Release performance and sustained-release efficacy of emamectin benzoate-loaded polylactic acid microspheres

High-performance liquid chromatography （HPLC） was employed to determine drug release rates based on emamectin benzoate concentrations in the medium. Release kinetics equations were used to fit the drug release behavior. The effects of particle size and release medium pH on the release rate were also investigated. The indoor toxicity of emamectin benzoate-loaded polylactic acid microspheres on the diamondback moth larva （Plutella xylostella） was studied to explore drug sustained-release performance. In acidic and neutral media, the drug release behavior of the microspheres was in accord with the first-order kinetics equation. Increasing the spray dosage of emamectin benzoate-loaded polylactic acid microspheres initially resulted in an equivalent insecticidal efficacy with the conventional emamectin benzoate microemulsion. However, the drug persistence period was four-fold longer than that observed using the conventional formulation. The developed emamectin benzoate-loaded polylactic acid microspheres showed dramatic sustained-release performance. A treatment threshold of greater than 35 mg mL-1 was established for an efficient accumulated release concentration of emamectin benzoate-loaded microspheres.

Study of targeted and controlled release of 5-fluorouracil-loaded PLA nanoparticles and microspheres on treatment of gastric tumor

The aim of this paper was to evaluate controlled release behavior and the therapeutic efficacy of 5-FU-loaded Poly(lactic acid) (PLA)microspheres to human gastric cancer xenograft, and the targeting effect of VEGF/5-FU loaded PLA nanoparticles. 5-FU-loaded PLA microspheres were prepared by an emulsion evaporation method, and were characterized by scanning electron microscopy (SEM). 5-FU loaded PLA nanoparticles were characterized by (TEM), and particle size analyzer determined the distribution of nanoparticles size. The release performances of 5-FU microspheres in vitro were studied in PH 7.4 phosphate buffered saline. The therapeutic efficacy of 5-FU-loaded PLA microspheres in vivo were studied using MGC-803 (human stomach cancer) xenograft. 32 nude mice were divided into four groups (n =8), 5-FU loaded PLA microspheres were injected at tumor site. VEGF121 monoclonal antibody was connected with 5-FU loaded PLA nanoparticles through carbodimide. The targeted effect of VEGF 5-FU loaded nanoparticles in vivo were observed by single photon emission computed tomography (SPECT) after tail vein injection at 1 h and 2 h. SEM observation showed that microspheres were spherical, and the diameters of two kinds of microspheres were 1 μm and 5 μm respectively. The mean diameter of nanoparticles was 191.0 nm, and the index of polydispersity was 0.202. The drug was released following biphasic kinetics, initial burst and the following steady phase. 1 μm and 5 μm 5-FU-loaded microspheres both resulted in increased life span (1 μm microspheres median survival time=40.63 days, 5 μm microspheres median survival time=62.25 days), against 5-FU pure drug (median survival time=14.5 days). These results strongly suggest that 5-FU-loaded PLA microspheres increase life span of nude mice bearing MGC-803 tumors. After injection for 2 h, almost all the VEGF/5-FU loaded PLA nanoparticles could centralize at the human gastric cancer xenograft sites. That demonstrated VEGF monoclonal antibody remain its bioactivity after connection with nanoparticles, VEGF/5-FU loaded PLA nanoparticles had very exact targeting function for gastric tumor xenograft.

Tissue Regeneration in Infected Wounds of Albino Rats Using Ciprofloxacin-Loaded Gelatin Microspheres Incorporated Collagen Scaffold: A Histological Approach with H&E Staining

A wound care system consisting of ciprofloxacin-loaded gelatin microspheres impregnated in a macroporous collagen scaffold was created to effectively control wound infection and regenerate soft tissue at the wound site.Histological and biochemical alterations were observed in infected wounds treated with these scaffolds in Albino Wistar rats.Furthermore,the study examined the immediate and prolonged release of ciprofloxacin from the scaffolds,as well as their function in eliminating bacterial infections and expediting the process of skin healing and regeneration.The developed technique was followed in the streamlined process of creating these collagen scaffolds.Compared to untreated wounds,the group receiving scaffold treatment experienced a faster rate of wound closure.It was noted that the rate of infections was considerably reduced and that full soft tissue regeneration occurred within 12 days.The development of well-deposited collagen bundles in the treated groups was demonstrated by H&E staining,which verified the flawless regeneration of the dermis and epidermis.The antimicrobial agent-loaded gelatin microspheres impregnated into the porous collagen scaffold demonstrated remarkable soft tissue regeneration and efficient infection control at the wound site.

