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Developing luminescent noble metal nanodots


Water soluble luminescent noble metal nanodots were achieved only in the past decade

Being few-atom clusters of reduced metal atoms, their photophysical properties approach those of semiconductor quantum dots

These fluorophores offer high luminescence quantum yields, large molar extinctions, and excellent photostability

They have been applied as probes, photoluminescent materials, electroluminescent materials and biolabels

However, they are yet perfect. Crital improvements are required, especially for the biological application


location of silver naodots


Template courtesy of Codify Design Studio




Synthesis and application of luminescent silver nanodot

Silver nanodots have been successfully encapsulated in dendrimers, microgels, and peptides, the single stranded DNA (ssDNA), resulting in water-soluble fluorophores. Many applications have been published as probes, photoluminescent materials, electroluminescent materials and biolabels


Peptides stablized gold nanodots and their applications

The low toxicity of gold species has prompted their wide biological applications. Gold clusters are commonly obtained under the stabilization of a monolayer of small molecules, but many of these show only strong absorption and rarely emission.Large proteins, mercapto and DNA molecules have been observed to assist the generation of luminescent gold clusters (gold nanodots). A comprehensive structure of the luminescent gold clusters (gold nanodots) has not yet been fully obtained. In addition, gold nanodots show significantly lower emission quantum yield (<8%) compared to silver nanodots (20%-60%).We are investigating the difference between the silver and the gold nanodots and trlying to understand the link between the photophysical properties and their structures.

peptide gold

Cellular imaging and libray

Understanding the interactions between silver nanodots and cellular matrices. We have found methods to selectively control the staining of cells with silver nanodots. For example, the 615-emitter silver nanodots showed highly specific staining of nucleoli with an excellent signal-to-background ratio. Binding between silver and sulhydryl group of proteins appeared to be the major factor that enforced the silver staining. We used potassium hexacyanoferrate(III) to block the active sites in the cells and significantly decreased the non-specific staining of cells. Our results indicated that controlling the coordinate binding between luminescent metal complexes and cell matrices might be an efficient way to improve specific staining. In addition, we utilize the cellular matrix as a library to screen specific proteins for nanodot stabilization.

Selective staining

Understanding the reactions on the metal nanoparticles

Addressing the electrostatic interactions between nanoparticles and substrates. Surface charge of nanoparticles became an important factor that determined the reactivity of the gold-nanoparticle-catalyzed transfer hydrogenation when electrostatic repulsion between nanoparticles and reactants occurred. The higher surface charge density of a smaller nanoparticle led to a stronger repulsion from the nanoparticle surface, resulting in a slower approach of reactants to nanoparticles. One examples is about the induction time during borohydride reduction catalyzed on metal nanoparticle surface. Negatively charged nanoparticles prevented the approach of borohydride anions, leading to the widely reported induction time. However, the aged borohydride showed no induction time when reducing 4-nitrophenol in the presence of metal nanoparticles. Neutral borane intermediates from the spontaneous hydrolysis of borohydride were detected and believed to react with nanoparticles instantly upon contact. Consequently, the parameters determining the spontaneous hydrolysis of borohydride, such as the pH of the solution, affected the induction time.

two photon

Principal investigator

Junhua Yu
Associate Professor

Department of Chemistry Education
Seoul National University
1 Gwanak-Ro, Gwanak-Gu
Seoul 08826 South Korea
Tel: +82-2-880-9159
Fax: +82-2-889-0749
Email: junhua@snu.ac.kr

Office: 12-518
Lab: 12-103

Click here for a CV in pdf format

Group members

group image

Research Associate

Dr. Sungmoon Choi

Graduate Students

Seong Mi Jeon

Min-Young Lim

Yanlu Zhao

Yonghyeon Park



Former Students

Kwahun Lee (Indiana University Bloomington)

Soonyoung Park (Ministry of Food and Drug Safety, 식품의약품안전처)

Yujin Jeong (High school teacher)

Sun-Ah Yang



  1. 1. Seon Mi Jeon, Sungmon Choi, Kwahun Lee, Kak-Sung Jung and Junhua Yu, Significantly improved stability of silver nanodots via nanoparticles encapsulation Journal of Photochemistry & Photobiology, A: Chemistry, 2017, in press, DOI: 10.1016/j.jphotochem.2017.05.045.

