水稳定的镁掺杂ZnO量子点:一锅法合成及细胞成像应用

一锅法合成了镁掺杂的ZnO量子点, 利用APTES对其进行表面包覆, 并采用XRD、TEM、UV-Vis、PL和FTIR等对材料进行了表征。结果表明镁掺杂能明显增强荧光发光强度, 在合适的掺杂浓度(30%)下其量子产率由11%增加到33%。通过APTES的表面包覆使镁掺杂的ZnO量子点具有良好的水溶性和荧光稳定性, 可用于MCF-7细胞成像研究。     

水溶性ZnO/氨丙基-硅氧烷量子点的合成与荧光特性

利用溶胶-凝胶法在非水体系中合成出ZnO量子点,并用3-氨丙基三乙氧基硅烷(APTES)对其进行包覆,制得水溶性ZnO/氨丙基-硅氧烷量子点(ZnO-ASQDs)。通过实验确定最佳包覆条件:t=60℃,T=30min,nSi:nZn=1:1,VPEG/Vtotal=1/9。合成的ZnO量子点分别在348与512nm处有2个荧光发射峰,且激发区域较宽(220~360nm)。经过APTES包覆,ZnO量子点荧光发射强度明显增强,同时具有良好的水溶性与荧光稳定性,稳定时间可达60d之久。由Brus公式计算表明,包覆层对ZnO量子点不但改性还起到保护作用,抑制其团聚。经XRD与TEM证实,ZnO-ASQDs具有核壳结构,ZnO核平均粒径为6nm,整体粒径约为20nm。此外,通过调整ZnO核的粒径可制备出不同荧光颜色的ZnO-ASQDs。     

水溶性ZnO量子点制备及其光学性质

利用3-巯丙基三乙氧基硅烷对ZnO进行表面修饰后沉积SiO2, 制备出水溶性SiO2包覆ZnO的量子点. 与直接采用正硅酸乙酯沉积包覆SiO2的ZnO量子点相比, 362 nm处的激子荧光发射峰的强度提高了将近4倍. 由于表面引入了巯基官能团, 量子点的水溶性明显提高, 稳定性增强, 即使在较高的盐浓度下也不会团聚. 通过改变条件, 制备出了发光波长在420 nm的蓝色荧光量子点.     

硫脲修饰Cd掺杂ZnO水溶性量子点的制备及表征

在非水稀溶液中以聚乙烯吡咯烷酮K-30为稳定剂,硫脲为表面修饰剂,制备Cd掺杂ZnO水溶性量子点荧光体;同时研究了基质的优化及硫脲含量对ZnO量子点发光性能的影响,Eu和Li的共掺杂对ZnO:Cd量子点发光性能的影响.采用紫外光谱、荧光发射光谱、红外光谱和透射电镜、XRD对样品进行表征.结果表明:经Cd优化基质后、Eu和Li的共掺杂使量子点荧光强度明显增强;硫脲修饰后纳米颗粒分布更加均匀、晶粒更小、荧光光谱蓝移、量子点产率增加;该样品XRD衍射峰是馒头峰.属于无定形态;红外光谱图中因硫脲引起的NH2和C-NH2伸缩振动吸收峰分别为3189.0,1088.2 cm-1,硫脲修饰的最佳浓度大约为32 mg/mL.该量子点制备方法简单易行,具有较好的稳定性及高荧光量子效率,为进一步应用于生物标记奠定基础.     

非水稀溶液中SiO2包覆ZnO量子点的制备及其发光特性研究

本文利用溶胶-凝胶法在非水稀溶液中制备出SiO₂包覆的ZnO量子点。通过紫外-可见吸收光谱(UV-Vis)和荧光光谱对合成量子点的发光特性进行了研究。结果表明，在n_SiO2:n_ZnO=1∶4的条件下，ZnO量子点的发光性能最佳。经过Brus公式计算，该量子点的平均半径在2.8 nm左右，稳定性显著提高。其荧光光谱在363 nm处有一强而窄的激子发射峰，在519 nm处有一个宽而弱的绿色发射峰。说明SiO₂对ZnO形成了有效包覆，明显减少了ZnO的表面缺陷。     

