Increased in vitro leishmanicidal activity of octyl gallate loaded poly(methyl methacrylate) nanoparticles

The current paucity of effective and affordable drugs for the treatment of leishmaniasis renders the search for new therapeutic alternatives a priority. Gallic acid-related compounds display anti-parasitic activities and their incorporation into drug carrier systems, such as polymeric nanoparticles may be a viable alternative for leishmaniasis treatment. Therefore, this study focused on the synthesis and characterization of octyl gallate (G8) loaded poly(methyl methacrylate) (PMMA) nanoparticles via miniemulsion polymerization in order to increase the leishmanicidal activity of this compound. G8 loaded PMMA nanoparticles presented a spherical morphology with a mean size of 108?nm, a negatively charged surface (?33?±?5?mV) and high encapsulation efficiency (83% ± 5). Fourier-transform infrared spectroscopy and X-ray diffraction analysis confirmed that G8 was encapsulated in PMMA nanoparticles and presented a biphasic release profile. The G8 loaded PMMA nanoparticles did not present cytotoxic effect on human red blood cells. G8 loaded PMMA nanoparticles displayed a leishmanicidal activity almost three times higher than free G8 while the cytotoxic activity against human THP-1 cells remained unchanged.     

Investigation of solute permeation across hydrogels composed of poly(methyl vinyl ether‐co‐maleic acid) and poly(ethylene glycol)

Objectives Swelling kinetics and solute permeation (theophylline, vitamin B₁₂ and fluorescein sodium) of hydrogels composed of poly(methyl vinyl ether‐co‐maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG) are presented. Methods The effects of PMVE/MA and PEG 10 000 content on swelling behaviour (percentage swelling, the type of diffusion and swelling rate constant) were investigated in 0.1 m phosphate buffer. Network parameters, such as average molecular weight between crosslinks (M_c) and crosslink density, were evaluated. Key findings The percentage swelling and M_c of hydrogels increased with decrease in PMVE/MA content, where the water diffusion mechanism into the hydrogels was Class‐II type. In contrast, increase in PMVE/MA content caused an increase in the crosslink density. Permeation of theophylline, vitamin B₁₂ and fluorescein sodium, with increasing hydrodynamic radii, was studied through the equilibrium swollen hydrogels composed of PMVE/MA and PEG. In general, the permeability and diffusion coefficients of all three solutes decreased with increase in the PMVE/MA content. In addition, permeability and diffusion coefficient values increased with decreases in the hydrodynamic radii of the solute molecules. Conclusions The hydrogels have shown a change in swelling behaviour, crosslink density, M_c and solute permeation with change in PMVE/MA content, thus suggesting a potential application in controlled drug‐delivery systems.     

One-step preparation of amino-PEG modified poly(methyl methacrylate) microchips for electrophoretic separation of biomolecules

A simple method for a chemical surface modification of poly(methyl methacrylate) (PMMA) microchips with amino-poly(ethyleneglycol) (PEG–NH₂) by nucleophilic addition–elimination reaction was developed to improve the separation efficiency and analytical reproducibility in a microchip electrophoresis (MCE) analysis of biomolecules such as proteins and enantiomers. In our procedure, the PEG chains were robustly immobilized only by introducing an aqueous solution of PEG–NH₂ into the PMMA microchannel. The electroosmotic mobilities on the modified chips remained almost constant during 35 days with 37 runs without any recoating. The PEG–NH₂ modified chip provided a fast, reproducible, efficient MCE separation of proteins with a wide variety of isoelectric points within 15 s. Furthermore, the application of the modified chip to affinity electrophoresis using bovine serum albumin gave a good chiral separation of amino acids.     

