掺杂比例和光敏剂对上转换纳米材料性能的影响

以NaYF_4材料为基质的上转换纳米颗粒(UCNPs)是最早报道的、应用范围最广的上转换材料之一。掺杂了稀土离子的颗粒不但可以在不同激发条件下发射出不同波长和强度的荧光,而且可以与多种光敏分子搭配使用,通过荧光共振能量转移产生单线态氧,实现生物医学成像或诊疗方面的应用。但是其形貌和荧光性能均受制备方法和工艺条件的影响较大。本文通过水热法合成了两类掺杂不同稀土离子的十种NaYF_4 UCNPs,在保持掺杂离子的终浓度不变的条件下,探究离子类型与比例对纳米材料的结构和上转换发光性能的影响。在此基础上,探索了多种卟啉类光敏剂分子与NaYF_4 UCNPs发生能量转换及单线态氧的产生能力。本工作可为基于NaYF_4材料的上转换颗粒的规模化制备和工艺升级提供数据支撑和理论参考。     

等离子体增强上转换发光及其应用

稀土上转换纳米材料（UCNPs）是一类在近红外光激发下发出可见光的纳米材料。与有机荧光染料、量子点等发光材料相比,UCNPs具有化学稳定性高、光稳定性强、荧光寿命长、反斯托克斯位移大、发光谱带窄和光穿透深度大等诸多优点,在生物成像、传感器、激光器、光动力疗法和太阳能电池等领域有潜在的应用价值。但是由于UCNPs激活离子的吸收截面太小,导致其发光效率偏低,限制了UCNPs的进一步应用。因而如何提高上转换发光强度成为当前的研究热点。针对上述问题,本文系统阐述了金属表面等离子体共振（SPR）增强上转换发光领域的研究进展。首先介绍了SPR增强上转换发光的三种机制,随后重点介绍了化学法和物理法这两种SPR-UCNPs体系的构建方法以及其在太阳能电池、生物成像、生物检测、光热治疗和光催化等领域的应用。文章最后指出了SPR增强上转换发光领域存在的不足和未来的研究方向。     

稀土掺杂正交发光纳米晶：从基础到前沿应用

镧系离子掺杂的上转换发光纳米材料具有独特的非线性反斯托克斯发光，在生命科学、光子传输、可编程控制和信息编码解码等领域有着广阔的应用。稀土掺杂的正交发光纳米晶是近年来在发光领域上的一大研究方向，是基于上转换发光机理，在合理的核壳结构设计中实现单一纳米粒子上的正交发光多功能性集成、拓宽光谱的可选择性范围和时空可调性，进而进一步推动其在相关领域应用的发展。本文综述了近10年来在合成稀土掺杂正交发光纳米晶的设计优化方面上所取得的进展，系统地探讨了基于核壳结构构建的稀土离子能量传递实现正交发光的调控过程，总结了其在信息安全防伪和生物成像与治疗前沿领域上的应用，并讨论了当前正交发光所面临的挑战以及未来的展望。     

稀土上转换纳米发光材料研究进展

上转换纳米发光材料(UCNPs)是一种能在长波长光激发下发出短波长光的发光材料.在较多的研究中UCNPs在980 nm红外光激发下,能发出不同颜色的可见光,可以显著提高信噪比,所以UCNPs在三维立体显示、上转换激光器、红外探测、防伪识别、生物检测等诸多领域都具有广阔的应用前景.从稀土上转换纳米发光材料的基质和稀土离子及其光学性能方面概述了近几年稀土上转换纳米发光材料的研究进展.     

