There is still a need for synthetic approaches that are much faster, easier to scale up, more robust and efficient for generating gold(I)-thiolates that can be easily converted into gold-thiolate nanoclusters. Mechanochemical methods can offer significantly reduced reaction times, increased yields and straightforward recovery of the product, compared to the solution-based reactions. For the first time, a new simple, rapid and efficient mechanochemical redox method in a ball-mill was developed to produce the highly luminescent, pH-responsive Au(I)-glutathionate, [Au(SG)]n. The efficient productivity of the mechanochemical redox reaction afforded orange luminescent [Au(SG)]n in isolable amounts (mg scale), usually not achieved by more conventional methods in solution. Then, ultrasmall oligomeric Au10-12(SG)10-12 nanoclusters were prepared by pH-triggered dissociation of [Au(SG)]n. The pH-stimulated dissociation of the Au(I)-glutathionate complex provides a time-efficient synthesis of oligomeric Au10-12(SG)10-12 nanoclusters, it avoids high-temperature heating or the addition of harmful reducing agent (e.g., carbon monoxide). Therefore, we present herein a new and eco-friendly methodology to access oligomeric glutathione-based gold nanoclusters, already finding applications in biomedical field as efficient radiosensitizers in cancer radiotherapy.

Centre for Structure Study Research Centre for Natural Sciences Budapest Hungary

High Performance Materials and Coatings for Industry Research Group Central European Institute of Technology Brno University of Technology Brno Czechia

ICGM Univ Montpellier CNRS ENSCM Montpellier France

Renewable Energy Research Group Institute of Materials and Environmental Chemistry Research Centre for Natural Sciences Budapest Hungary

Supramolecular Chemistry Research Group Institute of Materials and Environmental Chemistry Research Centre for Natural Sciences Budapest Hungary

See more in PubMed

Ardila-Fierro K. J., Hernández J. G. (2021). Sustainability assessment of mechanochemistry by using the twelve principles of green chemistry. ChemSusChem 14, 2145–2162. 10.1002/cssc.202100478 PubMed DOI

Baier D. M., Rensch T., Dobreva D., Spula C., Fanenstich S., Rappen M., et al. (2022). The mechanochemical beckmann rearrangement over solid acids: From the ball mill to the extruder. Chemistry–Methods 3. 10.1002/cmtd.202200058 DOI

Baranyai P., Marsi G., Jobbágy C., Domján A., Oláh L., Deák A. (2015). Mechano-induced reversible colour and luminescence switching of a gold(I)-diphosphine complex. Dalton Trans. 44 (30), 13455–13459. 10.1039/c5dt01795e PubMed DOI

Bau R. (1998). Crystal structure of the antiarthritic drug gold thiomalate (myochrysine): A double-helical geometry in the solid state. J. Am. Chem. Soc. 120, 9380–9381. 10.1021/ja9819763 DOI

Bera A., Busupalli B., Prasad B. L. V. (2018). Solvent-less solid state synthesis of dispersible metal and semiconducting metal sulfide nanocrystals. ACS Sustainable Chem. Eng. 6 (9), 12006–12016. 10.1021/acssuschemeng.8b02292 DOI

Bertorelle F., Russier-Antoine I., Calin N., Comby-Zerbino C., Bensalah-Ledoux A., Guy S., et al. (2017). Au10(SG)10: A chiral gold catenane nanocluster with zero confined electrons. Optical properties and first-principles theoretical analysis. J. Phys. Chem. Lett. 8 (9), 1979–1985. 10.1021/acs.jpclett.7b00611 PubMed DOI

Bonasia P. J., Gindelberger D. E., Arnold J. (1993). Synthesis and characterization of gold(I) thiolates, selenolates, and tellurolates: X-Ray crystal structures of Au4TeC(SiMea)3]4, Au4[SC(SiMea)3]4, and Ph3PAu[TeC(SiMe3)3]. Inorg. Chem. 32 (23), 5126–5131. 10.1021/ic00075a031 DOI

Briñas R. P., Hu M., Qian L., Lymar E. S., Hainfeld J. F. (2008). Gold nanoparticle size controlled by polymeric Au(I) thiolate precursor size. J. Am. Chem. Soc. 130, 975–982. 10.1021/ja076333e PubMed DOI PMC

Carta M., Colacino E., Delogu F., Porcheddu A. (2020). Kinetics of mechanochemical transformations. Phys. Chem. Chem. Phys. 22, 14489–14502. 10.1039/d0cp01658f PubMed DOI

