凝胶网络模板法可控制备NaYF4:Yb3+, Er3+稀土上转换纳米颗粒

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裘慕书, 林敏, 赵英, 董宇卿, 卢天健, 徐峰. 凝胶网络模板法可控制备NaYF₄:Yb³⁺, Er³⁺稀土上转换纳米颗粒 . 无机材料学报, 2014, 29(5): 545-549
QIU Mu-Shu, LIN Min, ZHAO Ying, DONG Yu-Qing, LU Tian-Jian, XU Feng. Synthesis of NaYF₄:Yb³⁺, Er³⁺Upconversion Nanoparticles Using Hydrogel Networks as a Template . Journal of Inorganic Materials, 2014, 29(5): 545-549 复制到剪切板

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凝胶网络模板法可控制备NaYF₄:Yb³⁺, Er³⁺稀土上转换纳米颗粒

裘慕书^1,², 林敏^1,², 赵英², 董宇卿², 卢天健², 徐峰^1,²

1. 生物医学信息工程教育部重点实验室西安交通大学

2. 生物仿生工程与生物力学中心, 西安 710049

通讯作者：林敏, 讲师. E-mail:minlin@mail.xjtu.edu.cn

作者简介：裘慕书(1990-), 男, 硕士研究生. E-mail:qiumushu@gmail.com

基金:国家重大国际(地区)合作研究项目(11120101002); 教育部科学研究重大项目(313045); 中央高校基本科研业务费专项基金(2012jdhz46); Major International Joint Research Program of China (11120101002); Key Project of Chinese Ministry of Education (313045); Fundamental Research Funds for the Central Universities (2012jdhz46);

摘要

采用水凝胶空间网孔结构作为纳米级反应容器可控制备了NaYF₄:Yb³⁺, Er³⁺稀土上转换发光纳米颗粒。通过控制交联剂密度可以改变网络凝胶网孔结构, 用不同网孔结构的凝胶模板可以控制合成纳米颗粒。通过XRD、TEM、PL等方法研究了不同凝胶模板对颗粒的尺寸、发光性能的影响。结果表明, 利用高分子交联后形成的凝胶网络, 可以制得粒径在10 nm左右的NaYF₄:Yb³⁺, Er³⁺纳米颗粒。随着交联剂浓度的升高, 颗粒粒径及荧光强度都有所下降。本研究为稀土上转换发光纳米颗粒的制备提供了工艺简单、绿色环保的新方法。

关键词: 稀土; 上转换; 纳米颗粒; 水凝胶网络结构; 交联度

中图分类号:TQ133 文献标志码:A 文章编号:1000-324X(2014)05-0545-05

Synthesis of NaYF₄:Yb³⁺, Er³⁺Upconversion Nanoparticles Using Hydrogel Networks as a Template

QIU Mu-Shu^1,², LIN Min^1,², ZHAO Ying², DONG Yu-Qing², LU Tian-Jian², XU Feng^1,²

1. The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi#cod#x02019;an Jiaotong University, Xi#cod#x02019;an 710049, China

2. Bioinspired Engineering and Biomechanics Center, Xi#cod#x02019;an Jiaotong University, Xi#cod#x02019;an 710049, China

Fund:

Abstract

Hydrogel network structures were used as nano-sized reactors for synthesizing NaYF₄:Yb³⁺, Er³⁺ upconversion nanoparticles with controlled size. By adjusting the crosslinking density, hydrogel networks with different sizes were prepared and used as reactor to control the size of synthesized nanoparticles. The particle size and upconversion luminescence property of the nanoparticles were characterized using XRD, TEM and photoluminescence (PL) spectra. The results show that the size of synthesized NaYF₄:Yb³⁺, Er³⁺ nanoparticles is around 10 nm. The diameter and the luminescence intensity decrease with increase of hydrogel crosslinking density. The increased crosslinking density reduces Ostwald ripening and increases pore pressure, which limit the growth of nanoparticles. The decreased particle size results in broken bonds on the particle surface and particle scattering. Besides, the hydrogel may also quench the fluorescence of the nanoparticles. This research provides a simple and environmentally friendly method for synthesizing uniform upconversion nanoparticles.

Keyword: rare earth; upconversion; upconversion nanoparticle; hydrogel network; crosslinking density

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引言

稀土上转换发光纳米材料由于其特殊的上转换发光性质而被广泛地用于生物成像^{[ 1]}、生物标记^{[ 2]}、生物检测^{[ 3]}、药物输送^{[ 4]}以及光动力治疗^{[ 5]}等生物医学领域^{[ 6]}。相比于其他荧光材料, 稀土上转换发光纳米材料具有荧光强度高, 无荧光漂白^{[ 7]}, 深层组织成像效果好^{[ 8]}, 发射波段可调^{[ 9]}, 生物相容性好^{[ 10]}等特点, 因而其制备方法成为研究者探索的热点。

制备稀土上转换发光纳米材料的方法主要包括热分解法^{[ 11]}、水热法^{[ 12]}、溶胶-凝胶法^{[ 13]}、共沉淀法^{[ 14]}等。其中, 热分解法是将有机前驱体溶解在高沸点的有机溶剂中, 在高温下使前驱体分解从而制备分散性好、粒径均一的纳米材料。然而这种方法需要价格昂贵且对空气敏感的金属醇盐^{[ 15]}, 制备过程需要有毒的有机试剂^{[ 16]}。而水热法则是利用高压反应釜, 在高温高压下提供了类似于自然界热液成矿的晶体生长条件来合成纳米颗粒的方法, 但其制备的纳米颗粒尺寸较大。溶胶-凝胶法是以金属醋酸盐或金属醇盐为基础的前驱体的水解和缩聚来制备纳米颗粒^{[ 13]}, 但该方法难以控制颗粒尺寸, 并可能出现团聚等问题^{[ 6]}。共沉淀法是在含有不同离子的溶液中加入适当的沉淀剂而获得纳米级的粉体。使用这种方法存在尺寸控制困难, 团聚严重, 通常需要后续高温煅烧等问题^{[ 17]}。因此, 需开发一种绿色环保、工艺简单且合成颗粒粒径较小、尺寸分布均匀的方法。

