Optimization of the biphasic release of indomethacin from HPMC/pectin/calcium chloride matrix tablet by response surface methodology

We studied the effect of two independent variables, the pectin/calcium chloride weight ratio and the overall matrix weight in HPMC/pectin/calcium matrix tablet, on the release of indomethacin. A two-factor 5-level central composite experimental design was employed. Responses of the Peppas correlation parameters n and K and the 10% release time （T0.1） were optimized by response surface methodology. Significant effect of the independent variables on the biphasic release parameters, n and K, was observed. N, K and T0.1 were well fitted with the second-order quadratic equations rather than linear equations. Moreover, the mathematic fitting and the response surfaces showed significant cross-interaction between the pectin/calcium chloride ratio and the overall matrix weight. The optimal formulation with larger n, longer T0.1 and smaller K consisted of medium pectin/calcium chloride ratio around 1.0 and medium matrix weight around 200 mg. Validation studies on the optimal formulations showed good predictability of the n, K and T0.1 values with biases within the range of-7.33% and 6.26%. Our results support that central composite design can be used to optimize drug release from HPMC/pectin/calcium matrix tablet with high predictability.

Application of D-Optimal Study Design with Contour Surface Response for Designing Sustained Release Gliclazide Matrix Tablets

An optimized formulation of a sustained release tablet of Gliclazide was developed. The use of Doptimal design with a polynomial statistical model to analyze dissolution data reduced the number of laboratory tests required to obtain an optimal dosage form. The final formulation contained 22 mg of Methocel&regE15LV, 16.5 mg Methocel&regE15 and 10.0 mg of Dibasic Calcium Phosphate per 30 mg Gliclazide sustained release tablet. Dissolution studies performed on tablets from 5000 tablet test batches released greater than 90 percent of loaded drug in eight hours. Drug release from the optimized tablets followed a pattern more closely similar to zero-order than other mechanisms of drug release tested. Storage of tablets in accelerated and ambient conditions for 6 and 12 months respectively did not alter any of the physico-chemical properties, drug release or the drug release rate compared to initial observations and dissolution data of the prepared tablets. The addition of potassium phosphate and monosodium phosphate to the tablet reduced the effect pH has on Gliclazide dissolution compared to the commercially available product.

The Drug-carrier Interactions, Release Behaviors and Cell Responses of Hydroxyapaptite Containing Several Chinese Medicines

The present work shows drug-carrier interactions, release behaviors and cell responses of hydroxyapatite （HA） containing salvianolic acid B （Sal B）, astragalus polysaecharide （APS）, and naringin. X-ray diffraction （XRD） showed that the crystallinity and crystal size of HA decreased significantly when Sal B was added （p〈0.05）. Transmission electron microscope （TEM） confirmed that the nano-acicular crystals of HA containing Sal B were the most fine among all specimens. It was conjectured that Sal B preferentially adsorbed on the positively charged surface of HA crystals to inhibit their growth. In vitro release of HA containing Chinese medicines followed the first-order equation. The drug-carrier affinity between HA and Sal B might have prolonged the release of Sal B. The proliferation and differentiation of osteoblasts were promoted by Chinese medicines containing HA in the time and dosage dependent manner. The osteoblasts displayed a polygonal morphology with cell-cell junctions in all cases. It is suggested that the contained Chinese medicines would promote the activities of the osteoblasts.

The Study on Immunological Response of Long－term Release System hCG Microsphere in C_(57） Black Mouse

This paper describes the study of the immunological response of C57 Black mouse to hCG by multiple inoculations with hCG and single injection with a long-term release system of hCG/poly(lactide-co-glycolide) microsphere(hCG/PGLA).Three parameters including1)the dynamic variation of hCG antibody titres,2)the capacity of biological neutralization by hCG antibodies in vitro and in vivo,and3)assay of the binding affinity constants of hCG antibodies,are compared.The results showed that the single injection with hCG/PGLA was capable of producing high titres of anti-hCG antibodies.The analyses of three parameters of antisera from C57 Black mouse showed that the properties of the antisera elicited using a single injection with hCG/PGLA were generally similar to those of the antisera raised by the multiple inoculations with hCG,and concentration of the antibodies was directly proportional to hCG bioneutralization capacity. Meanwhile,all of these results suggest us that a further long-term release system of β-hCG/PGLA as a vaccine may substitute for conventional vaccine and it also provides a new convenient inoculative method for widespread clinical application and research of hCG vaccine and other vaccines.

