动力学控制合成原子精确的银纳米团簇及催化还原4-硝基苯酚

Synthesizing atomically precise Ag nanoclusters (NCs), which is essential for the general development of NCs, is quite challenging. In this study, we report the synthesis of high-purity atomically precise Ag NCs via a kinetically controlled strategy. The Ag NCs were prepared using a mild reducing agent via a one-pot method. The as-prepared Ag NCs were confirmed to be Ag₄₉(D-pen)₂₄ (D-pen: D-penicillamine) on the basis of their matrix-assisted laser desorption ionization time-of-flight mass spectrometric and thermogravimetric characteristics. The interfacial structures of the Ag NCs were illustrated by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The Ag NCs were supported on activated carbon (AC) to form Ag NCs/AC, which displayed excellent activity for the catalytic reduction of 4-nitrophenol with a kinetic reaction rate constant k of 0.21 min?1. Such a high k value indicates that the composite could outperform several previously reported catalysts. Moreover, the catalytic activity of Ag NCs/AC remained nearly constant after six times of recycle, which suggests its excellent stability.     

A near-infrared fluorescent probe for fluorine ions and its application in the imaging of HepG2 cells

In this study, we have designed and synthesized a new near-infrared (NIR) fluorescent probe (BODIPY-Se) to detect fluorine ions (F-) using a B-Se bond to connect the fluorescent dye BODIPY and benzotrifluoride. The probe exhibited a highly selective fluorescence response to F- with a detection limit of 7.4×108 mol/L. The excitation and emission spectra of the probe in the NIR region avoid background fluorescence interference present in biological systems. The fluorescent imaging of HepG2 cells demonstrated ...     

Amidourea-based homoduplex as a super organogelator

The amidourea-based homoduplex was developed as a super organogelator,which could form stable gels in wide-tested solvents.And the reversible gel to solution transition was responsive to heat/cool and acid/base stimuli.The organogels were extensively investigated by 1 H NMR,UV-visible absorption spectroscopy,fluorescence spectroscopy,scanning electron microscopy,transmission electron microscopy and powder X-ray diffraction.Based on these data,the gelation mechanism was rationally proposed.The hydrogen-bonded homoduplexes served as the basic assembling units,and further aggregated into three dimensional networks via-stacking and van der Waals interactions,which consequently led to the entangled fibers for the gel formation.     

Full-angle optical imaging of near-infrared fluorescent probes implanted in small animals

To provide a valuable experimental platform for in vivo biomedical research of small animal model with fluorescence mediated approach, we developed a whole-body near-infrared fluorescence molecular imaging system as described in this paper. This system is based on a sensitive CCD camera and has the ability to achieve 360~ full-angle source illuminations and projections capture of the targets to obtain the dense sampling by performing rotational scan. The measurement accuracy is validated from cylinder phantom experiments by the comparison between the experimental data and theoretical predictions. Finally, we also present typical in vivo images of fluorescent tube implanted into the mouse body. The results are promising and have proved the system imaging performance for macroscopic optical biomedical research.     

Fabrication of metal nanoclusters on graphene grown on Ru（0001 ）

Monolayer graphene was epitaxially grown on Ru（0001） through exposure of the Ru（0001） to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structures were studied by scanning tunneling microscopy （STM）, X-ray photoelectron spectroscopy （XPS）, and ultraviolet photoelectron spectroscopy （UPS）. The graphene/Ru（0001） surface was used as a periodic template for growth of metal nanoclusters. Highly dispersed Pt clusters with well controlled size and spatial distribution were fabricated on the surface.     

Preparation and cytocompatibility of polylactic acid/hydroxyapatite/graphene oxide nanocomposite fibrous membrane

A series of polylactic acid (PLA) based nanocomposite fibrous membranes,including neat PLA,PLA/hydroxyapatite (HA) and PLA/HA/graphene oxide (GO),were fabricated via electrospinning method.The morphology and composition were investigated by scanning electron microscopy (SEM),X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) respectively.The thermal stability was determined by thermogravimetric analysis (TGA).To estimate the cytocompatibility of asprepared PLA/HA/GO fibrous membrane,MC3T3-E1 cells were cultured,and the corresponding cell adhesion and differentiation capability were investigated by fluorescence microscopy,SEM and MTT test.The electrospun ternary PLA/HA/GO membrane exhibited three-dimensional fibrous structure with relatively rough surface morphology,which made itself ideal for cell attachment and proliferation in bone tissue regeneration.The fluorescence microscopy,SEM and MTT test confirmed that the PLA/HA/GO nanocomposite fibrous membrane created a proper environment for the seeding and proliferation of MC3T3-E1 cells.     

Synthesis and molecular recognition properties of a novel chemical modified P-cyclodextrin

A new fluorescent chemosensor, a kind of P-cyclodextrin (CD) modified with N' N-dimethylamino-chalcone, was synthesized. The photophysical behavior and the molecular recognition of this compound were investigated by fluorescence spectroscopy. The results show that there exists an "in-out" movement of appended chalcone group from cyclodextrin cavity for "large dimension guest molecule such as 1-adamantanecarboxylic acid. But the long-chained guests such as cationic surfactants can be inserted into the CD cavity as a spacer to form a ternary inclusion complex with the CD cavity and the chalcone moiety.     

