title: Optimization of optical excitation of upconversion nanoparticles for rapid microscopy and deeper tissue imaging with higher quantum yield.
abstract: Relatively low quantum yield (QY), time-consuming scanning and strong absorption of light in tissue are some of the issues present in the development of upconversion nanoparticles (UCNPs) for biomedical applications. In this paper we systematically optimize several aspects of optical excitation of UCNPs to improve their applicability in bioimaging and biotherapy. A novel multi-photon evanescent wave (EW) excitation modality is proposed for UCNP-based microscopy. The scanning-free, ultrahigh contrast and high spatiotemporal resolution method could simultaneously track a few particles in a large area with a speed of ³⁺up to 350 frames per second. The HeLa cancer cell membrane imaging was successfully performed using NaYF₄: 20% Yb³⁺/2Er³⁺ targeting nanoparticles. Studies with different tissues were made to illustrate the impact of optical property parameters on the deep imaging ability of 920-nm band excitation. In the experiments a semiconductor laser with a 920 nm wavelength was used to excite UCNPs in tissue phantom at five depths. Our experimental and computational results have shown that in UCNP-based diffusion optical imaging with 920-nm laser excitation could lead to larger imaging depth range compared to traditional 974-nm excitation in a wide dynamic range of tissue species. As the QY is power density dependent, a pulsed laser is proposed to improve the QY of UCNPs. This proposal is promising in drastically increasing the imaging depth and efficiency of photodynamic therapy.
authors: ZJU-SCNU Joint Research Center of Photonics, Centre for Optical and Electromagnetic Research, South China Academy of Advanced Optoelectronics, South China Normal University-SCNU, 510006 Guangzhou, P. R. China.
authors: Qiuqiang
authors: Q
authors: Zhan
authors: Sailing
authors: S
authors: He
authors: Jun
authors: J
authors: Qian
authors: Hao
authors: H
authors: Cheng
authors: Fuhong
authors: F
authors: Cai
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D003952:Diagnostic Imaging / Q000379:methods*; D006367:HeLa Cells; D006801:Humans; D049449:Luminescence; D008853:Microscopy / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D061848:Optical Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D011789:Quantum Theory; D012996:Solutions
chemical_list: D012996:Solutions
keywords: deep imaging; pulsed excitation; quantum yield.; total internal reflection; upconverting
references: Nat Med. 2012 Oct;18(10):1580-5
references: 22983397
references: J Am Chem Soc. 2008 Mar 12;130(10):3023-9
references: 18278910
references: Phys Med Biol. 2005 Sep 7;50(17):4225-41
references: 16177541
references: Photomed Laser Surg. 2010 Aug;28(4):453-8
references: 19764900
references: ACS Nano. 2012 Apr 24;6(4):2969-77
references: 22401578
references: Lasers Surg Med. 2004;35(1):41-50
references: 15278927
references: Theranostics. 2013 Mar 20;3(4):249-57
references: 23606911
references: Nat Chem Biol. 2007 Feb;3(2):92-8
references: 17235347
references: ACS Nano. 2012 Sep 25;6(9):8280-7
references: 22928629
references: Angew Chem Int Ed Engl. 2012 Mar 26;51(13):3125-9
references: 22241651
references: J Biomed Opt. 2008 Jul-Aug;13(4):041304
references: 19021312
references: ACS Nano. 2011 Apr 26;5(4):3146-57
references: 21384900
references: ACS Nano. 2010 Jun 22;4(6):3163-8
references: 20509664
references: Chem Soc Rev. 2012 Feb 7;41(3):1323-49
references: 22008740
references: Nano Lett. 2007 Mar;7(3):847-52
references: 17302461
references: Biomaterials. 2010 Sep;31(27):7078-85
references: 20619791
references: Proc Natl Acad Sci U S A. 2009 Jul 7;106(27):10917-21
references: 19541601
references: Biomaterials. 2011 Feb;32(4):1148-56
references: 20965563
references: Adv Mater. 2012 Sep 11;24(35):OP236-41
references: 22760855
references: Adv Mater. 2012 Apr 17;24(15):1987-93
references: 22422477
references: J Mater Chem. 2011;21(46):18530-18533
references: 23472047
references: Nat Biotechnol. 2001 Mar;19(3):273-6
references: 11231563
references: Opt Lett. 2010 Mar 1;35(5):718-20
references: 20195330
references: Nano Lett. 2010 Jan;10(1):134-8
references: 20020691
references: ACS Nano. 2011 May 24;5(5):3744-57
references: 21513307
references: ACS Nano. 2012 Jun 26;6(6):4788-95
references: 22568960
references: Nano Lett. 2008 Nov;8(11):3834-8
references: 18928324
references: ACS Nano. 2012 Mar 27;6(3):2686-92
references: 22339653
references: ACS Nano. 2011 Jun 28;5(6):4981-6
references: 21557587
references: ACS Nano. 2010 Jun 22;4(6):3254-8
references: 20441184
references: J Biomed Opt. 2012 Jul;17(7):076003
references: 22894486
references: Acc Chem Res. 2013 Jul 16;46(7):1474-86
references: 23339661
references: Small. 2009 Oct;5(20):2285-90
references: 19598161
references: Nanoscale. 2010 Aug;2(8):1417-9
references: 20820726