Glutathione-Responsive Carboxymethyl Chitosan Nanoparticles for Controlled Release of Herbicides

Glutathione-responsive carboxymethyl chitosan nanoparticles cross-linked with disulfide bonds were developed for controlled release of herbicides. The nanoparticles were synthesized by selfassembly of amphiphilic carboxymethyl chitosan derivative (CMCS-MUA) in aqueous solution and subsequently producing disulfide cross-linking bonds by ultrasonic treatment. TEM showed that the nanoparticles had a spherical core-shell configuration with a size of about 250 nm. Assessment of stability of the nanoparticles (considering mean diameter, polydispersity, and Zeta potential) was conducted over a period of three months, and the nanoparticles were found to be stable in solution. Herbicide-loaded nanoparticles were prepared using diuron as a model herbicide. In vitro release study revealed that diuron can be released from nanoparticles in a controlled manner depended on the glutathione concentration. Herbicidal activity assays performed with preemergence treatment of target species (Echinochloa crusgalli) showed the effectiveness of diuron- loaded nanoparticles. Assays with nontarget species (Zea mays) showed that the diuronloaded nanoparticles did not affect plant growth. The results indicate that the glutathioneresponsive nanoparticles prepared in this work will be a promising candidate for controlled release of herbicides in agriculture.

Polymeric Hydrogel Nanocapsules: A Thermo and pH Dual-responsive Carrier for Sustained Drug Release

Hydrogel capsules show attractive prospects in drug delivery recently because of high drug loading and sustained release behavior. In this study we reported a simple and convenient route to fabricate poly(acrylic acid)-poly(N-isopropylacrylamide)(PAA-PNIPAm) hydrogel capsules by using hydroxypropylcellulose-poly(acrylic acid)(HPC-PAA) complexes as the templates. The capsules showed a high drug loading(～280% to the weight of capsules) for Doxorubicin hydrochloride. The release of drug from the capsules was responsive to the temperature and p H of the surroundings, showing a low-rate but sustained release behavior favorable for low-toxic and long-term therapy. Together with the convenient preparation, high drug loading, dual responsivity as well as the sustained release feature, it is implied that this polymeric hydrogel capsule might be a promising candidate for new drug carriers.

Inclusion-Interaction Assembly Strategy for Constructing pH/Redox Responsive Micelles for Controlled Release of 6-Mercaptopurine

An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic drug 6-mercaptopurine and a hydrophilic β-CD grafted carboxymethyl chitosan were synthesized. Then, a novel amphiphilic inclusion complex was prepared with the dimer being partially embedded into the cavity of β-CD moiety. It self-assembled into pH/redox responsive core-shell micelles in distilled water. TEM confirmed that the micelles possessed a spherical core-shell configuration with a mean size of about 160 nm. DLS showed that the micelles were stable in aqueous solution. Their particle diameters altered with pH values as well as glutathione (GSH) concentrations and respectively attained a maximum value at pH 6.0 and 20 mM GSH. Release profiles of 6-mercaptopurine showed a low release rate (about 27 wt% after 48 h) in pH 7.4 medium with 10 μM GSH, and a marked increase (over 88 wt% after 48 h) in pH 5.0 medium with 20 mM GSH. In vitro cytotoxicity test showed that the micelles had a dose-dependent toxicity for HeLa cells, indicating a great potential for controlled release of 6-mercaptopurine in tumor cells.

pH- and near-infrared light-responsive,biomimetic hydrogels from aqueous dispersions of carbon nanotubes

Owing to their low flexibility,poor processability and a lack of responsiveness,inorganic materials are usually non-ideal for constructing a living organism.Hence,to date,lifelike materials with structural hierarchies and adaptive properties usually rely on light and soft organic molecules,although few exceptions have been acquired using two-dimensional(2D)inorganic nanosheets.Herein,with a systematic study on the gelation behavior of carbon-based 0D quantum dots,1D nanotubes,and 3D fullerenes,we find that acidified 1D carbon nanotubes(CNTs)can serve as an alternative building block for fabricating purely inorganic biomimetic soft materials.The as-prepared CNT gels exhibit not only a pH-or photothermal-triggered mechanical and tribological adaptivity,which allows them to simulate the behavior of sea cucumbers,peacock mantis shrimps,and mammalian muscles or cortical bones,but also a unique damping property that is similar to spider’s cuticular pad.Their high elasticity,effective lubrication,excellent biocompatibility,and controllable friction and wear also allow them to function as a new type of smart lubricants,whose tribological properties can be regulated either by its internal pH changes or spatiotemporally by near-infrared(NIR)light irradiations,free of any toxic and flammable base oils or additives.