水凝胶以水为分散介质, 通过单体与交联剂产生物理或化学作用产生空间网络结构, 其内部的网孔大小可以通过改变交联剂浓度调控。目前已经有研究表明, 利用水凝胶空间网孔结构作为纳米级反应容器可以可控制备纳米Ni、Co、Au、Ag等贵金属^{[ 18, 19, 20]}。但以上研究都在室温下进行, 尚未见到在水热反应中引入水凝胶网络模板制备稀土上转换发光纳米颗粒的报道。本研究利用水凝胶网络结构为模板, 可控合成NaYF₄:Yb³⁺, Er³⁺稀土上转换纳米颗粒, 研究了不同交联剂浓度的凝胶模板对颗粒尺寸和发光性能的影响。

1 实验方法

1.1 试剂

实验中所用水均为超纯水, 所有试剂没有经过进一步提纯。Y(NO₃)₃•6H₂O、Yb(NO₃)₃•5H₂O和Er(NO₃)₃•5H₂O均从Alfa Aesar公司购买, 纯度均大于99.99%。NaF从国药集团化学试剂有限公司购买, 为优级纯。丙烯酰胺、甲叉双丙烯酰胺(MBA)、N, N, N', N'-四甲基二乙胺(TEMED)从MP Biomedicals公司购买, 过硫酸铵从Spectrum Chemical公司购买。

1.2 实验步骤

实验包括凝胶模板制备和纳米颗粒合成两部分, 具体步骤如下:

(1) 凝胶模板的制备

以原料易得、热稳定性好、无毒无害的聚丙烯酰胺(PAAm)凝胶作为凝胶模板。分别称取0.0045, 0.045、0.09、0.135 g甲叉双丙烯酰胺(MBA)和1.2 g丙烯酰胺(AM)、0.021 g过硫酸铵(SA)溶于6 mL水中, 搅拌使其完全溶解。再加入10.5 μL N, N, N', N'-四甲基二乙胺(TEMED), 迅速混合均匀后倒入圆柱形模具(5 mL注射器)成胶, 得到四组不同交联度的凝胶, 分别记为M₁、M₂、M₃和M₄。成胶后从模具中取出, 在超纯水中浸泡48 h, 其间换水两次, 使凝胶充分溶胀并除去凝胶内部未反应的单体及其它杂质。

(2) 纳米颗粒的合成

将25 g Y(NO₃)₃•6H₂O用50 mL的容量瓶, 配置出浓度为0.00131 mol/mL的溶液; 将25 g Er (NO₃)₃•5H₂O, 用500 mL的容量瓶, 配置出浓度为0.11 mmol/mL的溶液; 将10 g Yb(NO₃)₃•5H₂O, 用100 mL容量瓶配置浓度为0.22 mmol/mL的溶液。然后分别量取2260 μL硝酸钇、1460 μL硝酸镱和710 μL硝酸铒溶液, 加入16 mL水中, 配制成稀土盐溶液。1.129 g氟化钠溶解于20 mL水中, 配制成氟化钠过饱和溶液。然后将处理好的凝胶模板放入稀土盐溶液中浸泡24 h, 使稀土盐离子充分扩散至凝胶中, 24 h后加入氟化钠溶液, 氟离子和钠离子将通过扩散作用进入凝胶网络中。再过24 h, 将所有溶液及凝胶加入反应釜120 ℃反应8 h。取出凝胶并用超纯水冲洗干净以备后续处理及表征。

1.3 样品处理与表征

将所得样品在超纯水中浸泡2 d后, 冻干, 研碎, 采用帕那科χ'Pert PRO衍射仪表征纳米颗粒的晶体结构, 辐射源为CuKα, 扫描速度8°/min, 扫描范围为2 θ=10°~80°, 测试电压为40 kV, 电流为40 mA; 利用JEM-200CX型透射电镜表征纳米颗粒的形貌和尺寸; 采用QuantaMasterTM40荧光光谱仪外接发射波长为980 nm德国RGB Lasersystems公司的近红外激光器表征颗粒的荧光特性, 激发光功率为250 mW, 扫描波段为450~700 nm。

2 结果与讨论

2.1 不同交联度凝胶模板对纳米颗粒尺寸影响

聚丙烯酰胺凝胶是一种比较常见的凝胶, 目前广泛应用在凝胶电泳等方面, 原料易得、生物相容性好、无毒无害^{[ 21]}, 而且热稳定性较好。高分子网络凝胶法120℃反应8 h, 合成的稀土上转换纳米颗粒水凝胶体如图1(a)~(b)。凝胶由反应前的无色透明变成乳白色、不透明的状态, 显示在凝胶网络中已形成了上转换纳米颗粒。图1(c)为暗场条件下, 使用发射波长为980 nm近红外激光器激发时的照片, 可见稀土上转换纳米颗粒发出的光为稳定的绿光。

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	图1 水热反应前(a)、反应后(b)和反应后经980 nm激光激发(c)的水凝胶照片Fig. 1 Photographs of hydrogel before (a) and after (b) thermal reaction and fluorescence after 980 nm laser excitation (c)

图2为对四组凝胶模板合成的稀土上转换纳米颗粒的XRD图谱, 纳米颗粒主要为α相NaYF₄晶体, 但同时出现了β相小峰, 无杂峰出现。说明使用网络凝胶模板法在120℃可使微量α相颗粒向β相转变。

