辣椒碱微胶囊的释放动力学研究

测定合成辣椒碱微胶囊在盐水、碱性及酸性三种释放环境下的释放曲线.在三种释放环境下,合成辣椒碱的释放率(ARP)具有显著的差异,盐水环境下的释放率最小.通过零级动力学方程、一级动力学方程、Higuchi模型方程对所得数据进行拟合,结果表明,三种释放环境中合成辣椒碱的释放动力学均适用于一级动力学方程.     

原花青素微胶囊化工艺的研究

为扩大原花青素在食品工业中的应用，以原花青素为心材，对其微胶囊化工艺进行了研究。通过单因素实验确定微胶囊化工艺的最佳壁材组合为：乙基纤维素、阿拉伯胶、麦芽糊精；原花青素占复合壁材的最佳质量百分数为15％；乳化剂占原花青素的质量百分数为0．6％。通过混料实验确定复合壁材的最佳配比为：乙基纤维素25％，阿拉伯胶33．33％，麦芽糊精41．67％，包埋率可达88．1％。原花青素微胶囊在正己烷中的溶解度为87．1mg／g，而未包埋的原花青素溶解度仅为43．5mg/g。     

原花青素在HZ818树脂上的吸附热力学和动力学

通过在不同温度下的静态吸附实验,研究了葡萄籽原花青素在大孔树脂HZ818上的吸附热力学及动力学特性。分别采用Langmuir、Freundlich等温式对不同温度下的等温吸附数据进行拟合,采用Largergren拟一级动力学模型、拟二级动力学模型和颗粒内扩散动力学模型对吸附动力学数据进行分析。结果表明:原花青素在HZ818树脂上的吸附量随着温度的升高而增大,等温吸附数据更符合Langmuir等温吸附方程,吸附焓变大于0,吉布斯自由能变小于0,HZ818树脂对原花青素的吸附过程为自发进行的吸热过程;吸附动力学更符合拟二级动力学模型,过程受主要包括颗粒内扩散在内的多因素共同影响。     

界面聚合聚脲/聚氨酯复合壳体香精微胶囊的制备及性能

以茉莉香精为芯材,以异氟尔酮二异氰酸酯（IPDI）分别与二乙烯三胺（DETA）、β-环糊精（β-CD）及β-CD/DETA反应物为壁材,采用界面聚合法制备了聚脲、聚氨酯、聚脲/聚氨酯3种不同结构壳体的香精微胶囊。探究了不同微胶囊壳体对微胶囊表观形貌、热稳定性、香精微胶囊缓释性的影响并通过动力学模型分析了香精扩散方式。结果表明,以β-CD/DETA制备的聚脲/聚氨酯复合壳体微胶囊成囊性优异,壳体致密完整,热稳定性和缓释性能最好,经其整理的纺织品可保持较浓香味90多天。3种香精微胶囊在100℃、120℃高温缓释数据均符合零级、一级、Ritger-Peppas及Higuchi动力学模型。聚脲/聚氨酯复合壳体Ritger-Peppas方程拟合后n值更加接近0.45,更符合Fick扩散,缓释性能更好。     

马来酸桂哌齐特胃内漂浮片制备及释药机制研究

目的:制备马来酸桂哌齐特胃内漂浮片并研究其释药机制。方法:以粉末直压再包衣工艺制备漂浮片;以2 h、6 h、22 h累积释放度为指标,采用L_9(3~4)正交试验设计优选漂浮片HPMC、碳酸钙、Eudragit L30D-55的用量;以平均累积释放率对时间分别以零级方程、一级方程和Higuchi方程、Peppas方程进行拟合,用相关系数(r)判断释放机制。结果:漂浮片HPLC、起泡剂碳酸钙、Eudragit L30D-55的用量分别为25%、5%、10%;起漂时间小于5 min,可以维持24 h持续释放;体外释药模型符合Higuchi动力学方程,通过骨架溶蚀进行释放。结论:经三批产品工艺验证,表明马来酸桂哌齐特胃内漂浮片工艺稳定,重现性好,具有缓释作用。     

薰衣草精油微胶囊释放性能的测定

对采用喷雾干燥法制备的薰衣草精油微胶囊在不同温度下的释放过程进行考察.结果表明:微胶囊技术有效抑制了薰衣草精油的易挥发性及易氧化性,提高了其热稳定性;随着温度升高,精油的释放速度加快;微胶囊在空气中的释放机理与Avrami′s公式和一级动力学吻合良好.     

