改性SiO2气凝胶制备及其在ICF实验中的应用

 以正硅酸乙酯（TEOS）为前驱体，采用酸碱两步催化法制备了SiO₂醇凝胶。醇凝胶分别经过TEOS母液、甲基三乙氧基硅烷（MTEOS）处理后，以六甲基二硅胺烷（HMDSA）为疏水改性试剂，制备了改性SiO₂醇凝胶，醇凝胶经溶剂交换后以CO₂作为干燥介质，采用超临界干燥法制备了密度在30～100 mg/cm³的SiO₂气凝胶。用傅里叶变换红外光谱仪（FTIR）对疏水性SiO₂气凝胶进行了研究。研究结果表明,经过改性的气凝胶在潮湿环境中具有极好的尺寸稳定性和疏水性。采用精密车床加工得到了满足惯性约束聚变（ICF）物理试验要求的微柱。     

海藻酸改性的空心Fe3O4纳米颗粒的制备与应用

不使用任何模板一步制得空心Fe₃O₄纳米颗粒,然后将海藻酸钠嫁接在氨基化的空心Fe₃O₄表面,再利用海藻酸盐与钙离子的作用,在空心Fe₃O₄表面形成一个凝胶化层,制得海藻酸盐凝胶化的空心Fe₃O₄纳米颗粒,粒径约为400～500 nm．采用TEM、XRD、XPS、VSM等手段对纳米微球进行表征．VSM表征结果表明在室温下样品磁性材料为超顺磁性．改性Fe₃O₄纳米颗粒成功地用于柔红霉素的载负和缓释,最大载负率和载药量分别为28.4%和14.2%．缓释结果表明,海藻酸盐凝胶化层的存在,能更有效控制柔红霉素缓慢地释放．     

疏水介孔SiO2的制备与性能表征

以廉价的工业级正硅酸乙酯为原料,经过酸碱两步催化制备二氧化硅凝胶,以三甲基氯硅烷/六甲基二硅氧烷混合液对凝胶进行直接表面改性,常压干燥下得到高比表面积疏水性二氧化硅气凝胶.用SEM、IR、N2吸脱附、TG-DTA、接触角的测定等分析方法对二氧化硅化学成分、结构形貌、比表面积、热稳定性和疏水性能进行了研究.结果表明,经改...     

等离子体结合六甲基二硅胺烷处理提升增透膜抗真空污染性能研究

本文采用溶胶-凝胶法制备了SiO₂增透膜,然后对其进行等离子体结合六甲基二硅胺烷（HMDS）表面改性处理。研究了后处理改性对增透膜表面形貌、微观结构、光学性能及激光损伤性能的影响规律,获得了抗真空有机污染的二氧化硅增透膜。结果表明,增透膜在采用等离子体结合HMDS表面改性处理后,膜层收缩、粗糙度下降、极性羟基等有机基团含量减少;两步后处理改善了增透膜膜层结构和光学性能,显著提高了膜层疏水能力和真空条件下的抗污染性能,并且对溶胶-凝胶二氧化硅增透膜的高损伤阈值属性不产生影响。     

阿霉素凝胶体外释放度的测定

建立阿霉素凝胶的制备方法,并考察其体外释放度。采用紫外分光光度法,恒温空气浴摇床装置(温度为37℃±0.5℃,转速为50r/min),以pH7.4的PBS为溶出介质测定阿霉素凝胶的释放度,检测波长为254nm。阿霉素凝胶在24h内释放较快,体外释放率达到56.67%左右,随后可持续稳定释药,释放时间可达到7天以上。阿霉素凝胶体外释放性能良好,具有明显的缓释作用。     

雷公藤胃漂浮缓释胶囊的制备及体外释放度的考察

制备了雷公藤胃漂浮缓释胶囊,对其释放机制进行考察.建立HPLC法考察其体外释放度,以羟丙基甲基纤维素(HPMCK4M)为主要辅料,制备亲水凝胶型骨架胶囊,采用L9(34)正交试验筛选出胶囊的处方.所制备的胃漂浮缓释胶囊在12h内呈良好的零级释药特征;以正交试验设计的雷公藤胃漂浮缓释胶囊处方合理,体外释放性能良好.     

