核酸适配体功能化的稀土上转换纳米材料在生物检测中的应用

稀土上转换纳米材料可以吸收近红外光并发射出可见光或紫外光,在生物传感领域得到了广泛研究。核酸适配体能高特异性和高亲和性地与靶标物结合,被广泛应用于生物传感、疾病诊断等领域。将稀土上转换纳米材料与核酸适配体结合构建的检测体系,可实现对目标物灵敏、高选择性的检测。本文介绍了近几年核酸适配体功能化的稀土上转换纳米材料在生物小分子、蛋白质、核酸、病原微生物、细胞等方面的应用,并展望了其在分析检测领域的发展前景。     

新型氧化锌纳米材料在电化学检测对硝基苯酚中的应用

通过溶剂热法控制合成了花生形氧化锌纳米材料,并利用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和傅里叶变换红外光谱(FTIR)对材料进行了表征和分析.循环伏安和Nyquist测试结果表明,该材料具有良好的电化学导电性,且对对硝基苯酚(p-NP)具有良好的选择性.侧分脉冲伏安法(DPV)测试结果表明,在p-NP浓度为0.8~24μmol/L和32~80μmol/L这2个浓度范围内,电流强度与浓度呈线性关系,通过3倍信噪比计算得出检测限分别为0.25和0.61μmol/L.该材料修饰的电极具有良好的稳定性和重现性,用于实际样品中p-NP含量的测定显示出优良的效果.     

三维介孔钴酸锌立方体的制备及其优异的储锂性能

采用简易、温和、实际耐用的水热方法制备了新型三维介孔立方体结构的钴酸锌纳米材料。每个钴酸锌立方体的边长大约在3-4μm之间,并由大量的纳米粒子和密集的孔隙所构成。通过氮吸附/脱附手段测试发现所制备的钴酸锌纳米材料具有较大的比表面积(41.4 m2?g~(-1))和介孔(6.32 nm)特性。使用钴酸锌纳米材料作为锂离子电池负极,金属锂作为正极组装锂电池并测试了材料的储锂性能。研究发现该电极材料在较高的电流密度下循环100周后,仍能呈现较高的可逆容量和超强的循环稳定性。这种优异的储锂性能主要归因于钴酸锌纳米材料的新型结构,这种介孔立方体结构能够加速锂离子的扩散,增加电极与电解液的接触面积并缓解锂离子嵌入/嵌出期间产生的体积膨胀。     

原位限域生长策略制备有序介孔碳负载的超小MoO3纳米颗粒

采用原位限域生长策略制备了一系列有序介孔碳负载的超小MoO₃纳米颗粒复合物(OMC-US-MoO₃). 其中, 有序介孔碳被用作基质来原位限域MoO₃纳米晶的生长. 依此方法制备的MoO₃纳米晶具有超小的晶粒尺寸(<5 nm), 并在介孔碳骨架内具有良好的分散度. 制得的OMC-US-MoO₃复合物具有可调的比表面积(428~796 m²/g)、 孔容(0.27~0.62 cm³/g)、 MoO₃质量分数(4%~27%)和孔径(4.6~5.7 nm). 当MoO₃纳米晶的质量分数为7%时, 所得样品OMC-US-MoO₃-7具有最大的孔径、 最小的孔壁厚度和最规整的介观结构. 该样品作为催化剂时, 表现出优异的环辛烯选择性氧化性能.     

基于氮杂Mn咔咯二维纳米材料的单原子Mn中心催化氧化烷烃制醇

咔咯是由四个吡咯共轭相连而形成的具有芳香性的新型卟啉类大环化合物,但咔咯分子中存在一个直接连结两个吡咯环的C?C键,与卟啉相比,仅仅是少了一个“meso”位置的C原子.因此,在结构上,咔咯含有三个“吡咯型”氮原子和一个“吡啶型”氮原子,当咔咯失去三个内氢原子后变成了三价阴离子,易与金属形成高价态的稳定配合物.氮杂咔咯是一种咔咯的meso位上的C被取代为N的咔咯衍生物.与正常的咔咯相比,它更易于与过渡金属形成稳定配合物.正是由于这些独特的结构特点,使其在金属催化、染料敏化太阳能电池、光敏剂、金属传感器、甚至在医学上都有很好的应用前景.金属有机大环均相催化剂的非均相化,是改进反应产物分离和实现催化剂循环使用的最简单有效方法之一.环境友好的Mn氮杂咔咯催化剂,在温和条件下可以利用氧气直接将有机底物氧化.本文选用Mn氮杂咔咯催化剂作为基本构建单元,通过理论计算,构建了一种新型的具有高催化活性的含Mn氮杂咔咯环结构单元的二维纳米催化材料.我们分别使用高斯软件(Gaussian 09)和维也纳从头算模拟软件包(VASP)对孤立分子和周期性体系进行结构优化以及性质的计算.在这种二维材料中,每一个Mn原子作为相对独立的金属单原子中心(SAC),保留了单环中Mn金属中心的高催化活性.在温和的光照条件下,Mn金属中心可以直接活化氧气生成类自由基[Mn]-O-O中心,随后[Mn]-O-O中心可以有效地通过夺取有机底物中的H和紧接着新生自由基的偶合反应,选择性氧化C?H键为C?OH键.另外,通过沿[Mn]-O-O反应轴施加不同强度的外电场,可对此二维纳米材料的催化反应活性进行精细调控.本文为实验上制备基于Mn氮杂咔咯的非均相催化剂以及单原子Mn基催化剂提供了理论依据.     