Fabrication of PdSe2/GaAs Heterojunction for Sensitive Near-Infrared Photovoltaic Detector and Image Sensor Application

In this study,we have developed a high-sensitivity,near-infrared photodetector based on PdSe2/GaAs heterojunction,which was made by transferring a multilayered PdSe2 film onto a planar GaAs.The as-fabricated PdSe2/GaAs heterojunction device exhibited obvious photovoltaic behavior to 808 nm illumination,indicating that the near-infrared photodetector can be used as a self-driven device without external power supply.Further device analysis showed that the hybrid heterojunction exhibited a high on/off ratio of 1.16×10^5 measured at 808 nm under zero bias voltage.The responsivity and specific detectivity of photodetector were estimated to be 171.34 mA/W and 2.36×10^11 Jones,respectively.Moreover,the device showed excellent stability and reliable repeatability.After 2 months,the photoelectric characteristics of the near-infrared photodetector hardly degrade in air,attributable to the good stability of the PdSe2.Finally,the PdSe2/GaAs-based heterojunction device can also function as a near-infrared light sensor.

Simulation of near-infrared photodiode detectors based on β-FeSi_2/4H-SiC heterojunctions

In this paper,we propose a near-infrared p-type β-FeSi2/n-type 4H-SiC heterojunction photodetector with semiconducting silicide（β-FeSi2） as the active region for the first time.The optoelectronic characteristics of the photodetector are simulated using a commercial simulator at room temperature.The results show that the photodetector has a good rectifying character and a good response to near-infrared light.Interface states should be minimized to obtain a lower reverse leakage current.The response spectrum of the β-FeSi2/4H-SiC detector,which consists of a p-type β-FeSi2 absorption layer with a doping concentration of 1×1015cm-3 and a thickness of 2.5 μm,has a peak of 755 mA/W at 1.42 μm.The illumination of the SiC side obtains a higher responsivity than that of the β-FeSi2 side.The results illustrate that the β-FeSi2/4H-SiC heterojunction can be used as a near-infrared photodetector compatible with near-infrared optically-activated SiC-based power switching devices.

Chitosan nanoparticles crosslinked by glycidoxypropyltrimethoxysilane for pH triggered release of protein

pH-responsive-chitosan nanoparticles for the control release of protein drug were prepared by combining two-step crosslinking method, in which chitosan was subsequently crosslinked by sodium tripolyphosphate （TPP） and glycidoxypropyltrimethoxysilane （GPTMS）. Compared with TPP crosslinked chitosan particles, the two-step crosslinked nanoparticles were not only pH-responsive but also more stable in wide pH range. Fluorescein isothiocyanate （FITC） labeled anti-human-IgG antibody was used as a model protein drug for evaluating the control release profile of the nano-carrier. The amount of released antibody increased from 5.6% to 50% when the pH of solution shifted from 7.4 to 6.0. The results suggest the possible application of the nanoparticles as pH- responsive drug delivery materials.

Oxytocin and Stress Response

In response to a stressful unexpected experience, the brain activates a complex stress system that involves the organism in an adaptive response to the threatening situation. This stress system acts on several peripheral tissues and feeds back to the brain. One of its key players is oxytocin hormone. The neuropeptide, oxytocin (OT), has well-established roles during parturition and lactation. In addition to its peripheral actions, OT is released within multiple areas of the brain and influences behavioural and neuroendocrine responses to stress. Several studies suggest that oxytocin is implicated in the central control of responses to stress through modulation of corticotrophin releasing hormone (CRH). Intranasal OT application was associated with an inhibitory effect on adrenocorticotrophic hormone (ACTH) secretion and subsequent impairment of corticosterone secretion. This may be of importance for understanding and perhaps suggesting its utility to buffer stress. Synthesis and release of OT depend to a great extent on steroid hormones particularly on estradiol and corticosterone. Estrogens stimulate synthesis and release of OT and increase the number of OT receptors in some areas of the brain. However, the role of OT in mediating stress is variable and may also depend on gender and on external factors.

