NaYF4:Yb,Er/Tm上转换荧光纳米材料的合成、修饰及应用*

上转换荧光纳米材料NaYF4:Yb,Er/Tm因具有独特的上转换发光性能,在固体激光器、三维立体演示、红外成像等很多方面都有着重要的应用。近年来,NaYF4:Yb,Er/Tm上转换纳米颗粒作为荧光标记物用于生物标记引起了研究者的浓厚兴趣。合成出高质量、高荧光性能的NaYF4:Yb,Er/Tm上转换纳米颗粒是使之能够在生物医学等领域广泛应用的前提条件。本文针对NaYF4:Yb,Er/Tm上转换荧光纳米颗粒的合成方法、表面修饰以及生物应用等方面的研究进展进行综述。     

Near‐Infrared‐Light‐Driven Artificial Photosynthesis by Nanobiocatalytic Assemblies

Artificial photosynthesis in nanobiocatalytic assemblies aims to reconstruct man‐made photosensitizers, electron mediators, electron donors, and redox enzymes for solar synthesis of valuable chemicals through photochemical cofactor regeneration. Herein, we report, for the first time, on nanobiocatalytic artificial photosynthesis in near‐infrared (NIR) light, which constitutes over 46% of the solar energy. For NIR‐light‐driven photoenzymatic synthesis, we synthesized silica‐coated upconversion nanoparticles, Si‐NaYF4:Yb,Er and Si‐NaYF4:Yb,Tm, for efficient photon‐conversion through Förster resonance energy transfer (FRET) with rose bengal (RB), a photosensitizer. We observed NIR‐induced electron transfer by using linear sweep voltammetric analysis; this indicates that photoexcited electrons of RB/Si‐NaYF4:Yb,Er are transferred to NAD+ through a Rh‐based electron mediator. RB/Si‐NaYF4:Yb,Er nanoparticles, which exhibit higher FRET efficiency due to more spectral overlap than RB/Si‐NaYF4:Yb,Tm, perform much better in the photoenzymatic conversion.     

NaYF_4:Yb/Er-碳纳米管功能纳米材料的制备、表征及其在肿瘤细胞的靶向检测和治疗中的应用

将叶酸分子(FA)和2,3-二巯基丁二酸(DMSA)修饰的稀土上转换发光纳米粒子NaYF4:Yb/Er通过酰胺键偶联在多壁碳纳米管(MWCNT)的表面,得到NaYF4:Yb/Er-MWCNT-FA功能化复合纳米材料,并通过透射电子显微镜(TEM)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-vis)、荧光光谱(PL)和共聚焦激光扫描显微镜等手段表征了其形貌、结构、发光性能和靶向成像性能.共聚焦激光扫描显微镜结果表明,相对于正常的HLF细胞,所制备的复合材料能够靶向检测叶酸受体高表达的宫颈癌Hela细胞.此外,将阿霉素进一步通过ππ堆垛吸附在此复合材料后,该载药体系具有明显的抗肿瘤活性,能够实现对肿瘤细胞的一步检测和治疗.     

Novel heterometal-organic complexes as first single source precursors for up-converting NaY(Ln)F4 (Ln = Yb, Er, Tm) nanomaterials