高分子材料对卡铂-乳酸/羟基乙酸共聚物微球体外性质的影响

目的:制备卡铂-乳酸／羟基乙酸共聚物(poly(lactic-co-glycolic acid),PLGA)微球,比较不同PLGA所得微球的体外释药特点。方法:采用乳化-溶剂挥发法制备卡铂-PLGA微球,显微镜下测定微球的粒径和粒径分布。采用电感耦合等离子体质谱(ICP-MS)测定微球含药量,计算包封率,考察微球体外释药行为。结果:PLGA来源和规格不同,对微球的形态、粒径、载药量和包封率没有明显影响,所得微球球形较好,平均粒径为38-54μm,含药量为6．4-7．2μg·mg-1,包封率16．3％-22．7％。药物体外释放行为随PLGA不同而有很大差异,PLGA 50／50微球突释快,突释率高。PLGA(50／50,η=0．18)和PLGA(50／50,η=0．53)的微球2 h药物突释率分别为55．06％和83．10％;PLGA(75／25,η=0．19)和PLGA(75／25,η=0.30)的微球12 h药物突释率分别为38．43％和44．04％。缓慢释放期PLGA(50／50,η=0．53)微球释药符合零级释放模型,其他3种材料的微球符合Higuchi释放方程,PLGA (50／50,η=0．18)和PLGA(75／25,η=0．19)微球体外较好地控制药物释放,缓释期药物释放速度常数分别为1．18和2.40 h-1/2。结论:PLGA来源和组成不同,制备的微球体外释药行为差异较大。PLGA(75／25,η=0．19)微球体外较好地控制卡铂的释放。     

Chitosan-functionalised poly(2-hydroxyethyl methacrylate) core-shell microgels as drug delivery carriers: salicylic acid loading and release

This work presents the evaluation of chitosan-functionalised poly(2-hydroxyethyl methacrylate) (CS/PHEMA) core-shell microgels as drug delivery carriers. CS/PHEMA microgels were prepared by emulsifier-free emulsion polymerisation with N,N?′-methylenebisacrylamide (MBA) as a crosslinker. The study on drug loading, using salicylic acid (SA) as a model drug, was performed. The results showed that the encapsulation efficiency (EE) increased as drug-to-microgel ratio was increased. Higher EE can be achieved with the increase in degree of crosslinking, by increasing the amount of MBA from 0.01?g to 0.03?g. In addition, the highest EE (61.1%) was observed at pH 3. The highest release of SA (60%) was noticed at pH 2.4, while the lowest one (49.4%) was obtained at pH 7.4. Moreover, the highest release of SA was enhanced by the presence of 0.2 M NaCl. The pH- and ionic-sensitivity of CS/PHEMA could be useful as a sustained release delivery device, especially for oral delivery.     

Microencapsulation of ovalbumin in poly(lactide-co-glycolide) by an oil-in-oil (o/o) solvent evaporation method

Abstract

The objective of this study was to produce biodegradable poly(lactide-co-glycolide) (PLGA; 50/50) microspheres by an oil-in-oil (o/o) solvent evaporation method to prolong the in vitro release of ovalbumin (OVA) as a model protein. The effects, on loading efficiency, microsphere yield, morphology and drug release, of two dispersing agents, aluminum tristearate and Span 80, in mineral oil were examined. PLGA 50/50 microspheres containing OVA powder (sieved through a 53 μm mesh) were prepared using an o/o solvent evaporation method. When aluminum tristearate was employed as a dispersing agent, the loading efficiency and yield of OVA had maximum values of 89 and 72% at 0·15% (w/v) aluminum tristearate, respectively. Morphology studies suggested that the obtained microspheres were spherical, and had a smooth surface. The diameters of the microspheres ranged between 100 and 200 μm. The loading efficiency, or yield, for microspheres decreased significantly above or below 0·15% (w/v) aluminum tristearate, and microspheres wkh irregular shapes were observed. The minimum sedimentation volume ratio (F) was obtained at a dispersity of carbon black particles in ethanol containing 0·15% (w/v) aluminum tristearate by a sedimentation study, and the cloudy supernatant suggested a defiocculated suspension. However, on the contrary, when Span 80 was added into the mineral oil as a dispersing agent, the concentration of Span 80 had little or no effect on the characteristics of the prepared microspheres. Drug loadings (60–70%) were obtained within the Span 80 concentrations employed in the present study (0·05–1·0% (w/v)). The yields were also in the same levels. The microspheres prepared in mineral oil containing Span 80 had an average diameter less than 50 μm in all cases. Sustained-release characteristics were demonstrated for PLGA microspheres prepared in mineral oil containing aluminum tristearate as a dispersing agent, even though a burst release at the initial phase was observed. This initial burst release from PLGA microspheres was reduced to some extent by micronization of the OVA powder using a planetary-type ball mill. However, PLGA microspheres prepared in mineral oil containing Span 80 as a dispersing agent, exhibited a large initial burst release. This burst release seems to be due to the smaller size of microspheres and the OVA powder adhering to the surface of PLGA microspheres (confirmed by scanning electron microscope (SEM) study).     

