@article{bertorelle2021tailoring,

title = {Tailoring NIR-II photoluminescence of single thiolated Au25 nanoclusters by selective binding to proteins},

author = {Franck Bertorelle and David Wegner and Martina Perić Bakulić and Hussein Fakhouri and Clothilde Comby-Zerbino and Amin Sagar and Pau Bernadó and Ute Resch-Genger and Vlasta Bonačić Koutecky Koutecky and Xavier Le Guével and Rodolphe Antoine},

doi = {10.21203/rs.3.rs-958149/v1},

year  = {2021},

date = {2021-10-21},

urldate = {2021-10-21},

journal = {Research Square},

abstract = {Atomically precise gold nanoclusters (Au NCs) are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL), which is highly dependent on their structure and chemical environment. Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular and anatomical levels. In this work, we report a simple route to incorporating a preformed Au25 nanocluster into a model bovine serum albumin (BSA) protein. A new approach combining small-angle X-ray scattering and molecular modeling provides a clear localization of a single Au25 within the protein to a cysteine residue on the gold nanocluster surface. Attaching Au25 to BSA strikingly modifies the PL properties with enhancement and a redshift in the second near-infrared window (NIR-II). An extensive study based on a bottom-up approach that uses mixed-ligand nanoclusters Au25pMBA(18−x)Cysx with x=2, 5, 18 supported by experimental data (steady state, time-resolved spectroscopy) and theoretical calculations (DFT) provides new hints at the origin of NIR-II emission in such nanoclusters and their subsequent enhancement when selectively binding to a cysteine-rich protein. This study paves the way to controlling the design of selectively sensitive probes in biomolecules through a ligand-based strategy to enable the optical detection of biomolecules in a cellular environment by live imaging.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{combes2021functionalized,

title = {Functionalized Au 15 nanoclusters as luminescent probes for protein carbonylation detection},

author = {Guillaume F. Combes and Hussein Fakhouri and Christophe Moulin and Marion Girod and Franck Bertorelle and Srestha Basu and Romain Ladouce and Martina Perić Bakulić and Željka Sanader Maršić and Isabelle Russier-Antoine and Pierre-François Brevet and Philippe Dugourd and Anita Krisko and Katarina Trajković and Miroslav Radman and Vlasta Bonačić-Koutecký and Rodolphe Antoine},

doi = {10.1038/s42004-021-00497-z},

year  = {2021},

date = {2021-05-14},

urldate = {2021-05-14},

journal = {Communications Chemistry},

volume = {4},

number = {1},

pages = {1--11},

publisher = {Nature Publishing Group},

abstract = {Atomically precise, ligand-protected gold nanoclusters (AuNCs) attract considerable attention as contrast agents in the biosensing field. However, the control of their optical properties and functionalization of surface ligands remain challenging. Here we report a strategy to tailor AuNCs for the precise detection of protein carbonylation—a causal biomarker of ageing. We produce Au15SG13 (SG for glutathione) with atomic precision and functionalize it with a thiolated aminooxy moiety to impart protein carbonyl-binding properties. Mass spectrometry and molecular modelling reveal the key structural features of Au15SG12-Aminooxy and its reactivity towards carbonyls. Finally, we demonstrate that Au15SG12-Aminooxy detects protein carbonylation in gel-based 1D electrophoresis by one- and two-photon excited fluorescence. Importantly, to our knowledge, this is the first application of an AuNC that detects a post-translational modification as a nonlinear optical probe. The significance of post-translational modifications in life sciences may open avenues for the use of Au15SG13 and other nanoclusters as contrast agents with tailored surface functionalization and optical properties.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D0NR06401G,

title = {Size and ligand effects of gold nanoclusters in alteration of organellar state and translocation of transcription factors in human primary astrocytes},

author = {Evan Rizzel Gran and Franck Bertorelle and Hussein Fakhouri and Rodolphe Antoine and Martina Perić Bakulić and Željka Sanader Maršić and Vlasta Bonačić-Koutecký and Manon Blain and Jack Antel and Dusica Maysinger},

