顺铂前药接枝修饰硫代DNA及其自组装靶向纳米药物研究

选用具有良好生物相容性的硫代修饰嵌段核酸为载体,将其非硫代修饰部分设计为靶向MUC-1蛋白的核酸适配体序列,同时在其硫代修饰部分通过硫代磷酸酯基团（Phosphorothioate,PS）接枝修饰四价顺铂前药,制备了两亲性核酸-顺铂前药缀合物MUC-1/^PODNA-b-（^PSDNA-g-Pt）,并进一步自组装成类似球形核酸（Spherical nucleic acid,SNA）的含铂靶向纳米药物（MUC-1/Pt-SNAs）.结果表明,该纳米药物递送体系载药率高、形貌稳定、分散性好,能够高效靶向MUC-1蛋白过表达的MCF-7乳腺癌细胞,并在体内外实验中表现出优异的抗肿瘤效果和极低的毒副作用.     

XANES技术探究酸处理对义马煤中硫形态及其热变迁行为的影响

利用XANES技术研究了酸处理对义马煤的比表面积、体相及表面硫形态分布和热解过程中硫变迁行为的影响。结果表明,由于酸处理过程中部分镶嵌于有机质中的矿物质被脱除导致部分闭合孔打开,煤的比表面积有所增大。HCl-HF和HCl-HF-HNO_3处理脱除了煤中大部分矿物质和无机硫,由于HNO_3的强氧化性,YMN中亚砜和砜硫化物的相对含量均高于YMR和YMD。相比煤样体相,酸处理过程对表面形态硫的分布产生了更为明显的影响。酸处理煤样热解含硫气体释放量减少,但由于大部分碱性矿物质的脱除和煤中易分解形态硫相对含量的增加,含硫气体释放率增加。不同形态硫之间的内部转化使得酸处理煤焦中主要形态硫的分布更为均匀。通过HCl-HF-HNO_3处理可以有效地脱除煤中矿物质及无机硫,并改变煤中形态硫分布,从而为高灰分、富含黄铁矿的高硫煤的利用提供指导。     

绿色单体二氧化碳参与的新型聚合反应

二氧化碳（CO₂）是一种丰富、廉价、无毒以及可再生的一碳资源,也是一种可用于聚合的绿色单体.基于CO₂的聚合是近年来的研究热点之一.目前广泛报道的是CO₂和环氧单体的聚合反应,经过几十年的发展已经成功实现工业化生产.最近几年,一些CO₂参与的新型聚合反应被陆续报道,这些工作大都通过两种途径实现从CO₂到高分子材料的转变.第一个途径是先将CO₂转化为可以聚合的单体,例如：内酯、环状碳酸酯和2,5-二呋喃甲酸等,再利用开环或者逐步聚合将单体转化为聚合物;另一个途径是直接以CO₂为单体和其他类型单体共聚得到聚合物.这两种途径对于发展CO₂参与的新型聚合反应,拓展CO₂基聚合物种类都具有重要意义.本综述按照CO₂直接还是间接参与聚合反应分类总结了近年来在CO₂制备高分子材料方面的进展,并对未来发展方向进行了简单阐述.     

基于钴离子介导信号转换的抗坏血酸比色分析

抗坏血酸是许多生化过程所必需的一种生物小分子。借助于羟基氧化钴纳米片的氧化性和钴离子与硫氰酸根离子之间强的螯合作用,本研究首次报道了一种基于钴离子信号转换的新方法用于抗坏血酸的比色分析。在抗坏血酸存在时,羟基氧化钴纳米片被还原降解产生二价钴离子,钴离子与硫氰酸根离子之间通过螯合作用生成蓝色的[Co(NCS)₄]^_2-阴离子络合物,在625 nm处产生可见吸收信号。实验首先对羟基氧化钴纳米片与抗坏血酸的反应时间、硫氰酸铵和吐温-80的加入量等实验参数进行了优化,当反应时间为5 min,硫氰酸铵(3 mol/L)和吐温-80(10%, w%)的加入体积分别为30 μL和80 μL时,检测体产生最强的吸收信号。在优化的条件下,随着抗坏血酸浓度的增加,检测体系在625 nm处的吸收值线性增强,在0.03～0.45 mmol/L浓度范围内,检测体系在625 nm处的吸收值与AA浓度呈良好的线性关系,线性方程为A₆₂₅=0.638C (mmol/L)+0.042,相关系数R=0.993,检测限(3S/N)为1.5 μmol/L。     

Amino Acid Modified RNA Bases as Building Blocks of an Early Earth RNA-Peptide World