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	图2 由不同交联度凝胶模板合成稀土上转换纳米颗粒的XRD图谱Fig. 2 XRD patterns of nanoparticles synthesized in hydrogels of different crosslinking density

不同交联度凝胶模板合成的上转换纳米颗粒TEM照片和平均粒径统计(图 3)显示, 使用高分子网络凝胶法可以做到可控合成较小粒径的NaYF₄稀土上转换纳米颗粒, 并且均一性和分散性良好。图3(b)的插图是样品高分辨率透射电镜照片, 照片显示所合成的颗粒为单晶, 其晶面间距 d值为0.31 nm, 与α-NaYF₄(111)晶面间距一致, 也与XRD结果相符合。随着交联剂浓度的增加, 凝胶内部形成的颗粒越来越少, 这可能是由于随交联剂浓度升高, 渗透进凝胶中的离子数量逐渐减少的缘故。颗粒平均粒径也从12.65 nm逐渐减小到6.25 nm。出现这一现象的原因可能主要为以下两个方面:

(1) 随着凝胶交联剂浓度的增加, 水凝胶内部的网孔结构越来越密集。因此, 交联剂浓度越大的凝胶对物质传输的阻碍作用越强, 限制了奥斯特瓦尔德熟化作用, 即晶体生长是一个竞争的过程, 在颗粒生长竞争中占据优势的颗粒, 因为受到传质阻力, 而不能吞并周围不占优势的颗粒, 使不占优势的颗粒得以保留^{[ 22]}。所以, 凝胶模板法相较传统水热法可通过交联剂浓度使合成的颗粒粒径显著降低。

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图3 以不同交联度凝胶模板(M₁~M₄)合成的稀土上转换纳米颗粒((a)~(d))的TEM照片及其粒径统计结果(e)Fig. 3 TEM images ((a)-(d)) of upconversion nanoparticles synthesized in hydrogels of different crosslinking density and average size of nanoparticle sizes (e)M₁-M₄: Hydrogels crosslinked by 0.0045, 0.045, 0.09 and 0.135 g MBA, respectively. The inset image in (b) is HRTEM image of the sample

(2) 当颗粒长大到一定程度, 周围的凝胶网络将对其产生压力, 使其生长需要的更多能量克服压力造成的阻力^{[ 23]}。交联剂浓度大的凝胶其内部网孔结构更加密集, 使得颗粒在较小时就会受到较大压力, 对颗粒生长的限制作用越来越强, 阻碍其进一步长大。因此使用交联剂浓度高的凝胶模板合成的颗粒粒径较小。

2.2 不同交联度凝胶模板对纳米颗粒荧光特性的影响

四组凝胶模板合成的纳米颗粒/水凝胶复合物均发出稳定的绿色荧光, 发光强度差异不大(图4), 但随着交联剂浓度增加、纳米颗粒粒径减小, 荧光强度逐渐减弱(图5)。出现这一现象可能是由于以下两个方面的原因引起:

(1) 由颗粒形貌表征可见随着交联剂浓度的增加, 合成的颗粒粒径越来越小。而纳米荧光材料的尺寸存在最佳尺度范围, 颗粒太大或太小都容易引起泵浦光散射, 从而降低对泵浦光的吸收率, 导致发光强度下降。同时, 随着颗粒尺寸的减小, 其比表面积相对变大, 使得大量掺杂离子位于颗粒表面, 而颗粒表面因为存在大量的断键等表面缺陷可淬灭这些表面离子的发光。再者, 颗粒尺寸越小晶格对称性越高, 这也会降低稀土离子的受迫电偶极跃迁几率^{[ 24]}。这些因素都会造成颗粒的荧光强度下降。

(2) 随着凝胶交联剂浓度的增加, 凝胶内部的网络结构逐渐密集, 与颗粒的相互作用逐渐增强, 容易造成荧光淬灭。另一方面, 单位质量的凝胶中形成的颗粒数量也随凝胶交联剂浓度的增加而减少。以上原因也有可能造成交联剂浓度越高的凝胶模板合成出的颗粒荧光强度越低。

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	图4 以不同交联度凝胶模板(M₁~M₄)合成的稀土上转换纳米颗粒((a)~(d))的荧光照片Fig. 4 Fluorescence of upconversion nanoparticles ((a)-(d)) synthesized in hydrogels (M₁-M₄) of different crosslinking density(a)-(d): Nanoparticles synthesized in hydrogels from M₁ to M₄, respectively

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	图5 以不同交联度凝胶模板(M₁~M₄)合成的稀土上转换纳米颗粒的荧光光谱Fig. 5 Fluorescence spectra of upconversion nanoparticles synthesized in hydrogels of different crosslinking density(a-d): Nanoparticles synthesized in hydrogels crosslinked by 0.0045, 0.045, 0.09 and 0.135 g MBA, respectively

3 结论

本研究采用高分子网络凝胶模板法原位制备了NaYF₄: Yb³⁺, Er³⁺稀土上转换纳米颗粒。发现随着凝胶模板交联剂浓度的增加, 合成的颗粒粒径越来越小, 显示高分子网络凝胶模板法可以通过改变凝胶模板交联剂浓度, 控制合成纳米颗粒的粒径。与此同时, 相比于传统水热反应, 高分子网络凝胶法极大地降低了合成颗粒的平均粒径, 而无需添加表面活性剂等有毒有害溶剂, 符合绿色化学的要求。另一方面, 此种方法合成的颗粒均一性和分散性良好, 无团聚。