稀土上转换发光纳米材料的防伪安全应用

与有机荧光染料、量子点等传统发光材料相比,稀土上转换发光纳米材料(UCNPs)具有反斯托克斯位移大、发光谱带多且狭窄、荧光寿命长、光化稳定性高、无光闪烁和光漂白等独特优势,将其与图形编码、防伪印刷技术结合可获得难以仿冒的隐形荧光图案,这已经成为防伪安全领域的应用研究热点。本文首先介绍了UCNPs的上转换发光机理及其合成方法,然后阐述近年来UCNPs在防伪安全领域的研究现状,归纳总结出上转换防伪安全图案的四种形式(NIR单波长激发、NIR双波长激发、NIR/UV双波长激发以及三波长激发)。最后,本文指出UCNPs应用于防伪安全领域所面临的问题与挑战,并对未来的发展方向进行了展望。     

利用稀土功能材料调控细胞行为的新进展

稀土掺杂的上转换纳米材料(UCNPs)因其优异的光学性质而备受关注。在组织穿透能力强的近红外(NIR)光激发下,上转换纳米材料能够发射高能量的可见光。长久以来,其应用均集中在检测、成像及光动力学治疗方面。近年来利用上转换纳米材料对于细胞行为进行调控的研究得到了越来越广泛的关注。采用上转换纳米材料调控细胞的行为可以克服传统可见光调控难以治疗深层组织的缺点。主要从上转换纳米材料调控细胞黏附、分化及活性三方面介绍其在调控细胞行为领域的最新研究进展。     

稀土上转换发光纳米材料的应用

稀土上转换发光纳米材料(简称UCNPs)不仅光稳定性强、发射带窄、荧光寿命长、化学稳定性高、潜在生物毒性低,而且采用近红外连续激发光源激发还使其具有较大的光穿透深度、无光闪烁和光漂白、无生物组织自发荧光以及对生物组织几乎无损伤等显著优点,已经成为当前很多领域乃至交叉科学的应用研究热点。由于氟化物基质的UCNPs具有较高的发光效率,本文首先归纳总结了近年来氟化物UCNPs的主要合成及表面改性方法,然后重点综述了近年来UCNPs在免疫分析及生物传感、生物成像、载药、光动力理疗及热致理疗、光导开关和信息存储以及太阳能电池等方面的研究与应用进展。     

局域结构依赖的稀土上转换发光

稀土掺杂上转换发光纳米材料作为一种新型的荧光材料,因其发光性能优异、化学性质稳定以及自发荧光干扰小等优点受到国内外研究者的广泛关注。如何实现稀土上转换发光性能的可控调节一直是稀土纳米发光材料研究中的一个热点问题。简要总结了近年来关于局域结构依赖的稀土上转换发光性能的研究进展,分别从结构设计和晶体结构调节两个方面展开,主要内容包括核壳结构、复合结构和孔洞结构的设计对稀土上转换发光性能的影响及晶体结构对稀土上转换发光强度和上转换发光红绿比的影响,以期为制备高质量、可定制上转换发光性质的稀土掺杂纳米发光材料提供参考。     

稀土氟化物上转换荧光增强及应用

稀土氟化物上转换纳米材料具有化学稳定性高、反斯托克位移大、无光漂白、荧光寿命长、发光谱带窄和穿透深度深等优点,在荧光成像和光热疗、传感器、太阳能电池及防伪技术等领域具有广泛的应用前景,是一种极具发展潜力的荧光材料。然而该类材料在实际应用时还存在有荧光效率低、吸收截面小等亟待解决的瓶颈问题。针对以上问题,本文系统阐述了离子共掺杂、核壳结构、表面等离子耦合、光子晶体、宽频敏化和热效应等增强稀土氟化物上转换荧光的方法及其近年的研究进展。并在此基础上,总结了近年来荧光增强稀土氟化物上转换纳米材料在生物成像和光热疗、生物传感、太阳能电池及防伪技术等领域的应用研究现状。最后,分析了稀土氟化物UCNPs目前仍存在的不足,并对将来的发展方向进行了展望。     

具有红光发射的稀土上转换发光纳米晶及其介孔直接功能化

红光发射稀土上转换发光纳米晶(UCNPs)在光动力治疗(PDT)等方面具有特定的优势。将油溶性的UCNPs通过表面改性转变为水溶性,对其在生物医疗、疾病诊断等方面的应用具有重要意义。利用一种简单易行的方法将具有红光发射的UCNPs进行介孔直接功能化表面修饰,制备了一种具有良好水溶性的纳米材料NaYF4:Yb/Er/Mn@mSiO2。实验结果表明该材料核-壳结构明显,形貌均一,在980 nm的激发下保持了上转换发光特性。该材料在光动力治疗等方面具有良好的潜在应用价值。     