基于氮掺杂碳量子点荧光猝灭效应检测Fe3+

碳量子点光致发光性质取决于尺寸大小和表面官能团的性质.本研究以还原冶炼过程产生的生物质焦油为前驱体,采用小分子乙二胺进行氮掺杂,通过一步水热法合成荧光产率高、分散性能好的氮掺杂碳量子点,基于Fe3+对氮掺杂碳量子点选择性荧光猝灭效应,实现了对Fe3+快速准确检测.合成的氮掺杂碳量子点为规则的球形,尺寸均一,平均粒径为2.64 nm,晶面间距为0.25 nm,具备石墨碳晶格(100)晶格结构,其荧光量子产率为26.1%;Fe3+与N-CQDs表面官能团配位络合致使N-CQDs荧光猝灭,Fe3+浓度在0.23~600μmol/L范围内,与氮掺杂碳量子点荧光猝灭程度呈良好的线性关系,Fe3+的检出限为230 nmol/L.     

ZnS∶Co半导体量子点的制备及其光电化学性质

采用低温水热技术,分别以柠檬酸(CA)和巯基丙酸(MPA)为稳定剂,在70℃的水相中合成了单分散的,粒子尺寸约为4 nm的ZnS∶Co半导体量子点.研究了稳定剂、Co2+掺杂剂及其掺杂量对掺杂量子点发光性能和结构的影响.XRD结果表明,Co2+离子主要掺杂在量子点表面,对主体ZnS晶格没有影响.当采用MPA为稳定剂,掺杂量为5%(摩尔分数)时,掺杂量子点的荧光发射强度最高;而同样掺杂量下采用CA为稳定剂时,量子点的荧光发射强度有所下降.循环伏安研究显示,与空白ZnS量子点相比,Co2+离子的掺杂在ZnS的禁带中形成杂质能级,相应地,ZnS∶Co量子点的吸收边发生红移.与未掺杂ZnS量子点相比,掺杂量子点具有较少的表面非辐射复合中心,因而荧光发射强度显著提高.     

MAA修饰ZnO量子点及其发光特性

以ZnAc2·2H2O为原料,在乙醇中通过70℃回流4h,得到ZnO前驱物,与LiOH·H2O反应,制备出ZnO.采用巯基乙酸(mercaptoacetic acid,MAA)对所合成的ZnO进行表面修饰,修饰后的产物经SEM和XRD表征,证明获得了物相单一、近似球状、粒径为4.6nm的ZnO量子点.借助紫外-可见和荧光分析,研究了MAA对该量子点的修饰效果,探讨了设置条件下ZnO的发光机理和性质.发现该实验体系之所以产生荧光表面缺陷发射峰消失和激子发射峰明显增加的光学现象,是因为MAA有效地覆盖了ZnO的表面缺陷,并稳定包裹住ZnO粒子.同时还研究了MAA加量、温度、电解质对修饰产物发光性能的影响,发现经MAA修饰后的ZnO量子点具有较强的荧光发光性能、良好的长期陈放稳定性,以及一定的抗电解质影响能力.研究结果对ZnO量子点应用于生物分析具有重要参考价值.     

亲水性修饰的量子点的结构对荧光性能的影响研究

亲水性量子点的荧光性能是其作为生物检测探针的一个重要质量指标. 不同结构的量子点在亲水性修饰过程中, 其抵抗荧光淬灭的能力差异较大. 设计与制备具有不同结构和成分的核、核壳量子点, 再通过双亲性高分子对其亲水性改性, 利用荧光光谱监测亲水性修饰过程中的荧光性能变化来度量所合成量子点的光化学稳定性. 实验结果表明,在表面亲水性修饰过程中, 未包覆壳层的裸核量子点其抵抗荧光淬灭的能力最弱; 包覆壳层的核壳量子点, 其抵抗荧光淬灭的能力增强, 且壳层越多, 抵抗能力越强. 壳层的结构和成分直接影响核壳量子点抵抗荧光淬灭的能力, 具有合理晶格匹配的核壳量子点, 其抵抗荧光淬灭的能力较强. 另外, 通过优化设计与制备的核壳量子点经表面亲水性修饰后, 再偶联叶酸, 构建出特异性生物荧光探针, 对乳腺癌细胞进行靶向性标记后, 利用流式细胞仪进行细胞检测分析. 实验结果表明, 通过优化制备的核壳量子点, 亲水性修饰后仍具有很好的荧光性能, 偶联叶酸后具有较好的细胞靶向性.     