The Stability of Recombinant Human Growth Hormone in Poly(lactic-co-glycolic acid) (PLGA) Microspheres

Purpose. The development of a sustained release formulation for recombinant human growth hormone (rhGH) as well as other proteins requires that the protein be stable at physiological conditions during its in vivo lifetime. Poly(lactic-co-glycolic acid) (PLGA) microspheres may provide an excellent sustained release formulation for proteins, if protein stability can be maintained. Methods. rhGH was encapsulated in PLGA microspheres using a double emulsion process. Protein released from the microspheres was assessed by several chromatrographic assays, circular dichroism, and a cell-based bioassay. The rates of aggregation, oxidation, diketopiperazine formation, and deamidation were then determined for rhGH released from PLGA microspheres and rhGH in solution (control) during incubation in isotonic buffer, pH 7.4 and 37°C. Results. rhGH PLGA formulations were produced with a low initial burst (<20%) and a continuous release of rhGH for 30 days. rhGH was released initially from PLGA microspheres in its native form as measured by several assays. In isotonic buffer, pH 7.4 and 37°C, the rates of rhGH oxidation, diketopiperazine formation, and deamidation in the PLGA microspheres were equivalent to the rhGH in solution, but aggregation (dimer formation) occured at a slightly faster rate for protein released from the PLGA microspheres. This difference in aggregation rate was likely due to the high protein concentration used in the encapsulation process. The rhGH released was biologically active throughout the incubation at these conditions which are equivalent to physiological ionic strength and pH. Conclusions. rhGH was successfully encapsulated and released in its fully bioactive form from PLGA microspheres over 30 days. The chemical degradation rates of rhGH were not affected by the PLGA microspheres, indicating that the internal environment of the microspheres was similar to the bulk solution. After administration, the microspheres should become fully hydrated in the subcutaneous space and should experience similar isotonic conditions and pH. Therefore, if a protein formulation provides stability in isotonic buffer, pH 7.4 and 37°C, it should allow for a safe and efficacious sustained release dosage form in PLGA microspheres.     

Characterization and antitumor efficacy of poly(L-lactid acid)-based etoposide-loaded implants

Etoposide is widely used in the chemotherapy of a variety of malignancies. But the strong lipophilicity, poor bioavailability, and severe side effects of etoposide limit its clinical application. The aim of this study was to develop sustained-release etoposide-loaded implants and evaluate antitumor activity of the implants after intratumoral implantation. We prepared the implants containing etoposide, poly(L-lactid acid) and polyethylene glycol 4000 by the direct compression method. The implants were characterized regarding drug-excipient compatibility, content uniformity, morphology, sterility, in vitro, and in vivo release profiles. Then the antitumor activity of the implants was tested in xenograft model of A549 human non-small cell lung cancer. SEM images displayed smooth surface of the implant and indicated that etoposide was homogeneously dispersed in the polymeric matrix. The results of content uniformity met the requirements of the Chinese Pharmacopoeia. Both in vitro and in vivo release profiles of the implants were characterized by high burst release followed by sustained release of etoposide. Intratumoral implantation of etoposide-loaded implants could efficiently delay the tumor growth. Furthermore, increasing the dose of implants led to higher tumor suppression rate without adding systemic toxicity. These results indicated that etoposide-loaded implants have significant antitumor efficacy in xenograft model without dose-limiting side effects and they possess a strong potential to be used as an intratumoral chemotherapy option for lung cancer treatment.     

