单个纳米颗粒的上转换光谱现象研究

doi:10.15541/jim20160131

摘要/Abstract

摘要：

稀土离子掺杂上转换纳米颗粒具有独特的光谱学特征, 在太阳能利用、三维显示和生物医学等众多领域有着广泛的应用价值。然而, 传统基于统计平均效应的上转换纳米颗粒群体性光谱学研究忽视了众多来自单个颗粒的非均一性信息。单颗粒光谱检测成为一种突破上述瓶颈, 获取源自纳米颗粒非均一性本征结构的独特光谱现象, 并实现单个纳米颗粒器件化的有效技术手段。对于单个纳米颗粒电子行为的研究能够揭示来自微结构本身的信息, 甚至能够在没有介质干扰下清晰洞见材料本征结构和外部作用的相互影响, 从而为制备高质量的纳米颗粒提供指导意义。同时, 单颗粒光谱检测也具有在微纳米尺度探索晶体结构各向异性光学特性及一些尚未预见的新型光学现象的强大能力。本文介绍了单个纳米颗粒上转换发光表征的重要性以及常见的几种检测方法。论述了单颗粒上转换发光的一些最新研究成果, 并对未来发展方向进行了展望。

关键词: 上转换发光, 稀土离子, 单颗粒, 光谱学, 综述

Abstract:

Upconversion nanoparticles (UCNPs) have made a significant and valuable contribution to photophysics and biomedicine, due to their specific spectroscopic characteristics. However, the ensemble spectroscopy of UCNPs is limited for the electronic behavior in average effect, which ignores the fact that the nanoparticles are heterogeneous. Towards the research focus on heterogeneous intrinsic structure, unique photophysical phenomena, and advanced applications, the optical characterization of single UCNPs are promoted to a frontier breakthrough of UCNPs community. Electronic behavior detection aimed at a single nanoparticle displays signals from the micro-structure of nanoparticles, while single nanoparticle spectroscopy offers clear insight into the interplay between intrinsic and extrinsic influences without noise, and subsequently gives instructions for the high quality preparation of UCNPs. Single nanoparticle optical characterization possesses a powerful capacity to explore the crystalline structure anisotropy related optical differences, or some unexpected unique optical phenomena at sub-micron and even nano-scale. In this review, the importance of single UCNPs characterization and single particle detection methods are overviewed, in which the considerable emphasis is placed on the specific spectroscopic study of single UCNPs Showing fantastic photophysical phenomena beyond ensemble measurement. Finally, this review identifies promising opportunities in which single UCNPs characterization technique can accelerate on-going research with a remarkable depth and breadth, facilitate discovery of upconversion nanoparticles that overcome fundamental limitations of current ensemble level.

Key words: upconversion, lanthanides, single nanoparticle, spectroscopy, review

中图分类号:

TQ174

周佳佳, 邱建荣. 单个纳米颗粒的上转换光谱现象研究[J]. 无机材料学报, 2016, 31(10): 1023-1030.

ZHOU Jia-Jia, QIU Jian-Rong. Upconversion Spectroscopic Investigation of Single Nanoparticles[J]. Journal of Inorganic Materials, 2016, 31(10): 1023-1030.

图/表 8

图1 共聚焦显微荧光扫描系统原理示意图

Fig. 1 Schematic diagram of confocal microscopic fluorescent scanning system from upconversion nanoparticles

图2 光纤颗粒负载法检测上转换发光实验系统示意图[9]

Fig. 2 Schematic experimental configuration for capturing UC luminescence of nanoparticles using a suspended-core microstructured optical-fiber dip sensor[9]

图3 光镊法进行单颗粒上转换荧光探测系统示意图[35]

Fig. 3 Schematic diagram of the experimental setup used for luminescence acquisition of an optically trapped upconversion nanoparticle[35]

