[1] [1] X. D. Zhang, Z. Luo, J. Chen, X. Shen, S. Song, Y. Sun, S. Fan, F. Fan, D. T. Leong, J. Xie, "Ultrasmall Au1012(SG)1012 nanomolecules for high tumor specificity and cancer radiotherapy," Adv. Mater. 26, 4565–4568 (2014).

[2] [2] S. Wang, X. Meng, A. Das, T. Li, Y. Song, T. Cao, X. Zhu, M. Zhu, R. Jin, "A 200-fold quantum yield boost in the photoluminescence of silver-doped AgxAu25x nanoclusters: The 13th silver atom matters," Angew.Chem. Int. Ed. 53, 2376–2380 (2014).

[3] [3] Z. Gan, Y. Lin, L. Luo, G. Han, W. Liu, Z. Liu, C. Yao, L. Weng, L. Liao, J. Chen, "Fluorescent gold nanoclusters with interlocked staples and a fully thiolate-bound kernel," Angew. Chem. Int. Ed. 128, 11739–11743 (2016).

[4] [4] X.-D. Zhang, D. Wu, X. Shen, P.-X. Liu, F.-Y. Fan, S.-J. Fan, "In vivo renal clearance, biodistribution, toxicity of gold nanoclusters," Biomaterials 33, 4628–4638 (2012).

[5] [5] H. Wang, X. Mu, H. He, X.-D. Zhang, "Cancer radiosensitizers," Trends Pharmacol. Sci. 39, 24–48 (2018).

[6] [6] H. Wang, X. Mu, J. Yang, Y. Liang, X.-D. Zhang, D. Ming, "Brain imaging with near-infrared fluorophores," Coordin. Chem. Rev. 380, 550–571 (2019).

[7] [7] H. Haberland, Across the periodic table, Clusters of Atoms and Molecules:Theory, Experiment, and Clusters of Atoms, pp. 314–315, Springer-Verlag (1995).

[8] [8] R. Jin, C. Zeng, M. Zhou, Y. Chen, "Atomically precise colloidal metal nanoclusters and nanoparticles: Fundamentals and opportunities," Chem. Rev. 116, 10346 (2016).

[9] [9] L. Qi, T. Y. Luo, M. G. Taylor, S. Wang, X. Zhu, Y. Song, G. Mpourmpakis, N. L. Rosi, R. Jin, "Molecular "surgery" on a 23-gold-atom nanoparticle," Sci. Adv. 3, 1603193 (2017).

[10] [10] Q. Yao, X. Yuan, T. Chen, D. T. Leong, J. Xie, "Engineering functional metal materials at the atomic level," Adv. Mater. 30, 1802751 (2018).

[11] [11] H. Liu, G. Hong, Z. Luo, J. Chen, J. Chang, M. Gong, H. He, J. Yang, X. Yuan, L. Li, X. Mu, J. Wang, W. Mi, J. Luo, J. Xie, X.-D. Zhang, "Atomic-precision gold clusters for NIR-II imaging," Adv. Mater. 31, 1901015 (2019).

[12] [12] Z. K. Wu, R. C. Jin, "On the ligand's role in the fluorescence of gold nanoclusters," Nano Lett. 10, 2568–2573 (2010).

[13] [13] I. K. Robinson, "X-ray structure determination of the reconstructed Au(110) surface," Acta Crystallogr. Sec. A 40, C194–C194 (1984).

[14] [14] S. Kenzler, C. Schrenk, A. Schnepf, "Au108S24 (PPh3)16: A highly symmetric nanoscale gold cluster confirms the general concept of metalloid clusters," Angew. Chem. Int. Ed. 56, 393–396 (2017).

[15] [15] K. G. Stamplecoskie, P. V. Kamat, "Size-dependent excited state behavior of glutathione-capped gold clusters and their light-harvesting capacity," J. Am. Chem. Soc. 136, 11093–11099 (2014).