url = {http://dx.doi.org/10.1039/D0NR06401G},

doi = {10.1039/D0NR06401G},

year  = {2021},

date = {2021-01-01},

journal = {Nanoscale},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {Ultra-small gold nanoclusters (AuNCs) with designed sizes and ligands are gaining popularity for biomedical purposes and ultimately for human imaging and therapeutic applications. Human non-tumor brain cells, astrocytes, are of particular interest because they are abundant and play a role in functional regulation of neurons under physiological and pathological conditions. Human primary astrocytes were treated with AuNCs of varying sizes (Au10, Au15, Au18, Au25) and ligand composition (glutathione, polyethylene glycol, N-acetyl cysteine). Concentration and time-dependent studies showed no significant cell loss with AuNC concentrations <10 μM. AuNC treatment caused marked differential astrocytic responses at the organellar and transcription factor level. The effects were exacerbated under severe oxidative stress induced by menadione. Size-dependent effects were most remarkable with the smallest and largest AuNCs (10, 15 Au atoms versus 25 Au atoms) and might be related to the accessibility of biological targets toward the AuNC core, as demonstrated by QM/MM simulations. In summary, these findings suggest that AuNCs are not inert in primary human astrocytes, and that their sizes play a critical role in modulation of organellar and redox-responsive transcription factor homeostasis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bertorelle_2020,

title = {Covalent anchoring of atomically precise glutathione-protected gold nanoclusters on graphene oxide nanosheets},

author = {Franck Bertorelle and Srestha Basu and Hussein Fakhouri and Martina Peri{ć} Bakuli ć and Pierre Mignon and Isabelle Russier-Antoine and Pierre-Fran ç and Sabu Thomas and Nandakumar Kalarikkal and Rodolphe Antoine},

url = {https://doi.org/10.1088/2632-959x/abbe31},

doi = {10.1088/2632-959x/abbe31},

year  = {2020},

date = {2020-10-01},

journal = {Nano Express},

volume = {1},

number = {3},

pages = {030005},

publisher = {IOP Publishing},

abstract = {This paper describes the development of a novel method of producing nanocomposites consisting of gold nanoclusters anchored on graphene oxide nanosheets in a cost-effective and reproducible manner. The novelty of the technique hinges on the covalent functionalization of atomically precise subnanometer gold clusters protected by glutathione (Au15SG13 and Au25SG18) on to graphene oxide (GO) nanosheets according to the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride crosslinking method, using the existing carboxylic groups present both at the surfaces of the nanoclusters and the GO nanosheets. The atomic precision of glutathione-protected gold nanoclusters was evidenced by electrospray ionization mass spectrometry. The formed hybrid nanocomposites were characterized by TEM measurements and exhibit nonlinear optical properties characteristic of GO, in particular a strong second harmonic scattering response as well as a multi-photon excited fluorescence spectrum characterized by a broad band in the visible range between 350 and 700 nm. Atomically precise nanoclusters covalently linked to GO nanosheets are therefore promising for new applications in the areas of optoelectronics and photovoltaics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{comby2020structure,

title = {Structure and Charge Heterogeneity in Isomeric Au25 (MBA) 18 Nanoclusters—Insights from Ion Mobility and Mass Spectrometry},

author = {Clothilde Comby-Zerbino and Franck Bertorelle and Philippe Dugourd and Rodolphe Antoine and Fabien Chirot},

doi = {10.1021/acs.jpca.0c03131},

year  = {2020},

date = {2020-01-01},

journal = {The Journal of Physical Chemistry A},

volume = {124},

number = {28},

pages = {5840--5848},

publisher = {ACS Publications},

abstract = {Atomically precise Au25(MBA)18 nanoclusters were investigated by mass spectrometry and ion mobility spectrometry. We show that clusters sharing the same chemical composition and bearing the same net charge may display different structures and different charge repartition patterns, namely, the number of charges corresponding to deprotonation of the ligand moieties through carboxyl groups is not the same for all detected species. Part of the observed heterogeneity is a consequence of spontaneous electron loss occurring in the gas phase, which modifies the net charge of the clusters while maintaining the initial (de)protonation state.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{russier2020second,