Chakraborty I., Pradeep T. (2017). Atomically precise clusters of noble metals: Emerging link between atoms and nanoparticles. Chem. Rev. 117 (12), 8208–8271. 10.1021/acs.chemrev.6b00769 PubMed DOI

Chui S. S., Chen R., Che C. M. (2006). A chiral [2]catenane precursor of the antiarthritic gold(I) drug auranofin. Angew. Chem. .Int. Ed. 45, 1621–1624. 10.1002/anie.200503431 PubMed DOI

Colacino E., Carta M., Pia G., Porcheddu A., Ricci P. C., Delogu F. (2018). Processing and investigation methods in mechanochemical kinetics. ACS Omega 3, 9196–9209. 10.1021/acsomega.8b01431 PubMed DOI PMC

Colacino E., Isoni V., Crawford D., Garcia F. (2021). Upscaling mechanochemistry: Challenges and opportunities for sustainable industry. Trends Chem. 3, 335–339. 10.1016/j.trechm.2021.02.008 DOI

Colacino E., Porcheddu A., Charnay C., Delogu F. (2019). From enabling technologies to medicinal mechanochemistry: An eco-friendly access to hydantoin-based active pharmaceutical ingredients. React. Chem. Eng. 4 (7), 1179–1188. 10.1039/c9re00069k DOI

Corbierre M. K., Lennox R. B. (2005). Preparation of thiol-capped gold nanoparticles by chemical reduction of soluble Au(I)−Thiolates. Chem. Mat. 17 (23), 5691–5696. 10.1021/cm051115a DOI

COST Action CA18112 (2019–2023). For more information on COST action CA18112 'mechanochemistry for sustainable industry' (MechSustInd). COST Association. Available at: http://www.mechsustind.eu/and http://www.cost.eu/ .

Crawford D. E., Porcheddu A., McCalmont A. S., Delogu F., James S. L., Colacino E. (2020). Solvent-free, continuous synthesis of hydrazone-based active pharmaceutical ingredients by twin-screw extrusion. ACS Sustainable Chem. Eng. 8 (32), 12230–12238. 10.1021/acssuschemeng.0c03816 DOI

Cuccu F., De Luca L., Delogu F., Colacino E., Solin N., Mocci R., et al. (2022). Mechanochemistry: New tools to navigate the uncharted territory of "impossible" reactions. ChemSusChem 15, e202200362. 10.1002/cssc.202200362 PubMed DOI PMC

Dai C., Yu Y., Xu S., Li M., Zhang S. X. (2019). Self-templated assembly of Au(I)/Ag(I) -thiolate sheets with central holes. Chem. Asian J. 14 (18), 3149–3153. 10.1002/asia.201900981 PubMed DOI

de Oliveira P. F. M., Michalchuk A. A. L., Buzanich A. G., Bienert R., Torresi R. M., Camargo P. H. C., et al. (2020a). Tandem X-ray absorption spectroscopy and scattering for in situ time-resolved monitoring of gold nanoparticle mechanosynthesis. Chem. Commun. 56 (71), 10329–10332. 10.1039/d0cc03862h PubMed DOI

de Oliveira P. F. M., Quiroz J., de Oliveira D. C., Camargo P. H. C. (2019). A mechano-colloidal approach for the controlled synthesis of metal nanoparticles. Chem. Commun. 55 (95), 14267–14270. 10.1039/c9cc06199a PubMed DOI

de Oliveira P. F. M., Torresi R. M., Emmerling F., Camargo P. H. C. (2020b). Challenges and opportunities in the bottom-up mechanochemical synthesis of noble metal nanoparticles. J. Mater. Chem. A 8 (32), 16114–16141. 10.1039/d0ta05183g DOI

Deák A., Jobbágy C., Demeter A., Čelko L., Cihlář J., Szabó P. T., et al. (2021). Mechanochemical synthesis of mononuclear gold(I) halide complexes of diphosphine ligands with tuneable luminescent properties. Dalton Trans. 50 (38), 13337–13344. 10.1039/d1dt01751a PubMed DOI

Deák A., Jobbágy C., Marsi G., Molnár M., Szakács Z., Baranyai P. (2015). Anion-Solvent-Temperature-and mechano-responsive photoluminescence in gold(I) diphosphine-based dimers. Chem. Eur. J. 21 (32), 11495–11508. 10.1002/chem.201501066 PubMed DOI

Deák A. (2019). “Stimuli-responsive nanosized supramolecular gold(I) complexes,” in Nanomaterials design for sensing applications. Editor Zenkina O. V. (Elsevier Inc.), 281–324.