毛细管电泳表征巯基聚乙二醇与碲化镉量子点相互作用

本文采用毛细管电泳和荧光光谱法,研究了水相合成的碲化镉量子点与巯基聚乙二醇配体相互作用。研究发现巯基聚乙二醇能够包覆在碲化镉量子点表面。这种包覆层能够提高量子点的稳定性和生物相容性。     

UV luminescent organic-capped ZnO quantum dots synthesized by alkoxide hydrolysis with dilute water

A novel synthesis route to organic-capped and colloidal ZnO quantum dots (QDs) has been developed. Specifically, zinc-di-t-butoxide and zinc-di-n-butoxide are hydrolyzed by very dilute water (400-600 mass ppm) in hydrophilic benzylamine and polymerized to ZnO by dehydration and/or a butanol elimination reaction. Growth of the ZnO QDs and exchange of the surface capping ligand from the hydroxyl groups and/or benzylamine to the oleylamine occur by heating the colloidal solution after addition of the oleylamine at 100-180°C. The final ZnO QDs with diameters in the range of 3-7 nm are highly dispersible in various organic solvents. The ZnO QDs exhibit the quantum size effect upon UV emission; it was controlled between 3.39 and 3.54 eV in the present study. The defect-related Vis emission decreased and the UV emission becomes dominant when zinc-di-n-butoxide with a 99.99% zinc purity is used as the starting material. The intensity of the photoluminescence UV emission is 1.5 times higher than that of the Vis emission.     

氨基化单分散量子点/二氧化硅核壳纳米粒子的制备及其细胞标记

通过反向微乳液法, 在油溶性量子点表面包裹二氧化硅外壳, 使油溶性量子点水溶性化, 再利用3-氨丙基三乙氧基硅烷(APTES)在已形成的二氧化硅纳米颗粒表面进行氨基化改性, 制备富含氨基的二氧化硅包裹的量子点荧光纳米球. 通过透射电子显微镜(TEM)、粒径分析、zeta电位检测、紫外-可见分光光度、荧光分光光度和红外光谱等手段对产品进行了表征. 结果表明, 所制备的二氧化硅量子点纳米球(45 nm)具有单分散性、水溶性好及光化学稳定性强等优点. 通过静电作用, 所制备的单分散氨基化二氧化硅量子点对肿瘤细胞表面膜电荷进行了初步标记显像.     

One-bath synthesis of hydrophilic molecularly imprinted quantum dots for selective recognition of chlorophenol

A simple one-bath strategy has been developed to synthesize a novel CdTe@SiO₂@MIP（molecularly imprinted and silica-functionalized CdTe quantum dots,MISFQDs）,in which a silica shell was coated on the surface of CdTe quantum dots （CdTe@SiO₂ QDs） and then a polymer for selective recognition of 4-chlorophenol（4-CP） was constructed on the surface of CdTe@SiO₂ QDs using mercaptoacetic acid as stabilizer,3-aminopropyl-trimethoxysilane（APTES） as functional monomers and tetraethoxysilane（TEOS） as crosslink agent.The structures of CdTe@SiO₂@MIP were analyzed by ultraviolet-visible absorption. Fluorescence,FT-IR spectrum and powder X-ray diffraction.The application and characterization of the CdTe@SiO₂@MIP were investigated by experiments.All results indicated that the CdTe@SiO₂@MIP can selectively recognize 4-chlorophenol.     

Stable aqueous dispersion of ZnO quantum dots with strong blue emission via simple solution route

The aqueous dispersion of ZnO quantum dots (QDs) with strong blue emission (quantum yield of 76%) was synthesized through a simple solution route. The water stability of such QDs is provided by the hydroxyl groups on their surface, and the strong blue emission is suggested to arise from the formation of surface ZnO/oleic acid complexes. Under irradiation, these complexes are thought to absorb the excitation light with 3.54 eV and then generate the blue emission with 2.82 eV.     

