Nanomedicine: Nanotechnology, Biology, and Medicine xx (2011) xxx – xxx www.nanomedjournal.com
Upconversion nanoparticles: synthesis, surface modification and biological applications Meng Wang, PhDa,c , Gopal Abbineni, MSb , April Clevenger, MSb , Chuanbin Mao, PhDb , Shukun Xu, MSa,⁎ a College of Sciences, Northeastern University, Shenyang, People's Republic of China Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA c Shenyang National Laboratory for Materials Sciences, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, People's Republic of China Received 14 November 2010; accepted 19 February 2011 b
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. © 2011 Elsevier Inc. All rights reserved. Key words: Upconversion; Rare earth; Luminescent materials; Nanomaterials; Biological detection
Recent advancements in science have allowed a greater availability of enhanced sensitive analytical techniques, in particular, advanced tools for fluorescence imaging.1 The last decade's research has provided a tremendous awareness regarding the use of fluorescent labeled molecules for cell and tissue labeling.2 Despite the remarkable applicability of fluorescent dyes in imaging, their current use in visualizing mammalian cells is still greatly limited by the autoflourescence resulting from the excitation of fluorescent dyes. Thus, to meet
We are grateful for the support from the National Science Foundation of China (Grant No. 20875011) and the Education Committee of Liaoning Province of China. C.-B. M. would also like to thank the financial support from US National Institutes of Health (R21EB009909-01A1, R03AR056848-01, R01HL092526-01A2), National Science Foundation (DMR-0847758, CBET-0854414, CBET-0854465), Department of Defense Breast Cancer Research Program (W81XWH07-1-0572), and Oklahoma Center for the Advancement of Science and Technology (HR06-161S). ⁎Corresponding authors: Shukun Xu is to be contacted at College of Sciences, Northeastern University, Shenyang 110819, P.R. China. Chuanbin Mao, Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA. E-mail address: firstname.lastname@example.org (S. Xu). 1549-9634/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.nano.2011.02.013
the demands of modern technology, the development of next generation fluorescence probes is essential.3 Recent progress in nanoscience has enabled scientists to develop new fluorescent nanoparticles (NPs) for biolabeling. These fluorescent labels are conjugated with biomolecules to generate detectable fluorescent signals used for investigating and understanding the complexity and dynamics of biological interactions at the molecular level.4 In general, an ideal fluorescent probe should be ultrasensitive, resistant to photobleaching, biocompatible and nontoxic. Additionally, it should possess high fluorescent efficiency and superior chemical and physical stability.3,5 In the last decade, organic dyes and fluorescent proteins have been the...