title = {Second harmonic scattering from mass characterized 2D graphene oxide sheets},

author = {Isabelle Russier-Antoine and Hussein Fakhouri and Srestha Basu and Franck Bertorelle and Philippe Dugourd and Pierre-François Brevet and Prajitha Velayudhan and Sabu Thomas and Nandakumar Kalarikkal and Rodolphe Antoine},

doi = {10.1039/D0CC00111B},

year  = {2020},

date = {2020-01-01},

journal = {Chemical Communications},

volume = {56},

number = {27},

pages = {3859--3862},

publisher = {Royal Society of Chemistry},

abstract = {In this communication, we report the second harmonic scattering from mass characterized 2D graphene oxide sheets dispersed in an aqueous suspension, in the femtosecond regime at 800 nm laser excitation. Charge-detection mass-spectrometry, performing at the single sheet level, allows for an exhaustive molar mass distribution and thus concentration for these 2D nanomaterials samples. The orientation-averaged hyperpolarizability value is (1.36 ± 0.15) × 10−25 esu as determined by the concentration-dependent harmonic scattering signal. In addition, the multi-photon excited fluorescence spectrum is characterized by a broad band in the visible range between 350 and 700 nm centered at about 500 nm.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{maysinger2020gold,

title = {Gold nanoclusters elicit homeostatic perturbations in glioblastoma cells and adaptive changes of lysosomes},

author = {Dusica Maysinger and Evan R Gran and Franck Bertorelle and Hussein Fakhouri and Rodolphe Antoine and Esha S Kaul and Dana M Samhadaneh and Ursula Stochaj},

doi = {10.7150/thno.37674},

year  = {2020},

date = {2020-01-01},

journal = {Theranostics},

volume = {10},

number = {4},

pages = {1633},

publisher = {Ivyspring International Publisher},

abstract = {Unique physicochemical features place gold nanoclusters at the forefront of nanotechnology for biological and biomedical applications. To date, information on the interactions of gold nanoclusters with biological macromolecules is limited and restricts their use in living cells. Methods: Our multidisciplinary study begins to fill the current knowledge gap by focusing on lysosomes and associated biological pathways in U251N human glioblastoma cells. We concentrated on lysosomes, because they are the intracellular destination for many nanoparticles, regulate cellular homeostasis and control cell survival. Results: Quantitative data presented here show that gold nanoclusters (with 15 and 25 gold atoms), surface-modified with glutathione or PEG, did not diminish cell viability at concentrations ≤1 µM. However, even at sublethal concentrations, gold nanoclusters modulated the abundance, positioning, pH and enzymatic activities of lysosomes. Gold nanoclusters also affected other aspects of cellular homeostasis. Specifically, they stimulated the transient nuclear accumulation of TFEB and Nrf2, transcription factors that promote lysosome biogenesis and stress responses. Moreover, gold nanoclusters also altered the formation of protein aggregates in the cytoplasm. The cellular responses elicited by gold nanoclusters were largely reversible within a 24-hour period. Conclusions: Taken together, this study explores the subcellular and molecular effects induced by gold nanoclusters and shows their effectiveness to regulate lysosome biology. Our results indicate that gold nanoclusters cause homeostatic perturbations without marked cell loss. Notably, cells adapt to the challenge inflicted by gold nanoclusters. These new insights provide a framework for the further development of gold nanocluster-based applications in biological sciences.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{martinet2020performances,

title = {Performances of the Lamb Model to Describe the Vibrations of Gold Quantum-Sized Clusters},

author = {Quentin Martinet and Alice Berthelot and Adrien Girard and Baira Donoeva and Clothilde Comby-Zerbino and {É}lodie Romeo and Franck Bertorelle and Marte van der Linden and Nathalie Tarrat and Nicolas Combe and others},