Spectroscopic investigation of the interactions between gold nanoparticles and bovine serum albumin

The interactions between bovine serum albumin(BSA) and gold nanoparticles(AuNPs) ,and the conformational changes of BSA induced by this interaction,were investigated by UV-visible absorption spectroscopy,fluorescence spectroscopy,and Fourier transform infrared in combination with attenuated total reflection spectroscopy(ATR-FTIR) .The critical adsorption density for preventing AuNP aggregation in 0.1 mol/L phosphate buffered saline(pH 7.2) was 23 BSA molecules per gold particle or 3.8×1012 BSA molecules/cm2.BSA bound to the AuNPs with high affinity(binding constant Ks=7.59×108 L/mol) ,and the intrin-sic fluorescence of BSA was quenched by the AuNPs in accordance with the static quenching mechanism.Both fluorescence spectroscopy and ATR-FTIR showed that AuNPs induced conformational changes in BSA,which resulted in it becoming less compact and increased the polarity of the microenvironment around the tryptophan residue Trp-212.     

Functionalization of PCL fibrous membrane with RGD peptide by a naturally occurring condensation reaction

Poly(e-caprolactone)(PCL)is widely adopted as an ingredient for tissue engineering scaffolds.To improve its cell affinity,in this study,we developed a new method to introduce bioactive RGD peptides onto the surface of PCL via condensation reaction between 2-cyanobenzothiazole(CBT)and D-cysteine.The PCL fibrous membranes were prepared by electrospinning,and RGD functionalization was characterized by fluorescence microscopy,scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and water contact angle(WCA).As expected,our results demonstrated the successful RGD immobilization on the surface of PCL.RGD modification improved the hydrophilicity of PCL,changing their WCA from 112.20°to38.35°.Cell adhesion,spreading and proliferation of 3T3fibroblasts were also enhanced.We therefore believe that the methods reported in this study was facile and effective for functional modification of the hydrophobic PCL scaffolds.The moderate reaction conditions are also suitable for covalent immobilization of bioactive molecules onto PCL.     

Hacking the optical diffraction limit: Review on recent developments of fluorescence nanoscopy

Subject to the diffraction limit, the resolution of conventional optical microscopy is constrained to about 200 and 500 nm in the lateral and axial planes, respectively. The advantage of optical microscopy in the life sciences over electronic microscopy, especially fluorescence microscopy, drives scientists to develop novel "hacks" to reach nanoscale resolutions by optical means. In this review, three aspects of the techniques are discussed: (1) lateral super-resolution; (2) axial super-resolution; (3) super-resolution in three dimensions. The principles of how the methods achieve the cross-barrier resolution are discussed, and recent advances in current techniques are described. With these methods, the use of fluorescence microscopy is growing quickly toward a new era: fluorescence nanoscopy that will reveal 2 orders of magnitude more information on cellular structure and dynamics.     

基于荧光纳米传感的DEHP快速检测方法研究

采用一锅法制备了超支化聚乙烯亚胺-铜纳米簇(hPEI-Cu NCs),并利用其构建“turn on”荧光纳米传感器对邻苯二甲酸二(2-乙基)己酯(DEHP)进行定量快速检测.hPEI-Cu NCs的最佳激发波长为385 nm,在510 nm处有强发射,透射电镜(TEM)分析结果表明:其形态呈现良好的分散性,粒径为(1.3±0.3)nm.在加入Cu²⁺后,hPEI-Cu NCs的荧光被Cu²⁺淬灭; 但当存在DEHP时,Cu²⁺不能淬灭hPEI-Cu NCs的荧光,且使其荧光强度比不加DEHP时有所上升.随着DEHP质量浓度的增加,hPEI-Cu NCs的荧光逐渐增强,从而达到检测DEHP的目的.荧光强度变化率((I-I₀)/I₀)与DEHP的质量分数在1.0～7.0 mg·kg^-1的范围内呈现良好的线性关系,当信噪比为3 时计算出DEHP的最低检出限约为0.4 mg·kg^-1.     

水溶性荧光金银纳米簇的生物效应研究进展

荧光金属纳米簇是一种具有独特物理化学特性的新型纳米材料,在生物医学的许多应用中显示出巨大的潜力.阐明它们在复杂的生物环境中的行为对于设计基于金属纳米簇的高效、安全的纳米医药至为关键.在这篇综述中,概述了水溶性的金属纳米簇与生物体系相互作用的最新研究进展,讨论了影响这些生物相互作用过程中的关键参数,并对未来金属纳米簇的生物效应的研究做了展望.     