Structure-Property Relationships and Models of Controlled Drug Delivery of Biodegradable Poly (D, L-lactic acid) Microspheres

An oil-in-water (O/W) solvent evaporation method was used to prepare biodegradable microspheresbased on poly(D,L-lactic acid) (PLA). Nifedipine, a hydrophobic drug, was chosen as a model molecule in the studyof drug entrapment and release. Effect of preparation conditions on the size, morphology, drug loading, and releaseprofiles of micropheres was investigated. Based on in vitro release experimental findings, a diffusion/dissolutionmodel was presented for quantitative description of the resulting release behaviors and drug release kinetics fromPLA microspheres analyzed. The mathematical models were used to predict the effect of microstructure on theresulting drug release. It provided an approach to determine the suitable structure parameters for microspheres toachieve desired drug release behaviors.

Preparation, Characterization and Drug-Release Behaviors of Crosslinked Chitosan/Attapulgite Hybrid Microspheres by a Facile Spray-Drying Technique

A series of chitosan/attapulgite (CTS/APT) hybrid microspheres were prepared by a facile spray-drying technique. The developed hybrid microspheres were characterized by Fourier transform infrared spectra (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and the zeta potential. The encapsulation efficiency and in vitro controlled release properties of the microspheres for drug were evaluated using diclofenac sodium (DS) as a model drug. Results indicated that the introduction of APT into crosslinked CTS microspheres can achieve narrow size distribution and make them more uniform. The isoelectric point of the microspheres increased from 8.14 to 9.18 with increasing the content of APT to 10 wt.%. DS loaded in hybrid microspheres is hardly released in simulated gastric fluid, but quickly released in simulated intestinal fluid. The electrostatic interaction between hybrid microspheres and DS can improve the encapsulation efficiency and controlled release behavior of CTS/APT microspheres, and the release mechanism fits Fickian diffusion.

Preparation and Characterization of IPN Microspheres for Controlled Delivery of Naproxen

Interpenetrating network (IPN) microspheres of sodium alginate (NaAlg) and poly (vinyl alcohol) (PVA) were prepared and crosslinked with glutaraldehyde (GA) by using the water in oil (W/O) emulsification method to deliver naproxen sodium (NS). NS was successfully encapsulated into IPN microspheres in different ratios of NaAlg and PVA (w/w), drug loading percentage (w/w) and crosslinking time. Crosslink density of the matrices was affected by the time of crosslinker. The prepared microspheres were characterized by Fourier transform infrared spectroscopy (FTIR). Pictures of selected microspheres were determined using optic microscope. Results confirmed the dispersion of NS in the microspheres. Release of NS from the microspheres was investigated in pH 1.2, 6.8 and 7.4 media for two hours respectively. The highest NS release was obtained as 92% (w/w) by using UV spectroscopy. Equilibrium swelling was performed in pH 7.4 buffer solution at 37℃.

Drug-nanoencapsulated PLGA microspheres prepared by emulsion electrospray with controlled release behavior

The development of modern therapeutics has raised the requirement for controlled drug delivery system which is able to efficiently encapsulate bioactive agents and achieve their release at a desired rate satisfying the need of the practical system.In this study,two kind of aqueous model drugs with different molecule weight,Congo red and albumin from bovine serum(BSA)were nanoencapsulated in poly(DL-lactic-co-glycolic acid)(PLGA)microspheres by emulsion electrospray.In the preparation process,the aqueous phase of drugs was added into the PLGA chloroform solution to form the emulsion solution.The emulsion was then electrosprayed to fabricate drugnanoencapsulated PLGA microspheres.The morphology of the PLGA microspheres was affected by the volume ratio of aqueous drug phase and organic PLGA phase(V_(w)/V_(o))and the molecule weight of model drugs.Confocal laser scanning microcopy showed the nanodroplets of drug phase were scattered in the PLGA microspheres homogenously with different distribution patterns related to V_(w)/V_(o).With the increase of the volume ratio of aqueous drug phase,the number of nanodroplets increased forming continuous phase gradually that could accelerate drug release rate.Moreover,BSA showed a slower release rate from PLGA microspheres comparing to Congo red,which indicated the drug release rate could be affected by not only V_(w)/V_(o)but also the molecule weight of model drug.In brief,the PLGA microspheres prepared using emulsion electrospray provided an efficient and simple systemto achieve controlled drug release at a desired rate satisfying the need of the practices.