不过此种方法受限于凝胶模板的热稳定性, 无法达到160℃或更高的反应温度条件, 从而使合成的稀土纳米上转换颗粒主要为α相, 只存在少量的β相。在后续研究中, 将通过选取热稳定性更好的凝胶模板来制备纯β相颗粒。本方法为所有可水热合成的纳米颗粒提供了一种新方法, 克服了水热法粒径偏大的不足, 可实现对颗粒粒径的控制, 是一种简单、绿色、有效的纳米颗粒合成方法。

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[11]	YE X, COLLINS J E, KANG Y, et al. Morphologically controlled synthesis of colloidal upconversion nanophosphors and their shape-directed self-assembly. Proceedings of the National Academy of Sciences, 2010, 107(52): 22430-22435. [本文引用:1]
[12]	HE QI, FAN JUN, HU XIAO-YUN, et al. Hydrothermal synthesis of NaYF₄: Er³+ and its ultraviolet up-conversion light emitting property. Chinese Journal of Luminescence, 2012, 33(2): 122. [本文引用:1] [CJCR: 0.743]
[13]	LIU Y, PISARSKI W A, ZENG S, et al. Tri-color upconversion luminescence of rare earth doped BaTiO₃ nanocrystals and lowered color separation. Opt. Express, 2009, 17(11): 9089-9098. [本文引用:2] [JCR: 3.546]
[14]	LI LI-PING, GAO WEI, CHEN XUE-MEI, et al. Preparation and luminescence properties of NaYF₄: Yb, Er. Chinese Rare Earths, 2012, 33(002): 35-39. [本文引用:1] [CJCR: 0.6832]
[15]	WANG M, ABBINENI G, CLEVENGER A, et al. Upconversion nanoparticles: synthesis, surface modification and biological appli-cations, .Nanomedicine: Nanotechnology Biology and Medicine, 2011, 7(6): 710-729. [本文引用:1] [JCR: 6.93]
[16]	MAHALINGAM V, NACCACHE R, VETRONE F, et al. Sensitized Ce³+ and Gd³+ ultraviolet emissions by Tm³+ in colloidal LiYF₄ nanocrystals. Chemistry-A European Journal, 2009, 15(38): 9660-9663. [本文引用:1]
[17]	YI G, LU H, ZHAO S, et al. Synthesis, characterization, and biological application of size-controlled nanocrystalline NaYF4: Yb, Er infrared-to-visible up-conversion phosphors. Nano Letters, 2004, 4(11): 2191-2196. [本文引用:1] [JCR: 13.025]
[18]	SAHINER N, SAGBAS S. The preparation of poly(vinyl phosphonic acid) hydrogels as new functional materials for in situ metal nanoparticle preparation. Colloids and Surfaces A: Physicoche-mical and Engineering Aspects, 2013, 418: 76-83. [本文引用:1]
[19]	SHEN J S, CHEN Y L, HUANG J L, et al. Supramolecular hydrogels for creating gold and silver nanoparticles in situ. Soft Matter, 2013, 9(6): 2017-2023. [本文引用:1] [JCR: 3.909]
[20]	SAHINER N, BUTUN S, TURHAN T. P (AAGA) hydrogel reactor for in situ Co and Ni nanoparticle preparation and use in hydrogen generation from the hydrolysis of sodium borohydride. Chemical Engineering Science, 2012, 82(12): 114-120. [本文引用:1] [JCR: 2.386]
[21]	DARNELL M C, SUN J Y, MEHTA M, et al. Performance and biocompatibility of extremely tough alginate/polyacrylamide hydrogels. Biomaterials, 2013, 34(33): 8042-8048. [本文引用:1] [JCR: 7.604]
[22]	DADYBURJOR D B, RUCKENSTEIN E. Kinetics of Ostwald ripening. Journal of Crystal Growth, 1977, 40(2): 279-290. [本文引用:1] [JCR: 1.552]
[23]	LI H Y, ESTROFF L A. Calcite Growth in hydrogels assessing the mechanism of polymer-network incorporation into single crystals. Adv. Mater. ,2009, 21: 470-473. [本文引用:1] [JCR: 14.829]
[24]	YI G S, CHOW G M. Synthesis of hexagonal-phase NaYF₄: Yb, Er and NaYF₄: Yb, Tm nanocrystals with efficient up-conversion fluorescence. Advanced Functional Materials, 2006, 16(18): 2324-2329. [本文引用:1] [JCR: 9.765]

2012

24.892

0.0

... 引言稀土上转换发光纳米材料由于其特殊的上转换发光性质而被广泛地用于生物成像^[1]、生物标记^[2]、生物检测^[3]、药物输送^[4]以及光动力治疗^[5]等生物医学领域^[6] ...

2012

35.749

0.0

Nature Materials. 2012, 11(9):817-826

Tuning the autophagy-inducing activity of lanthanide-based nanocrystals through specific surface-coating peptides

The induction of autophagy on exposure of cells to a variety of nanoparticles represents both a safety concern and an application niche for engineered nanomaterials. Here, we show that a short synthetic peptide, RE-1, identified by means of phage display, binds to lanthanide (LN) oxide and upconversion nanocrystals (UCN), forms a stable coating layer on the nanoparticles’ surface, and effectively abrogates their autophagy-inducing activity. Furthermore, RE-1 peptide variants exhibit a differentially reduced binding capability, and correspondingly, a varied ability to reduce the autophagic response. We also show that the addition of an arginine–glycine–aspartic acid (RGD) motif to RE-1 enhances autophagy for LN UCN through the interaction with integrins. RE-1 and its variants provide a versatile tool for tuning material–cell interactions to achieve the desired level of autophagy, and may prove useful for the various diagnostic and therapeutic applications of LN-based nanomaterials and nanodevices.