doi = {10.1021/acs.jpcc.0c04722},

year  = {2020},

date = {2020-01-01},

journal = {The Journal of Physical Chemistry C},

volume = {124},

number = {35},

pages = {19324--19332},

publisher = {ACS Publications},

abstract = {Lamb modes describe the vibrations of an object as a whole from the stellar scale to the nanometer one. Lamb description has been built from the linear elasticity theory and considers a homogeneous elastic sphere. Our work tries to determine the minimum scale where this description remains valid by studying the vibration of quantum-sized gold clusters (Au6, Au9, and Au25) stabilized by organic molecules. First, our work shows that experimental frequencies of small-functionalized gold clusters obtained by low-frequency Raman spectroscopy can be interpreted with density functional theory calculations. Moreover, the Lamb model broadly succeeds in predicting these Raman acoustic modes only if a correction considering the mass of the surrounding ligands is added. Ligands affect vibrational modes of the core by their mass but also by their covalent bond with the core. The unexpected consequence of this electronic stabilization by the ligands is the sustainability of the Lamb description for clusters as small as six atoms. Finally, the limit of the Lamb model can be reached out at low temperature where the vibration mode spectrum presents a substructuration that the Lamb description, developed for a homogeneous sphere, is unable to predict.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.jpcc.9b08492,

title = {Influence of the Spatial Conformation of Charged Ligands on the Optical Properties of Gold Nanoclusters},

author = {Estelle Porret and Muriel Jourdan and Beatrice Gennaro and Clothilde Comby-Zerbino and Franck Bertorelle and Vanessa Trouillet and Xue Qiu and Claude Zoukimian and Didier Boturyn and Niko Hildebrandt and Rodolphe Antoine and Jean-Luc Coll and Xavier Le Guével},

url = {https://doi.org/10.1021/acs.jpcc.9b08492},

doi = {10.1021/acs.jpcc.9b08492},

year  = {2019},

date = {2019-01-01},

journal = {The Journal of Physical Chemistry C},

volume = {123},

number = {43},

pages = {26705-26717},

abstract = {Photoluminescent gold nanoclusters (Au NCs) were synthesized in one step in aqueous conditions using a mixture of glutathione and (mono or multivalent) glutathione-modified arginine peptides. By controlling the ratio of coligands, we investigated how the multivalency and the amount of arginines influenced the growth of Au NCs, their surface chemistry, their colloidal stability, and their optical properties. We demonstrated using two-dimensional nuclear magnetic resonance spectroscopy that the organization of the ligand on the Au surface was composed by an inner rigid layer and an outer flexible part via inter- and/or intraligand spatial proximity. This directly impacted the structure of the Au NCs, as confirmed by gel electrophoresis, high-resolution transmission electron microscopy, diffusion-ordered spectroscopy, and mass spectrometry. Increasing arginine content also induced an increase of positive surface charge and an enhancement of the near infrared emission intensity at ∼670 nm with quantum yield up to 10% validating the significant influence of the ligands to the optical properties of Au NCs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{C9CP00829B,

title = {Sub-100 nanometer silver doped gold–cysteine supramolecular assemblies with enhanced nonlinear optical properties},

author = {Hussein Fakhouri and Martina Perić and Franck Bertorelle and Philippe Dugourd and Xavier Dagany and Isabelle Russier-Antoine and Pierre-François Brevet and Vlasta Bonačić-Koutecký and Rodolphe Antoine},

