Highly sensitive room-temperature method of non-invasive in vivo detection of magnetic nanoparticles

Methods of non-invasive in vivo quantification of magnetic nanoparticles (MP) have been proposed and realized. The methods are based on non-linear MP magnetization at two frequencies and measuring the response at combinatorial frequencies. The first method is developed for real-time study of MP dynamics and their clearance from the blood system of animals. High sensitivity of 3 ng of Fe₃O₄ in 0.1 ml was achieved for MP detection in mice tail veins. The second technique is proposed for MP detection inside animal tissues by an external probe. The proposed methods could essentially widen capabilities of biomedical research which involves magnetic nanoparticles.     

两亲性壳聚糖基聚合物碳点的合成及其在载药方面的应用

通过水热法合成了系列具有高荧光量子产率（42.9%）辛基化壳聚糖基两亲性聚合物碳点荧光材料。利用红外光谱、紫外吸收光谱、光电子能谱、透射电镜、X射线衍射及荧光光谱对聚合物碳点进行了表征。以阿霉素为模型药物,研究了聚合物碳点对阿霉素的载药性能。当辛基取代度为76.42%时,其最大载药量和包封率分别为49.6%与47.4%。在磷酸盐缓冲液中,载药纳米胶束呈前期快速释放,后期缓慢释放的双相特征。将载药纳米胶束与鼻咽癌细胞作用,发现其存活率随着载药纳米胶束加入量的增加而降低,说明该纳米胶束对鼻咽癌细胞有一定的抑制作用。总之,该聚合物碳点材料在药物载体与荧光示踪方面有潜在的应用价值。     

HIV-1逆转录酶的分子对接及运动功能相关性分析

目的研究逆转录酶的运动性和生理功能的关系,以及N-乙酰基-β-芳基-1,2-二脱氢乙胺类衍生化合物与其的分子识别,方法采用高斯网络模型和各向异性网络模型研究了p66和p66-DNA的运动模式差异,并用分子对接方法研究化合物与逆转录酶的识别.结果 DNA的结合对p66各区域的运动方向影响不大,但其运动的幅度大大降低.分子对接结果发现Y115和M184的疏水结构在识别的过程中起到重要作用.结论基于各个区域的运动方向分析,推测手指区和RNase H区的开合运动可能是逆转录酶发挥逆转录功能的重要原因.并且,N-乙酰基-β-芳基-1,2-二脱氢乙胺类衍生化合物的N-甲基取代和反式的双键结构更有利于与逆转录酶的识别     

基于超临界流体技术制备葡萄糖脂质体的实验研究

脂质体由于其特殊的结构和性能,是一种很有发展潜力的药物载体,在医药和化妆品等行业具有广阔的应用前景。超临界逆向蒸发法是用超临界流体代替有机溶剂制备脂质体的方法,具有对水溶性药物脂质体制备过程简单、包覆率高等特点。以葡萄糖为模型药物,利用该方法制备出了葡萄糖脂质体,并详细考察了不同工艺条件对脂质体粒径和包覆率的影响。结果表明:用超临界逆向蒸发法可成功地制备出最小粒径为290nm、包覆率最高可达41.3%的葡萄糖脂质体。压力、温度和平衡时间对粒径和包覆率都有较大的影响。压力在10~30MPa时,随压力的增加,脂质体粒径显著减小至某一值后,基本趋于稳定,而包覆率逐渐增加,达到25.7%~27.5%,随后包覆率逐渐减小;温度在35~65℃时,随温度的增加粒径显著减小至最小值,然后逐渐增大,而包覆率一直增大,最高可达41.3%;平衡时间在15~45min时,随平衡时间的增加,粒径相对稳定,而包覆率显著增加,超过45min之后,粒径显著增加,包覆率显著下降。     

Polycaprolactone biopolymer thin films obtained by matrix assisted pulsed laser evaporation

We report the successful deposition of polycaprolactone polymer by MAPLE using a KrF* excimer laser (λ = 248 nm, τ = 7 ns). According to FTIR spectra the deposited films have similar chemical structure to the dropcast material. The fluence plays a key role in optimizing the performances of MAPLE-synthesized polycaprolactone structures. We demonstrated that MAPLE allows for controlling the morphology of films to the level required in targeted drug delivery of pharmacologic agents.     

In vitro study of magnetic particle seeding for implant assisted-magnetic drug targeting

The concept of using magnetic particles (seeds) as the implant for implant assisted-magnetic drug targeting (IA-MDT) was analyzed in vitro. Since this MDT system is being explored for use in capillaries, a highly porous (ε∼70%), highly tortuous, cylindrical, polyethylene polymer was prepared to mimic capillary tissue, and the seeds (magnetite nanoparticles) were already fixed within. The well-dispersed seeds were used to enhance the capture of 0.87 μm diameter magnetic drug carrier particles (MDCPs) (polydivinylbenzene embedded with 24.8 wt% magnetite) under flow conditions typically found in capillary networks. The effects of the fluid velocity (0.015–0.15 cm/s), magnetic field strength (0.0–250 mT), porous polymer magnetite content (0–7 wt%) and MDCP concentration (C=5 and 50 mg/L) on the capture efficiency (CE) of the MDCPs were studied. In all cases, when the magnetic field was applied, compared to when it was not, large increases in CE resulted; the CE increased even further when the magnetite seeds were present. The CE increased with increases in the magnetic field strength, porous polymer magnetite content and MDCP concentration. It decreased only with increases in the fluid velocity. Large magnetic field strengths were not necessary to induce MDCP capture by the seeds. A few hundred mT was sufficient. Overall, this first in vitro study of the magnetic seeding concept for IA-MDT was very encouraging, because it proved that magnetic particle seeds could serve as an effective implant for MDT systems, especially under conditions found in capillaries.     

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.     

作物残茬覆盖度遥感监测研究进展

作物残茬作为农田生态系统的重要组成部分,影响着农田生态系统中的营养物质、碳、水和能量的流动与循环。作物残茬覆盖度作为描述作物残茬数量和分布的重要指标,对于农田生态系统C循环和全球气候变化均有实际意义,具备重要的定量监测价值。遥感技术具有准确、经济、快速大面积监测的能力,因此利用遥感监测区域尺度的作物残茬覆盖度,受到国内外学者的关注。工作回顾总结了目前利用遥感监测作物残茬覆盖度的主要方法和最新研究进展,并根据基本方法的差异以及数据源的不同,从五个类别分别介绍了遥感监测原理与技术革新,对每一类方法的优点和缺陷进行分析,并提出了相应的改进措施。最后对作物残茬覆盖度遥感监测方法的发展趋势进行了展望。     

荧光碳量子点的制备与生物医学应用研究进展

碳量子点是一类具有优异的荧光性能和高生物相容性的纳米材料,在很多领域有广泛的应用,是目前研究的热点材料。本文介绍了碳量子点不同的合成方法,以及碳量子点的荧光、化学发光、电化学发光、类过氧化物酶的活性及毒性等性能的最新研究进展。此外,还对碳量子点在生物传感、生物成像及药物传递等生物医学应用进行了概述。     

Fissility effects on evaporation residue spin distributions

Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the spin distribution of evaporation residue cross sections of nuclei ¹⁹⁰Os and ²¹⁰Po which have the same neutron-to-proton ratio N/Z$N/Z$ but have a difference in fissility. We find that a large fissility enhances the sensitivity of the residue spin distribution to pre-saddle friction substantially. The results suggest that on the experimental side, to obtain accurate information of pre-saddle dissipation strength by measuring the evaporation residue spin distribution it is optimal to populate among various compound systems with equal N/Z$N/Z$ those with high fissility.