2013

5.437

0.0

Biosensors and Bioelectronics. 2013, 43:null-null

Upconversion nanoparticle based LRET system for sensitive detection of MRSA DNA sequence

2013

0.0

Angewandte Chemie. 2013, 125(16):4471-4475

NIR-Triggered Anticancer Drug Delivery by Upconverting Nanoparticles with Integrated Azobenzene-Modified Mesoporous Silica

Jianan Liu,Prof. Wenbo Bu * ,Limin Pan andProf. Jianlin Shi *

State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Ding-Xi Road, Shanghai 200050 (China) *State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Ding-Xi Road, Shanghai 200050 (China)

2012

22.864

0.0

Nature Medicine. 2012, 18(10):1580-1585

In vivo photodynamic therapy using upconversion nanoparticles as remote-controlled nanotransducers

Conventional photodynamic therapy (PDT) is limited by the penetration depth of visible light needed for its activation. Here we used mesoporous-silica–coated upconversion fluorescent nanoparticles (UCNs) as a nanotransducer to convert deeply penetrating near-infrared light to visible wavelengths and a carrier of photosensitizers. We also used the multicolor-emission capability of the UCNs at a single excitation wavelength for simultaneous activation of two photosensitizers for enhanced PDT. We showed a greater PDT efficacy with the dual-photosensitizer approach compared to approaches using a single photosensitizer, as determined by enhanced generation of singlet oxygen and reduced cell viability. In vivo studies also showed tumor growth inhibition in PDT-treated mice by direct injection of UCNs into melanoma tumors or intravenous injection of UCNs conjugated with a tumor-targeting agent into tumor-bearing mice. As the first demonstration, to the best of our knowledge, of the photosensitizer-loaded UCN as an in vivo–targeted PDT agent, this finding may serve as a platform for future noninvasive deep-cancer therapy.

2012

9.599

0.0

Biotechnology Advances. 2012, 30(6):null-null

Recent advances in synthesis and surface modification of lanthanide-doped upconversion nanopart-icles for biomedical applications

... 溶胶-凝胶法是以金属醋酸盐或金属醇盐为基础的前驱体的水解和缩聚来制备纳米颗粒^[13], 但该方法难以控制颗粒尺寸, 并可能出现团聚等问题^[6] ...

2009

14.829

0.0

Advanced Materials. 2009, 21(44):4467-4471

Nonblinking and Nonbleaching Upconverting Nanoparticles as an Optical Imaging Nanoprobe and T1 Magnetic Resonance Imaging Contrast Agent

Yong Il Park 2 ,Jeong Hyun Kim 2 ,Kang Taek Lee 1 ,Ki-Seok Jeon 1 ,Hyon Bin Na 2 ,Jung Ho Yu 2 ,Hyung Min Kim 1 ,Nohyun Lee 2 ,Seung Hong Choi 3 ,Sung-Il Baik 4 ,Hyoungsu Kim 3 ,Seung Pyo Park 2 ,Beom-Jin Park 5 ,Young Woon Kim 4 ,Sung Ho Lee 6 ,Soo-Young Yoon 7 ,In Chan Song 3 ,Woo Kyung Moon 3 ,Yung Doug Suh 1,* andTaeghwan Hyeon 2,*

1NanoBio Fusion Research Center, Korea Research Institute of Chemical Technology, Daejeon, 305-600 (Korea) 2Center for Oxide Nanocrystalline Materials, School of Chemical & Biological Eng., Seoul National University, Seoul, 151-744 (Korea) 3Diagnostic Radiology, Seoul National Univ. Hospital, Seoul, 110-744 (Korea) 4School of Materials Science & Eng., Seoul National University, Seoul, 151-744 (Korea) 5Radiology, Korea Univ. Anam Hospital, College of Medicine, Korea University, Seoul, 136-705 (Korea) 6Thoracic & Cardiovascular Surgery, Korea Univ. Anam Hospital, College of Medicine, Korea University, Seoul, 136-705 (Korea) 7Laboratory Medicine, Korea Univ. Ansan Hospital, College of Medicine, Korea University, Ansan, 425-707 (Korea) *NanoBio Fusion Research Center, Korea Research Institute of Chemical Technology, Daejeon, 305-600 (Korea).

... 相比于其他荧光材料, 稀土上转换发光纳米材料具有荧光强度高, 无荧光漂白^[7], 深层组织成像效果好^[8], 发射波段可调^[9], 生物相容性好^[10]等特点, 因而其制备方法成为研究者探索的热点 ...

2008

7.604

0.0

Biomaterials. 2008, 29(7):937-943 DOI:10.1016/j.biomaterials.2007.10.051

Upconversion fluorescence imaging of cells and small animals using lanthanide doped nanocrystals

Abstract

Upconversion fluorescence imaging technique with excitation in the near-infrared (NIR) region has been used for imaging of biological cells and tissues. This has several advantages, including absence of photo-damage to living organisms, very low auto-fluorescence, high detection sensitivity, and high light penetration depth in biological tissues. In this report we demonstrate the use of a new upconversion fluorophore, lanthanide doped nanocrystals, for imaging of cells and some deep tissues in animal. Polyethyleneimine (PEI) coated NaYF₄:Yb,Er nanoparticles were synthesized, which produce very strong upconversion fluorescence when excited at 980 nm by a NIR laser. The nanoparticles were shown to be stable in physiologic buffered saline (PBS), non-toxic to bone marrow stem cells, and resistant to photo-bleaching. The nanoparticles delivered into some cell lines or injected intradermally and intramuscularly into some tissues either near the body surface or deep in the body of rats showed visible fluorescence, when exposed to a 980 nm NIR laser. To the best of our knowledge, this represents the first demonstration of use of upconversion fluorophores for cellular and tissue imaging.