基于亚甲基蓝二氧化硅纳米颗粒的细胞与活体成像

采用反相微乳液法,制备了以亚甲基蓝为内核材料的亚甲基蓝二氧化硅纳米颗粒,通过优化亚甲基蓝的包裹浓度获得荧光信号较强的纳米颗粒,并初步考察了其用于He-la细胞标记与体内示踪的可行性.通过MTT实验考察了颗粒对细胞的毒性影响以及较为适宜的标记细胞的浓度,结果表明:当颗粒浓度为1mg/mL时,细胞的存活率仍有80%左右.利用激光共聚焦显微镜考察了Hela细胞对颗粒的吞噬情况以及颗粒在细胞内的分布情况,结果表明,该颗粒能被Hela细胞吞噬且主要分布在溶酶体内.活体荧光成像结果显示,尾静脉注射该颗粒后,裸鼠全身都发射出近红外荧光信号,随着血液的循环,颗粒慢慢聚集在肝脏等器官中.以上结果表明,包裹亚甲基蓝的二氧化硅纳米颗粒可以用于细胞的标记和体内示踪成像.     

发光铜纳米粒子的制备及其在生化传感、环境监测中的应用综述

发光铜纳米簇具有与金、银贵金属纳米簇相媲美的荧光性质,还具有原料储量丰富、制备经济、合成过程简便等优点,具有广阔的应用前景。系统地介绍了铜纳米簇的主要性质、制备方法及应用现状,重点总结了近年来荧光铜纳米簇在生化传感器、生物探针、细胞成像、环境标志物检测等领域的应用进展。     

电荷稳定分散聚合制备光活性聚苯乙烯微球

采用苯乙烯磺酸钠电荷稳定分散聚合体系,在甲醇/水混合溶剂中,通过后滴加功能单体4-烯丙氧基-2-羟基苯甲酮（BP-OH）,制备出表面带有二苯甲酮光引发基团的聚苯乙烯（PS）微球。研究了功能单体BP-OH的补加时间及总反应时间对微球形貌及功能基团结合量的影响,并将所制备的功能性PS微球在紫外光辐照下引发荧光单体7-甲基丙烯酰氧乙基-4-甲基香豆素（MCMA）反应;并通过场发射扫描电子显微镜（FESEM）、傅里叶变换红外光谱（FT-IR）、紫外可见光谱（UV-Vis）及荧光显微镜（FM）对微球进行测试表征。结果表明,所制备的微球具有光引发活性。     

金纳米团簇荧光探针的合成与生物检测应用

近年来,纳米技术发展迅速。荧光金纳米材料展现出的独特光学特性使其在生物检测和医学诊断中表现出了很好的应用前景。通过改变配体或者生物支架合成的各种荧光金纳米团簇(gold nanocluster,Au NCs),在传感检测、医学成像和光电子学等领域具有潜在的应用前景。就荧光和共振光散射技术和方法对水溶性的荧光金纳米团簇的合成以及检测机理作出介绍,并简单总结了金纳米团簇作为荧光探针在生物检测,包括金属离子、阴离子、有机小分子、蛋白质和核酸等各种分析物检测中的应用。同时,评述和展望了荧光金纳米团簇研究的发展方向和应用前景。     

基于DNA-AuNCs的荧光传感新方法灵敏检测胰蛋白酶活性

以DNA模板金纳米簇(DNA-AuNCs)作为荧光探针,发展了一种灵敏检测胰蛋白酶活性的荧光分析新方法.在胰蛋白酶存在条件下,牛血清白蛋白水解成多肽片段,释放出游离的半胱氨酸残基.半胱氨酸残基与金纳米簇通过Au-S键形成非荧光的配合物,导致金纳米簇的荧光强度显著降低.该方法对胰蛋白酶的线性检测范围为0.1～2.0mg/L,检出限为20μg/L(R_(SN)=3).此外,该方法被成功应用于人血清样品中胰蛋白酶含量的测定.     

基于谷胱甘肽稳定铜纳米簇的荧光传感方法灵敏检测汞离子

以谷胱甘肽(GSH)为保护配体和还原剂,制备了稳定的水溶性荧光铜纳米簇(CuNCs).所合成的铜纳米簇在590nm处发射出红色荧光,量子产率约为2.3%,具有良好的光稳定性.以谷胱甘肽稳定铜纳米簇(GSH-CuNCs)作为信号探针,报道了一种荧光传感新方法用于灵敏检测Hg~(2+).结果表明,Hg~(2+)的线性检测范围为2.0×10~(-8)～2.0×10~(-6) mol/L,检出限为4.0×10~(-9) mol/L(R_(SN)=3).该方法成功地实现了湖水样品中汞离子的检测,为汞离子的快速和灵敏监测提供了一种新途径.     

N-乙酰基靛蓝对CTAB临界胶束浓度的测定

本文以靛蓝为原料,在吡啶存在下与乙酰氯反应值得的N-乙酰基靛蓝是一种具有大斯托克斯位移值的近红外荧光化合物,以此为探针采用光谱法对阳离子表面活性剂十六烷基三甲基溴化铵(简称CTAB)的梯度浓度下的荧光光谱进行了测定,结果表明,在N-乙酰基靛蓝原发射峰位置发生了明显的荧光强度变化,在测试体系的荧光强度-浓度(I-C)图中有明显的突变点,此突变点对应的CTAB浓度值与其临界胶束浓度文献值0.80 mmol·L-1一致.