  2. 2. Sungmoon Choi, Yujin Jeong and Junhua Yu, Temperature and Viscosity Dependence of Gold Nanodot Luminescence European Journal of Inorganic Chemistry, 2017, 2017, 4696-4701. Front Cover Story. Cover Profile..

  3. Sungmoon Choi and Junhua Yu, Recent development in deciphering the structure of luminescent silver nanodots APL Materials, 2017, 5, 053401.

  4. Sungmoon Choi and Junhua Yu, Understanding Interactions between Cellular Matrices and Metal Complexes: Methods To Improve Silver Nanodot-Specific Staining Chemistry - A European Journal, 2016, 22, 12660 – 12664.

  5. Sungmoon Choi, Yujin Jeong and Junhua Yu, Tuning the hydride reductions catalyzed on metal nanoparticle surfaces. RSC Advances, 2016, 6, 73805.

  6. Sungmoon Choi, Yujin Jeong, Junhua Yu, Spontaneous hydrolysis of borohydride required before its catalytic activation by metal nanoparticles. Catalysis Communications, 2016, 84, 80-84.

  7. Sungmoon Choi, Soonyoung Park and Junhua Yu, Selective self-assembly of adeninesilver nanoparticles forms rings resembling the size of cells. Scientific Reports, 2015, 5, 17805.

  8. Sungmoon Choi, Soonyoung Park and Junhua Yu, Ligand-assisted etching: the stability of silver nanoparticles and the generation of luminescent silver nanodots. Chemical Communications, 2014, 50, 15098-15100.

  9. Junhua Yu, From coinage metal to luminescent nanodots: the impact of size on silver’s optical properties. Journal of Chemical Education, 2014, 91, 701−704.

  10. Soonyoung Park, Sungmoon Choi and Junhua Yu, DNA-encapsulated silver nanodots as ratiometric luminescent probes for hypochlorite detection. Nanoscale Research Letters, 2014, 9, 129.

  11. Yanbo Yang, Zhiyi Yao, Baiyang Tang, Junhua Yu, Xiaolin Bi, Yuliang Zhao and Hai-Chen Wu, Visual detection of Cu(II) ions based on a simple pyrene derivative using click chemistry. Analytical Methods, 2014, 6, 4977-4981.

  12. Sungmoon Choi, Soonyoung Park, Kwahun Lee and Junhua Yu, Oxidant-Resistant Imaging and Ratiometric Luminescence Detection by Selective Oxidation of Silver Nanodots. Chemical Communications, 2013, 49, 10908-10810. Featured as ChemComm front cover story

  13. Zhiyi Yao, Xianping Hu, Wenjuan Ma, Xueliang Chen, Li Zhang, Junhua Yu, Yuliang Zhaoa and Hai-Chen Wu, Colorimetric and fluorescent dual detection of paraquat and diquat based on an anionic polythiophene derivative. Analyst, 2013, 138, 5572-5575.

  14. Kwahun Lee, Sungmoon Choi, Chun Yang,Hai-Chen Wu and Junhua Yu, Autofluorescence generation and elimination: a lesson from glutaraldehyde. Chemical Communications, 2013, 49, 3028-3030.

  15. Sungmoon Choi, Robert M. Dickson and Junhua Yu, Developing luminescent silver nanodots for biological applications. Chemical Society Reviews, 2012, 41, 1867–1891. This article was selected as (Hot Article)

  16. Sungmoon Choi, Joon-Kyu Lee, Robert M. Dickson and Junhua Yu, Generation of luminescent noble metal nanodots in cell matrices. Photochemical &  Photobiological Sciences, 2012, 11, 274 - 278.