Fabrication of hollow porous PLGA microspheres for controlled protein release and promotion of cell compatibility

This letter reports on the fabrication of hollow,porous and non-porous poly（D,L-lactide-co-glycolide） （PLGA） microspheres（MSs） for the controlled release of protein and promotion of cell compatibility of tough hydrogels.PLGA MSs with different structures were prepared with modified double emulsion methods,using bovine serum albumin（BSA） as a porogen during emulsification.The release of the residual BSA from PLGA MSs was investigated as a function of the MS structure.The hollow PLGA MSs show a faster protein release than the porous MSs,while the non-porous MSs have the slowest protein release.Compositing the PLGA MSs with poly（vinyl alcohol）（PVA） hydrogels promoted chondrocyte adhesion and proliferation on the hydrogels.

Preparation of PLLA/bpV(pic) Microspheres and Their Effect on Nerve Cells

In this study, we prepared PLLA/bpV（pic） microspheres, a bpV（pic） controlled release system and examined their ability to protect nerve cells and promote axonal growth. PLLA microspheres were prepared by employing the o/w single emulsification-evaporation technique. Neural stem cells and dorsal root ganglia were divided into 3 groups in terms of the treatment they received： a routine medium group（cultured in DMEM）, a PLLA microsphere group（DMEM containing PLLA microspheres alone） and a PLLA/bpV（pic） group [DMEM containing PLLA/bpV（pic） microspheres]. The effects of PLLA/bpV（pic） microspheres were evaluated by the live-dead test and measurement of axonal length. Our results showed that PLLA/bpV（pic） granulation rate was（88.2±5.6）%; particle size was（16.8±3.1）%, drug loading was（4.05±0.3）%; encapsulation efficiency was（48.5±1.8）%. The release time lasted for 30 days. In PLLA/bpV（pic） microsphere group, the cell survival rate was（95.2 ±4.77）%, and the length of dorsal root ganglion（DRG） was 718±95 μm, which were all significantly greater than those in ordinary routine medium group and PLLA microsphere group. This preliminary test results showed the PLLA/bpV（pic） microspheres were successfully prepared and they could promote the survival and growth of neural cells in DRG.

NaClO_(2)复合凝胶微球控释降解气态甲醛

甲醛是最主要的室内VOC污染源之一,目前常用多孔材料加以吸附。然而,这些吸附材料的吸附能力和使用周期均有限。亚氯酸钠(NaClO_(2))在酸性条件下释放得到二氧化氯(ClO_(2)),可将甲醛氧化为二氧化碳。但NaClO_(2)在常规条件下易于吸湿和分解,极不稳定。采用乳化交联法将NaClO_(2)作为芯材,将具有高生物相容性的天然高分子材料海藻酸钠(SA)和羧甲基纤维素钠(CMC-Na)作为壁材,制备NaClO_(2)复合凝胶微球以提高其稳定性和缓释性能。借助SEM、DLS、FTIR、TGA等分析测试仪器对所得微球进行形貌、官能团及热性能表征,并通过降解实验评价NaClO_(2)复合凝胶微球去除气态甲醛的能力。结果表明,制备的NaClO_(2)复合凝胶微球呈现规整球形,平均粒径为662.5 nm,具备良好的热稳定性能;当pH为6.5,甲醛初始质量浓度为4 mg/m^(3)时,250 mgNaClO_(2)复合凝胶微球表现出持续降解甲醛的能力,在前5 min对甲醛的降解率已达60.00%,30 min时对甲醛的降解率可至90.45%。由此可见,NaClO_(2)复合凝胶微球有望用于空调滤网或者室内装饰纺织品,起到吸附甲醛、净化室内空气的功效。

