A new drug carrier: Magnetite nanoparticles coated with amphiphilic block copolymer

This paper reports on the synthesis and characterization of 4 nm magnetite nanoparticles coated with amphiphilic block copolymers of poly(ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PEMA- b-PHEMA) by surface-initiated atom transfer radical polymerization (ATRP), which can act as new po-tential carriers for hydrophobic targeted drug delivery. Vibrating sample magnetometer analysis indi-cated that the magnetite nanoparticles were superparamagnetic at room temperature. Thermogravim-etric analysis (TGA) was applied to studying the property of surface of magnetite nanoparticles, and the surface density of macromolecules was calculated. The grafting density of oleic acid, BrMPA and PEMA was 5.8, 3.9, 0.16 chain/nm2 respectively, which indicates that the initiation efficiency decreases due to the influence of large space of oleic acid molecules. In vitro progesterone and (-)-isoproterenol hy-drochloride release in phosphate buffered saline (PBS) at pH 7.0 and 37℃ was conducted in order to demonstrate the function of drug loading and release. The results showed that the amount of drug carried into the core-shell Fe₃O₄@PEMA-b-PHEMA depends on the length of hydrophobic segment of block copolymer. The release of progesterone (37% after 22 h in our previous work) was compared with the release of (-)-isoproterenol hydrochloride (80% after 50 min), demonstrating that the strong hy-drophobic interaction between hydrophobic segment and drug can effectively control the release of hydrophobic drugs.     

恒定电流密度分布与霍耳电场

研究了恒定电流场中电流密度沿导体径向的分布和霍耳电场产生的机理及作用,结果表明,沿径向载流子密度增大、载流子定向运动速度增大,载流子在晶格势场中的能态逐步升高;无论在载流的导体内还是在处于超导载流态的超导体内都存在着径向的霍耳电场;霍耳电场的存在是载流子力学平衡的必备条件,霍耳电场关于径向的线积分是载流子在晶格势场中能量增量的量度.霍耳电场与电流磁场的坡印亭矢量表示了电流能量的传输方向,同时证明了焦耳热来源于载流子在晶格势场中的能态变化——从高能态向低能态跃迁,它可以用导体内的轴向电场和电流磁场的坡印亭矢量来表示,导体外表面附近的电场来源于载流子的运动状态变化,而不是直接来自于电源.用处于载流超导态的超导体不存在轴向电场的事实,说明了载流导体内的轴向电场并不是稳定分布的电荷产生的.     

长距离HF射频识别信号检测技术研究与实现

针对UHF频段射频识别（RFID）技术的不足,提出一种长距离HF频段的RFID信号检测方案,重点在于增强灵敏度、提高标签感应距离.先分析标签负载调制的基本原理和反射信号的调制特点,再详细阐述检测通道关键环节设计与实现.     

天然药物靶向给药系统的研究进展

脂质体、微球、乳剂等新型药物载体在天然药物靶向给药系统研究中已广泛应用。靶向给药系统的研究已取得了很大的进展,但是在生产和临床上应用还存在不少问题,应遵循传统中药理论,结合现代技术进行研究。通过查阅了近年来国内外天然药物靶向给药系统的研究进展的相关资料,并对其进行分析和整理。     

电流变活性的若干判据

给出了一个简化模型描述载流子在电流变液中的输运 .颗粒极化可分为两部分 ,慢极化分量由载流子的受阻输运所致 ;快极化分量是载流子所在介电背景的极化 .在切变场中 ,一个强的电流变强度要求强而相对稳定的颗粒相互作用 .大的极化强度确保相互作用强度 ,合适的极化速率和介电损耗以保证颗粒相互作用的相对稳定性 .根据计算结果并考虑到切变场对介电响应的影响 ,这里给出一个半经验电流变活性判据 :对于ω <10 3s-1,ωτ >10 -4 ,存在 1相似文献   

