NaYF_4:Er~(3+),Yb~(3+)纳米晶基于尺寸和激发功率的上转换荧光性能研究

采用热分解法制备出纯β相的NaYF_4:Er~(3+),Yb~(3+)稀土上转换纳米晶,通过改变表面配体的种类和用量,合成出了两种不同尺寸和形貌的纳米颗粒。使用较少表面配体所合成的纳米颗粒具有更大的尺寸和更规则的形貌。比较了两种纳米颗粒的荧光性能,在980 nm激发光照射下,随着激发光功率的增加,纳米颗粒的荧光强度也逐渐增强,尺寸较大的纳米颗粒的荧光强度比尺寸较小的高了1个数量级。绿光与红光的比例也与纳米颗粒的尺寸和激发光功率密度相关,荧光性能较弱的小尺寸颗粒的绿光比例随激发光功率密度的增加而增大;荧光性能较好的大尺寸颗粒的绿光比例则在增大到一定程度后逐渐减小。此项工作可能在生物体荧光成像、荧光标记、光动力治疗以及生物传感等方面提供指导。     

NiFe_(2-x)Sm_xO_4纳米丝的制备与磁性能

采用溶胶-凝胶法、静电纺丝技术和热处理技术相结合制备了一维NiFe_(2-x)Sm_xO_4(x=0,0.02,0.04,0.06,0.08,0.1)纳米丝。利用X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和振动样品磁强计(VSM)对NiFe_(2-x)Sm_xO_4纳米丝的结构、形貌和磁性能进行表征。结果表明:NiFe_(2-x)Sm_xO_4纳米丝表面光滑、直径均匀、连续,直径约60 nm。掺杂Sm~(3+)没有改变NiFe_2O_4的尖晶石结构,随着Sm~(3+)掺杂量的增大,晶粒尺寸D从44.8 nm减小到19.6 nm。NiFe_(2-x)Sm_xO_4纳米丝表现出软磁特性。随着Sm~(3+)掺杂量的增大,NiFe_(2-x)Sm_xO_4纳米丝的饱和磁化强度(Ms)、剩余磁化强度(Mr)和矫顽力(Hc)先减小后增大,在x=0.08时分别达到最小值22.54,2.98emu·g~(-1),90.33 Oe。     

不同形貌镍纳米粒子-石墨烯复合材料的制备及微波吸收性能

采用原位化学还原方法制备出了两种不同形貌的镍纳米粒子-石墨烯(Ni-GNs)复合材料, 并研究了形貌对复合材料电磁吸收性能的影响. 制备过程中通过改变反应物的加入顺序, 制备出球形和刺球形镍纳米粒子-石墨烯复合材料. 利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和矢量网络分析仪(VNA)对复合材料的形貌、结构和微波吸收性能进行了表征. 结果表明: 刺球形镍纳米粒子-石墨烯复合材料相比于球形镍纳米粒子-石墨烯复合材料具有优异的电磁吸收性能, 其原因是由于复合材料中刺球形镍纳米粒子独特的各向同性天线形貌引起的尖端放电效应. 因此利用简单的原位化学还原制备不同形貌镍纳米粒子-石墨烯复合材料的方法可以作为其他复合材料制备的总体路线.     

温和条件下制备形貌可控的羟基磷灰石

在温和条件下采用简单的实验方法成功制备出不同结构和形貌的羟基磷灰石(HAP)纳米粒子。采用沉淀-水解两步法,以PEG和PVP为表面活性剂,在沉淀步骤制备出前驱体CaHPO₄粒子,然后在100℃、常压条件下水解获得高结晶度的HAP纳米棒。采用PEG制备的纳米棒形貌均匀、纵横比高;采用PVP制备的纳米棒尺寸范围较宽且尺寸较小。直接采用一步沉淀法也能够成功制备出HAP纳米粒子。采用PEG制备出麦穗状的纳米粒子;采用PVP制备出尺寸小的纳米棒和纳米粒子混合物。HAP纳米晶的结构和形貌因制备条件不同发生很大变化,故而控制其合成,有望用于生物医药领域。     