药物递送微球的制备及其在肿瘤治疗领域的应用

微球是一种理想的药物递送系统,为肿瘤治疗提供了新的手段。负载在微球中的抗肿瘤药物能够以可控且持续的方式释放,从而增强疗效,降低药物的副作用和毒性。药物递送微球的制备方法包括乳化溶剂挥发法、相分离法、喷雾干燥法、微流控技术等。这些方法具有各自的优势及局限。根据制备材料的不同,药物递送微球可分为天然聚合物微球、合成聚合物微球和生物陶瓷微球。天然聚合物微球具有良好的生物相容性和可降解性,合成聚合物微球机械性能优异,生物陶瓷微球因其具有生物相容性和特定的生物功能而广泛应用于骨组织工程领域。药物递送微球治疗肿瘤的方式多种多样,除传统的化疗外,还包括光热疗法、光动力疗法、放射性栓塞治疗和免疫治疗等。本文综述了当前微球作为纳米药物递送系统在肿瘤治疗中的最新进展,以期为微球的临床转化和推广应用提供参考。

原位制备ZIF-8/纤维素微球及其控制释放5-氟尿嘧啶的研究

在纤维素微球(CM)上设计了沸石型咪唑骨架材料8/纤维素复合微球(ZIF-8@CM)作为5-氟尿嘧啶(5-FU)的载体并对5-FU进行控制释放。以CM、硝酸锌和2-甲基咪唑为原料,采用原位法制备了ZIF-8@CM。通过氢键、静电相互作用和π-π堆积作用将5-FU加载到ZIF-8@CM上。利用扫描电子显微术、能量色散X射线分析法、傅里叶变换红外光谱法、X射线衍射、X射线光电子能谱法和热重分析对样品进行表征,结果表明成功制备了ZIF-8@CM,并在ZIF-8@CM上成功加载了5-FU。ZIF-8@CM对5-FU的负载量可达74.10 mg·g^(-1),远高于CM(2.84 mg·g^(-1))。此外,ZIF-8@CM-5-FU可在pH=5.0的磷酸缓冲溶液(PBS)环境下持续释放5-FU 600 min,释放量达到63.4%,但在pH=7.4的PBS环境下仅释放37.6%。5-FU的释放遵循一级动力学和Fickian扩散机制。在细胞实验中已证实ZIF-8@CM具有良好的生物相容性和极低的细胞毒性,是5-FU安全释放的合适载体。本研究为设计一种5-FU的新型载体提供了思路。

In Vitro Cytotoxicity and Protein Drug Release Properties of Chitosan/Heparin Microspheres

Chitosan/heparin microspheres were prepared using the water-in-oil emulsification solvent evaporation technique. The microsphere diameters were controlled by selecting the fabrication process parameters. Scanning electron micrographs showed that the chitosan/heparin microspheres were regular and the surface morphology was smooth. Fourier transform infrared showed that the chitosan amino groups reacted with heparin carboxylic groups to form acylamides in the microspheres. Analysis of the microsphere cytotoxicity showed that they had no cytotoxic effect and behaved very similar to the negative control （polystyrene）. To analyze the protein drug release profiles of the microspheres, bovine serum albumin was loaded as a model drug into the microspheres and released in vitro. Marked retardation was observed in the BSA release profiles. The results show that chitosan/heparin microspheres may provide a useful controlled release protein drug system for used in pharmaceutics.

TGF-β1壳聚糖缓释微球的制备和体外检测

【目的】通过制备新型的转化生长因子鄄茁1(TGF鄄茁1)缓释系统,并对其载药、体外释药及降解特性进行检测,评估应用生物可降解壳聚糖微球作为TGF鄄茁1控制释放载体的可行性。【方法】应用三聚磷酸钠(TPP)作为交联剂,以乳化交联法制备具有控制释放功能的负载TGF鄄茁1的壳聚糖微球;以牛血清白蛋白(BSA)作为模板蛋白,应用相同的方法制备负载BSA的微球。应用扫描电镜、微镜粒度分、药物包封率测定、体外药物释放动力学检测等方法分析微球的特性。【结果】制备的微球球形良好,球体表面光滑,具有较高的TGF鄄茁1包封效率90.1%)。持续7d的药物释放试验表明,BSA与TGF鄄茁1两种蛋白均可以从微球中缓慢释放,其中TGF鄄茁1的释放率低于BSA的释放率。溶菌酶溶液降解作用下,4周的体外降解过程中,可见微球质量持续下降并伴有明显的微球形貌改变。【结论】应用乳化交联法可制备负载TGF鄄茁1的壳聚糖缓释微球。这种新型药物控制释放系统在细胞因子的控制释放及软骨组织工程中有潜在的应用价值。