First heterometal-organic single source precursors for NaYF(4) nanomaterials as a host matrix for up-conversion emission are reported. These novel heterobimetallic derivatives NaY(TFA)(4)(diglyme) (1), [Na(triglyme)(2)][Y(2)(TFA)(7)(THF)(2)] (2) and Na(2)Y(TFA)(5)(tetraglyme) (3) (TFA = trifluoroacetate), which were fully characterized by elemental analysis, FT-IR and (1)H NMR spectroscopy, TG-DTA data as well as single crystal X-ray structures, are advantageous in terms of being anhydrous and having lower decomposition temperatures in comparison to the homometallic precursor Y(TFA)(3)(H(2)O)(3). In addition, they also contain chelating glyme ligands, which act as capping reagents during decomposition to control the NaYF(4) particle size and render them monodisperse in organic solvents. On decomposition in 1-octadecene, the molecular derivatives 1 and 3 are converted, in the absence of any surfactant or capping reagent, to cubic NaYF(4) nanocrystals at significantly lower temperatures (below 250 °C). At higher temperature, a mixture of the cubic and hexagonal phases was obtained, the relative ratio of the two phases depending on the reaction temperature. A pure hexagonal phase, which is many folds more efficient for UC emission than the cubic phase, was obtained by calcining nanocrystals of mixed phase at 400 °C. In order to co-dope this host matrix with up-converting lanthanide cations, analogous complexes NaLn(TFA)(4)(diglyme) [Ln = Er (4), Tm (5), Yb (6)] and Na(2)Ln(TFA)(5)(tetraglyme) [Ln = Er (7), Yb (8)] were also prepared and characterized. The decomposition in 1-octadecene of suitable combinations and appropriate molar ratios of these yttrium, ytterbium and erbium/thulium derivatives gave cubic and/or hexagonal NaYF(4): Yb(3+), Er(3+)/Tm(3+) nanocrystals (NCs) capped by diglyme or tetraglyme ligands, which were characterized by IR, TG-DTA data, EDX analysis and TEM studies. Surface modification of these NCs by ligand exchange reactions with poly acrylic acid (PAA) and polyethyleneglycol (PEG) diacid 600 was also carried out to render them water soluble. The THF solutions of suitable combinations of the diglyme derivatives were also used to elaborate the thin films of NaYF(4):Yb(3+), Er(3+)/Tm(3+) on a glass or Si wafer substrate by spin coating. The multicolour up-conversion fluorescence was successfully realized in the Yb(3+)/Er(3+) (green/red) and Yb(3+)/Tm(3+) (blue/violet) co-doped NaYF(4) nanoparticles and thin films, which demonstrates that they are promising UC nanophosphors of immense practical interest. The up-conversion excitation pathways for the Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) co-doped materials are discussed.     

A NIR-responsive up-conversion nanoparticle probe of the NaYF4:Er,Yb type and coated with a molecularly imprinted polymer for fluorometric determination of enrofloxacin

Microchimica Acta - The paper describes the preparation of a fluorescent probe based on the use of up-conversion particles (UCPs) of the type NaYF4: Er, Yb and shelled with a molecularly imprinted...     

NaYF4∶Er3＋, Yb3＋纳米晶的液相合成

采用丙三醇液相结晶法制备了NaYF4∶Er3＋, Yb3＋上转换纳米晶, 合成步骤被简化. 常温下, 用980 nm的红外激光激发可以观察到很强的绿光、红光发射, 用荧光光谱仪记录了该上转换光谱. X射线粉末衍射(XRD)结果表明, 该方法制备NaYF4∶Er3＋, Yb3＋纳米晶属于立方混合六方晶系. 研究了纳米晶的上转换发光机理, 根据晶体场理论对Er3＋的两个上转换能级进行了Stark分裂计算, 对两个能级之间的谱线进行了归属, 进一步证实了980 nm光子激发Er3＋离子的上转换机理, 一个是连续吸收两个980 nm光子的过程(激发态吸收), 另一个是吸收980 nm光子后, 电子转移到亚稳态能级, 然后再吸收980 nm光子过程(能量转移上转换).     

Green upconversion nanocrystals for DNA detection

By combining magnetic-field-assisted bioseparation and concentration technology with magnetite nanoparticles, novel green upconversion (UC) fluorescence nanocrystals (NaYF4:Yb3+/Er3+) have been applied to the sensitive detection of DNA.     

Branched NaYF(4) nanocrystals with luminescent properties

In this article, branched NaYF(4) nanocrystals have been successfully synthesized via a simple hydrothermal method. On the basis of the analysis of HRTEM and TEM images, the growth modes of the branched structure and further branching behavior have been proposed. The up- and down-conversion luminescence of branched NaYF(4):Er(3+)/Yb(3+) and NaYF(4):Eu(3+) have been characterized. Multiarmed NaYF(4) phosphors can be introduced into polystyrene to form composite luminescent polymers because of its special geometrical shape. In conclusion, the luminescent branched particles should be of wide potential application as building blocks in the future nanoscience and nanotechnology.     

An optical sensor for Cu(II) detection with upconverting luminescent nanoparticles as an excitation source

The first optical sensor for Cu(II) detection, with upconverting luminescent nanoparticles as an excitation source, showing high selectivity and good linear Stern-Volmer characteristics, has been achieved through a fluorescence resonance energy transfer (FRET) process between NaYF(4):Yb(3+)/Er(3+) and RB-hydrazide. The sensing mechanism is then discussed.     

Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence

Hexagonal-phase core-shell-structured NaYF 4:Yb,Tm@beta-NaYF 4:Yb,Er and beta-NaYF 4:Yb,Tm@beta-NaYF 4:Yb,Er@beta-NaYF 4:Yb,Tm nanocrystals were synthesized by a seeded growth approach. beta-NaYF 4:Yb,Tm nanocrystals with 20 nm diameter were used as seed crystals to induce the growth of beta-NaYF 4:Yb,Er and then beta-NaYF 4:Yb,Tm crystals, resulting in the formation of core-shell-structured nanocrystals with upconverting lanthanide ions Tm and Er doped in the core and shell, respectively.     

Controlled hydrothermal growth and up-conversion emission of NaLnF(4) (Ln = Y, Dy-Yb)

The controlled hydrothermal preparation of NaYF(4) as both cubic and hexagonal phase types with specific associated morphologies, nanospheres and microtubes, respectively, has been achieved in the absence of organic solvents. The hexagonal NaYF(4) compound can be prepared in novel microtubular form and directly co-doped with Yb(3+)/Er(3+) ions. When excited by infrared light of 980 nm, these hexagonal NaYF(4) microtubes display strong green up-conversion emission, which was much more intense than that of cubic NaYF(4) or hexagonal NaYF(4) nanoparticles. Other related hexagonal-prismatic microtubes of NaLnF(4) (Ln = Dy-Yb) were also synthesized. A growth mechanism for the microtubes is proposed. In general, the diameter of the hexagonal NaLnF(4) microtubes is strongly dependent on the Ln(3+) size and increases as the rare-earth ionic radius decreases.     

Synthesis of colloidal upconverting NaYF4 nanocrystals doped with Er3+, Yb3+ and Tm3+, Yb3+ via thermal decomposition of lanthanide trifluoroacetate precursors

Upconverting lanthanide-doped nanocrystals were synthesized via the thermal decomposition of trifluoroacetate precursors in a mixture of oleic acid and octadecene. This method provides highly luminescent nanoparticles through a simple one-pot technique with only one preparatory step. The Er3+, Yb3+ and Tm3+, Yb3+ doped cubic NaYF4 nanocrystals are colloidally stable in nonpolar organic solvents and exhibit green/red and blue upconversion luminescence, respectively, under 977 nm laser excitation with low power densities.     

六方相NaYF4:Yb/Er纳米晶制备方法研究进展

综述了六方相NaYF4:Yb/Er纳米晶的制备方法,着重总结了三氟乙酸盐热分解法、共沉淀法、碳酸盐热分解法、离子热法、水热法及两步法的研究进展,并就其发展前景进行了展望.     

Preparation of yttrium oxysulfide phosphor nanoparticles with infrared-to-green and -blue upconversion emission using an emulsion liquid membrane system

Yttrium oxysulfide upconverting phosphor nanoparticles, doped with Yb as a sensitizer and Er (or Ho, Tm) as an activator, have been prepared via a solid-gas reaction using precursor oxalate particles obtained in an emulsion liquid membrane (ELM, water-in-oil-in-water (W/O/W) emulsion) system. The resulting Y(2)O(2)S:Yb,Er particles, mainly smaller than 50 nm in diameter, demonstrated green upconversion emission under infrared excitation (lambdaex = 980 nm) via a two-photon process. Distinct green and blue upconversion emission were also demonstrated under the same infrared excitation from Y(2)O(2)S:Yb,Ho and Y(2)O(2)S:Yb,Tm nanoparticles, respectively. These upconverting phosphor nanoparticles, together with Y(2)O(3):Yb,Er infrared-to-red upconverting phosphor particles, with different emission under the same infrared excitation may be applied to the luminescent reporter materials for the detection of the targeted analyte in multiplexed assays.     

Upconversion multicolor fine-tuning: visible to near-infrared emission from lanthanide-doped NaYF4 nanoparticles

A general approach to fine-tuning the upconversion emission colors, based upon a single host source of NaYF4 nanoparticles doped with Yb3+, Tm3+, and Er3+, is presented. The emission intensity balance can be precisely controlled using different host-activator systems and dopant concentrations. The approach allows access to a wide range of luminescence emission from visible to near-infrared by single-wavelength excitation.     