荧光增强核壳结构NaYF_4:Yb,Er@NaGdF_4@SiO_2@Ag上转换荧光纳米粒子的制备与性能

通过热分解法合成了NaYF_4:Yb,Er油溶性上转换荧光纳米粒子,并以NaYF_4:Yb,Er为晶种制备了核壳结构的NaYF_4:Yb,Er@Na Gd F4荧光纳米粒子,经荧光测试纳米粒子的荧光性能提高了8倍。用反相微乳液法在纳米粒子表面包覆了一层Si O2-(CH2)3-NH2,有效地改善了纳米粒子的水溶性。在Si O2表面沉积Ag纳米粒子,通过贵金属纳米粒子表面等离子共振效应进一步增强了复合纳米粒子的荧光性能,经测试纳米粒子荧光性能又提高了8倍。通过小鼠体内成像实验,发现所合成的纳米粒子生物体内具有较强荧光成像功能。试验中还发现表面活性剂Igepal CO-520和TEOS对包覆层形貌有着重要的影响。     

链霉亲和素-异硫氰酸荧光素偶联核壳型Fe_3O_4/Au纳米晶的合成及性质

采用改进的Polyol合成法,以PEO-PPO-PEO为表面活性剂制备了链霉亲和素-异硫氰酸荧光素偶联的Fe3O4/Au纳米粒子;利用透射电镜和X射线衍射仪分析证实了Fe3O4/Au的核壳型纳米结构,确定了其粒径和分布;采用紫外-可见吸收光谱仪和荧光光谱仪测定了所制备的纳米粒子的光学活性和荧光特性,并采用振动样品磁强计(VSM)测量了其磁化率.结果表明,所制备的Fe3O4/Au纳米粒子具有光学活性和荧光特性,以及优异的磁性.     

温和条件下制备形貌可控的羟基磷灰石（英文）

在温和条件下采用简单的实验方法成功制备出不同结构和形貌的羟基磷灰石(HAP)纳米粒子。采用沉淀-水解两步法,以PEG和PVP为表面活性剂,在沉淀步骤制备出前驱体CaHPO_4粒子,然后在100℃、常压条件下水解获得高结晶度的HAP纳米棒。采用PEG制备的纳米棒形貌均匀、纵横比高;采用PVP制备的纳米棒尺寸范围较宽且尺寸较小。直接采用一步沉淀法也能够成功制备出HAP纳米粒子。采用PEG制备出麦穗状的纳米粒子;采用PVP制备出尺寸小的纳米棒和纳米粒子混合物。HAP纳米晶的结构和形貌因制备条件不同发生很大变化,故而控制其合成,有望用于生物医药领域。     

硅量子点支撑钯纳米粒子的可控制备

采用微乳法制备烯丙胺修饰的硅量子点(Si QDs),通过紫外-可见吸收光谱、荧光光谱和红外光谱对其光学性能进行了表征,通过透射电镜(TEM)对其形貌进行了表征,测得其荧光量子产率为10.06%,荧光寿命τ1=3.1982ns,τ2=12.4527ns。依据Si QDs的光学性质,制备了Si QDs支撑Pd纳米粒子材料(Si QDs/Pd)。通过量子点的浓度实现了Pd纳米粒子形貌和尺寸的有效控制。结果表明制备的Pd纳米材料具有较好的分散性,在有机催化和能源转化领域具有潜在的应用价值。     

共沉淀-连续微反应法制备Fe_3O_4纳米粒子

采用共沉淀-连续微反应法制备了Fe3O4纳米粒子(1),其结构和形貌经XRD和TEM表征。1具有很好的尖晶石结构,形貌均一,分散性好,尺寸分布窄,粒径15 nm~20 nm。磁性测量结果表明,1具有超顺磁性,饱和磁化强度为62.24 emu·g-1。     

Eu3+掺杂纳米羟基磷灰石生物荧光探针的制备、性能与表征

以Ca(NO3)2·4H2O,Eu2O3和(NH4)2HPO4为原料,采用反相微乳液-水热法制备出Eu3+掺杂羟基磷灰石纳米粒子.通过对产物纳米粒子的荧光光谱,TEM、XRD等测试分析,重点考察了Eu3+掺杂量对产物纳米结构和荧光性能的影响,并对荧光性能随其形貌变化的关系等进行了简要讨论.     

Interface dominated high photocatalytic properties of electrostatic self-assembled Ag(2)O/TiO(2) heterostructure

Electrostatic self-assembled Ag(2)O/TiO(2) nanobelts heterostructure was synthesized via simple physical mixing of Ag(2)O nanoparticles and TiO(2) nanobelts. The morphologies and microstructures of Ag(2)O/TiO(2) nanobelt heterostructure were characterized by high resolution transmission electron microscopy. The interface dominated high UV photocatalytic activity and degraded photoluminescence strength of composite catalyst confirmed the heterostructure effect between Ag(2)O nanoparticles and TiO(2) nanobelts. X-ray photoelectron spectroscope provided direct evidence of charge transfer on the heterostructures between them.     