2008

10.677

0.0

Journal of the American Chemical Society. 2008, 130(17):5642–5643-null

Upconversion Multicolor Fine-Tuning: Visible to Near-Infrared Emission from Lanthanide-Doped NaYF₄ Nanoparticles

Feng Wang and Xiaogang Liu

<div>Department of Chemistry, National University of Singapore, 3 Science Drive 3,Singapore 117543</div><div></div>

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.

2010

7.604

0.0

Biomaterials. 2010, 31(27):7078-7085 DOI:10.1016/j.biomaterials.2010.05.065

Long-term in vivo biodistribution imaging and toxicity of polyacrylic acid-coated upconversion nanophosphors

Abstract

Rare-earth upconversion nanophosphors (UCNPs) have become one of the most promising classes of luminescent materials for bioimaging. However, there remain numerous unresolved issues with respect to the understanding of how these nanophosphors interact with biological systems and the environment. Herein, we report polyacrylic acid (PAA)-coated near-infrared to near-infrared (NIR-to-NIR) upconversion nanophosphors NaYF₄:Yb,Tm (PAA-UCNPs) as luminescence probes for long-term in vivo distribution and toxicity studies. Biodistribution results determined that PAA-UCNPs uptake and retention took place primarily in the liver and the spleen and that most of the PAA-UCNPs were excreted from the body of mice in a very slow manner. Body weight data of the mice indicated that mice intravenously injected with 15 mg/kg of PAA-UCNPs survived for 115 days without any apparent adverse effects to their health. In addition, histological, hematological and biochemical analysis were used to further quantify the potential toxicity of PAA-UCNPs, and results indicated that there was no overt toxicity of PAA-UCNPs in mice at long exposure times (up to 115 days). The study suggests that PAA-UNCPs can potentially be used for long-term targeted imaging and therapy studies in vivo.

2010

0.0

Proceedings of the National Academy of Sciences. 2010, 107(52):22430-22435

Morphologically controlled synthesis of colloidal upconversion nanophosphors and their shape-directed self-assembly

Xingchen Ye a , Joshua E. Collins b , Yijin Kang a , Jun Chen c , Daniel T. N. Chen d , Arjun G. Yodh d , and Christopher B. Murray a , c , 1

aDepartment of Chemistry, University of Pennsylvania, Philadelphia, PA 19104;bIntelligent Material Solutions, Inc., Princeton, NJ 08540;cDepartment of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104; anddDepartment of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104

We report a one-pot chemical approach for the synthesis of highly monodisperse colloidal nanophosphors displaying bright upconversionluminescence under 980 nm excitation. This general method optimizes the synthesis with initial heating rates up to 100 °C/minutegenerating a rich family of nanoscale building blocks with distinct morphologies (spheres, rods, hexagonal prisms, and plates)and upconversion emission tunable through the choice of rare earth dopants. Furthermore, we employ an interfacial assemblystrategy to organize these nanocrystals (NCs) into superlattices over multiple length scales facilitating the NC characterizationand enabling systematic studies of shape-directed assembly. The global and local ordering of these superstructures is programmedby the precise engineering of individual NC’s size and shape. This dramatically improved nanophosphor synthesis together withinsights from shape-directed assembly will advance the investigation of an array of emerging biological and energy-relatednanophosphor applications.

... 制备稀土上转换发光纳米材料的方法主要包括热分解法^[11]、水热法^[12]、溶胶-凝胶法^[13]、共沉淀法^[14]等 ...

2012

0.0

0.743

Chinese Journal of Luminescence. 2012, 33(2):122- DOI:10.3788/fgxb20123302.0122

Hydrothermal synthesis of NaYF₄:Er³+ and its ultraviolet up-conversion light emitting property

1. Institute of Chemical Engineering, Northwest University, Xi'an 710069, China; 2. Department of Physics, Northwest University, Xi'an 710069, China

Er³⁺ doped NaYF₄ up-conversion luminescence material was successfully prepared by hydrothermal method. The X-ray diffraction (XRD) indicates that when the reaction temperature is 180 ℃ or 200 ℃, the crystal structure is a mixture of hexagon and quadrangle, when the reaction temperature is 220 ℃, the crystal shows a hexagon phase structure. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicate that the crystal grain has a hexagon structure, and possesses an average size of about 100 nm with a uniform distribution. The fluorescence spectra show that under the exciting wavelength of 500 nm, the sample emits ultraviolet light. It can be concluded from the energy level diagram that the ground state ⁴I_15/2 electrons of Er³⁺ will first transmit to ²H_11/2 and ⁴S_3/2 levels, and then give out the 310 nm and 340 nm ultraviolet light through the energy transmit up-conversion (ETU) process, respectively. Considering the up-conversion emission mechanism, both the 310 nm and 340 nm up-conversion peaks can be characterized as biphotonic processes. The research results demonstrate that the Er³⁺ doped NaYF₄ exhibites an ultraviolet up-conversion light emitting property;and it has a promising way in biomedical imaging, photocatalytic reaction and biomark process, etc.

采用水热法制备了Er³⁺掺杂的NaYF₄上转换发光材料,X射线衍射结果表明,当反应温度为180 ℃和200 ℃时,晶体属于六方晶型和四角晶型混合相态;当反应温度为220 ℃时,该晶体属于纯六方晶型结构。SEM和TEM观察发现,晶粒为六角形,样品颗粒分散性好,平均粒径约为100 nm。荧光光谱测试结果表明,当激发波长为500 nm时,样品发射出紫外光。从Er³⁺能级图谱可以得出,Er³⁺基态电子⁴I_15/2首先跃迁到²H_11/2与⁴S_3/2能级上,随即经过能量转移上转换过程(ETU)分别发射出310 nm和340 nm的紫外光。结合Er³⁺发光机理可以推出上转换峰310 nm和340 nm均属于双光子过程。研究结果表明,以NaYF₄为基质掺杂Er³⁺产生的紫外上转换光在生物成像、光催化发应及生物标记等方面有着广阔的应用前景。

... 制备稀土上转换发光纳米材料的方法主要包括热分解法^[11]、水热法^[12]、溶胶-凝胶法^[13]、共沉淀法^[14]等 ...