Fossils of extinct species allow us to reconstruct the process of Darwinian evolution that led to the species diversity we see on Earth today. The origin of the first functional molecules able to undergo molecular evolution and thus eventually able to create life, are largely unknown. The most prominent idea in the field posits that biology was preceded by an era of molecular evolution, in which RNA molecules encoded information and catalysed their own replication. This RNA world concept stands against other hypotheses, that argue for example that life may have begun with catalytic peptides and primitive metabolic cycles. The question whether RNA or peptides were first is addressed by the RNA-peptide world concept, which postulates a parallel existence of both molecular species. A plausible experimental model of how such an RNA-peptide world may have looked like, however, is absent. Here we report the synthesis and physicochemical evaluation of amino acid containing adenosine bases, which are closely related to molecules that are found today in the anticodon stem-loop of tRNAs from all three kingdoms of life. We show that these adenosines lose their base pairing properties, which allow them to equip RNA with amino acids independent of the sequence context. As such we may consider them to be living molecular fossils of an extinct molecular RNA-peptide world.     

MVF Sensor Enables Analysis of Nucleic Acids with Stable Secondary Structures

One major challenge in nucleic acids analysis by hybridization probes is a compromise between the probe's tight binding and sequence‐selective recognition of nucleic acid targets folded into stable secondary structures. We have been developing a four‐way junction (4WJ)‐based sensor that consists of a universal stem‐loop (USL) probe immobilized on an electrode surface and two adaptor strands (M and F). The sensor was shown to be highly selective towards single base mismatches at room temperature, able to detect multiple targets using the same USL probe, and have improved ability to detect folded nucleic acids. However, some nucleic acid targets, including natural RNA, are folded into very stable secondary and tertiary structures, which may represent a challenge even for the 4WJ sensors. This work describes a new sensor, named MVF since it uses three probe stands M, V and F, which further improves the performance of 4WJ sensors with folded targets. The MVF sensor interrogating a 16S rRNA NASBA amplicon with calculated folding energy of ?32.82 kcal/mol has demonstrated 2.5‐fold improvement in a signal‐to‐background ratio in comparison with a 4WJ sensor lacking strand V. The proposed design can be used as a general strategy in the analysis of folded nucleic acids including natural RNA.     

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.     

Preparation, characterization and MRI application of carboxymethyl dextran coated magnetic nanoparticles

Superparamagnetic nanoparticles functionalized with carboxymethyl dextran (CM-dextran) were synthesized by a two-step method. First, the magnetic nanoparticles (MNPs) coated with dextran (M_w ≈ 20000) were prepared by co-precipitation of Fe²⁺ and Fe³⁺ ions. Then, dextran on the surface of MNPs reacted with monochloroacetic acid (MCA) in alkaline condition. The influences of temperature and reactant concentration on the amount of -COOH on the surface of nanoparticles were systematically studied. The obtained MNPs coated with CM-dextran were stable over the entire range of pH and NaCl concentration. The MRI experiment indicated that the CM-dextran MNPs could potentially be used as MRI contrast agents for magnetic resonance molecular imaging.     

A simple solution-immersion process for the fabrication of superhydrophobic cupric stearate surface with easy repairable property

The present work reports a simple and time-saving method to fabricate cupric stearate film on zinc substrate by a solution-immersion process. Superhydrophobic surfaces are conventionally prepared employing two steps: roughening a surface and lowering its surface energy. The fabrication of superhydrophobic cupric stearate surface is reported using a one-step process by immersing a zinc plate coated with copper into the stearic acid solution, simplifying the complexity of two different steps involved in the conventional methods. The surface of the zinc plate coated with copper is found to be covered with low surface energy cupric stearate film providing the water contact angle of 160 ± 1° with the rolling off properties. In addition, the damaged superhydrophobic surface can restore superhydrophobicity property by immersing the surface into the stearic acid solution again.     

Superhydrophobic alumina surface based on stearic acid modification

A novel superhydrophobic alumina surface is fabricated by grafting stearic acid layer onto the porous and roughened aluminum film. The chemical and phase structure, morphology, and the chemical state of the atoms at the superhydrophobic surface were investigated by techniques as FTIR, XRD, FE-SEM, and XPS, respectively. Results show that a super water-repellent surface with a contact angle of 154.2° is generated. The superhydrophobic alumina surface takes on an uneven flowerlike structure with many nanometer-scale hollows distribute in the nipple-shaped protrusions, and which is composed of boehmite crystal and γ-Al₂O₃. Furthermore, the roughened and porous alumina surface is coated with a layer of hydrophobic alkyl chains which come from stearic acid molecules. Therefore, both the roughened structure and the hydrophobic layer endue the alumina surface with the superhydrophobic behavior.