多层塑料微球的研制

2004年研究了PVA溶液的浓度对PS微球成活率的影响；并且通过O3处理，提高了PS微球球壳强度；并且还进行了内表面掺硫的多层塑料微球的研制；同时完成了二氧化硅气凝胶的增强和疏水改性研究。     

纳米金刚石的分散、修饰及载药应用研究

纳米金刚石(nanodiamond,ND)作为一种重要的碳纳米材料,具有表面易修饰、比表面积大、生物毒性低以及物理化学稳定性好等特点,使其在生物医学领域具有独特的优势.本文通过对ND进行分散和化学修饰得到了分散性良好的羧基化纳米金刚石(ND-COOH),并通过透射电子显微镜、X-射线衍射、傅里叶变换红外谱仪等手段对其形貌和结构进行了表征分析.ND-COOH在水溶液中水解后呈现出较高的负电位,致使其可以通过静电相互作用吸附带正电的抗癌药物盐酸阿霉素(dox),且对阿霉素的负载量可达325μg/mg.由于ND-COOH与dox之间通过带负电的羧酸根与带正电的质子化氨基结合,因此在H~+浓度较高的酸性溶液中,药物复合体ND-dox呈现出显著的p H值依赖药物释放特性,在p H值为5.0的磷酸盐缓冲液中药物释放率达到85%,而在p H值为7.4的PBS中药物释放率低于40%.此外,ND-COOH和ND-dox的细胞毒性和体外细胞杀伤能力结果表明,ND-COOH在0—150μg/m L范围内对细胞活性没有明显抑制,而ND装载药物dox后的ND-dox对SGC-7901胃癌细胞活性则表现出显著的抑制作用,表明ND-COOH作为药物载体具有较低的生物毒性,而负载药物后则对肿瘤细胞具有较强的杀伤能力.通过对ND进行简单的分散和表面改性,使ND具备良好的药物装载和独特的p H值依赖药物释放特性,这对于促进纳米金刚石在药物载体方面的应用具有重要的借鉴意义.     

硅镁凝胶对杉木的强化及固着机制研究

硅镁凝胶浸渍改性杉木在物理力学性能方面提升较佳,探究硅镁凝胶在杉木中的固着性能和机制,对后续研究与创新具有一定意义。以硅镁凝胶为改性药剂,人工林杉木为基材,浸渍干燥后制得改性杉木。通过FTIR和XPS分析杉木素材和改性杉木的化学成分和结合方式,并对硅镁凝胶在木材中的分布以及改性杉木的渗透性进行探讨。实验结果表明：硅镁凝胶浸渍改性杉木的物理力学性能得到明显改善,密度均达到0.5 g·cm-3以上,抗压强度和抗弯强度相比杉木素材分别提升了99.73%和58.48%,端面硬度从3 659 N提升到5 843 N,基本已达到中等木材的性能指标。EDS结果证明药剂在杉木细胞腔中填充状况良好,Si,O,Na和Mg等主要元素与浸渍药剂硅镁凝胶相符且分布均匀。对浸洗前后的改性杉木试样和素材分别进行分层XPS测试,改性材的O/C增大,各元素在不同深度的含量十分接近,硅镁凝胶在杉木中分布均匀,具有良好的渗透性;浸洗后Si元素含量稳定,而钠元素有所降低,可能是部分钠盐的溶解流失造成,且不同深度的元素含量变化趋于一致,改性杉木的抗流失性较好。相比于硅酸钠浸渍改性杉木,硅镁凝胶改性杉木在96 h流失率降低到10.8%,抗流失效果较好。FTIR测试结果表明硅酸钠溶液对杉木的木质素和半纤维素有破坏和脱出作用,对杉木的通透性有所改善,且更容易与药剂形成化学键结合。C,O和Si元素的XPS谱图结果表明,改性后C(1s)向低结合能偏移,性质更加稳定,O—H结合大量减少,Si—O结合增多,硅镁凝胶能够在杉木中形成稳定的Si—O—C化学结构,药剂能够在细胞壁上实现高效固着。研究结果为改性材的药剂流失性检测和固着性研究提供新的思路,为硅镁凝胶浸渍改性杉木后续研究提供一定的理论支持。     