2009

3.546

0.0

... 制备稀土上转换发光纳米材料的方法主要包括热分解法^[11]、水热法^[12]、溶胶-凝胶法^[13]、共沉淀法^[14]等 ...

... 溶胶-凝胶法是以金属醋酸盐或金属醇盐为基础的前驱体的水解和缩聚来制备纳米颗粒^[13], 但该方法难以控制颗粒尺寸, 并可能出现团聚等问题^[6] ...

2012

0.0

0.6832

... 制备稀土上转换发光纳米材料的方法主要包括热分解法^[11]、水热法^[12]、溶胶-凝胶法^[13]、共沉淀法^[14]等 ...

2011

6.93

0.0

Nanomedicine: Nanotechnology Biology and Medicine. 2011, 7(6):710-729 DOI:10.1016/j.nano.2011.02.013

Upconversion nanoparticles: synthesis, surface modification and biological appli-cations

Abstract

New generation fluorophores, also termed upconversion nanoparticles (UCNPs), have the ability to convert near infrared radiations with lower energy into visible radiations with higher energy via a nonlinear optical process. Recently, these UCNPs have evolved as alternative fluorescent labels to traditional fluorophores, showing great potential for imaging and biodetection assays in both in vitro and in vivo applications. UCNPs exhibit unique luminescent properties, including high penetration depth into tissues, low background signals, large Stokes shifts, sharp emission bands, and high resistance to photobleaching, making UCNPs an attractive alternative source for overcoming current limitations in traditional fluorescent probes. In this article, we discuss the recent progress in the synthesis and surface modification of rare-earth doped UCNPs with a specific focus on their biological applications.

From the Clinical Editor

Upconversion nanoparticles – a new generation of fluorophores - convert near infrared radiations into visible radiations via a nonlinear optical process. These UCNPs have evolved as alternative fluorescent labels with great potential for imaging and biodetection assays in both in vitro and in vivo applications.

Graphical Abstract

Rare earth doped upconversion nanoparticles, which can convert long wavelength near infrared radiation into short wavelength visible radiation via a non-linear optical process, are emerging as a new class of fluorescent biolables. They can overcome some of the limitations of conventional biolables including organic dyes and quantum dots. This review highlights recent advances in the synthesis, surface modification, and biological applications of rare earth doped upconversion nanoparticles.

View high quality image (371K)

... 然而这种方法需要价格昂贵且对空气敏感的金属醇盐^[15], 制备过程需要有毒的有机试剂^[16] ...

2009

0.0

Chemistry - A European Journal. 2009, 15(38):9660-9663

Sensitized Ce³⁺ and Gd³⁺ Ultraviolet Emissions by Tm³⁺ in Colloidal LiYF₄ Nanocrystals

Venkataramanan Mahalingam Dr.,Rafik Naccache,Fiorenzo Vetrone Dr. andJohn A. Capobianco Prof.

Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W. Montreal, QC, H4B 1R6 (Canada), Fax: (+1) 514-848-2868

... 然而这种方法需要价格昂贵且对空气敏感的金属醇盐^[15], 制备过程需要有毒的有机试剂^[16] ...

2004

13.025

0.0

Nano Letters. 2004, 4(11):2191–2196-null

Synthesis, Characterization, and Biological Application of Size-Controlled Nanocrystalline NaYF₄:Yb,Er Infrared-to-Visible Up-Conversion Phosphors

Guangshun Yi ,* † ‡ Huachang Lu , ‡ Shuying Zhao , § Yue Ge , § Wenjun Yang , § Depu Chen ,* ‡ and Liang-Hong Guo * § ‖

<div>Faculty of Materials Science & Engineering, Shandong University of Technology, Zibo 255049, China, Department of Chemistry, Tsinghua University, Beijing 100084, China, Beijing National Biochip Research & Engineering Center, 18 Life Science Parkway, Changping District, Beijing 102206, China, and Research Center for Eco-environmental Sciences, Chinese Acedemy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China</div><div></div>

Nanocrystalline infrared-to-visible up-conversion phosphors, ytterbium and erbium co-doped sodium yttrium fluoride, were synthesized. Spherical particles with narrow size distribution were prepared by a co-precipitation method in the presence of ethylenediaminetetraacetic acid (EDTA). Particles of controlled size in the range of 37 to 166 nm diameter were obtained by adjusting the molar ratio of EDTA to total lanthanides. Although the as-prepared nanoparticles emit very weak up-conversion fluorescence when excited by infrared light, the emission was enhanced by up to 40-fold after they were annealed at temperatures between 400 and 600 °C. By comparison with the bulk phosphor, the luminescence efficiency of the nanoparticle was estimated to be 1%. Factors affecting the particle size and their up-conversion fluorescence intensity were investigated by various microscopic and spectroscopic techniques. Preliminary results demonstrated the nanoparticles as promising up-converting fluorescence labels in the detection of biological interactions.

... 使用这种方法存在尺寸控制困难, 团聚严重, 通常需要后续高温煅烧等问题^[17] ...