效应面法优化盐酸昂丹司琼微球的制备工艺

目的：优化盐酸昂丹司琼聚乳酸乙醇酸嵌段共聚物（PLGA）微球的处方工艺。方法：o／o型乳化溶剂挥发法制备微球，采用小复合设计安排实验，考察盐酸昂丹司琼和PLGA的重量比（X1）、PLGA在内相中的浓度（X2）以及正己烷加入的时间（X3）对微球性质的影响。微球性质的评价指标是包封率（Y1）、载药量（Y2）、粒径（Y3）、体外释曲曲线零级方程拟合的相关系数（Y4）和16d的累积释放度（Y5）。根据最佳数学模型绘制效应面图，通过效应面法优化制备工艺。结果：最优工艺：X1为1：10，X2为32％，X3为65min。按照优化工艺制备的微球的包封率为50．69％，载药量4．6l％，粒径为58μm，体外释药曲线符合零级释放（r=0．99），16d的累积释放度约为91％。优化工艺的预测值和实洲值比较接近。结论：采用效应面法完成了盐酸昂丹司琼微球的多目标优化。     

水溶性添加剂对聚乳酸-聚乙烯醇酸共聚物基质释药动力学的影响

目的选择不同亲水性及空间构型的添加剂，研究其对聚乳酸-聚乙烯醇酸共聚物(poly lactic-co-glycolic acid, PLGA)药物释放动力学的影响，为心血管药物局部用药控释制剂的研究提供理论依据。方法用抗细胞增生药物2-氨基色酮(U-86)作为代表性药物，用溶剂浇铸和压膜结合的方法制备药物/PLGA/添加剂双层膜，在37 ℃磷酸缓冲液中测定体外药物释放并用扫描电镜观察表面形态。结果水溶性添加剂明显地提高了U-86的释放率，并转变为近似的单阶段模式。药物释放速率与基质的失重速率非常吻合。水溶性添加剂的基质在水中形成高度多孔的结构。结论添加剂的水溶性、分子量大小及空间构型等对于聚合物基质的孔隙结构具有决定性作用，而这些孔隙结构的特征又影响着药物释放机制以及释放动力学模式。     

紫杉醇PLGA微球制备及体外性质评估

目的：以乳酸-羟基乙酸共聚物（PLGA）为材料,制备用于肿瘤内注射的紫杉醇PLGA长效缓释微球.方法：采用改良溶剂蒸发法制备,对微球的体外性质以及不同剂量（10,15,25 kGy）60Coγ射线对微球性质的影响进行考察.结果：制得的微球形态圆整,载药量、包封率、平均粒径和跨距分别为1.53%,97.29%,42.72μm和0.95.药物体外释放30 d累计释放达到56.19%,体外降解30 d后微球失去完整结构,表面粗糙.3个剂量60Coγ射线的灭菌效果均良好,且对微球的体外性质均无明显影响.微球中二氯甲烷的残留量低于药典规定的限度.结论：紫舷杉醇PLGA微球满足缓释长效的要求,对恶性肿瘤的间质化疗具有一定前景.     

超氧化物歧化酶乳酸-羟乙酸共聚物微球的制备及其性质

利用复乳溶剂挥发法制备了超氧化物歧化酶（SOD）的乳酸－羟乙酸共聚物（PLGA）微球，考察了各工艺因素对微球粒径、包封率等的影响，通过扫描电子显微镜（SEM）、差示扫描量热分析（DSC）初步研究了其性质，结果表明，通过调整内水相的体积及浓度，分散相体积及PH值，可得到较高包封率，粒径在20－30μm，形态圆整，表面多孔的SOD微球，DSC表明SOD被有效地包入了PLGA微球中。     

Microencapsulation of lobster carotenoids within poly(viny1 alcohol) and poly(D,L-lactic acid) membranes

Abstract

The use of natural pigments such as lobster carotenoids in fish feed formulations offers advantages over the use of the synthetic alternatives. Microencapsulation of the pigments, with or without the addition of antioxidants to the formulation, may be of benefit in terms of stabilizing pigment colour. In the present study, lobster carotenoids were extracted from lobster shell into petroleum ether and microencapsulated by phase separation and salt coacervation within poly(viny1 alcohol) and poly(viny1 alocohol)/poly(D,L-lactic acid) membranes. Spherical microcapsules, with smooth, thin and resilient membranes were obtained with mean diameters ranging from 50 to 150μm, depending on the membrane material, and source of pigment. The microcapsules were pink-orange in colour, and colour stability was followed spectrophotometrically. Enhanced stability was observed in both membrane materials, in comparison to the non-encapsulated control. Rates of discoloration were determined under a variety of storage conditions, including the absence of light, reduced temperatures and under nitrogen atmosphere. The best stability of lobster carotenoids was observed under a nitrogen atmosphere within PVA/PLA membranes, representing an 11-fold enhancement of pigment stability in comparison to the controls. Under ambient conditions, the enhancement in pigment stability was approximately 6-fold. The optimum concentration of PVA during microencapsulation was 3–4%, and the microencapsulated pigments appeared most stable under acidic conditions. The rate of discoloration appeared independent of pigment concentration.     