利用氟硅烷提高溶胶-凝胶SiO2增透膜的疏水性

 以正硅酸乙酯为前驱体，氨水为催化剂，采用溶胶 凝胶法制备了二氧化硅增透膜；通过自组装技术，用氟硅烷对膜层进行表面修饰，制得了疏水增透膜，克服了常规增透膜亲水的缺点。采用红外光谱、分光光度计、扫描探针显微镜和静滴接触角测量仪等测试手段分析了薄膜的特性。结果表明：疏水增透膜的峰值透光率为99.7％，疏水角为110°；氟硅烷自组装改性不影响二氧化硅增透膜的光学性能。     

Controlled Release of an Antihypertensive Drug through Interpenetrating Polymer Network Hydrogel Tablets of Tamarind Seed Polysaccharide and Sodium Alginate

The application of interpenetrating polymer network (IPN) hydrogel tablets of tamarind seed polysaccharide and sodium alginate for controlled release of a water-soluble antihypertensive drug, propranolol HCl (PPL), was investigated. The IPN tablets loaded with PPL or PPL–resin complex (resinate) were prepared by a wet granulation/covalent cross-linking method. Fourier Transform Infrared Spectroscopic confirmed the cross-linking reaction and IPN formation, while X-ray Diffraction and Scanning Electron Microscopy studies confirmed the amorphous dispersion of the drug within the IPN tablets. The plain drug PPL showed complete release within 1 h, while drug release from the resinate was prolonged for 2.5 h and the IPN matrices showed drug release up to 24 h. The drug release rate from the IPN matrices was affected by polymer concentration and cross-linking time; the higher the cross-linking time, the slower was the drug release. The drug release mechanism was found to be of a non-Fickian type.     

Ultrasound stimulated release of mimosa medicine from cellulose hydrogel matrix

Ultrasound (US) drug release system using cellulose based hydrogel films was developed as triggered to mimosa. Here, the mimosa, a fascinating drug to cure injured skin, was employed as the loading drug in cellulose hydrogel films prepared with phase inversion method. The mimosa hydrogels were fabricated from dimethylacetamide (DMAc)/LiCl solution in the presence of mimosa, when the solution was exposed to ethanol vapor. The US triggered release of the mimosa from the hydrogel matrix was carried out under following conditions of US powers (0–30 W) and frequencies (23, 43 and 96 kHz) for different mimosa hydrogel matrix from 0.5 wt% to 2 wt% cellulose solution. To release the drug by US trigger from the matrix, the better medicine release was observed in the matrix prepared from the 0.5 wt% cellulose solution when the 43 kHz US was exposed to the aqueous solution with the hydrogel matrix. The release efficiency increased with the increase of the US power from 5 to 30 W at 43 kHz. Viscoelasticity of the hydrogel matrix showed that the hydrogel became somewhat rigid after the US exposure. FT-IR analysis of the mimosa hydrogel matrixes showed that during the US exposure, hydrogen bonds in the structure of mimosa–water and mimosa–cellulose were broken. This suggested that the enhancement of the mimosa release was caused by the US exposure.     

Preparation and Properties of Polyurethane Hydrogels Based on Methylene Diphenyl Diisocyanate/Polycaprolactone-Polyethylene Glycol

Polyurethane (PU) hydrogel is an important biomedical material for drug controlled release systems, wound dressings and medical bandages. Three series of polyurethane prepolymers based on methylene diphenyl diisocyanate (MDI), polycaprolactone (PCL) and polyethylene glycol (PEG), using diethylene glycol (DEG), N-methyldiethanolamine (MDEA) or dimethylolpropionic acid (DMPA), as the chain-extender, were prepared. Then the polyurethane hydrogels were obtained from the prepolymers, using benzoyl peroxide (BPO) as a cross-linking agent, by free radical polymerization. The influences of the types of chain-extenders and polyols on the contact angle, swelling ratio and morphology of the polyurethane hydrogels were investigated. The effect of the variety of the chain-extenders in the PU hydrogel on the drug release behavior was also studied. The FT-IR results showed that the PU hydrogels were successfully synthesized. The introduction of PEG improved the hydrophilicity of the PU hydrogels. The MDI/PCL-PEG/DEG hydrogel was hydrophobic, and there were small micropores on its surface; while the MDI/PCL-PEG/DMPA and MDI/PCL-PEG/MDEA hydrogels had high hydrophilicity and a micropouous structure on their surface due to the existence of carboxyl and tertiary amino functional groups. The change of chain-extenders had no significant effect on the cumulative drug release of chloramphenicol from the PU hydrogels. However, the introduction of PEG increased the drug release rate. The chloramphenicol release kinetics from the MDI/PCL-PEG hydrogels indicated non-Fickian diffusion.     