表1 单个上转换纳米颗粒的光稳定性和亮度评价

Table 1 Photostability and brightness assessment of single UCNPs

UCNPs	Particle size/nm	Monitoring wavelength/nm	Assessing mode	Power density /(W·cm^-2)	Time range /min	Ref.
β-NaYF₄: Yb³⁺, Er³⁺	~27	550/650	photostability	5 ×10⁶	60	[24]
NaGdF₄: Yb³⁺, Er³⁺@NaGdF₄	~40	550/650	photostability	150	240	[23]
YVO₄: Yb³⁺, Er³⁺	~39	520/550/650	photostability	8×10³	8	[41]
NaYF₄ : Yb³⁺, Ho³⁺, Tm³⁺@NaYF₄	~22	450/475/545/645	photostability	8×10⁶	360	[42]
β-NaYF₄: Yb³⁺/Er³⁺	~10	550/650	photostability	10⁶	60	[29]
β-NaGdF₄: Yb³⁺, Er³⁺@NaYF₄	~20	520/550/650	brightness	/	/	[43]
β-NaGdF₄: Yb³⁺, Er³⁺@NaGdF₄ @SiO₂@NPTAT-doped SiO₂	~39	550	photostability	/	15	[14]
β-NaGdF₄: Yb³⁺, Tm³⁺@NaGdF₄ @SiO₂@NPTAT-doped SiO₂	~38	480
NaYbF₄: Er³⁺@NaYF₄@SiO₂@rhodamine B isothiocyanate-doped SiO₂	~24	650

图4 (a) 系列Tm掺杂纳米颗粒上转换发光积分强度随激发功率变化关系; (b) 掺杂20%Yb3+-20%Er3+(蓝色)/2%Er3+(红色)的8 nm单颗粒上转换强度随功率的变化关系。照片对应左图I、II、III功率下的共聚焦显微荧光图像; (c) 单个β-NaYF4: 20% Yb3+-2% Tm3+纳米颗粒在~1.1×107 W/cm2 980nm激光激发下的是上转换荧光光谱图[13, 30, 44]

Fig. 4 (a) Integrated upconrersion luminescence intensity (~400- 850 nm) as a function of excitation irradiance for a series of Tm3+-doped nanoparticles. (b) Luminescence intensity of single 8 nm UCNPs with 20% (blue circles) and 2% (red circles) Er3+, each with 20%Yb3+, plotted as a function of excitation intensity. Confocal luminescence images taken at points shown in (b) of single UCNPs containing a mixture of 2% and 20% Er3+. (c) Emission spectra of single β-NaYF4: 20% Yb3+-2% Tm3+ nanoparticle excited with 980 nm laser illumination at the power density of ~1.1×107 W/cm2[13, 30, 44]

图5 (a~d)单根β-NaYF4: Tm3+-Yb3+微米棒的上转换发射光谱图, 分别对应Tm3+跃迁: (a) 1G4→3F4, (b) 3F3→3H6, 1D2→3F3, (c) 1G4→3H5, (d)3H4→3H6; (e~h)各跃迁荧光强度随发射偏振角的变化关系; (i, j)单个纳米盘其晶体学a轴(i)或c轴(j)平行水平面时, 上转换发射光谱随激发偏振角变化; (k)单根NaYF4: Er3+, Yb3+纳米棒其处于两个相垂直发射偏振角度时的发射光谱图。曲线1和曲线2表示发射偏振角平行和垂直纳米棒光轴。插图表示电场下两个不同偏振方向, 产生截然不同的光谱; (l)二维图谱表示红光波段的发射强度随发射偏振角的变化关系[27,31]

Fig. 5 (a-d) Emission spectra of UC from β-NaYF4: Tm3+-Yb3+ single micro-rod in the transitions of Tm3+: (a) 1G4→3F4, (b) 3F3→3H6, 1D2→3F3, (c) 1G4→3H5, (d) 3H4→3H6, respectively. (e-h) The dependence of the corresponding spectra on emission polarization angle (φem). (i, j) UC luminescence spectra of a single nanodisk, whose a axis or c axis is parallel to horizontal plane, recorded at excitation polarization angles varying from 0° to 360°, with no polarizer placed in the detection part. (k) Emission spectra from a single NaYF4: Er3+, Yb3+ UCNR immobilized on a surface for two perpendicular emission polarization angles. Purple (blue) line represents recovered emission parallel (perpendicular) to the optical axis of the NaYF4: Er3+, Yb3+ UCNR. Inset represents these two different polarizations of the electric field that gives the two distinct spectra. (l) Two dimensional map represents emission intensity of red band as a function of emission polarization angle[27, 31]

图6 荧光寿命调节示范, 即NaYF4: Yb, Tm上转换纳米颗粒的时间分辨共聚焦图像[10]

Fig. 6 Lifetime tuning scheme and time-resolved confocal images for NaYF4: Yb, Tm upconversion nanocrystals[10]