The pharmacokinetics of recombinant human interferon-alpha-2b poly(lactic-co-glycolic acid) microspheres in rats

Interferon-alpha2b (IFN α-2b) microspheres were prepared at various concentrations (5%, 10%, 15%, 20% and 25%) and viscosities (0.39, 0.6, 0.89 and 1.13?dL/g) of poly(lactic-co-glycolic acid) (PLGA) using double emulsion solvent evaporation. The optimal formulation of IFN α-2b microspheres was determined to be 0.89?dL/g PLGA, as assessed by the in vitro release test. The pharmacokinetics of IFN α-2b microspheres was investigated. Nine groups of rats were injected intramuscularly with three doses (0.5, 1 and 2?MIU) of commercial lyophilized IFNα-2b injection or IFN α-2b microspheres. At a dose of 0.5?MIU, the IFN α-2b microsphere released significantly longer than that of the IFN α-2b injection. At a dose of 2?MIU, each pharmacokinetics parameter of microspheres prepared with the IFNa-2b stock solution was manifestly greater than those of the injection. Our study indicated that the IFN α-2b microspheres prepared in 15% of 0.89?dL/g PLGA provided a sustained drug effect for up to 21 days in rats.     

Pharmacokinetic and pharmacodynamic profiles of recombinant human erythropoietin-loaded poly(lactic-co-glycolic acid) microspheres in rats

Aim:

To characterize the pharmacokinetic and pharmacodynamic profiles of the recombinant human erythropoietin (rhEPO)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres in rats.

Methods:

The rhEPO-loaded microspheres were prepared using a solid-in-oil-in-water emulsion method. Pharmacokinetics and pharmacodynamics of the rhEPO-loaded microspheres were evaluated in male Sprague-Dawley rats. The serum rhEPO level was determined with ELISA. The level of anti-rhEPO antibody in the serum was measured to assess the immunogenicity of rhEPO released from the microspheres.

Results:

rhEPO was almost completely released from the PLGA microspheres in vitro, following zero-order release kinetics over approximately 30 d. After intramuscular injection (10 000 or 30 000 IU rhEPO/kg) in the rats, the serum rhEPO concentration reached maximum levels on d 1, then decreased gradually and was maintained at nearly steady levels for approximately 4 weeks. Furthermore, the release of rhEPO from the PLGA microspheres was found to be controlled mainly by a dissolution/diffusion mechanism. A good linear correlation (R²=0.98) was obtained between the in vitro and in vivo release data. A single intramuscular injection of the rhEPO-loaded PLGA microspheres (10 000 or 30 000 IU rhEPO/kg) in the rats resulted in elevated hemoglobin and red blood cell concentrations for more than 28 d. Moreover, the immunogenicity of rhEPO released from the PLGA microspheres was comparable with that of the unencapsulated rhEPO.

Conclusion:

The results prove the feasibility of using the PLGA-based microspheres to deliver rhEPO for approximately 1 month.     

雷公藤甲素聚乳酸纳米粒的制备及毒性

目的探索可生物降解聚乳酸［poly(D,L-lactic acid)，PLA］纳米粒口服给药后降低毒性的可能性。方法 采用改良的自乳化溶剂蒸发法制备雷公藤甲素聚乳酸纳米粒；透射电子显微镜(TEM)观察纳米粒的形态；动态激光粒度分析仪测定其平均粒径大小和分布；采用反相高效液相色谱法(RP-HPLC)测定纳米粒的包封率及载药量；X-射线粉末衍射(X-ray)初步研究纳米粒中药物的物理状态；考察雷公藤甲素的体外释放特性；评价口服给予纳米粒对大鼠的降毒性作用。 结果确定适合处方的工艺为：水相-有机相为40∶15(v/v)，表面活性剂浓度为1% (w/v)，药物在有机相中的浓度为0.3% (w/w)，TP-PLA为1∶15 (w/w)。处方条件下制备的纳米粒平均粒径为149.7 nm，多分散指数为0.088，平均包封率及载药量分别为74.27% 和1.36%；雷公藤甲素的体外释放分为两相；纳米粒非常显著降低肝的毒性(P<0.01)，显著降低肾的毒性(P<0.05)。结论聚乳酸纳米粒可能成为雷公藤甲素口服给药的新型载体。     