  17. Sungmoon Choi, Junhua Yu, Sandeep A. Patel, Yih-Ling Tzeng and Robert M. Dickson. Tailoring silver nanodots for intracellular staining. Photochemical & Photobiological Sciences, 2011, 10, 109-115.

  18. Chris I. Richards, Jung-Cheng Hsiang, Dulal Senapati, Sandeep Patel, Junhua Yu, Tom Vosch, and Robert M. Dickson. Optically Modulated Fluorophores for Selective Fluorescence Signal Recovery. Journal of the American Chemical Society, 2009, 131, 4619-4621.

  19. Junhua Yu, Sungmoon Choi and Robert M. Dickson, Shuttle-Based Fluorogenic Silver-Cluster Biolabels. Angewandte Chemie International Edition, 2009, 48, 318-32.

  20.  Junhua Yu, Sungmoon Choi, Chris I. Richards, Yasuko Antoku and Robert M. Dickson, Live Cell Surface Labeling with Fluorescent Ag Nanocluster Conjugates. Photochemistry and Photobiology, 2008, 84, 1435-1439.

  21. Dongwon Lee, Venkata R Erigala, Madhuri Dasari, Junhua Yu, Robert M Dickson, Niren Murthy, Detection of hydrogen peroxide with chemiluminescent micelles. International Journal of Nanomedicine, 2008, 3, 471-476.

  22. Junhua Yu, Sandeep A. Patel and Robert M. Dickson, In Vitro and Intracellular Production of Peptide-Encapsulated Fluorescent Silver Nanoclusters. Angewandte Chemie International Edition, 2007, 46, 2028. (HOT PAPER)

  23. Shashi Pandya, Junhua Yu and David Parker, Engineering Emissive Europium and Terbium Complexes for Molecular Imaging and Sensing. Dalton Transactions, 2006, 2757-2766.
  24. Junhua Yu, David Parker, Robert Pal, Robert A. Poole and Martin J. Cann, A Europium Complex That Selectively Stains Nucleoli of Cells. Journal of the American Chemical Society, 2006, 128, 2294-2299.

  25. Paul Atkinson, Karen S. Findlay, Filip Kielar, Robert Pal, David Parker, Robert A. Poole, Horst Puschmann, Siobhan L. Richardson, Philip A. Stenson, Amber L. Thompson and Junhua Yu, Azaxanthones and Azathioxanthones Are Effective Sensitisers for Europium and Terbium Luminescence. Organic and Biomolecular Chemistry, 2006, 4, 1707-1722.

  26. Huiying Ding, Xuesong Wang, Linqing Song, Jingrong Chen, Junhua Yu, Chao Li and Baowen Zhang, Aryl-Modified Ruthenium bis(Terpyridine) Complexes: Quantum Yield of 1O2 Generation and Photocleavage on DNA. Journal of Photochemistry and Photobiology A: Chemistry, 2006, 177, 286-294.

  27. Fuyou Li, Junhua Yu, Baowen Zhang, Chunhui Huang, Study on Photocurrent Generation of Tthree Porphyrin Monolayer Modified Electrodes with Various Side Chain Lengths. Huaxue Xuebao, 2006, 64, 301-305.

  28. Junhua Yu and David Parker, Synthesis of a Europium Complex for Anion-Sensing Involving Regioselective Substitution of Cyclen. European Journal of Organic Chemistry, 2005, 4249-4252.

  29. David Parker and Junhua Yu, A pH-Insensitive Ratiometric Chemosensor for Citrate Using Europium Luminescence. Chemical Communications, 2005, 3141-3143.

  30. Junhua Yu, Jingrong Chen, Chao Li, Xuesong Wang, Baowen Zhang, and Huiying Ding, ESR Signal of Superoxide Radical Anion Adsorbed on TiO2 Generated at Room Temperature. Journal of Physical Chemistry B, 2004, 108, 2781-2783.