图7 (a) AFM图像展示纳米组装方式: 60 nm金纳米球在AFM针尖拨动下靠近上转换纳米颗粒。黄色箭头表示激发光的偏振方向; (b) 上转换纳米颗粒和金属小球靠近(曲线1)、远离(曲线2)时的发射光谱; (c) 上转换绿光(左侧)和红光(右侧)的上升(上侧)及衰减(下侧)曲线; (d) 单个上转换纳米颗粒针尖增强效应示意图; (e) 针尖缩回和靠近时的上转换发射光谱; (f) 660 nm处上转换发光在针尖靠近和离开时的荧光衰减曲线[26, 55]

Fig. 7 (a) AFM image showing the nanoassembly approach: The 60 nm gold nanosphere is attached to the UCNPs with the help of the AFM tip. The yellow arrow indicates the polarization axis of the excitation light. (b) Upconversion emission spectra of the nanoparticle without (violet curve) and with (blue curve) the gold nanosphere in close vicinity. (c) Rise (upper) and decay times (lower) of the green (left) and red (right) emission with the color code as in part (b). (d) Schematic of the tip-enhancement of a single Upconversion nanoparticle. (e) Upconversion emission spectra with retracted and approached tip, respectively. (f) Decay curves for red emission detected with and without tip at 660 nm[26, 55]