生物降解聚酯包埋利福平缓释微球的制备及释放行为

以生物可降解乙交酯和丙交酯的无规共聚物 ( PL GA )为载体 ,将抗结核病药利福平溶解于 PLGA的有机溶液中 ,采用通常乳化 -溶剂挥发方法制备了药物缓释微球 .研究了影响微球制备的工艺条件 .用电子显微镜观察了微球及降解后的表面形态 ,测定了微球粒径及载药量 ,评价了载药微球的体外释放行为 .结果表明 ,以质量分数为 1%的明胶为稳定剂 ,制备的微球形态完整 ,粒径范围为 10～ 30 μm,微球中利福平的平均质量分数为 2 4 .3% .体外释药时间可以通过高分子的降解速率来调控 ,本实验的释药时间可以在 4 2～84 d之间调控 ,药物缓释达到了理想的零级动力学释放 .因此 ,利福平 PL GA微球具有显著的长效、恒量药物缓释作用 .

尺寸均一的壳聚糖微球的制备及其作为胰岛素控释载体的研究

采用新型微孔膜乳化技术制备了载胰岛素的壳聚糖微球。研究表明,要制备粒径均一的壳聚糖微球,必须将亲水性膜修饰成疏水性;制得的微球粒径和所采用的膜孔径之间存在很好的线性关系,使得微球粒径可控;以胰岛素为模型药物,主要考察了交联剂用量和交联时间对微球表面形态、药物包埋率和微球体外释药特性的影响。结果表明当氨基与醛基的摩尔比为1∶0.7、交联时间为1h时,所得载药微球的包埋率最高,随着戊二醛用量的增加和交联时间的延长,药物体外释放速率减慢。

磁性顺铂微球的药物控释研究

目的：改善磁性顺铂微球的药物突释和滞释，实现控释。方法：用不同的工艺制备磁性顺铂微球并进行体外、体内药物释放的测定。结果：当高分子骨架材料中，疏水性纤维多糖含水解键的苯酐聚合物＝７∶３，搅拌速度１５００ｒ·ｍｉｎ－１，成型温度２０℃时，制备的磁性顺铂微球具有较好的控释特性。

振荡磁场下超顺磁性链霉素PELA微球体外药物释放特征探索

目的制备超顺磁性硫酸链霉素-聚乳酸-聚乙二醇(PELA)微球(superparamagnetic chitosan streptomycin PELA micro-spheres,spCSPM),研究此微球的特性,并对其在振荡磁场作用下体外药物释放规律进行研究。方法用化学共沉淀法合成纳米超顺磁Fe304壳聚糖纳米粒(superparamagnetic chitosan Fe3O4 nanospheres,spFCN),再用双乳化(W/O/W)溶剂蒸发法制备spCSPM。将spCSPM混合入兔血中形成血凝块,在37℃模拟体液中进行体外药物溶出试验,用振荡磁场干预,用酶联免疫法(ELISA)检测硫酸链霉素的释放量。结果振荡磁场能够增加spCSPM血凝块中链霉素释放速率,与非磁性的壳聚糖聚乳酸-聚乙二醇(PELA)微球(chitosan streptomycin PELA microspheres,CSPM)相比,26d时使药物释放量提高3倍左右。结论spCSPM具有药物缓释功能,振荡磁场可重复性增加体系中药物的溶出,此体系药物缓释周期超过三周。

海藻酸盐控释微球的制备及其体外释药特性

研制白蛋白海藻酸钠(BSA-海藻酸钙微球)控释微球,并对其体外释药特性等进行考察,为应力控释VEGF促进组织工程骨血管化提供理论依据。以海藻酸钠为载体,采用W/O乳化-离子交联法制备BSA-海藻酸钙微球;检测粒径大小、外观、包封率等理化特性;考察微球的体外释药特性。微球球形圆整,分散性好,平均粒径为230±60μm,载药量达80.3μg/mg,包封率为61%;微球的体外释药速率平稳,周期达2周余。海藻酸钠可以作为蛋白、多肽类药物的可生物降解辅料;乳化离子交联法的制备工艺简便,有利于蛋白、多肽类药物结构和功能的稳定性并有效延长其作用时间。