2013

0.0

Colloids and Surfaces A: Physicoche-mical and Engineering Aspects. 2013, 418:76-83 DOI:10.1016/j.colsurfa.2012.11.026

The preparation of poly(vinyl phosphonic acid) hydrogels as new functional materials for in situ metal nanoparticle preparation

<ul><li id="aff0005">aFaculty of Science & Arts, Chemistry Department and Application Center (NANORAC), Canakkale Onsekiz Mart University, Terzioglu Campus, 17100 Canakkale, Turkey</li><li id="aff0010">bNanoscience and Technology Research and Application Center (NANORAC), Canakkale Onsekiz Mart University, Terzioglu Campus, 17100 Canakkale, Turkey</li></ul>

Bulk poly(vinyl phosphonic acid) (p(VPA)) hydrogels were synthesized via a photo polymerization technique using polyethylene glycol diacrylate with different molecular weights as crosslinker. The prepared hydrogel was also used as template for in situ metal nanoparticle preparations of Co, Ni and Cu, by loading the corresponding metal ions from aqueous solution into the p(VPA) hydrogel networks and then reducing the metal ions with sodium boron hydride (NaBH₄) within the hydrogel matrices. The amount of metal in hydrogel composites was determined by atomic absorption spectroscopy (AAS) and thermogravimetric analysis (TGA) measurements. Moreover, p(VPA)–M (M: Co, Ni, Cu, etc) were used as a soft reactor for the generation of hydrogen by hydrolysis of NaBH₄,and in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). P(VPA)–Co composite demonstrated the best catalytic performance and its activation energy was calculated as 23.01 kJ mol⁻¹ which is comparable and mostly better than similar work in the literature.

... 目前已经有研究表明, 利用水凝胶空间网孔结构作为纳米级反应容器可以可控制备纳米Ni、Co、Au、Ag等贵金属^[18,19,20] ...

2013

3.909

0.0

... 目前已经有研究表明, 利用水凝胶空间网孔结构作为纳米级反应容器可以可控制备纳米Ni、Co、Au、Ag等贵金属^[18,19,20] ...

2012

2.386

0.0

Chemical Engineering Science. 2012, 82(12):null-null

P (AAGA) hydrogel reactor for in situ Co and Ni nanoparticle preparation and use in hydrogen generation from the hydrolysis of sodium borohydride

... 目前已经有研究表明, 利用水凝胶空间网孔结构作为纳米级反应容器可以可控制备纳米Ni、Co、Au、Ag等贵金属^[18,19,20] ...

2013

7.604

0.0

Biomaterials. 2013, 34(33):null-null

Performance and biocompatibility of extremely tough alginate/polyacrylamide hydrogels

... 1 不同交联度凝胶模板对纳米颗粒尺寸影响聚丙烯酰胺凝胶是一种比较常见的凝胶, 目前广泛应用在凝胶电泳等方面, 原料易得、生物相容性好、无毒无害^[21], 而且热稳定性较好 ...

1977

1.552

0.0

Journal of Crystal Growth. 1977, 40(2):null-null

Kinetics of Ostwald ripening

... 因此, 交联剂浓度越大的凝胶对物质传输的阻碍作用越强, 限制了奥斯特瓦尔德熟化作用, 即晶体生长是一个竞争的过程, 在颗粒生长竞争中占据优势的颗粒, 因为受到传质阻力, 而不能吞并周围不占优势的颗粒, 使不占优势的颗粒得以保留^[22] ...

2009

14.829

0.0

Advanced Materials. 2009, 21(4):470-473

Calcite Growth in Hydrogels: Assessing the Mechanism of Polymer-Network Incorporation into Single Crystals

Hanying Li andLara A. Estroff *

Department of Materials Science and Engineering Cornell University Ithaca, NY 14853 (USA) *Department of Materials Science and Engineering Cornell University Ithaca, NY 14853 (USA).

... (2) 当颗粒长大到一定程度, 周围的凝胶网络将对其产生压力, 使其生长需要的更多能量克服压力造成的阻力^[23] ...

2006

9.765

0.0

Advanced Functional Materials. 2006, 16(18):2324-2329

Synthesis of Hexagonal-Phase NaYF₄:Yb,Er and NaYF₄:Yb,Tm Nanocrystals with Efficient Up-Conversion Fluorescence

G. S. Yi 1 andG. M. Chow 1,2

1Molecular Engineering of Biological and Chemical Systems, Singapore–Massachusetts Institute of Technology Alliance, Singapore 119260, Singapore 2Department of Materials Science and Engineering, National University of Singapore, Singapore 119260, Singapore

IR-to-visible up-conversion fluorescent nanocrystals of hexagonal-phase NaYF₄:20 %Yb,2 %Er and NaYF₄:20 %Yb,2 %Tm have been synthesized by decomposition of multiprecursors of CF₃COONa, (CF₃COO)₃Y, (CF₃COO)₃Yb, and (CF₃COO)₃Er/(CF₃COO)₃Tm in oleylamine at 330 °C. The average particle size is 10.5 ± 0.7 nm (from random measurements of 200 particles from five transmission electron microscopy images) and 11.1 ± 1.3 nm (from dynamic-light-scattering measurements). The up-conversion fluorescence intensity of the hexagonal nanocrystals in this work is much higher than that of other cubic-phase NaYF₄:Yb,Er nanocrystals, including the ones in this work (by a factor of 7.5). Mechanisms for nucleation and growth of the hexagonal-phase nanoparticles are proposed. These nanocrystals are easily dispersed in organic solvents, producing a transparent colloidal solution. The hydrophobic surfaces of the particles are made hydrophilic using a bipolar surfactant. These nanoparticles and their dispersions in various media have potential applications in optical nanodevices and bioprobes.

... 再者, 颗粒尺寸越小晶格对称性越高, 这也会降低稀土离子的受迫电偶极跃迁几率^[24] ...