Spectral response modeling and analysis of p-n-p In_(0.53)Ga_(0.47)As/InP HPTs

We report our results on the modeling of the spectral response of the near-infrared（NIR） lattice-matched p-n-p In_（0.53）Ga_（0.47）As/InP heterojunction pbototransistors（HPTs）.The spectral response model is developed from the solution of the steady state continuity equations that dominate the excess optically generated minority-carriers in the active regions of the HPTs with accurate boundary-conditions.In addition,a detailed optical-power absorption profile is constructed for the device modeling.The calculated responsivity is in good agreement with the measured one for the incident radiation at980 nm,1310 nm,and 1550 nm.Furthermore,the variation in the responsivity of the device with the base region width is analyzed.

Release of Anticancer Drug 5-Fluorouracil from Different Ionically Crosslinked Alginate Beads

In this research;the release of 5-Fluorouracil (5-FU) from different ionically crosslinked alginate (Alg) beads was investigated by using Fe3+, Al3+, Zn2+, and Ca2+, ions as crosslinking agent. The prepared beads were characterized by Fourier Transform Infrared Spectroscopy (FTIR) Differential Scanning Calorimetry (DSC) and Scanning Electron Micros-copy (SEM). The drug release studies were carried out at three pH values 1.2, 6.8 and 7.4 respectively each for two hours. The effects of the preparation conditions as crosslinker type, drug/polymer (w/w) ratio, crosslinker concentration and time of exposure to crosslinker on the release of 5-FU were investigated for 6 hours at 37℃. It was observed that 5-FU release from the beads followed the order of Fe > Zn > Al > Ca-Alg and increased with increasing drug/polymer ratio. At the end of 6 hours, the highest 5-FU release was found to be 90% (w/w) for Fe-Alg beads at the drug/polymer ratio of 1/8 (w/w), crosslinker concentration of 0.05 M, exposure time of 10 minutes respectively. The swelling measurements of the beads supported the release results. Release kinetics was described by Fickian and non-Fickian approaches.

粉煤灰基充填膏体制备过程中氨气释放的超声强化特性

将粉煤灰作为主要胶凝材料的膏体充填开采不仅能有效控制地面沉降、解决“三下”压煤问题、提高煤炭采出率,还可解决燃煤电厂粉煤灰堆积难题。而粉煤灰基充填膏体的氨气释放会对充填作业面的气体环境造成污染,亟需治理。提出一种利用超声波促进膏体氨气释放的新思路。通过对粉煤灰浆液进行超声处理,采用以超声时长(A)、超声功率(B)、固液比(C)作为考察因素,进行单因素实验,结果表明:随着超声时长、超声功率以及固液比的的增加氨气释放速率呈现出先增大后减小的趋势,并在超声时长、超声功率以及固液比分别为30 min、80 W和1∶10时达到最大值。在单因素实验结果的基础上进行响应面实验建立回归模型。通过响应面优化确定最佳实验参数。结果表明:影响因素主次顺序为:A>B>C,AB>AC>BC;去除氨气最佳实验参数为:超声时长为32 min,超声功率为80 W,固液比为1∶7.7。验证结果表明:实测值与预测值仅存在-1.6%的相对误差。利用优化后的实验参数处理粉煤灰,并制备成充填膏体测定氨气释放量,发现膏体氨气释放量平均减少了95.94%,氨气释放速率提高84.02%,膏体3 d和28 d的单轴抗压强度分别提高185.00%和86.50%,坍塌度、泌水率和凝结时间均降低,同时减少了膏体内部多害孔数量,使孔隙率由33.58%降低到28.13%,为粉煤灰基充填膏体的氨气释放治理提供新的方法与思路。

负载花色苷的抗酸性羧甲基壳聚糖凝胶微球的缓释研究

为拓宽壳聚糖基水凝胶的应用范围,构筑可食用的花色苷(ACNs)递送体系,采用反相乳液法,以玉米油为连续相,水杨醛(SA)为交联剂,制备了具有抗酸性能的载ACNs羧甲基壳聚糖(CMCS)凝胶微球(ACNs/CMCS-SA),表征了其结构和形貌,研究了其稳定性、溶胀性能和缓释性能。结果表明,ACNs/CMCSSA具有微米级粒径,表面光滑呈圆形;ACNs/CMCS-SA在酸性条件下稳定性良好,溶胀和缓释过程展现pH响应性;ACNs的释放行为符合Weibull模型,pH7和9时为扩散和骨架溶蚀复合释放机制控制,pH3和5时为菲克扩散和Case Ⅱ transport(0级-溶胀依赖性释放)联合释放机制控制。ACNs/CMCS-SA制备方法简单,过程绿色;对ACNs展现良好的胃酸保护和肠道释放性能,为环境友好型药物包封材料的开发和ACNs的应用提供了理论和实践参考。