Multicolor output and shape controlled synthesis of lanthanide-ion doped fluorides upconversion nanoparticles

A general and facile approach for tailoring the multicolor output and shapes of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) within a given composition is presented. By adjusting the temperature and time in the thermolysis procedure, the color output and shapes of NaYF(4):20%Yb, 2%Er UCNPs can be readily manipulated. The nanoparticles were characterized through the use of transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and upconversion luminescence spectroscopy. It is shown that the relative intensities of green emissions gradually increased with the rise of temperature and prolongation of growth time under excitation of 980 nm, which resulted in multicolor output of NaYF(4):20%Yb, 2%Er UCNPs. Simultaneously, the shapes for UCNPs can also be controlled. TEM images, estimated micro-stress by Williamson-Hall methodology and a series of control experiments and analyses reveal that crystallinity is mainly responsible for the multicolor output of UCNPs. Based on the above method, the tailoring of color output is also successfully realized in Ho(3+) and Tm(3+) ions. It is expected that this method may be used to tune the physical properties of other nanoparticles, and these multicolored UCNPs are promising for applications in multiplexed bioimaging, biodetection, display, other optical technologies, etc.     

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。     

Upconversion Nanoparticle-Assisted Photopolymerization

Near-infrared (NIR) laser has deeper penetration and lower thermal effect compared with ultraviolet–visible (UV/vis) laser. NIR laser can stimulate upconversion nanoparticles (UCNPs) to emit UV/vis light efficiently. Therefore, the UCNPs become an important kind of materials to produce upconversion luminescence through NIR laser. Compared with photopolymerization induced with UV/vis laser, the UV/vis light from UCNP-assisted photopolymerization presents some unique characters. This review focuses on the research progress of UCNP-assisted photopolymerization and its potential applications. We will discuss the influencing factors of UCNP-assisted polymerization, illustrate the relation between the gel size and monomer concentration and propose the development prospects of UCNP-assisted polymerization in the biological field.     

Upconversion nanomaterials: a platform for biosensing,theranostic and photoregulation

Upconversion nanoparticles (UCNPs) are a kind of unique optical material, that are able to emit ultraviolet (UV), visible or near infrared (NIR) luminescence upon NIR light excitation. Because of their excellent physic-chemical characters including enormous anti-Stokes spectral shift, high resistance to photobleaching, fairly long luminescent lifetime, excellent chemical stability, sharp emission band, and deep tissue penetration depth, UCNPs have become a useful tool in bioimaging, biosensing, as well as cancer therapy. In particularly, the emissions light from UCNPs can activate photosensitive molecules, which has the potential to realize the regulation of cell behaviors, including cell growth, adhesion and differentiation. This review consequently introduces the principle and achievements of UCNPs in biomedical field to the general readers for promoting both fundamental research and bio-applications of UCNPs. After the brief introduction of the physical mechanism of upconversion luminescence (UCL), we introduce several strategies to enhance the emissions brightness in detail, then discuss various biomedical applications of UCNPs.     

协同发光效应及其分析应用研究

在研究共存元素对钐、铕、铽和镝配合物荧光发射的影响时,人们曾分别观察到这些配合物的荧光强度不但不随某些共存稀土和非稀土离子浓度的增加而降低;而是在一定浓度范围内随共存离子浓度的增加,配合物的荧光发射大大增强,利用这种效应可大大提高这类配合物的荧光分析灵敏度,我们采用自己组装的激光诱导荧光光谱测定装置,选取铕(钐)-     

Novel microwave-assisted solvothermal synthesis of NaYF4:Yb,Er upconversion nanoparticles and their application in cancer cell imaging