[16] [16] A. Kim, C. Zeng, M. Zhou, R. Jin, "Surface engineering of Au36(SR)24 nanoclusters for photoluminescence enhancement," Part. Part. Sys. Charact. 34, 1600388 (2017).

[17] [17] Y. Yu, S. Y. New, J. Xie, X. Su, Y. N. Tan, "Protein-based fluorescent metal nanoclusters for small molecular drug screening," Chem. Commun. 50, 13805–13808 (2014).

[18] [18] Y. Shichibu, Y. Negishi, H. Tsunoyama, M. Kanehara, T. Teranishi, T. Tsukuda, "Extremely high stability of glutathionate-protected Au25 clusters against core etching," Small 3, 835–839 (2007).

[19] [19] C. A. J. Lin, T. Y. Yang, C. H. Lee, S. H. Huang, R. A. Sperling, M. Zanella, J. K. Li, J. L. Shen, H. H. Wang, H. Yeh, "Synthesis, characterization, and bioconjugation of fluorescent gold nanoclusters toward biological labeling applications," ACS Nano 3, 395 (2009).

[20] [20] Z. Wu, R. Jin, "Stability of the two Au-S binding modes in Au25(SG)18 nanoclusters probed by nmr and optical spectroscopy," ACS Nano 3, 2036–2042 (2009).

[21] [21] I. Chakraborty, T. Udayabhaskararao, T. Pradeep, "High temperature nucleation and growth of glutathione protected
Ag75 clusters," Chem. Commun. 48, 6788–6790 (2012).

[22] [22] M. Bardaji, M. J. Calhorda, P. J. Costa, P. G. Jones, A. Laguna, M. R. Perez, M. D. Villacampa, "Synthesis, structural characterization, and theoretical studies of gold(I) and gold(I)-gold(III) thiolate complexes: Quenching of gold(I) thiolate luminescence," Inorg. Chem. 45, 1059–1068 (2006).

[23] [23] Y. T. Chen, T. Q. Yang, H. F. Pan, Y. F. Yuan, L. Chen, M. W. Liu, K. Zhang, S. J. Zhang, P. Wu, J. H. Xu, "Photoemission mechanism of watersoluble silver nanoclusters: Ligand-to-metal-metal charge transfer vs strong coupling between surface plasmon and emitters," J. Am. Chem. Soc. 136, 1686–1689 (2014).

[24] [24] J. Zheng, P. R. Nicovich, R. M. Dickson, "Highly fluorescent noble-metal quantum dots," Annu. Rev. Phys. Chem. 58, 409–431 (2007).

[25] [25] Z. Luo, X. Yuan, Y. Yu, Q. Zhang, D. T. Leong, J. Y. Lee, J. Xie, "From aggregation-induced emission of Au(I)-thiolate complexes to ultrabright Au(0)@Au(I)-thiolate core-shell nanoclusters," J. Am. Chem. Soc. 134, 16662–16670 (2012).

[26] [26] Z. Wang, Z. Zhu, C. Zhao, Q. Yao, X. Li, H. Liu, F. Du, X. Yuan, J. Xie, "Silver doping induced luminescence enhancement and red shift of gold nanoclusters with aggregation-induced emission," Chem. Asian J. 14, 765–769 (2019).

[27] [27] X. L. Pei, Y. Yang, Z. Lei, S. S. Chang, Z. J. Guan, X. K. Wan, T. B. Wen, Q. M. Wang, "A highly active gold(I)-silver(I) oxo cluster activating sp3 C–H bonds of methyl ketones under mild conditions," J. Am. Chem. Soc. 137, 5520–5525 (2015).

[28] [28] G. Soldan, M. A. Aljuhani, M. S. Bootharaju, L. G. AbdulHalim, M. R. Parida, A. H. Emwas, O. F. Mohammed, O. M. Bakr, "Gold doping of silver nanoclusters: A 26-fold enhancement in the luminescence quantum yield," Angew. Chem. Int. Ed. 55, 5749–5753 (2016).