罗丹明B-PdI2-4缔合纳米粒子体系的极谱猝灭效应

缔合纳米微粒;共振散射;罗丹明B-PdI2-4缔合纳米粒子体系的极谱猝灭效应     

Preparation of functionally Pegylated gold nanoparticles with narrow distribution through autoreduction of auric cation by alpha-biotinyl-PEG-block-[poly(2- (N,N-dimethylamino)ethyl methacrylate)

PEGylated gold nanoparticles with biotin moieties installed at the distal end of the PEG tethered chains were prepared by the autoreduction of HAuCl4 catalyzed by alpha-biotinyl-PEG-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (biotinyl-PEG/PAMA) in aqueous medium at room temperature. The size of the gold nanoparticles was controllable in a range of 6-13 nm by changing the initial Au3+/polymer ratio, while retaining their narrow size distribution. The dispersion stability of the nanoparticles in aqueous medium was extremely high even under the condition of salt concentration as high as I = 2.0. Biotinyl-PEG/PAMA-anchored gold nanoparticles underwent specific aggregation in the presence of streptavidin, revealing their promising utility as colloidal sensing systems applicable under biological condition.     

Keggin结构纳米硅钨酸铵的室温固相合成与物性

首次以H4SiW12O40 * 22H2O和(NH4)2C2O4 * H2O为原料,室温固相反应合成出(NH4)4SiW12O40纳米微粒;用元素分析、 FTIR确定产物的组成和结构; XRD、 TEM和BET对产物的形貌、晶粒尺寸和比表面积进行了表征; TG-DTA确定了产物的稳定温区.结果表明,产物为纳米粒子,平均粒径为60 nm,比表面积为108.7 m2/g,在430℃以下具有良好的热稳定性.在固相反应中,研磨和放热反应热效应能加快反应物扩散速率和生成物成核速率,使产物粒径减小;反应物含有结晶水和生成物H2C2O4 * 2H2O,对形成小粒径的(NH4)4SiW12O40纳米粒子起关键作用.     

Facile synthesis of highly biocompatible poly(2-(methacryloyloxy)ethyl phosphorylcholine)-coated gold nanoparticles in aqueous solution

Diblock copolymers comprising a highly biocompatible poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) block and a poly(2-(dimethylamino)ethyl methacrylate) (PDMA) block were evaluated for the synthesis of sterically stabilized gold nanoparticles in aqueous solution. The PDMA block becomes partially protonated on addition of HAuCl4, and the remaining nonprotonated tertiary amine groups reduce the AuCl4- counterion to zerovalent gold in situ. This approach results in the adsorption of the PDMA block onto the gold nanoparticle surface while the PMPC chains serve as a stabilizing block, producing highly biocompatible gold sols in aqueous solution at ambient temperature without any external reducing agent. The size and shape of gold nanoparticles could be readily controlled by tuning synthesis parameters such as the block composition and the relative and absolute concentrations of the PMPC-PDMA diblock copolymer and HAuCl4. These highly biocompatible gold sols have potential biomedical applications.     

2-(4-N-硝基，N-甲基氨基苯基)-(4-硝基苯基)-5-(2,4,6- 三硝基苯基)噻唑的 合成及其性能研究

为解决非线性光学活性有机分子透明性差及熔点低的问题,设计合成了2-(4-N-硝基,N-甲基氨基苯基)-(4-硝基苯基)-5-(2,4,6-三硝基苯基)噻唑化合物,并研究了其热性能及光学性质。根据实验结果得出由于杂环的引入,提高了化合物的裂解温度,并较好地改善了有机分子的透明性。     

Synthesis of gold nanoparticles stabilized with poly(N-isopropylacrylamide)-co-poly(4-vinyl pyridine) colloid and their application in responsive catalysis

The copolymer of poly(N-isopropylacrylamide)-co-poly(4-vinylpyridine) was synthesized by free radical copolymerization of 4-vinylpyridine and N-isopropylacrylamide. The copolymer synthesized with the feed monomer ratio of 4-vinylpyridine/N-isopropylacrylamide equal to 1/3 was associated to form thermoresponsive colloid in neutral water at room temperature, the average size and the cloud-point temperature of which were 40 nm and 32 °C, respectively. The thermoresponsive colloid was used as scaffold to load 2-nm Au nanoparticles to form the responsive catalyst of colloid-stabilizing gold nanoparticles. The catalysis in the model reduction of 4-nitrophenol with NaBH₄ suggested that the catalytic reduction could be modulated due to the thermoresponsive phase-transition of the colloid-stabilizing gold nanoparticles. That was, the catalytic reduction firstly accelerated with the increase in temperature below the cloud-point temperature and then decelerated with the increase in temperature above the cloud-point temperature of the thermoresponsive colloid-stabilizing Au nanoparticles.     