复合二氧化氯油井解堵剂的释放动力学研究

复合二氧化氯油井解堵剂是一种新型的油井解堵剂.本文主要对其释放动力学进行了研究.得到了其不同释放阶段所遵循的宏观动力学规律:释放初期,近似一级反应,动力学方程1nCA=0.6020t+1.8692;释放中期,近似零级反应,动力学方程CA=0.9t+0.695;释放末期,近似二级反应,动力学方程1/CA-0.0079t+...     

复合二氧化氯油井解堵剂的释放动力学研究

复合二氧化氯油井解堵剂是一种新型的油井解堵剂。本文主要对其释放动力学进行了研究。得到了其不同释放阶段所遵循的宏观动力学规律:释放初期,近似一级反应,动力学方程lnCA=0.6020t+1.8692;释放中期,近似零级反应,动力学方程CA=0.9t+0.695;释放末期,近似二级反应,动力学方程1/CA=-0.0079t+0.2460。     

NR硫化返原过程的动力学研究

采用依据ＮＲ硫黄硫化返原机理建立起来的硫化返原动力学模型,对普通硫黄硫化体系和半有效硫化体系的ＮＲ在不同温度下的硫化曲线进行了计算机非线性拟合,从而求出了各步反庆的速率常数,并进上步得到多硫键、双硫键和单硫键密度之和及交联密度随硫化时间变化的关系。结果表明：不同温度下两种体系采用该模型得到的模拟曲线与实际数据相吻合,求出的同一体系速率常数与硫化温度的关系符合Ａｒｒｈｅｎｉｕｓ方程。两种体系多硫键的     

缓释二氧化氯凝胶的释放动力学研究

缓释二氧化氯凝胶能通过长时间持续释放出二氧化氯气体对空气进行消毒。讨论了缓释二氧化氯凝胶的制备原理和释放机理,通过测定缓释二氧化氯凝胶释放曲线,研究了其释放动力学规律。结果表明,缓释二氧化氯凝胶二氧化氯的活化释放过程可简化为一个不可逆的扩散反应过程模型,并得到了其不同释放阶段所遵循的宏观动力学规律：释放初期,近似一级反应,动力学方程lgρ=-0.005 3t＋1.649 3;释放中期,近似零级反应,动力学方程ρ=-0.678t＋45.346;释放末期,近似二级反应,动力学方程1/ρ=0.000 9t＋0.012 8。     

APPLICATION OF GELATIN FOR ENCAPSULATING ASPIRIN INTO ETHYL CELLULOSE MICROCAPSULE IN AN O/W EMULSION

The application of gelatin protective colloid for microencapsulating aspirin in ethylcellulose was demonstrated using an oil-in-water emulsification/solvent evaporation technique. The gelatin concentration, alcohol co-solvent amount, and ethylcellulose viscosity were investigated by analyzing the recovered weight, particle size distribution, drug loading efficiency, aspirin release rate, surface characteristics, and release kinetics. Results showed that recovery increased with greater concentrations of gelatin (up to 1%). Adding co-solvent (ethanol) also changed the microcapsule particle size distribution. Higher recovery and release rates were obtained when the ethanol content in polymer solvent was at 25% and the viscosity of ethylcellulose was low (45cps). The release rate followed Higuchi matrix release kinetics, suggesting a monolithic system with aspirin uniformly distributed over the microcapsule.     