参考文献 55

[1]	AUZEL F.Upconversion and anti-Stokes processes with f and d ions in solids.Chem. Rev. , 2004, 104(1): 139-173.
[2]	WANG X, ZHUANG J, PENG Q, et al.A general strategy for nanocrystal synthesis.Nature, 2005, 437(7055): 121-124.
[3]	WANG F, HAN Y, LIM C S, et al.Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping.Nature, 2010, 463(7284): 1061-1065.
[4]	ZHANG F, LI J, SHAN J, et al.Shape, size, and phase-controlled rare-earth fluoride nanocrystals with optical up-conversion properties.Chem-Eur. J., 2009, 15(41): 11010-11019.
[5]	YI G S, CHOW G M.Synthesis of hexagonal-phase NaYF4: Yb, Er and NaYF4: Yb, Tm nanocrystals with efficient up-conversion fluorescence.Adv. Funct. Mater., 2006, 16(18): 2324-2329.
[6]	LIU D, XU X, DU Y, et al.Three-dimensional controlled growth of monodisperse sub-50 nm heterogeneous nanocrystals.Nat. Commun. , 2016, 7: 10254.
[7]	ZHOU B, SHI B, JIN D, et al.Controlling upconversion nanocrystals for emerging applications.Nat. Nanotechnol., 2015, 10(11): 924-936.
[8]	WANG F, DENG R, WANG J, et al.Tuning upconversion through energy migration in core-shell nanoparticles.Nat. Mater., 2011, 10(12): 968-973.
[9]	ZHAO J B, JIN D Y, SCHARTNER E P, et al.Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence.Nat. Nanotechnol., 2013, 8(10): 729-734.
[10]	LU Y, ZHAO J, ZHANG R, et al.Tunable lifetime multiplexing using luminescent nanocrystals.Nat. Photonics, 2014, 8(1): 33-37.
[11]	LU Y, LU J, ZHAO J, et al.On-the-fly decoding luminescence lifetimes in the microsecond region for lanthanide-encoded suspension arrays.Nat. Commun., 2014, 5: 3741.
[12]	WANG J, DENG R, MACDONALD M A, et al.Enhancing multiphoton upconversion through energy clustering at sublattice level.Nat. Mater. , 2014, 13(2): 157-162.
[13]	GARGAS D J, CHAN E M, OSTROWSKI A D, et al.Engineering bright sub-10-nm upconverting nanocrystals for single-molecule imaging.Nat. Nanotechnol., 2014, 9(4): 300-305.
[14]	ZHOU L, WANG R, YAO C, et al.Single-band upconversion nanoprobes for multiplexed simultaneous in situ molecular mapping of cancer biomarkers.Nat. Commun., 2015, 6: 6938.
[15]	FERNEE M J, TAMARAT P, LOUNIS B.Spectroscopy of single nanocrystals.Chem. Soc. Rev. , 2014, 43(4): 1311-1337.
[16]	SONNTAG M D, KLINGSPORN J M, ZRIMSEK A B, et al.Molecular plasmonics for nanoscale spectroscopy.Chem. Soc. Rev., 2014, 43(4): 1230-1247.
[17]	CUI J, BEYLER A P, BISCHOF T S, et al.Deconstructing the photon stream from single nanocrystals: from binning to correlation.Chem. Soc. Rev., 2014, 43(4): 1287-1310.
[18]	EMPEDOCLES S A, NEUHAUSER R, SHIMIZU K, et al.Photoluminescence from single semiconductor nanostructures.Adv. Mater., 1999, 11(15): 1243-1256.
[19]	BLANTON S A, HINES M A, GUYOT-SIONNEST P.Photoluminescence wandering in single CdSe nanocrystals.Appl. Phys. Lett., 1996, 69(25): 3905-3907.
[20]	NIRMAL M, DABBOUSI B O, BAWENDI M G, et al.Fluorescence intermittency in single cadmium selenide nanocrystals.Nature, 1996, 383(6603): 802-804.
[21]	EMPEDOCLES S, BAWENDI M.Quantum-confined stark effect in single CdSe nanocrystallite quantum dots.Science, 1997, 278(5346): 2114-2117.
[22]	PARK Y I, LEE K T, SUH Y D, et al.Upconverting nanoparticles: a versatile platform for wide-field two-photon microscopy and multi-modal in vivo imaging.Chem. Soc. Rev., 2014, 44(6): 1302-1317.
[23]	PARK Y I, KIM J H, LEE K T, et al.Nonblinking and nonbleaching upconverting nanoparticles as an optical imaging nanoprobe and T1 magnetic resonance imaging contrast agent.Adv. Mater., 2009, 21(44): 4467-4471.
[24]	WU S W, HAN G, MILLIRON D J, et al.Non-blinking and photostable upconverted luminescence from single lanthanide- doped nanocrystals.Proc. Natl. Acad. Sci. USA, 2009, 106(27): 10917-10921.
[25]	SCHIETINGER S, MENEZES L D, LAURITZEN B, et al.Observation of size dependence in multicolor upconversion in single Yb3+, Er3+ codoped NaYF4 nanocrystals.Nano Lett., 2009, 9(6): 2477-2481.
[26]	SCHIETINGER S, AICHELE T, WANG H Q, et al.Plasmon-enhanced upconversion in single NaYF4: Yb3+/Er3+ codoped nanocrystals.Nano Lett., 2010, 10(1): 134-138.
[27]	ZHOU J J, CHEN G X, WU E, et al.Ultrasensitive polarized up-conversion of Tm3+-Yb3+ doped beta-NaYF4 single nanorod.Nano Lett., 2013, 13(5): 2241-2246.
[28]	KOLESOV R, XIA K, REUTER R, et al.Optical detection of a single rare-earth ion in a crystal.Nat. Commun., 2012, 3: 1029.
[29]	OSTROWSKI A D, CHAN E M, GARGAS D J, et al.Controlled synthesis and single-particle imaging of bright, sub-10 nm lanthanide-doped upconverting nanocrystals.ACS Nano, 2012, 6(3): 2686-2692.