Demeter A. (2014). First steps in photophysics. I. Fluorescence yield and radiative rate coefficient of 9,10-bis(phenylethynyl)anthracene in paraffins. J. Phys. Chem. A 118 (43), 9985–9993. 10.1021/jp507626h PubMed DOI

Do J. L., Tan D., Friščić T. (2018). Oxidative mechanochemistry: Direct, room-temperature, solvent-free conversion of palladium and gold metals into soluble salts and coordination complexes. Angew. Chem. Int. Ed. Engl. 57 (10), 2667–2671. 10.1002/anie.201712602 PubMed DOI

Du B., Jiang X., Das A., Zhou Q., Yu M., Jin R., et al. (2017). Glomerular barrier behaves as an atomically precise bandpass filter in a sub-nanometre regime. Nat. Nanotechnol. 12, 1096–1102. 10.1038/nnano.2017.170 PubMed DOI PMC

Fantozzi N., Volle J.-N., Porcheddu A., Virieux D., Garcia F., Colacino E. (2022). Green metrics in mechanochemistry. ChemRxiv (Cambridge: Cambridge Open Engage; ). Available at: https://chemrxiv.org/engage/chemrxiv/article-details/639f63d9a2da4b43d4088747 . PubMed

Friščić T., Mottillo C., Titi H. M. (2020). Mechanochemistry for synthesis. Angew. Chem. Int. Ed. 59, 1018–1029. 10.1002/anie.201906755 PubMed DOI

Galant O., Cerfeda G., McCalmont A. S., James S. L., Porcheddu A., Delogu F., et al. (2022). Mechanochemistry can reduce life cycle environmental impacts of manufacturing active pharmaceutical ingredients. ACS Sustainable Chem. Eng. 10, 1430–1439. 10.1021/acssuschemeng.1c06434 DOI

Hernández J. G., Halasz I., Crawford D. E., Krupicka M., Baláž M., André V., et al. (2020). European research in focus: Mechanochemistry for sustainable industry (COST action MechSustInd). Eur. J. Org. Chem. 2020 (1), 8–9. 10.1002/ejoc.201901718 DOI

Howard J. L., Cao Q., Browne D. L. (2018). Mechanochemistry as an emerging tool for molecular synthesis: What can it offer? Chem. Sci. 9, 3080–3094. 10.1039/c7sc05371a PubMed DOI PMC

Ingner F. J. L., Giustra Z. X., Novosedlik S., Orthaber A., Gates P. J., Dyrager C., et al. (2020). Mechanochemical synthesis of (hetero)aryl Au(i) complexes. Green Chem. 22 (17), 5648–5655. 10.1039/d0gc02263b DOI

James S. L., Adams C. J., Bolm C., Braga D., Collier P., Friščić T., et al. (2012). Mechanochemistry: Opportunities for new and cleaner synthesis. Chem. Soc. Rev. 41 (1), 413–447. 10.1039/c1cs15171a PubMed DOI

Jin M., Seki T., Ito H. (2017). Mechano-responsive luminescence via crystal-to-crystal phase transitions between chiral and non-chiral space groups. J. Am. Chem. Soc. 139, 7452–7455. 10.1021/jacs.7b04073 PubMed DOI

Jin R., Zhu Y., Qian H. (2011). Quantum-sized gold nanoclusters: Bridging the gap between organometallics and nanocrystals. Chem. Eur. J. 17 (24), 6584–6593. 10.1002/chem.201002390 PubMed DOI

Jobbágy C., Baranyai P., Marsi G., Rácz B., Li L., Naumov P., et al. (2016). Novel gold(I) diphosphine-based dimers with aurophilicity triggered multistimuli light-emitting properties. J. Mater. Chem. C 4 (43), 10253–10264. 10.1039/C6TC01427E DOI

Jobbágy C., Molnár M., Baranyai P., Deák A. (2014). Mechanochemical synthesis of crystalline and amorphous digold(I) helicates exhibiting anion- and phase-switchable luminescence properties. Dalton Trans. 43 (31), 11807–11810. 10.1039/C4DT01214C PubMed DOI