  31. Junhua Yu, Xuesong Wang, Baowen Zhang, Yuyiang Weng, and Lei Zhang, Prolonged Excited-State Lifetime of Porphyrin Due to the Addition of Colloidal SiO2 to Triton X-100 Micelles. Langmuir, 2004, 20, 1582-1586.

  32. Junhua Yu, Xuesong Wang, Baowen Zhang, Yuyiang Weng, and Yi Cao, Amphiphilic Porphyrins in Reverse Micelles: the Influence of the Molar Ratio of Water to Surfactant and Side-Chain Length on Their Triplet-State Lifetimes. A Case Study. Physical Chemistry Chemical Physics, 2003, 5, 3660-3665.

  33. Junhua Yu, Jingrong Chen, Xuesong Wang, Baowen Zhang, and Yi Cao, Porphyrin capped TiO2 nanocluster, tyrosine methyl ester enhanced electron transfer. Chemical Communications, 2003, (15), 1856-1857.

  34. Jun Hua Yu, Yu Xiang Weng, Xue Song Wang, Lei Zhang, Bao Wen Zhang, and Yi Cao, The triplet-excited-state changes of amphiphilic porphyrins with different side-chain length in AOT reverse micelles. Journal of Photochemistry and Photobiology A: Chemistry, 2003, 156, 139-144.

  35. Jun Hua Yu, Yu Xiang Weng, Xue Song Wang, Lei Zhang, Bao Wen Zhang, and Yi Cao, Porphyrins in reverse micelles: the side-chain length and the triplet-state lifetime. Chinese Chemical Letters, 2003, 14, 844-847.

  36. Lin-qing Song, Xue-song Wang, Pu-hui Xie, Jun-hua Yu, Bao-wen Zhang        Juan Feng, Jun-feng Xiang, Xi-cheng Ai, and Jian-ping Zhang, Dual emissions from 3MLCT and 3ILCT excited states in a new Ru(II) diimine complex. Inorganic Chemistry, 2003, 42, 3393-3395.

  37. Yuxiang Weng, Lei Zhang, Jian Yang, Donghui Quan, Li Wang, Guozhen Yang, Ritssuko Fujii, Yasushi Koyama, Jianping Zhang, Juan Feng, Junhua Yu, and Baowen Zhang, Distance-dependent long-range electron transfer in proteins: a case study of photosynthetic bacterial light-harvesting antenna complex LH2 assembled on TiO2 nanoparticle. Acta Botanica Sinica, 2003, 45, 488-493.

  38. Jun-Hua Yu, Fu-You Li, Xue-Song Wang, Yanyi Huang, Bao-Wen Zhang, Chun-Hui Huang, and Yi Cao, Chain-length dependence of photoelectric conversion from a porphyrin monolayer modified electrode. Optical Materials, 2002, 21, 467-473.

  39. Jun Hua Yu, Xue Song Wang, Bao Wen Zhang, and Cao Yi, Absorption complex between porphyrin and phenothiazine in reverse micelles. Chinese Chemical Letters, 2002, 13, 1007-1010.

  40. Tingli Ma, Kozo Inoue, Ken Yao, Kiroaki Noma, Tsunematsu Shuji, Eiichi Abe, Junhua Yu, Xuesong Wang, and Baowen Zhang, Photoelectrochemical properties of TiO2 electrodes sensitized by porphyrin derivatives with different numbers of carboxyl groups. Journal of Electroanalytical Chemistry, 2002, 537, 31-38.

  41. Shrong-Shi Lin, Xiaoping Nie, Junhua Yu, and Xiulin Ye, Regiosselective Friedel-Crafts Acylation with Unsymmetrically Substituted Furandicarboxylic Acid Anhydride and Furan Acid Chloride. Heterocycles, 2001, 55, 265-277.

  42. Shrong-Shi Lin, Junhua Yu, Jianmei Wang, Bo Yang, and Xiulin Ye, The Synthesis of 4-Arylcarbonyl-3-methoxycarbonyl-2-phenylfurans by Friedel-Crafts Acylation Reactions. Chinese Chemical Letters, 2000, 11, 11-14.