[29] [29] K.-B. Cai, H.-Y. Huang, L.-Y. Chang, C.-T. Yuan, The Glutathione-Capped Gold Nanoclusters Based on Doping Zinc Ion with Aggregation-Induced Emission Enhancement, p. 6. SPIE Photonics Europe, SPIE (2018).

[30] [30] E. Oh, J. B. Delehanty, L. D. Field, A. J. Makinen, R. Goswami, A. L. Huston, I. L. Medintz, "Synthesis and characterization of pegylated luminescent gold nanoclusters doped with silver and other metals," Chem. Mater. 28, 8676–8688 (2016).

[31] [31] X. Kang, S. Wang, Y. Song, S. Jin, G. Sun, H. Yu, M. Zhu, "Bimetallic Au2Cu6 nanoclusters: Strong luminescence induced by the aggregation of copper (I) complexes with gold(0) species," Angew. Chem. Int. Ed. 55, 3675–3678 (2016).

[32] [32] Y. Sha, J. Chai, C. Tao, R. Bo, Y. Pan, H. Yu, M. Zhu, "Crystal structures of two new gold– copper bimetallic nanoclusters: CuxAu25x (PPh3)10(PhC2H4S)5Cl2t 2 and Cu3Au34(PPh3)13 (tBuPhCH2S)6S3t 2 ," Inorg. Chem. 56, 1771–1774 (2017).

[33] [33] Y. Liu, X. Chai, X. Cai, M. Chen, R. Jin, W. Ding, Y. Zhu, "Central doping of a foreign atom into the silver cluster for catalytic conversion of CO2 toward C-C bond formation," Angew. Chem. Int. Ed. 55, 9775–9779 (2018).

[34] [34] Z. Wang, R. Senanayake, C. M. Aikens, W. M. Chen, C. H. Tung, D. Sun, "Gold-doped silver nanocluster [Au3Ag38(SCH2Ph)24X5]2 (X = Cl or Br)," Nanoscale 8, 18905–18911 (2016).

[35] [35] S. Wang, X. Meng, A. Das, T. Li, Y. Song, T. Cao, X. Zhu, M. Zhu, R. Jin, "A 200-fold quantum yield boost in the photoluminescence of silver-doped AgxAu25x nanoclusters: The 13th silver atom matters," Angew. Chem. Int. Ed. 126, 2408–2412 (2014).

[36] [36] D. R. Kau?man, D. Alfonso, C. Matranga, H. Qian, R. Jin, "A quantum alloy: The ligand-protected Au25xAgx(SR)18 cluster," J. Phys. Chem. C 117, 7914–7923 (2013).

[37] [37] S. A. Patel, M. Cozzuol, J. M. Hales, C. I. Richards, M. Sartin, J. C. Hsiang, T. Vosch, J. W. Perry, R. M. Dickson, "Electron transfer-induced blinking in ag nanodot fluorescence," J. Phys. Chem. C 113, 20264–20270 (2009).

[38] [38] S. H. Cha, J. U. Kim, K. H. Kim, J. C. Lee, "Preparation and photoluminescent properties of gold(i)-alkanethiolate complexes having highly ordered supramolecular structures," Chem. Mater. 19, 6297–6303 (2007).

[39] [39] A. T. R. Williams, S. A. Winfield, J. N. Miller, "Relative fluorescence quantum yields using a computer-controlled luminescence spectrometer," Analyst 108, 1067–1071 (1983).

[40] [40] M. M. Alvarez, J. T. Khoury, T. G. Schaa?, M. N. Shafigullin, I. Vezmar, R. L. Whetten, "Optical absorption spectra of nanocrystal gold molecules," J. Phys. Chem. B 101, 3706–3712 (1997).

[41] [41] W. H. Ding, C. Q. Huang, L. M. Guan, X. H. Liu, Z. X. Luo, W. X. Li, "Water-soluble au-13 clusters protected by binary thiolates: Structural accommodation and the use for chemosensing," Chem. Phys. Lett. 676, 18–24 (2017).

[42] [42] A. Das, C. Liu, H. Y. Byun, K. Nobusada, S. Zhao, N. Rosi, R. C. Jin, "Structure determination of [Au18(SR)14]," Angew. Chem. Int. Ed. 54, 3140– 3144 (2015).