Jobbágy C., Tunyogi T., Pálinkas G., Deák A. (2011). A versatile solvent-free mechanochemical route to the synthesis of heterometallic dicyanoaurate-based coordination polymers. Inorg. Chem. 50 (15), 7301–7308. 10.1021/ic200893n PubMed DOI

Katoh R., Suzuki K., Furube A., Kotani M., Tokumaru K. (2009). Fluorescence quantum yield of aromatic hydrocarbon crystals. J. Phys. Chem. C 113 (7), 2961–2965. 10.1021/jp807684m DOI

Konnert L., Dimassi M., Gonnet L., Lamaty F., Martinez J., Colacino E. (2016). Poly(ethylene) glycols and mechanochemistry for the preparation of bioactive 3,5-disubstituted hydantoins. RSC Adv. 6, 36978–36986. 10.1039/c6ra03222b DOI

Lavenn C., Guillou N., Monge M., Podbevsek D., Ledoux G., Fateeva A., et al. (2016). Shedding light on an ultra-bright photoluminescent lamellar gold thiolate coordination polymer [Au(p-SPhCO2Me)]n. Chem. Commun. 52, 9063–9066. 10.1039/c5cc10448c PubMed DOI

Lavenn C., Okhrimenko L., Guillou N., Monge M., Ledoux G., Dujardin C., et al. (2015). A luminescent double helical gold(i)–thiophenolate coordination polymer obtained by hydrothermal synthesis or by thermal solid-state amorphous-to-crystalline isomerization. J. Mater. Chem. C 3, 4115–4125. 10.1039/c5tc00119f DOI

Luo Z., Yuan X., Yu Y., Zhang Q., Leong D. T., Lee J. Y., et al. (2012). 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. 10.1021/ja306199p PubMed DOI

Martina K., Rotolo L., Porcheddu A., Delogu F., Bysouth S. R., Cravotto G., et al. (2018). High throughput mechanochemistry: Application to parallel synthesis of benzoxazines. Chem. Comm. 54, 551–554. 10.1039/c7cc07758k PubMed DOI

Mocci R., Colacino E., Luca L. D., Fattuoni C., Porcheddu A., Delogu F. (2021). The mechanochemical beckmann rearrangement: An eco-efficient “cut-and-paste” strategy to design the “good old amide bond”. ACS Sustainable Chem. Eng. 9, 2100–2114. 10.1021/acssuschemeng.0c07254 DOI

Mulas G., Delogu F., Enzo S., Schiffini L., Cocco G. (2010). A phenomenological approach to mechanically activated processes.

Negishi Y., Nobusada K., Tsukuda T. (2005). Glutathione-protected gold clusters revisited: Bridging the gap between gold(I)-thiolate complexes and thiolate-protected gold nanocrystals. J. Am. Chem. Soc. 127 (14), 5261–5270. 10.1021/ja042218h PubMed DOI

Negishi Y., Takasugi Y., Sato S., Yao H., Kimura K., Tsukuda T. (2004). Magic-numbered Aun clusters protected by glutathione monolayers (n = 18, 21, 25, 28, 32, 39): Isolation and spectroscopic characterization. J. Am. Chem. Soc. 126 (21), 6518–6519. 10.1021/ja0483589 PubMed DOI

Nie H., Li M., Hao Y., Wang X., Gao S., Wang P., et al. (2014). Morphology modulation and application of Au(I)–thiolate nanostructures. RSC Adv. 4 (92), 50521–50528. 10.1039/c4ra06500j DOI

Nie H., Li M. J., Hao Y. J., Wang X. D., Zhang S. X. A. (2013). Time-resolved monitoring of dynamic self-assembly of Au(I)-thiolate coordination polymers. Chem. Sci. 4 (4), 1852–1857. 10.1039/c3sc22215b DOI

Odriozola I., Loinaz I., Pomposo J. A., Grande H. J. (2007). Gold-glutathione supramolecular hydrogels. J. Mater. Chem. 17 (46), 4843–4845. 10.1039/b713542d DOI

Pérez-Venegas M., Juaristi E. (2020). Mechanochemical and mechanoenzymatic synthesis of pharmacologically active compounds: A green perspective. ACS Sustainable Chem. Eng. 8, 8881–8893. 10.1021/acssuschemeng.0c01645 DOI