温度敏感型缓/控释肥料的温度响应特征、养分释放性能与温敏机理研究进展

温度是影响缓/控释肥料养分释放特性的重要因素,开发温度敏感型缓/控释肥料可以使肥料养分释放与作物养分需求更加匹配,从而提高肥料利用效率,促进农业可持续发展。本文综述了聚酰胺类、聚醚类、聚酯类、多糖类以及温敏聚氨酯等常见的温敏聚合物材料的来源、类型和机理,详细阐述了聚N-异丙基丙烯酰胺(PNIPAM)、聚N-乙烯基己内酰胺(PNVCL)、环氧乙烷/环氧丙烷嵌段共聚物(EO/PO)、甲基纤维素和温敏聚氨酯等常见温敏聚合物材料用作温敏缓/控释肥料包膜材料的国内外研究进展,并评估了其在温敏缓/控释肥料中应用的可行性与优缺点。根据温敏特性,将温敏缓/控释肥料分为低临界溶解温度(LCST)响应型和结晶转变温度(Tm)/玻璃化转变温度(Tg)响应型两大类,并详细总结了这两种类型的制备方法、特征、养分释放性能以及分子作用机制。最后,指出温敏型缓/控释肥料的研发尚处于初级阶段,未来应深入开展天然高分子温敏材料的基础研究和创新,筛选绿色可生物降解温敏聚氨酯材料,研发作物和区域专用型温敏缓/控释肥料。

钢筋混凝土环境中负载型阻锈剂的研究进展

阻锈剂技术是抑制混凝土中钢筋锈蚀的重要途径,但传统阻锈剂的应用仍然面临功能单一、与混凝土的兼容性不佳、环保性和有效性难以兼顾等问题。将阻锈剂装载入载体中,以载体负载阻锈剂(Carrier-loaded corrosion inhibitor,CLCI)的形式将阻锈剂“间接”掺入混凝土,能够在避免阻锈剂原有缺陷的基础上,发挥载体的特有功能。本文围绕CLCI的离子固化、缓释效应、智能响应、pH自免疫系统、载体吸附效应等功能机制,结合CLCI对水泥基材料性能的影响,系统综述了CLCI的研究进展。最后,对其在混凝土中的研究和应用进行了展望,并提出了需要解决的问题,以期为CLCI在混凝土工程中的应用提供更多可能性。

智能响应型农药微囊缓控释系统的研究进展

提高农药利用率并降低其对非靶标生物的影响一直是现代农药发展的重要方向。近年来,新材料、新方法等多领域交叉学科技术的引入为传统农药制剂研究带来了新的重大突破,推动农药制剂由缓释向智能控释的转变。本文结合国内外智能缓控释系统的最新研究进展及自身的工作实践,分析了农药智能缓控释系统的构成、响应因子和触发机理,评述了智能响应性农药微囊缓控释系统在杀虫剂、杀菌剂和除草剂领域的应用,展望了其发展趋势和面临的挑战,以期为农药智能缓控释系统的产业化提供借鉴。

羧甲基壳聚糖-蓖麻油基聚氨酯农药缓释微球的制备及性能

以羧甲基壳聚糖(CMCS)、蓖麻油(CO)和异佛尔酮二异氰酸酯(IPDI)为原料,通过自乳化法制备了羧甲基壳聚糖-蓖麻油基聚氨酯微球(CO-CMCS-PU),通过分子自组装法负载阿维菌素(AVM)得到载药微球(CO-CMCS-PU@AVM)。采用FTIR、1HNMR、SEM、TGA对产品结构及形貌进行了表征,并探究了不同药量载药微球的包封率、缓释性能、抗紫外性能、叶面接触角和黏附性能。结果表明,相比AVM分散液,紫外光照射后载药微球中AVM的保留率提高到43%以上,说明CO-CMCS-PU载体的抗紫外性能良好;载药微球溶液比AVM分散液在黄瓜叶面上的接触角降低了21%以上,滞留量提高了40%以上,说明其在叶面上有较好的黏附性和润湿性;载药微球包封率可达82%以上,具有良好的缓释和pH响应释放性能,释药行为符合First-order动力学模型和Korsmeyer Peppas模型,药物释放受Fickian扩散控制。