Rare-Earth nanoparticles with enhanced upconversion emission and suppressed rare-Earth-ion leakage

Upconversion emissions from rare-earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF(4):Yb,Er@CaF(2) nanoparticles (NPs) with a small size (10-13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF(2) shell protects the rare-earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF(4):Yb,Er@CaF(2) NPs, HeLa cells were imaged with low background interference.     

Facile and mass production synthesis of β-NaYF4:Yb3+, Er3+/Tm3+ 1D microstructures with multicolor up-conversion luminescence

Well defined, pure hexagonal-phased NaYF(4):Yb(3+),Er(3+)/Tm(3+) microtubes and microrods were first prepared by a facile and mass production molten salt method without using any surfactant, which offers a new alternative in synthesizing such materials and opens the possibility to meet the increasing commercial demand.     

Phase- and size-controllable synthesis of hexagonal upconversion rare-earth fluoride nanocrystals through an oleic acid/ionic liquid two-phase system

Herein, we introduce a facile, user- and environmentally friendly (n-octanol-induced) oleic acid (OA)/ionic liquid (IL) two-phase system for the phase- and size-controllable synthesis of water-soluble hexagonal rare earth (RE = La, Gd, and Y) fluoride nanocrystals with uniform morphologies (mainly spheres and elongated particles) and small sizes (<50?nm). The unique role of the IL 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF(6)) and n-octanol in modulating the phase structure and particle size are discussed in detail. More importantly, the mechanism of the (n-octanol-induced) OA/IL two-phase system, the formation of the RE fluoride nanocrystals, and the distinctive size- and morphology-controlling capacity of the system are presented. BmimPF(6) is versatile in term of crystal-phase manipulation, size and shape maintenance, and providing water solubility in a one-step reaction. The luminescent properties of Er(3+)-, Ho(3+)-, and Tm(3+)-doped LaF(3), NaGdF(4), and NaYF(4) nanocrystals were also studied. It is worth noting that the as-prepared products can be directly dispersed in water due to the hydrophilic property of Bmim(+) (cationic part of the IL) as a capping agent. This advantageous feature has made the IL-capped products favorable in facile surface modifications, such as the classic Stober method. Finally, the cytotoxicity evaluation of NaYF(4):Yb,Er nanocrystals before and after silica coating was conducted for further biological applications.     

Tunable red-green upconversion luminescence in novel transparent glass ceramics containing Er: NaYF4 nanocrystals

To develop NaYF(4) as bulk luminescence material, transparent glass ceramics containing Er(3+): NaYF(4) nanocrystals were fabricated for the first time, and the influences of heat-treatment temperature and Er(3+) doping level on their upconversion luminescence were investigated. With increasing heating temperature, the upconversion intensity enhanced accordingly, attributing to the incorporation of more Er(3+) into the grown NaYF(4). Notably, when the heating temperature reached 650 degrees C, the upconversion intensity augmented drastically due to the occurrence of phase transition from the cubic NaYF(4) to the hexagonal one. Interestingly, for the samples heat-treated at 620 degrees C, when the Er(3+) doping level was increased from 0.05 to 2.0 mol %, the upconversion emission was whole-range tunable from monochromatic green to approximately monochromatic red, which could be mainly attributed to the cross-relaxation between Er(3+) ions. The excellent optical properties and its convenient, low-cost synthesis of the present glass ceramic imply that it is an excellent substitution material for the unobtainable bulk NaYF(4) crystal, potentially applicable in many fields.     

Two-way photoswitching using one type of near-infrared light, upconverting nanoparticles, and changing only the light intensity

Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle photoresponsive organic compounds between their two unique optical, electronic, and structural states by modulating merely the intensity of the 980 nm excitation light. This reversible "remote-control" photoswitching employs an excitation wavelength not directly absorbed by the organic chromophores and takes advantage of the fact that designer core-shell-shell NaYF(4) nanoparticles containing Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) ions doped into separate layers change the type of light they emit when the power density of the near-infrared light is increased or decreased. At high power densities, the dominant emissions are ultraviolet and are appropriate to drive the ring-closing, forward reactions of dithienylethene (DTE) photoswitches. The visible light generated from the same core-shell-shell UCNPs at low power densities triggers the reverse, ring-opening reactions and regenerates the original photoisomers. The "remote-control" photoswitching using NIR light is as equally effective as the direct switching with UV and visible light, albeit the reaction rates are slower. This technology offers a highly convenient and versatile method to spatially and temporally regulate photochemical reactions using a single light source and changing either its power or its focal point.