Porcheddu A., Colacino E., De Luca L., Delogu F. (2020). Metal-Mediated and metal-catalyzed reactions under mechanochemical conditions. ACS Catal. 10, 8344–8394. 10.1021/acscatal.0c00142 DOI

Rak M. J., Friscic T., Moores A. (2014). Mechanochemical synthesis of Au, Pd, Ru and Re nanoparticles with lignin as a bio-based reducing agent and stabilizing matrix. Faraday Discuss. 170, 155–167. 10.1039/c4fd00053f PubMed DOI

Rao T. U., Nataraju B., Pradeep T. (2010). Ag9 quantum cluster through a solid-state route. J. Am. Chem. Soc. 132 (46), 16304–16307. 10.1021/ja105495n PubMed DOI

Schaaff T. G., Knight G., Shafigullin M. N., Borkman R. F., Whetten R. L. (1998). Isolation and selected properties of a 10.4 kDa gold: Glutathione cluster compound. J. Phys. Chem. B 102, 10643–10646. 10.1021/jp9830528 DOI

Schröter I., Strähle J. (2006). Thiolatokomplexe des einwertigen Golds. Synthese und Struktur von [(2,4,6-iPr3C6H2S)Au]6 und (NH4)[(2,4,6-iPr3C6H2S)2Au]. Chem. Ber. 124, 2161–2164. 10.1002/cber.19911241003 DOI

Seki T., Ozaki T., Okura T., Asakura K., Sakon A., Uekusa H., et al. (2015). Interconvertible multiple photoluminescence color of a gold(I) isocyanide complex in the solid state: Solvent-induced blue-shifted and mechano-responsive red-shifted photoluminescence. Chem. Sci. 6, 2187–2195. 10.1039/C4SC03960B PubMed DOI PMC

Seki T., Sakurada K., Muromoto M., Seki S., Ito H. (2016). Detailed investigation of the structural, thermal, and electronic properties of gold isocyanide complexes with mechano-triggered single-crystal-to-single-crystal phase transitions. Chem. Eur. J. 22, 1968–1978. 10.1002/chem.201503721 PubMed DOI

Sharma P., Vetter C., Ponnusamy E., Colacino E. (2022). Assessing the greenness of mechanochemical processes with the DOZN 2.0 tool. ACS Sustainable Chem. Eng. 10, 5110–5116. 10.1021/acssuschemeng.1c07981 DOI

Shaw C. F., III (1999). Gold-based therapeutic agents. Chem. Rev. 99 (9), 2589–2600. 10.1021/cr980431o PubMed DOI

Shichibu Y., Negishi Y., Tsunoyama H., Kanehara M., Teranishi T., Tsukuda T. (2007). Extremely high stability of glutathionate-protected Au25 clusters against core etching. Small 3 (5), 835–839. 10.1002/smll.200600611 PubMed DOI

Tan D., Garcia F. (2019). Main group mechanochemistry: From curiosity to established protocols. Chem. Soc. Rev. 48, 2274–2292. 10.1039/c7cs00813a PubMed DOI

Vaidya S., Veselska O., Zhadan A., Diaz-Lopez M., Joly Y., Bordet P., et al. (2020). Transparent and luminescent glasses of gold thiolate coordination polymers. Chem. Sci. 11, 6815–6823. 10.1039/d0sc02258f PubMed DOI PMC

Vainauskas J., Topic F., Arhangelskis M., Titi H. M., Friscic T. (2023). Polymorphs and solid solutions: Materials with new luminescent properties obtained through mechanochemical transformation of dicyanoaurate(I) salts. Faraday Discuss. 241, 425–447. 10.1039/d2fd00134a PubMed DOI

Veselska O., Guillou N., Ledoux G., Huang C. C., Dohnalova Newell K., Elkaim E., et al. (2019). A new lamellar gold thiolate coordination polymer, [Au(m-SPhCO(2)H)](n), for the formation of luminescent polymer composites. Nanomaterials 9, 1408. 10.3390/nano9101408 PubMed DOI PMC

Veselska O., Okhrimenko L., Guillou N., Podbevšek D., Ledoux G., Dujardin C., et al. (2017). An intrinsic dual-emitting gold thiolate coordination polymer, [Au(+I)(p-SPhCO2H)]n, for ratiometric temperature sensing. J. Mat. Chem. C 5, 9843–9848. 10.1039/c7tc03605a DOI