[30]	ZHOU J J, CHEN G X, ZHU Y B, et al.Intense multiphoton upconversion of Yb3+-Tm3+ doped beta-NaYF4 individual nanocrystals by saturation excitation. J. Mater. Chem. C, 2015, 3(2): 364-369.
[31]	CHEN P, SONG M, WU E, et al.Polarization modulated upconversion luminescence: single particle vs. few-particle aggregates.Nanoscale, 2015, 7(15): 6462-6466.
[32]	SCHARTNER E P, JIN D Y, EBENDORFF-HEIDEPRIEM H, et al.Lanthanide upconversion within microstructured optical fibers: improved detection limits for sensing and the demonstration of a new tool for nanocrystal characterization.Nanoscale, 2012, 4(23): 7448-7451.
[33]	SCHARTNER E P, JIN D, EBENDORFF-HEIDEPRIEM H, et al.Lanthanide upconversion nanocrystals within microstructured optical fibres; a sensitive platform for biosensing and a new tool for nanocrystal characterisation. Third Asia Pacific Optical Sensors Conference, 2012, 8351.
[34]	SCHARTNER E P, JIN D Y, ZHAO J B, et al.Sensitive Detection of NaYF4: Yb/Tm Nanoparticles Using Suspended Core Microstructured Optical Fibers. Colloidal Nanocrystals for Biomedical Applications Viii, 2013: 8595.
[35]	RODRIGUEZ-SEVILLA P, RODRIGUEZ-RODRIGUEZ H, PEDRONI M, et al.Assessing single upconverting nanoparticle luminescence by optical tweezers.Nano Lett. , 2015, 15(8): 5068-5074.
[36]	RODRIGUEZ-SEVILLA P, LABRADOR-PAEZ L, WAWRZYN CZYK D, et al.Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy.Nanoscale, 2015, 8(1): 300-308.
[37]	DICKSON R M, CUBITT A B, TSIEN R Y, et al.On/off blinking and switching behaviour of single molecules of green fluorescent protein.Nature, 1997, 388(6640): 355-358.
[38]	NIRMAL M, DABBOUSI B, BAWENDI M, et al.Fluorescence intermittency in single cadmium selenide nanocrystals.Nature, 1996, 383(6603): 802-804.
[39]	GALLAND C, GHOSH Y, STEINBRUCK A, et al.Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots.Nature, 2011, 479(7372): 203-207.
[40]	BARNES M, MEHTA A, THUNDAT T, et al.On-off blinking and multiple bright states of single europium ions in Eu3+: Y2O3 nanocrystals.J. Phys. Chem. B, 2000, 104(26): 6099-6102.
[41]	MIALON G, TURKCAN S, DANTELLE G, et al.High up-conversion efficiency of YVO4: Yb, Er nanoparticles in water down to the single-particle level.J. Phys. Chem. C, 2010, 114(51): 22449-22454.
[42]	ZHANG F, SHI Q, ZHANG Y, et al.Fluorescence upconversion microbarcodes for multiplexed biological detection: nucleic acid encoding.Adv. Mater., 2011, 23(33): 3775-3779.
[43]	LI X, WANG R, ZHANG F, et al.Engineering homogeneous doping in single nanoparticle to enhance upconversion efficiency.Nano Lett., 2014, 14(6): 3634-3639.
[44]	ZHAO J, JIN D, SCHARTNER E P, et al.Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence.Nat. Nanotechnol., 2013, 8(10): 729-734.
[45]	ZHANG H, LI Y, LIN Y, et al.Composition tuning the upconversion emission in NaYF4: Yb/Tm hexaplate nanocrystals.Nanoscale, 2011, 3(3): 963-966.
[46]	YIN A X, ZHANG Y W, SUN L D, et al.Colloidal synthesis and blue based multicolor upconversion emissions of size and composition controlled monodisperse hexagonal NaYF4 : Yb, Tm nanocrystals.Nanoscale, 2010, 2(6): 953-959.
[47]	MAHALINGAM V, VETRONE F, NACCACHE R, et al.Colloidal Tm3+/Yb3+-doped LiYF4 nanocrystals: multiple luminescence spanning the UV to NIR regions via low-energy excitation.Adv. Mater., 2009, 21(40): 4025-4028.
[48]	KR MER K W, BINER D, FREI G, et al. Hexagonal sodium yttrium fluoride based green and blue emitting upconversion phosphors.Chemistry of Materials, 2004, 16(7): 1244-1251.
[49]	LIANG L, WU H, HU H, et al.Enhanced blue and green upconversion in hydrothermally synthesized hexagonal NaY1-xYbxF4: Ln3+(Ln3+=Er3+ or Tm3+).J. Alloys Compd., 2004, 368(1): 94-100.
[50]	ZHANG Y H, ZHANG L X, DENG R R, et al.Multicolor barcoding in a single upconversion crystal.J. Am. Chem. Soc., 2014, 136(13): 4893-4896.
[51]	GLASS A M, LIAO P F, BERGMAN J G, et al.Interaction of metal particles with adsorbed dye molecules: absorption and luminescence.Opt. Lett., 1980, 5(9): 368-370.
[52]	LAKOWICZ J R.Radiative decay engineering: biophysical and biomedical applications.Anal. Biochem., 2001, 298(1): 1-24.
[53]	DULKEITH E, MORTEANI A C, NIEDEREICHHOLZ T, et al.Fluorescence quenching of dye molecules near gold nanoparticles: radiative and nonradiative effects.Phys. Rev. Lett., 2002, 89(20): 203002.
[54]	SABOKTAKIN M, YE X, OH S J, et al.Metal-enhanced upconversion luminescence tunable through metal nanoparticle-nanophosphor separation.ACS Nano, 2012, 6(10): 8758-8766.
[55]	MAUSER N, PIATKOWSKI D, MANCABELLI T, et al.Tip-enhancement of up-conversion photoluminescence from rare- earth ion doped nanocrystals.ACS Nano, 2015, 9(4): 3617-3626.