Influence of Mass Ratio of Polyols on Properties of Polycaprolactone-Polyethylene Glycol/Methylene Diphenyl Diisocyanate/Diethylene Glycol Hydrogels

Polyurethane (PU) hydrogels with good hydrophilicity and biocompatibility have been applied as biomedical materials. A series of polyurethane prepolymers based on methylene diphenyl diisocyanate (MDI), polycaprolactone (PCL) and polyethylene glycol (PEG), using diethylene glycol (DEG) as the chain-extender, were synthesized; then the polyurethane hydrogels were obtained from the prepolymers using benzoyl peroxide (BPO) as a cross-linker by free radical polymerization. The influences of the ratio of polyols (PCL and PEG) on the contact angle, swelling ratio and morphology of the polyurethane hydrogel were investigated. The loading capacity and release behavior of chloramphenicol from the PCL-PEG/MDI/DEG hydrogels with different compositions were also studied. The contact angle and swelling degree results showed that the PCL-PEG/MDI/DEG hydrogel with PCL/PEG mass ratio of 3:1 had higher hydrophilicity than that with PCL/PEG mass ratios of 1:1 and 1:3. All PCL-PEG/MDI/DEG hydrogels showed three dimensional porous structures; however, the pore size increased with increasing PEG content. The chloramphenicol release kinetics from PCL-PEG/MDI/DEG hydrogels indicated Fickian diffusion, and the drug release rate increased with increasing PEG content in the PU hydrogels.     

An in vitro controlled release study of valproic acid encapsulated in a titania ceramic matrix

Despite the therapeutic efficacy of valproic acid towards numerous diseases, its poor bioavailability and systemic side effects pose significant barriers to long term treatment. In order to take advantage of controlled release implants of valproic acid, the drug was encapsulated into titania ceramic matrices via a sol-gel process. The integrity and structure of valproic acid-containing matrices were characterized through the use of FESEM, TEM, and BET analyses. In vitro controlled release studies and kinetic analyses were performed under ambient conditions (25 °C, atmospheric pressure) and controlled release behaviors were studied using a GC-MS method. Results showed first order dependence in the rate of valproic acid release as a function of drug concentrations in the titania ceramic device. A marked dependence on the surface area and pore size distribution with drug loading was also observed. This research opens new possibilities for the design of novel time-delayed controlled release systems for valproic acid encapsulates.     

Fabrication of silk sericin/alginate microparticles by electrohydrodynamic spraying technique for the controlled release of silk sericin

Silk sericin has been recently investigated for many biological roles. This study aimed to develop the new delivery system to control the release of silk sericin. The alginate microparticles encapsulating silk sericin were fabricated by electrospraying technique. Concentrations of silk sericin and alginate polyelectrolyte solutions were investigated. All microparticles had an average size of 264–284 μm and could entrap silk sericin with high entrapment efficiency (84–89%). The microparticles could deliver silk sericin in a rate-controlled manner. This study would show a promising controlled release application of silk sericin protein from alginate microparticles fabricated by the means of electrostatic forces.     

Ultrasound-triggered nicotine release from nicotine-loaded cellulose hydrogel

Ultrasound (US)-triggered nicotine release system in a cellulose hydrogel drug carrier was developed with three different cellulose concentrations of 0.45 wt%, 0.9 wt%, and 1.8 wt%. The nicotine-loaded cellulose hydrogels were fabricated by the phase inversion method when the nicotine and cellulose mixture in the 6 wt% LiCl/N, N-dimethylacetamide solvent was exposed to water vapor at room temperature. Nicotine was used as the medicine due to its revealed therapeutic potential for neurodegenerative diseases like Alzheimer's and Parkinson's diseases. The behavior of US-triggered nicotine release from nicotine-cellulose hydrogel was studied at 43 kHz US frequency at the changing US output powers of 0 W, 5 W, 10 W, 20 W, 30 W, and 40 W. The significant US-triggered nicotine release enhancement was noted for the hydrogels made with 0.9 wt% and 1.8 wt% cellulose loading. The matrix made with 0.9 wt% cellulose was exhibited the highest nicotine release at the 40 W US power, and differences in nicotine release at different US powers were noticeable than at 0.45 wt% and 1.8 wt% cellulose loadings. For the three cellulose hydrogel systems, the storage modulus (G′) values at the 0.01 wt% strain rate were dropped from their initial values due to the US irradiation. This reduction was proportionately decreased when the US power was increased. The deconvolution of FTIR spectra of nicotine-loaded cellulose films before and after US exposure was suggested breakage of cellulose-nicotine and cellulose-water in the matrix; thus, the stimulated nicotine release from the cellulose matrix was promoted by the US irradiation.     