基于CoFe(Ⅲ)PBA/GO过氧化物模拟酶化学发光法检测H2O2和抗坏血酸

制备了一种具有过氧化物酶活性的类普鲁士蓝/氧化石墨烯复合纳米材料(CoFe(Ⅲ)PBA/GO)。将具有过氧化物酶活性的CoFe(Ⅲ)PBA/GO和化学发光法相结合,构建了一种用于检测H₂O₂和抗坏血酸(AA)的化学发光分析法。CoFe(Ⅲ)PBA/GO催化H₂O₂产生的O₂·^-,·OH,1O₂自由基氧化Luminol会产生很强的化学发光信号,通过检测化学发光强度可以实现对H₂O₂的检测。该方法检测H₂O₂的线性范围为0~0.8μmol/L,检测限为11 nmol/L。利用AA作为活性氧消除剂可以抑制化学发光反应的特点,实现了AA的检测。该方法测定AA的线性范围为0.02~0.8μmol/L,检测限为20 nmol/L。方法已应用于H₂O₂消毒水中H₂O₂和维生素C片中抗坏血酸的检测。     

基于混酸回流制备碳点的中和过程

Carbon dots (C dots) are relatively novel carbon nanomaterials that have attracted significant interest due to their unique photoluminescence, good biocompatibility, and stability. The preparation methods of C dots was usually summarized into "top-down" and "bottom-up", and mixed acid reflux is a top-down strategy that can be used to synthesize C dots, during which neutralization is a necessary step that can significantly influence the properties and potential applications of the final product. Previously, this research area mainly focused on tuning the properties of C dots by changing the starting materials and/or varying the reaction conditions; the influence of the reagents used during neutralization has been largely ignored. As the previously reported C dots prepared by mixed acid reflux were obtained from different starting materials under varied conditions, a meaningful comparison is difficult. Herein, yellow-emitting C dots were prepared by mixed acid-refluxing a carbon-rich material derived from fullerene carbon soot. For the same batch of as-prepared C dots, the influences of four reagents, i.e., NaOH, Na₂CO₃, K₂CO₃, and NH₃·H₂O, during neutralization on the structures and photoluminescence of the resulting C dots were investigated in detail. The results of thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy clearly showed that the reagent used during neutralization can affect the degree of dissociation of the acidic functional groups on the C dots. This is further supported by examination of the C dot/surfactant mixtures where subtle changes in the phase behavior were observed. Structural changes of the C dots cause variations in their surface states, ultimately altering the optical characteristics, including UV-vis absorption and fluorescence. Among the treated C dots, the sample prepared with Na₂CO₃ showed the strongest emission under the same excitation wavelength, while that prepared with NH₃·H₂O exhibited a distinct red shift (~8 nm) in the emission curve. The results presented herein provide clear evidence that neutralization reagent selection is important for optimizing the properties of the resulting C dots obtained by mixed acid reflux. In addition, the photoluminescence of the C dots can be influenced by their counterions, providing a novel method for tuning the properties of C dots while explaining their behavior in saline solutions. In short, the basicity of the neutralizing reagent and the type of counterions affect the structure of the C dots surface, which brings different performances. This work reminds researchers that it is necessary to use the type of neutralizing reagent as an experimental condition when preparing C dots in the future.     

无机纳米材料在骨代谢调控中的应用

与有机和高分子纳米材料相比,无机纳米材料具有化学性质稳定、力学性能优良、生物相容性和骨诱导性良好等优势,是用于骨代谢调控的主要材料。文章分别从细胞、分子及动物水平总结了羟基磷灰石、稀土纳米材料、金纳米颗粒、碳纳米管等无机纳米材料在骨代谢调控中的作用及其机制,并对无机纳米材料在骨代谢调控中面临的挑战进行了展望。     

MD simulation for nanocrystals

Molecular dynamic (MD) provided anab initio simulation for nano-scale mechanical behavior of materials, provided that the inter-atomic potential is accurately prescribed. MD is particularly suitable in simulating the formation, the deformation, and the evolution of nanocrystals under a fast strain rate. To tackle large scale system and nano-seconds time duration, parallel algorithm is desired. The present paper reviews the recent advances in MD simulation for nanocrystals rithm is desired. The present paper reviews the recent advances in MD simulation for nanocrstals with attention focused on the applications toward nanomechanics. The examined issues are: formation of nanocrystalline metals, nanoindentation on nancorystals, fast deformation of nanocrystals, orderdisorder transition, and nano-particle impact. The project supported by the National Natural Science Foundation of China (101212202 and 90205023)     

“微／纳系统国际会议（ICMNS2002）”简介

由中国力学学会、中科院力学所非线性力学国家重点实验室(LNM)、香港中文大学和香港科技大学联合主办的“微／纳系统国际会议(ICMNS2002)”于2002年8月ll－14日在云南昆明万恰酒店隆重举行。