Thermogelling properties of triblock copolymers in the presence of hydrophilic fe(3)o(4) nanoparticles and surfactants

We investigate the supramolecular structure formed by thermogelation of a triblock polymer in the presence of nanoparticles and surfactant using rheometry and small-angle X-ray scattering (SAXS). The triblock copolymer, nanoparticle, and surfactant used in this study are poly(oxyethylene-oxypropylene-oxyethylene), Pluronic F108, Fe(3)O(4) nanoparticles, and sodium dodecyl surfactant, respectively. Addition of 1-5 wt % of Fe(3)O(4) nanoparticle, of average particle size ～10 nm, in a weak template of F108 (15 wt %) shows a decrease in the onset of gelation temperature and dramatic alteration in the viscoelastic moduli. The nanocomposite samples show a linear viscoelastic regime up to 5% strain. The SAXS measurement shows that the intermicellar spacing of the supramolecular structure of pure F108 is ～16.5 nm, and the supramolecular structure is destroyed when nanoparticles and surfactants are incorporated in it. Further, the addition of anionic surfactant to nanocomposites leads to a dramatic reduction in the viscoelastic properties due to strong electrostatic barrier imparted by the surfactant headgroup that prevents the formation of hexagonally ordered micelles. Our results show that the thermogelation is due to the clustering of nanoparticles into a fractal network rather than a close-packed F108 micelles, in agreement with the recent findings in Pluronic F127-laponite systems.     

Formation of supramolecular nanobelt arrays consisting of cobalt(II) "picket-fence" porphyrin on Au surfaces

Adlayers of cobalt(II) 5,10,15,20-tetrakis(alpha,alpha,alpha,alpha-2-pivalamidophenyl)porphyrin (CoTpivPP) were prepared by immersing either Au(111) or Au(100) substrate in a benzene solution containing CoTpivPP molecules, and they were investigated in 0.1 M HClO4 and 0.1 M H2SO4 by cyclic voltammetry and in situ scanning tunneling microscopy (STM). The adlayer structure and electrochemical properties of CoTpivPP are compared to those of 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (CoTPP). Characteristic nanobelt arrays consisting of CoTpivPP molecules were produced on both Au(111) and Au(100) surfaces. The stability of the nanobelt arrays was controlled by manipulating the electrode potential. On the other hand, the formation of nanobelt arrays consisting of O2-adducted CoTpivPP molecules depended upon the crystallographic orientation of Au. The state of O2 trapped in the cavity of CoTpivPP was distinctly observed in STM images as a bright spot in the nanobelt array formed on reconstructed Au(100)-(hex) surface, but not on Au(111) surface. This result suggests that the arrangement of underlying Au atoms plays an important role in the formation of nanobelt arrays with the sixth ligand coordination.     

Assessment of 4-(dimethylamino)pyridine as a capping agent for gold nanoparticles

Gold nanoparticles stabilized with 4-(dimethylamino)pyridine (DMAP) were prepared by ligand exchange and phase transfer (toluene/water) of functionalized gold nanoparticles. DMAP-protected gold nanoparticles are water-soluble, positively charged, and fairly monodisperse (6.2 +/- 0.9 nm). To understand the scope of this interesting system, the details of the binding of DMAP to gold nanoparticles were investigated. The adsorption of DMAP onto gold surfaces was studied by electrochemistry and surface plasmon resonance. It is concluded that of the three most likely binding modes, the one involving the pyridine nitrogen binding to the gold surface, as suggested previously (Gittins, D. I.; Caruso, F. Angew. Chem., Int. Ed. 2001, 40, 3001), is consistent with experimental data. Other 4-substituted pyridines were also assessed as capping agents. The solubility in toluene and basicity of the incoming ligand, as well as the ability to form charged nanoparticles, determine whether ligand exchange and subsequent phase transfer of the nanoparticles occur. The solubility and stability of the DMAP-protected gold nanoparticles were studied as a function of pH using UV-visible spectroscopy and transmission electron microscopy (TEM). These nanoparticles are soluble and stable over a wide pH range (5.0-12.8). It was found that excess DMAP is necessary for both the preparation and the stability of the DMAP-protected gold nanoparticles.