A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection

In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN)₆]^3−/4−. Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10 fM–100 nM) and a detection limit on the order of 0.90 fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health.     

A weighted finite difference method for the fractional diffusion equation based on the Riemann–Liouville derivative

A one dimensional fractional diffusion model with the Riemann–Liouville fractional derivative is studied. First, a second order discretization for this derivative is presented and then an unconditionally stable weighted average finite difference method is derived. The stability of this scheme is established by von Neumann analysis. Some numerical results are shown, which demonstrate the efficiency and convergence of the method. Additionally, some physical properties of this fractional diffusion system are simulated, which further confirm the effectiveness of our method.     

甲氨蝶呤/层状双金属氢氧化物的性能调控及细胞生物实验研究

在乙醇-水混合体系中,以氨水为沉淀剂共沉淀合成了甲氨蝶呤/层状双金属氢氧化物（MTX/LDH）纳米复合物,采用控制水热处理时间的方式来调控其性能。利用X-射线衍射（XRD）、透射电镜（TEM）和红外光谱（FT-IR）等表征手段,对其结构及形貌进行了表征。研究表明：MTX分子以单层倾斜或垂直方式插入LDH层间,随着水热处理时间的不同,MTX在层间的倾斜角度发生了变化;水热处理时间对产物的结晶度、粒径和层间排列方式都有影响,当水热处理时间为12h时,得到的MTX/LDH纳米复合物的结晶度最高,单分散性最好。在磷酸缓冲液中考察了MTX/LDH纳米复合物的缓释性能,结果表明样品均呈现出良好的缓释性能,释放速率先快后慢。重点考察了这几种MTX/LDH纳米复合物作用于肺癌细胞A549的细胞生物实验,研究表明这几种复合物对肺癌细胞A549都具有良好的抑制作用,其效果与纳米复合物的单分散性和粒径有密切的关系,单分散性越好,粒径分布越均匀,对A₅₄₉癌细胞的抑制效果越好。     

A facile and sensitive colorimetric detection for RNase A activity based on target regulated protection effect on plasmonic gold nanoparticles aggregation

In this work, a facile and sensitive colorimetric detection method was firstly reported for RNase A activity detection based on target regulated protection effect of chimeric DNA probe on the salt-induced aggregation of plasmonic gold nanoparticles.Compared with previous works of RNase A activity detection, this colorimetric assay integrated the advantages of sensitive, low cost, facile operation, rapid response and low biological toxicity.     

导电聚合物在药物可控释放领域的应用

导电聚合物(conducting polymers,CPs)是一类与金属具有相似的电、磁和光学特性的有机聚合物,电刺激会引起其氧化-还原状态的改变,从而导致CPs的电荷量、掺杂水平、导电性以及体积发生变化.利用CPs的这些特性,可将其用于药物、蛋白质以及基因等的传递和可控释放.通过对CPs基体进行化学物理修饰,可以扩大CPs基体的载药品种、提高载药量以及优化药物控释手段.本文简要介绍了CPs的性能和制备方法,对CPs基药物传递体系的药物担载和释放机理进行了详细的讨论,并归纳总结了近年来国内外以CPs为基体的药物传递体系的研究进展,最后对CPs基药物传递体系所面临的问题和未来发展进行了总结和展望.     

多金属氧酸盐催化苯甲醇的选择性氧化：一个绿色可循环的高效催化氧化体系

以Keggin结构的几类杂多酸和三乙胺（TEA）为原料,通过简单的酸碱反应合成了相应杂多酸的TEA盐。 并以它们作为催化剂,30％H2O2作氧化剂,在不使用长链相转移剂的条件下,研究了它们催化苯甲醇选择氧化制备苯甲醛的反应性能。 结果表明,该类催化剂在苯甲醇的选择氧化反应中具有比相应杂多酸更高的催化活性或选择性。 其中[TEAH]H2PW12O40为最佳催化剂,在适宜的反应条件下,该催化剂上苯甲醇转化率可达99.5％以上,苯甲醛选择性达~100％。 催化剂可以被分离和循环使用多次,活性、选择性基本不变。 用水作溶剂,避免了有机溶剂的使用,是一个高效、绿色的苯甲醛选择氧化体系。     

Ultrasound-driven titanium modification with formation of titania based nanofoam surfaces