Intercalated synthesis of zinc oxide quantum dots between multilayered organic films: preparation of 2D superlattices in colloidal solutions

Intercalation of ZnO quantum dots into two-dimensional (2D) laminated sodium lauryl sulfonate films in a colloidal solution was demonstrated. Without any substrates, hybrid films composed of a dispersed ZnO dots layer and organic films exhibit a high stability and regular 2D superlattice stacking after removal of cosurfactant molecules and water. The 2D superlattice films were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). UV-visible absorption and photoluminescence spectra were used to investigate the growth of ZnO QDs between organic films and study their collective optical characteristics.     

Quenching of Photoluminescence in ZnO QDs Decorating Multiwalled Carbon Nanotubes

We report the controlled growth of ZnO quantum dots (QDs) on the sidewalls of multiwalled carbon nanotubes (MWCNTs) by a one‐step process and study the effect on the photoluminescence (PL) properties of the ZnO QDs‐MWCNT composite. The PL intensity of the composite is quenched and the lifetime is reduced compared to the only ZnO QDs. The origin of the PL quenching is discussed in terms of energy transfer, which is examined by varying the density and size of ZnO QDs by changing the molar concentration of the precursor solution for ZnO and the amount of MWCNT.     

Microstructure-controlled aerosol-gel synthesis of ZnO quantum dots dispersed in SiO2 nanospheres

ZnO quantum dots dispersed in a silica matrix were synthesized from a TEOS:Zn(NO(3))(2) solution by a one-step aerosol-gel method. It was demonstrated that the molar concentration ratio of Zn to Si (Zn/Si) in the aqueous solution was an efficient parameter with which to control the size, the degree of agglomeration, and the microstructure of ZnO quantum dots (QDs) in the SiO(2) matrix. When Zn/Si ≤ 0.5, unaggregated quantum dots as small as 2 nm were distributed preferentially inside SiO(2) spheres. When Zn/Si ≥ 1.0, however, ZnO QDs of ～7 nm were agglomerated and reached the SiO(2) surface. When decreasing the ratio of the Zn/Si, a blue shift in the band gap of ZnO was observed from the UV/Visible absorption spectra, representing the quantum size effect. The photoluminescence emission spectra at room temperature denoted two wide peaks of deep-level defect-related emissions at 2.2-2.8 eV. When decreasing Zn/Si, the first peak at ～2.3 eV was blue-shifted in keeping with the decrease in the size of the QDs. Interestingly, the second visible peak at 2.8 eV disappeared in the surface-exposed ZnO QDs when Zn/Si ≥ 1.0.     

Synthesis of silane surface modified ZnO quantum dots with ultrastable, strong and tunable luminescence

Surface modified ZnO quantum dots (QDs) with ultrastable, strong and tunable luminescence have been successfully prepared via silanization during the growth process by (3-(2,3-epoxypropoxy)propyl)trimethoxysilane. The as-prepared ZnO QDs are demonstrated to be promising for anti-counterfeit applications in expensive high-end liquors, etc.     

Transparent polymeric hybrid film of ZnO nanoparticle quantum dots and PMMA with high luminescence and tunable emission color

ZnO nanoparticle quantum dots (QDs)/poly(methyl methacrylate) (PMMA) composites are synthesized by conventional radical polymerization in the presence of 3-(trimethoxysilyl)propylmethacrylate (TPM)-modified ZnO nanoparticle QDs. Although unmodified ZnO nanoparticle QDs were precipitated in tetrahydrofuran (THF) and show only weak emissions under UV irradiation, ZnO nanoparticle QDs/PMMA composite is well dispersed in THF and shows high emissions. TPM acts as the stabilizer and promotes the compatibility between the ZnO nanoparticle QDs and the PMMA matrix. After evaporation of THF from the ZnO nanoparticle QDs/PMMA composite solution, transparent polymeric hybrid films of ZnO nanoparticle QDs and PMMA are obtained. These polymeric hybrid films are characterized by photoluminescence (PL) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and thermogravimetric analysis. The hybrid film exhibited a high quantum yield and PL emission under ultraviolet excitation. PL emission has been successfully tuned from blue to yellow.