APPLICATION OF GELATIN FOR ENCAPSULATING ASPIRIN INTO ETHYL CELLULOSE MICROCAPSULE IN AN O/W EMULSION

The application of gelatin protective colloid for microencapsulating aspirin in ethylcellulose was demonstrated using an oil-in-water emulsification/solvent evaporation technique. The gelatin concentration, alcohol co-solvent amount, and ethylcellulose viscosity were investigated by analyzing the recovered weight, particle size distribution, drug loading efficiency, aspirin release rate, surface characteristics, and release kinetics. Results showed that recovery increased with greater concentrations of gelatin (up to 1%). Adding co-solvent (ethanol) also changed the microcapsule particle size distribution. Higher recovery and release rates were obtained when the ethanol content in polymer solvent was at 25% and the viscosity of ethylcellulose was low (45cps). The release rate followed Higuchi matrix release kinetics, suggesting a monolithic system with aspirin uniformly distributed over the microcapsule.     

Preparation and characterization of pH responsive poly(methacrylic acid‐acrylamide‐N‐hydroxyethyl acrylamide) hydrogels for drug delivery systems

In this study, pH responsive polymers composed of methacrylic acid, acrylamide, and N‐hydroxyethyl acrylamide were synthesized by free radical polymerization technique. The characterization was done with Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling and drug release behavior of the hydrogels was determined as a function of time at 37°C in pH 2.1 and 7.4. The swelling and drug release studies showed that increased methacrylic acid amount caused a higher increase in swelling and drug release values at pH 7.4 than those at pH 2.1. In addition, the drug release data were applied to kinetic models such as zero order, first order, and Higuchi equations, and it fit well in the Higuchi model of the hydrogel. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43226.     

Development of mixed matrix membranes for controlled release of ibuprofen

In this work was studied the effect of different zeolite topologies on the release of ibuprofen from mixed matrix membranes (MMMs). The main parameters investigated were: zeolite concentration, its hydrophilic/hydrophobic character, and drug loading. About the different investigated systems, the PDMS NaX (I) membrane seems to be the most promising for its application as transdermal device. The release data were fitted with different mathematical models (zero order, first order, Higuchi, Bhaskar, and Korsemeyer‐Peppas) to give a possible explanation of the release mechanism of the drug from MMMs. The release data of the drug from pure PDMS membranes (PDMS IBU) were fitted by the Higuchi model (R² pari a 0.97). In the case of MMMs, the correlation coefficients are very far from the unit value except for the PDMS NaX (I) system that obeys to the Korsmeyer–Peppas (0.98) and Bashkar (0.99) models. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of 2‐hydroxyethylmethacrylate/2‐(3‐indol‐yl)ethylmethacrylamide‐based novel hydrogels as drug carrier with in vitro antibacterial properties

In this study, a new cationic monomer 2‐(3‐indol‐yl)ethylmethacrylamide (IEMA) derived from tryptamine was synthesized in a single step and characterized by Fourier transform infrared (FTIR), ¹H‐NMR, and ¹³C‐NMR. Then, one‐step preparation of novel poly[2‐hydroxyethylmethacrylate‐c‐2‐(3‐indol‐yl)ethylmethacrylamide], or p(HEMA‐c‐IEMA), copolymeric hydrogels has been performed successfully with IEMA and 2‐hydroxyethylmethacrylate (HEMA) as monomers using free radical aqueous polymerization. The hydrogels were characterized with scanning electron microscopy, FTIR, elemental analysis, thermogravimetric analysis, and texture profile analysis instruments. p(HEMA‐c‐IEMA) hydrogels were used for swelling, diffusion, drug release, and antibacterial activity studies. The drug‐release behavior of the hydrogels was determined as a function of time at 37 °C in pH 1.2 and 7.2. The swelling and drug‐release studies showed that an increased IEMA amount caused a higher increase in swelling and drug‐release values. Additionally, zero‐order, first‐order, and Higuchi equation kinetic models were applied to the drug‐release data, and the data fit well in the Higuchi model, and the Peppas power‐law model was applied to the release mechanism. Finally, the antibacterial activities of the hydrogels were screened against Gram‐positive bacteria (Bacillus cereus and Staphylococcus aureus) and Gram‐negative bacteria (Escherichia coli and Salmonella typhimurium). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45550.     