琥珀酰亚胺类固定化酶载体的合成与胺解研究

选用丙烯酸(AA)、N′-羟基琥珀酰亚胺(NHM)为单体,以N′,N′-亚甲基双丙烯酰胺(MBAA)为交联剂,以乙醇水溶液为制孔剂条件下进行反相悬浮聚合,得到珠状共聚物载体,该载体是一种新的酶载体形式,在国内外的相关文献中均未见报道.用红外光谱对其结构进行了表征.对载体与有机胺的胺解反应进行了研究,发现共聚物载体分子链上的丙烯酸-N′-羟基琥珀酰亚胺酯基易于在温和条件下与胺基发生胺解反应,从而为该类载体应用于含游离胺基的生物活性物质分子的固定化提供了依据.     

Intracellular siRNA delivery with novel spermine based surfactants

The design and development of safe and effective multifunctional siRNA delivery systems are critical for clinical application of RNAi therapeutics. Here we evaluated eight new spermine-based surfactant multifunctional carriers for siRNA delivery. These carriers complexed with siRNA forming stable compact nanoparticles with sizes around 100 nm. The multifunctional carriers mediated higher intracellular siRNA transfection than Lipofectamine-2000. The siRNA nanoparticles of the multifunctional carriers exhibited low cytotoxicity as shown by MTT assay. Three of the eight multifunctional carriers showed higher silencing efficiency than Lipofectamine-2000 in both U87-Luc cells and CHO-GFP cells. SKAHCO showed the highest siRNA delivery efficiency among the carriers. It resulted in 84.6±5.5% silencing of luciferase activity in U87-Luc cells, much higher than that (62.8± 3.4%) from Lipofectamine-2000. In conclusion, the spermine based multifunctional carriers are promising for highly efficient intracellular siRNA delivery.     

“1111”型稀磁半导体的研究进展

我们成功地制备了载流子和自旋分离的"1111"型块材稀磁半导体(La,AE)(Zn,TM)AsO(AE=Ba,Sr;TM=Mn,Fe)居里温度TC可以达到40K.我们研究了载流子和局域磁矩对铁磁有序的调制作用,在(La1-xSrx)(Zn0.9Mn0.1)AsO(x=0.10,0.20,0.30)中,控制Mn的浓度为10%,改变Sr的掺杂浓度,当Sr的掺杂量为10%时,我们可以观测到～30 K的铁磁转变温度;而当Sr的掺杂量达到30%时,铁磁转变温度和有效磁矩都大幅度地降低.我们运用缪子自旋共振和中子散射等微观测量手段研究了该系列材料的自旋动力学,缪子自旋共振的测量表明铁磁有序转变发生在整个样品内,即样品是块材稀磁半导体;缪子自旋共振测量得到的"1111"型稀磁半导体静态局域场振幅as与居里温度TC的关系和(Ga,Mn)As,"111"型Li(Zn,Mn)As,以及"122"型(Ba,K)(Zn,Mn)2As2一致,表明这些体系拥有相同的磁性起源机制.我们对该系列稀磁半导体的研究有利于进一步揭示包括(Ga,Mn)As在内的稀磁半导体的磁性起源机制.     

创业教育与高校社团的载体作用

近年来,社会对创业型人才的需求日益突出,开展创业教育,培养大学生具有开拓能力和创新精神,成为当前高校的一项紧要任务。今在理论分析和实践探索的基础上,寻求创业教育和高校社团的契合点,通过创新运行模式,配备创业导师,健全激励机制,建立创业基地等方面,探讨大学生社团作为创业教育新载体的建设和实现途径。     

采用谱分析法的大型散货船结构疲劳可靠性分析

基于Ｓ－Ｎ曲线和Ｍｉｎｅｒ线性疲劳累积损伤原理，建立了运用谱分析法通过整船有限元分析进行船体结构疲劳可靠性分析的定整过程，并使用ＤＮＶ的ＳＥＳＡＭ程序系统，对一４５５００ｔ大型散货船的船体结构进行了疲劳可靠性分析