[43] [43] L. Shang, S. J. Dong, G. U. Nienhaus, "Ultra-small fluorescent metal nanoclusters: Synthesis and biological applications," Nano Today 6, 401–418 (2011).

[44] [44] J. Akola, M. Walter, R. L. Whetten, H. H?kkinen, H. Gr€onbeck, "On the structure of thiolate-protected Au25," J. Am. Chem. Soc. 130, 3756–3757 (2008).

[45] [45] A. Tlahuice, I. L. Garzón, "On the structure of the Au18(SR)14 cluster," Phys. Chem. Chem. Phys. 14, 3737 (2012).

[46] [46] D. E. Jiang, S. H. Overbury, S. Dai, "Structure of Au15(SR)13 and its implication for the origin of the nucleus in thiolated gold nanoclusters," J. Am. Chem. Soc. 135, 8786–8789 (2013).

[47] [47] T. Udayabhaskararao, M. S. Bootharaju, T. Pradeep, "Thiolate-protected Ag32 clusters: Mass spectral studies of composition and insights into the Ag-thiolate structure from NMR," Nanoscale 5, 9404–9411 (2013).

[48] [48] S. Malola, H. H?kkinen, "Electronic structure and bonding of icosahedral core–shell gold–silver nanoalloy clusters Au144xAgx(SR)60," J. Phys. Chem. Lett. 2, 2316–2321 (2011).

[49] [49] S. Roy, A. Baral, R. Bhattacharjee, B. Jana, A. Datta, S. Ghosh, A. Banerjee, "Preparation of multi-coloured different sized fluorescent gold clusters from blue to nir, structural analysis of the blue emitting Au-7 cluster, and cell-imaging by the NIR gold cluster," Nanoscale 7, 1912–1920 (2015).

[50] [50] Q. Yao, X. Yuan, V. Fung, Y. Yu, D. T. Leong, D. Jiang, J. Xie, "Understanding seed-mediated growth of gold nanoclusters at molecular level," Nat. Commun. 8, 927 (2017).

[51] [51] Y. Negishi, Y. Takasugi, S. Sato, H. Yao, K. Kimura, T. Tsukuda, "Magic-numbered Au-n clusters protected by glutathione monolayers (n = 18, 21, 25, 28, 32, 39): Isolation and spectroscopic characterization," J. Am. Chem. Soc. 126, 6518–6519 (2004).

[52] [52] E. S. Shibu, M. A. H. Muhammed, T. Tsukuda, T. Pradeep, "Ligand exchange of Au25SG18 leading to functionalized gold clusters: Spectroscopy, kinetics, and luminescence," J. Phys. Chem. C 112, 12168–12176 (2008).

[53] [53] Y. Q. Qiao, Y. Liu, H. X. Liu, Y. H. Li, W. Long, J. Y. Wang, X. Y. Mu, J. Chen, H. L. Liu, X. T. Bai, L. F. Liu, Y. M. Sun, Q. Liu, M. L. Guo, X. D. Zhang, "Fluorescence enhancement of gold nanoclusters via Zn doping for biomedical applications," RSC Adv. 8, 7396–7402 (2018).

[54] [54] W. Zhou, Y. Cao, D. Sui, W. Guan, C. Lu, J. Xie, "Ultrastable bsa-capped gold nanoclusters with a polymer-like shielding layer against reactive oxygen species in living cells," Nanoscale 8, 9614–9620 (2016).

[55] [55] X. Le Guevel, V. Trouillet, C. Spies, K. Li, T. Laaksonen, D. Auerbach, G. Jung, M. Schneider, "High photostability and enhanced fluorescence of gold nanoclusters by silver doping," Nanoscale 4, 7624–7631 (2012).

[56] [56] S. A. Patel, M. Cozzuol, J. M. Hales, C. I. Richards, M. Sartin, J. C. Hsiang, T. Vosch, J. W. Perry, R. M. Dickson, "Electron transfer-induced blinking in ag nanodot fluorescence," J Phys. Chem. C 113, 20264–20270 (2009).