Functionalized alginate/chitosan biocomposites consisted of cylindrical struts and biologically designed for chitosan release

A novel alginate/chitosan composite scaffold was developed. The composite scaffolds were fabricated at low temperature using a three-axis robot system connected to a micro-dispenser and a core/shell nozzle. The structure of the composite scaffolds included hollow struts; deposited chitosan on the inner walls (core region) of the struts reacted electrostatically with the alginate layer (shell region). The fabricated, highly porous composite scaffolds exhibited excellent mechanical properties and controllable chitosan release, which was closely dependent on the weight fraction of the alginate in the shell region. The tensile strength in the dry state was ∼1.8-fold greater than that of pure alginate scaffold due to the ionic interaction between alginate and chitosan. To determine the feasibility of using the developed scaffold in tissue regeneration applications, in vitro cellular responses were evaluated using osteoblast-like-cells (MG63). The cell proliferation on the composite scaffold was ∼3.4-fold greater than that on the pure alginate scaffold. Alkaline phosphate activity and calcium deposition of the composite scaffold after 14 and 21 days of cell culture were significantly enhanced (1.6- and 1.8-fold greater, respectively) compared with those of the pure alginate scaffold. These results suggested that the alginate/chitosan composite scaffolds with a controlled chitosan release have great potential for use in regenerating various tissues.     

Silver release from nanocomposite Ag/alginate hydrogels in the presence of chloride ions: experimental results and mathematical modeling

A stepwise experimental and mathematical modeling approach was used to assess silver release from nanocomposite Ag/alginate microbeads in wet and dried forms into water and into normal saline solution chosen as a simplified model for certain biological fluids (e.g., blood plasma, wound exudates, sweat, etc). Three phenomena were connected and mathematically described: diffusion of silver nanoparticles (AgNPs) within the alginate hydrogel, AgNP oxidation/dissolution and reaction with chloride ions, and diffusion of the resultant silver-chloride species. Mathematical modeling results agreed well with the experimental data with the AgNP diffusion coefficient estimated as 1.3 × 10^?18 m² s^?1, while the first-order kinetic rate constant of AgNP oxidation/dissolution and diffusivity of silver-chloride species were shown to be inversely related. In specific, rapid rehydration and swelling of dry Ag/alginate microbeads induced fast AgNP oxidation/dissolution reaction with Cl^? and AgCl precipitation within the microbeads with the lowest diffusivity of silver-chloride species compared to wet microbeads in normal saline. The proposed mathematical model provided an insight into the phenomena related to silver release from nanocomposite Ca-alginate hydrogels relevant for use of antimicrobial devices and established, at the same time, a basis for further in-depth studies of AgNP interactions in hydrogels in the presence of chloride ions.     

Regulating the thermal response of PNIPAM hydrogels by controlling the adsorption of magnetite nanoparticles

Thermoswitchable magnetic hydrogels are being extensively investigated because of their great potential for medical applications. Indeed, they can behave as smart carriers able to transport drugs to a chosen part of the body and release them via magneto-thermal activation by an external alternating magnetic field. We report on the magnetization of the thermosensitive poly(N-isopropylacrylamide) hydrogel through the adsorption of controlled amounts of magnetite nanoparticles. We show that the temperature at which the hydrogel contraction occurs (i.e. the lower critical solution temperature) can be controlled from 32 ^°C to 52 ^°C by varying the concentration of adsorbed nanoparticles. This is clearly shown by photon correlation spectroscopy. The results are an advance in the use of the magnetized poly(N-isopropylacrylamide) hydrogel as a flexible and adjustable nanomaterial and are of great interest in numerous applications which require drug release on demand.