Titanium has been widely used as biomaterial for various medical applications because of its mechanical strength and inertness. This on the other hand makes it difficult to structure it. Nanostructuring can improve its performance for advanced applications such as implantation and lab-on-chip systems. In this study we show that a titania nanofoam on titanium can be formed under high intensity ultrasound (HIUS) treatment in alkaline solution. The physicochemical properties and morphology of the titania nanofoam are investigated in order to find optimal preparation conditions for producing surfaces with high wettability for cell culture studies and drug delivery applications. AFM and contact angle measurements reveal, that surface roughness and wettability of the surfaces depend nonmonotonously on ultrasound intensity and duration of treatment, indicating a competition between HIUS induced roughening and smoothening mechanisms. We finally demonstrate that superhydrophilic bio-and cytocompatible surfaces can be fabricated with short time ultrasonic treatment.     

Biomass-derived porous material synthesized by one-step calcination method for the magnetic solid-phase extraction of polychlorinated biphenyls in water

Recent findings unfold that biomass materials with the micro/mesoporous structure were often treated as adsorbents for organic substances. In this work, a one-step calcination method was adopted in the preparation of magnetic porous green bean biomass material. It has the properties of magnetism and porosity after the addition of Co(NO₃)₂ and high-temperature calcination. A variety of characterizations have been operated, including energy dispersive X-ray detector, vibrating sample magnetometer, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and so on. It has a specific surface area of 168.1611 m²/g and a pore volume of 0.1764 cm³/g. The material was used in magnetic solid-phase extraction of three polychlorinated biphenyls: 2-chlorobiphenyl, 4-chlorobiphenyl, and 2,2,5-trichlorobiphenyl. Several factors were investigated, such as material amount, eluents, adsorption time, solution pH, salinity, and reusability. Under optimized conditions, good recoveries (90.24–93.34%) were achieved with the relative standard deviation in a range from 2.30 to 4.83%. Three real water samples (tap, river, and lake water) were tested to verify the accuracy of the method. This method can be successfully used in the analysis of some polychlorinated biphenyls congeners in water.     

Ethylenediamine tetramethylene phosphonic acid assisted synthesis of palladium nanocubes and their electrocatalysis of formic acid oxidation

The synthesis of Pd nanocrystals of controlled size and morphology has drawn enormous interest due to their catalytic activity. We report a new and efficient strategy for the one-step synthesis of monodispersed Pd nanocubes with ethylenediamine tetramethylene phosphonate (EDTMP) as a complex-forming and capping agent. The morphology, structure, and growth mechanism of the Pd nanocubes were fully characterized via selected area electron diffraction (SAED), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found that the morphology of the Pd nanocrystals in the proposed EDTMP–PdCl₂ system could be changed from octahedrons to nanocubes simply by adjusting the amount of iodide used during synthesis. After UV/ozone and electrochemical cleaning, the as-prepared Pd nanocubes demonstrated excellent electrocatalytic activity and stability during formic acid oxidation, owing to their abundant {100} facets and small particle size.     

氯化血红素分子对牛血清白蛋白电子传输能级的调控

蛋白质分子的电子传输(ETp)性能,即导带(CB)和价带(VB)的能量差(带隙)是影响蛋白质电子器件性能的主要因素之一。因此,调控蛋白质ETp带隙是提高这些电子器件性能并扩展其应用领域的重要途径。本文报道一种通过外部分子结合调控蛋白质ETp带隙的方法。以氯化血红素(hemin)与牛血清白蛋白(BSA)结合为例,首先运用分子对接方法从理论上确定hemin分子能结合到BSA分子IIA域的疏水口袋中,位于Tpr213附近;然后实验(荧光光谱和吸收光谱)证实hemin与BSA结合后,能形成hemin-BSA复合物,并且没有改变BSA的原有结构;最后将hemin-BSA通过BSA分子表面Cys34的―SH固定在金电极表面,形成有序的分子层,研究其ETp性能;I–V结果表明,BSA表现出半导体的ETp特征,并且hemin的结合能使BSA的带隙由原来的~1.50±0.05e V降低到~0.93±0.05e V。本文的结果为调控蛋白质分子的ETp带隙提供了一种简单有效的方法,通过选择不同的结合分子能使蛋白质分子的带隙调控至所需要的范围,并且形成的蛋白质复合物还能用于各种电子器件的制作。