[57] [57] G. W. T. M. J. Frisch, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox, Gaussian 09, Revision D, Gaussian, Inc., Wallingford CT, 2009.

[58] [58] J. Towns, T. Cockerill, M. Dahan, I. Foster, K. Gaither, A. Grimshaw, V. Hazlewood, S. Lathrop, D. Lifka, G. D. Peterson, "Xsede: Accelerating scientific discovery," Comput. Sci. Eng. 16, 62–74 (2014).

[59] [59] J. Xu, M. Yu, C. Peng, P. Carter, J. Tian, X. Ning, Q. Zhou, Q. Tu, G. Zhang, A. Dao, "Dose dependencies and biocompatibility of renal clearable gold nanoparticles: From mice to non-human primates," Angew. Chem. Int.l Ed. 57, 266–271 (2018).

[60] [60] B. Du, X. Jiang, A. Das, Q. Zhou, M. Yu, R. Jin, J. Zheng, "Glomerular barrier behaves as an atomically precise bandpass filter in a sub-nanometre regime," Nat. Nanotechnol. 12, 1096–1102 (2017).

[61] [61] X. D. Zhang, J. Chen, Z. T. Luo, D. Wu, X. Shen, S. S. Song, Y. M. Sun, P. X. Liu, J. Zhao, S. D. Huo, S. J. Fan, F. Y. Fan, X. J. Liang, J. P. Xie, "Enhanced tumor accumulation of sub-2 nm gold nanoclusters for cancer radiation therapy," Adv. Healthcare Mater. 3, 133–141 (2014).

[62] [62] Q. Liu, B. D. Guo, Z. Y. Rao, B. H. Zhang, J. R. Gong, "Strong two-photon-induced fluorescence from photostable, biocompatible nitrogen-doped graphene quantum dots for cellular and deep-tissue imaging," Nano Lett. 13, 2436–2441 (2013).

[63] [63] K. G. Stamplecoskie, Y. S. Chen, P. V. Kamat, "Excited-state behavior of luminescent glutathioneprotected gold clusters," J. Phys. Chem. C 118, 1370–1376 (2014).

[64] [64] M. Zhou, J. Zhong, S. Wang, Q. Guo, M. Zhu, Y. Pei, A. Xia, "Ultrafast relaxation dynamics of luminescent rod-shaped, silver-doped AgxAu25x clusters," J. Phys. Chem. C 119, 18790–18797 (2015).

[65] [65] K. Zheng, M. I. Setyawati, T. P. Lim, D. T. Leong, J. Xie, "Antimicrobial cluster bombs: Silver nanoclusters packed with daptomycin," ACS Nano 10, 7934–7942 (2016).

[66] [66] X. Mu, H. He, J. Wang, W. Long, Q. Li, H. Liu, Y. Gao, L. Ouyang, Q. Ren, S. Sun, J. Wang, J. Yang, Q. Liu, Y. Sun, C. Liu, X.-D. Zhang, W. Hu, "Carbogenic nanozyme with ultrahigh reactive nitrogen species selectivity for traumatic brain injury," Nano Lett. 19, 4527–4534 (2019).

[67] [67] X. Mu, J. Wang, Y. Li, F. Xu, W. Long, L. Ouyang, H. Liu, Y. Jing, J. Wang, H. Dai, Q. Liu, Y. Sun, C. Liu, X.-D. Zhang, "Redox trimetallic nanozyme with neutral environment preference for brain injury," ACS Nano 13, 1870–1884 (2019).

[68] [68] R. Yan, S. Sun, J. Yang, W. Long, J. Wang, X. Mu, Q. Li, W. Hao, S. Zhang, H. Liu, Y. Gao, L. Ouyang, J. Chen, S. Liu, X.-D. Zhang, D. Ming, "Nanozymebased bandage with single-atom catalysis for brain trauma," ACS Nano 13, 11552–11560 (2019).