This work reports the novel microwave-assisted solvothermal synthesis and structural, topographic, spectroscopic characterization of NaYF(4):Yb,Er upconversion nanoparticles (UCNPs) as well as their application in the labeling of HeLa cells. The nanoparticles were prepared in ethylene glycol, with rare earth acetates as precursor and NH(4)F and NaCl as the fluorine and sodium sources. X-ray diffraction, transmission electron microscopy, and luminescence spectroscopy were applied to characterize the nanoparticles. Experimental results showed that the microwave-assisted solvothermal method is an effective approach to create highly crystalline, strongly luminescent UCNPs at a lower temperature (160 °C) and within a significantly shortened reaction time (only 1 h) compared to the traditional methods. The effect of fluorine source on the optical properties of UCNPs was investigated by using NH(4)F, NH(4)HF(2), NaF, and 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF(4)) as different fluorine sources; NH(4)F proved to be the best one, making the luminescent intensity increase at least 2 orders of magnitude. The UCNPs with four different colors (green, yellow, orange, and cyan) were successfully obtained. After being modified with amino groups and coupled with CEA-8 antibody, the obtained nanoparticles were successfully applied in the specific fluorescent immunolabeling and imaging of HeLa cells to further verify their function as a marker in immunolabeling.     

A DNA–Azobenzene Nanopump Fueled by Upconversion Luminescence for Controllable Intracellular Drug Release

Stimulus‐responsive drug release possesses considerable significance in cancer therapy. This work reports an upconversion‐luminescence‐fueled DNA–azobenzene nanopump for rapid and efficient drug release. The nanopump is constructed by assembling the azobenzene‐functionalized DNA strands on upconversion nanoparticles (UCNPs). Doxorubicin (DOX) is loaded in the nanopump by intercalation in the DNA helix. Under NIR light, the UCNPs emit both UV and visible photons to fuel the continuous photoisomerization of azo, which acts as an impeller pump to trigger cyclic DNA hybridization and dehybridization for controllable DOX release. In a relatively short period, this system demonstrates 86.7 % DOX release. By assembling HIV‐1 TAT peptide and hyaluronic acid on the system, targeting of the cancer‐cell nucleus is achieved for perinuclear aggregation of DOX and enhanced anticancer therapy. This highly effective drug delivery nanopump could contribute to chemotherapy development.     

Liquid Marbles Based on Magnetic Upconversion Nanoparticles as Magnetically and Optically Responsive Miniature Reactors for Photocatalysis and Photodynamic Therapy

Magnetic liquid marbles have recently attracted extensive attention for various potential applications. However, conventional liquid marbles based on iron oxide nanoparticles are opaque and inadequate for photo‐related applications. Herein, we report the first development of liquid marbles coated with magnetic lanthanide‐doped upconversion nanoparticles (UCNPs) that can convert near‐infrared light into visible light. Apart from their excellent magnetic and mechanical properties, which are attractive for repeatable tip opening and magnetically directed movements, the resultant UCNP‐based liquid marbles can act as ideal miniature reactors for photodynamic therapy of cancer cells. This work opens new ways for the development of liquid marbles, and shows great promise for liquid marbles based on UCNPs to be used in a large variety of potential applications, such as photodynamic therapy for accelerated drug screening, magnetically guided controlled drug delivery and release, and multifunctional actuation.     

纳米银米表面等离子激元增强上转换发光

上转换纳米发光材料因发光效率普遍较低限制了其在应用领域的进一步发展。利用贵金属的局域表面等离子体共振特性调控发射体的局域场成为提高上转换纳米粒子发光性能的有效途径之一。在这个工作中,我们利用合成工艺简单的贵金属米状结构,通过调控上转换纳米颗粒周围的局域场,实现了上转换发光强度的大幅提高。结合三维有限元方法研究了在实际薄膜中Ag米之间可能出现的不同接触方式对所产生的局域场增强效果的影响,同时证实这种局域等离激元耦合所引起的电磁场增强是提高上转换发光性能的重要因素,并且获得了上转换发光将近百倍的增强效果。最后,通过调控等离子层和发光层的厚度,实现上转换发光性能的进一步优化。