替硝唑聚乳酸微球的制备及其体外释药性能

目的：采用聚乳酸[poly（DL-lactide）]制备替硝唑微球。方法：考察分散递质明胶溶液的浓度、油相中聚乳酸的浓度、投药比和搅拌速度等因素的影响，应用正交实验优选最佳制备工艺条件。结果：替硝唑聚乳酸微球的最佳制备工艺稳定、重复性好，微球表面圆整，粒径分布均匀，微球平均粒径为30．2μm，平均载药量为6．7％，平均包封率为64．5％。该微球在14d的药物累积释放率达81．2％。结论：替硝唑聚乳酸微球缓释时间长达14d，用于牙周炎的治疗是有效的。     

聚(油酸/亚油酸-癸二酸)-庆大霉素在家兔体内的释药实验及相容性研究*

目的:观察聚(油酸/亚油酸-癸二酸)-庆大霉素在家兔体内释药情况及相容性。方法:将聚(油酸/亚油酸-癸二酸)-庆大霉素药丸植入家兔骨髓腔,数周后观察家兔骨、肌肉、肝、肾及血清中的庆大霉素浓度,并检测局部骨组织上清液的抑菌能力。在家兔背部脊柱旁肌肉组织和皮下植入不含庆大霉素的聚(油酸/亚油酸-癸二酸)-庆大霉素空药丸,以观察其与家兔组织的生物相容性。结果:药丸在家兔骨髓腔中释药良好,药丸释出的庆大霉素浓集在植入部位的骨组织中超过4周,在血清、肝、肾及局部肌肉中的庆大霉素含量甚微,骨组织上清液对常见的骨髓炎感染菌金葡球菌和大肠杆菌均有强大的抑菌活性。此外,聚(油酸/亚油酸-癸二酸)-庆大霉素还可在家兔体内自动降解。在观察期间没有发现明显的生物不相容性。结论:聚(油酸/亚油酸-癸二酸)-庆大霉素有望用于治疗慢性骨髓炎。     

PLGA的结构和分子量对纳曲酮微球体外释药的影响

制备了分子量、比旋度、摩尔比及分子链末端修饰不同的丙交酯-乙交酯共聚物,并测定理化参数.以其为载体制备纳曲酮微球,比较了体外释药速率.结果表明,用分子量较小、有光学活性、单体摩尔比较小、分子链末端未酯化的共聚物制备的微球体外释药速率较快.     

Fatty acid composition and antibacterial potential of Cassia tora (leaves and stem) collected from different geographic areas of India

The comparative analysis of the fatty acid composition of Cassia tora (leaves and stem) was determined using gas chromatography–mass spectrometry. Twenty-seven fatty acids were identified in C. tora (leaves and stem) which was collected from three different geographical areas of India: Lucknow (Uttar Pradesh), Nainital (Uttarakhand), and Bhavnagar (Gujarat), coded as CT-1, CT-2, and CT-3, respectively. The gas chromatography–mass spectrometry analysis showed the presence of various saturated and unsaturated fatty acids. The major fatty acids found were palmitic acid, linoleic acid, linolenic acid, margaric acid, melissic acid, and behenic acid. The highest amounts of saturated fatty acids were found in leaves of C. tora collected from Bhavnagar (Gujarat) (60.7% ± 0.5%). Thus, the study reveals that C. tora has a major amount of nutritionally important fatty acids, along with significant antimicrobial potential. Fatty acids play a significant role in the development of fat products with enhanced nutritional value and clinical application. Remarkable differences were found in the present study between fatty acid profiles of C. tora collected from different locations in India. To the best of our knowledge there is no previously reported comparative study of the fatty acids of C. tora.