Virieux D., Delogu F., Porcheddu A., Garcia F., Colacino E. (2021). Mechanochemical rearrangements. J. Org. Chem. 86, 13885–13894. 10.1021/acs.joc.1c01323 PubMed DOI

Wiseman M. R., Marsh P. A., Bishop P. T., Brisdon B. J., Mahon M. F. (2000). Homoleptic gold thiolate catenanes. J. Am. Chem. Soc. 122, 12598–12599. 10.1021/ja0011156 DOI

Wu M. H., Zhao J., Chevrier D. M., Zhang P., Liu L. J. (2019). Luminescent Au(I)-Thiolate complexes through aggregation-induced emission: The effect of pH during and post synthesis. J. Phys. Chem. C 123 (10), 6010–6017. 10.1021/acs.jpcc.8b11716 DOI

Wu Z., Gayathri C., Gil R. R., Jin R. (2009a). Probing the structure and charge state of glutathione-capped Au25(SG)18 clusters by NMR and mass spectrometry. J. Am. Chem. Soc. 131, 6535–6542. 10.1021/ja900386s PubMed DOI

Wu Z., Suhan J., Jin R. (2009b). One-pot synthesis of atomically monodisperse, thiol-functionalized Au25 nanoclusters. J. Mater. Chem. 19 (5), 622–626. 10.1039/b815983a DOI

Wu Z., Yao Q., Chai O. J. H., Ding N., Xu W., Zang S., et al. (2020). Unraveling the impact of gold(I)-Thiolate motifs on the aggregation-induced emission of gold nanoclusters. Angew. Chem. 59 (25), 9934–9939. 10.1002/anie.201916675 PubMed DOI

Yagai S., Seki T., Aonuma H., Kawaguchi K., Karatsu T., Okura T., et al. (2016). Mechanochromic luminescence based on crystal-to-crystal transformation mediated by a transient amorphous state. Chem. Mater. 28, 234–241. 10.1021/acs.chemmater.5b03932 DOI

Yanez-Aulestia A., Gupta N. K., Hernandez M., Osorio-Toribio G., Sanchez-Gonzalez E., Guzman-Vargas A., et al. (2022). Gold nanoparticles: Current and upcoming biomedical applications in sensing, drug, and gene delivery. Chem. Commun. 58, 10886–10895. 10.1039/d2cc04826d PubMed DOI

Ying P., Yu J., Su W. (2021). Liquid‐assisted grinding mechanochemistry in the synthesis of pharmaceuticals. Adv. Synth. Catal. 363, 1246–1271. 10.1002/adsc.202001245 DOI

Yu Y., Chen X., Yao Q., Yu Y., Yan N., Xie J. (2013). Scalable and precise synthesis of thiolated Au10–12, Au15, Au18, and Au25 nanoclusters via pH controlled CO reduction. Chem. Mater. 25 (6), 946–952. 10.1021/cm304098x DOI

Yu Y., Luo Z., Chevrier D. M., Leong D. T., Zhang P., Jiang D. E., et al. (2014). Identification of a highly luminescent Au22(SG)18 nanocluster. J. Am. Chem. Soc. 136 (4), 1246–1249. 10.1021/ja411643u PubMed DOI

Zhang X. D., Chen J., Luo Z., Wu D., Shen X., Song S. S., et al. (2014a). Enhanced tumor accumulation of sub-2 nm gold nanoclusters for cancer radiation therapy. Adv. Healthc. Mater. 3, 133–141. 10.1002/adhm.201300189 PubMed DOI

Zhang X. D., Luo Z., Chen J., Shen X., Song S., Sun Y., et al. (2014b). Ultrasmall Au10-12(SG)10-12 nanomolecules for high tumor specificity and cancer radiotherapy. Adv. Mater. 26, 4565–4568. 10.1002/adma.201400866 PubMed DOI

Zhang X. D., Luo Z., Chen J., Song S., Yuan X., Shen X., et al. (2015). Ultrasmall glutathione-protected gold nanoclusters as next generation radiotherapy sensitizers with high tumor uptake and high renal clearance. Sci. Rep. 5, 8669. 10.1038/srep08669 PubMed DOI PMC

Zhou C., Sun C., Yu M., Qin Y., Wang J., Kim M., et al. (2010). Luminescent gold nanoparticles with mixed valence states generated from dissociation of polymeric Au (I) thiolates. J. Phys. Chem. C 114 (17), 7727–7732. 10.1021/jp9122584 PubMed DOI PMC