoparticles were in the range 95.5–395 nm and zeta potentials were 39.3–45.7 mV, depending on the concentration and molecular weight of the chitosan. The lower the concentration and molecular weight of the chitosan, the smaller the chitosan nanoparticles and the higher the zeta potential. Testing for antibacterial activity against S. aureus indicated that chitosan nanoparticles strongly inhibited growth of the bacteria; the minimum inhibitory concentration, 20 μg/mL, was lower than those of chitosan solution or amoxicillin. The antibacterial capacity of chitosan nanoparticles also depended on the size, zeta potential, and molecular weight of the chitosan. Complexation of chitosan nanoparticles with amoxicillin improved the antibacterial activity of amoxicillin.     

Shape-controlled production of biodegradable calcium alginate gel microparticles using a novel microfluidic device

In this paper we describe a novel method of manufacturing shape-controlled calcium alginate gel microparticles in a microfluidic device. Both manufacturing shape-controlled microparticles and synthesizing hydrogel microparticles could be performed simultaneously in the microfluidic device. The novel microfluidic device comprised of two individual flow-focusing channels and a synthesizing channel was successfully applied as a continuous microfluidic reactor to synthesize gel microparticles with size and shape control. By passive control based on the microchannel geometric confinement and liquid-phase flow rates, we succeeded in producing monodisperse sodium alginate microparticles with diverse shapes (such as plugs, disks, microspheres, rods, and threads) in the flow-focusing channels of the microfluidic device. The shape and size of the sodium alginate microparticles could be tuned by adjusting the flow rates of the various streams. Further stages of the chemical reaction could be initiated by mixing sodium alginate microparticles and calcium chloride (CaCl2) solution in the synthesizing channel. The shapes of the sodium alginate microparticles could be permanently preserved by the synthesis of calcium alginate gel microparticles. The preparation conditions of size- and shape-controlled calcium alginate microparticles and influence factors were studied.