Hexane and ethanol as peanut oil solvents

Absolute ethanol is a better solvent for extracting peanut grits than 95% ethanol, with hexane intermediate in its action. More nonlipids solids are extracted by 95% ethanol than absolute ethanol as compared with none by hexane. Ethanol-extracted oils are slightly higher in color and free fatty acids than hexane-extracted oils.     

椰壳活性炭对加替沙星的吸附及缓释性能研究

研究了水溶液中椰壳活性炭对喹诺酮药物加替沙星（GTFX）的吸附性能,测定了不同温度下的吸附等温线并分析了其吸附热力学参数。结果表明：活性炭对加替沙星的吸附符合Freundlich方程,ΔH=-1.7374kJ/mol,说明活性炭对GTFX的吸附过程为放热过程,且ΔH<20kJ/mol,表明吸附过程主要为物理吸附。同时,测得吉布斯自由能ΔG<0,表明吸附质从溶液到吸附剂表面的吸附过程是自发过程,其吸附主要是熵驱动。对椰壳活性炭进行了硝酸及氨水改性,研究了3种不同活性炭对GTFX的缓释性能,结果显示,与椰壳活性炭相比,经硝酸氧化改性后的活性炭缓释性能有较大的提升,而经氨水改性的活性炭缓释性能有所下降,3种不同活性炭对GTFX的缓释均符合Higuchi方程释药模式。     

Vancomycin release kinetics from Mg–Ca silicate porous microspheres developed for controlled drug delivery

In this work, sol-gel derived bredigite (MgCa₇Si₄O₁₆), akermanite (MgCa₂Si₂O₇), and diopside (MgCaSi₂O₆) porous microspheres were loaded with vancomycin, and the release kinetics of this drug from them was evaluated. In this regard, mathematical models of Higuchi, Peppas, Baker-Lonsdale, Hixson-Crowell, first order, and zero order were considered in terms of linear and nonlinear regression analyses. Using the goodness of fitting correlation coefficients, the number of release stages was determined, and then diffusion- and degradation-controlled mechanisms were assigned to each stage. It was found that the diopside microspheres presented a two-step diffusional drug delivery. For akermanite and bredigite, an initial burst diffusion-controlled release followed by a sustained mixed-mode release mechanism of diffusion and degradation was identified, with the domination of the latter especially for bredigite.     

Synthesis and Characterization of New Biodegradable Injectable Thermosensitive Smart Hydrogels for 5-Fluorouracil Delivery

In this paper, injectable, thermosensitive smart hydrogel local drug delivery systems (LDDSs) releasing the model antitumour drug 5-fluorouracil (5-FU) were developed. The systems were based on biodegradable triblock copolymers synthesized via ring opening polymerization (ROP) of ε-caprolactone (CL) in the presence of poly(ethylene glycol) (PEG) and zirconium(IV) acetylacetonate (Zr(acac)₄), as co-initiator and catalyst, respectively. The structure, molecular weight (M_n) and molecular weight distribution (Đ) of the synthesized materials was studied in detail using nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) techniques; the optimal synthesis conditions were determined. The structure corresponded well to the theoretical assumptions. The produced hydrogels demonstrated a sharp sol–gel transition at temperature close to physiological value, forming a stable gel with good mechanical properties at 37 °C. The kinetics and mechanism of in vitro 5-FU release were characterized by zero order, first order, Higuchi and Korsmeyer–Peppas mathematical models. The obtained results indicate good release control; the kinetics were generally defined as first order according to the predominant diffusion mechanism; and the total drug release time was approximately 12 h. The copolymers were considered to be biodegradable and non-toxic; the resulting hydrogels appear to be promising as short-term LDDSs, potentially useful in antitumor therapy.