url = {http://dx.doi.org/10.1039/C9CP00829B},

doi = {10.1039/C9CP00829B},

year  = {2019},

date = {2019-01-01},

journal = {Phys. Chem. Chem. Phys.},

volume = {21},

pages = {12091-12099},

publisher = {The Royal Society of Chemistry},

abstract = {The ability of gold(i) thiolates to self-assemble into supramolecular architectures opens the route for a new class of nanomaterials with a unique structure–optical property relationship. However, for a confirmed structure–optical property relationship, a control of the supramolecular architectures is required. In this work, we report a simple synthesis of sub-100 nanometer gold–cysteine and silver doped gold–cysteine supramolecular assemblies. We explore in particular silver-doping as a strategy to enhance the optical properties of these supramolecular assemblies. By an accurate characterization of as-synthesized supramolecular nanoparticles, we have been able to measure for the first time, their absolute two-photon absorption cross-section, two-photon excited fluorescence cross-section and first hyperpolarizabilities at different near-IR wavelengths. Huge values are obtained for silver doped gold–cysteine supramolecular assemblies, as compared to their corresponding undoped counterpart. In addition, we employ DFT and TD-DFT methods to study the geometric and electronic structures of model gold–cysteine and silver doped gold–cysteine compounds in order to address the structure−linear/nonlinear optical property relationship. The aim is to gain insights into the origin of the nonlinear optical enhancement of silver-doped gold supramolecular assemblies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{C9CP05262C,

title = {Ligand shell size effects on one- and two-photon excitation fluorescence of zwitterion functionalized gold nanoclusters},

author = {Martina Perić and Željka Sanader Maršić and Isabelle Russier-Antoine and Hussein Fakhouri and Franck Bertorelle and Pierre-François Brevet and Xavier le Guével and Rodolphe Antoine and Vlasta Bonačić-Koutecký},

url = {http://dx.doi.org/10.1039/C9CP05262C},

doi = {10.1039/C9CP05262C},

year  = {2019},

date = {2019-01-01},

journal = {Phys. Chem. Chem. Phys.},

volume = {21},

pages = {23916-23921},

publisher = {The Royal Society of Chemistry},

abstract = {Gold nanoclusters (Au NCs) are an emerging class of luminescent nanomaterials but still suffer from moderate photoluminescence quantum yields. Recent efforts have focused on tailoring their emission properties. Introducing zwitterionic ligands to cap the metallic kernel is an efficient approach to enhance their one-photon excitation fluorescence intensity. In this work, we extend this concept to the nonlinear optical regime, i.e., two-photon excitation fluorescence. For a proper comparison between theory and experiment, both ligand and solvent effects should be considered. The effects of ligand shell size and of aqueous solvent on the optical properties of zwitterion functionalized gold nanoclusters have been studied by performing quantum mechanics/molecular mechanics (QM/MM) simulations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1080/17435390.2018.1543468,

title = {Organotypic and primary neural cultures as models to assess effects of different gold nanostructures on glia and neurons},

author = {Jeff Ji and Alexandre Moquin and Franck Bertorelle and Philip KY Chang and Rodolphe Antoine and Julia Luo and Anne R McKinney and Dusica Maysinger},

url = {https://doi.org/10.1080/17435390.2018.1543468},

doi = {10.1080/17435390.2018.1543468},

year  = {2019},

date = {2019-01-01},

journal = {Nanotoxicology},

volume = {13},

number = {3},

pages = {285-304},

publisher = {Taylor & Francis},

abstract = {Gold nanoparticles (AuNP) have unique physicochemical properties and have been used as delivery vehicles, contrast agents, and therapeutic compounds. Although the effects of AuNPs on peripheral tissues and immortalized cell lines have been extensively characterized, their effects on the central nervous system (CNS) are predominantly unknown. The main objective of the current study was to evaluate how AuNPs of varying sizes (1–100 nm), shapes (clusters, spheres, rods, flowers), and surfaces impact synaptic structures in the hippocampus, a brain structure often affected in neurodegeneration. Using a combination of organotypic hippocampal, as well as, primary neuronal, glial, and astrocytic cultures, we examined AuNPs impact on hippocampal dendritic spine density, internalization in various neural cells, and lysosomal status in astrocytes. Considering that neurons interact with astrocytes, and that lysosomes play a role in dendritic spine status, transcription factor TFEB and abundance of lysosomal marker, LAMP1 were evaluated. Both biomarkers were significantly increased in astrocytes exposed to AuNPs, suggesting that AuNPs not only enter lysosomes, but also increase lysosome biogenesis. Results from our studies show that AuNPs with poly(ethylene glycol) (AuNPs-PEG) or glutathione (AuNP-GSH) surfaces do not substantially decrease hippocampal dendritic spine density. Conversely, AuNPs coated with the detergent, CTAB, significantly decreased total spine density. Interestingly small gold nanoclusters (Au15(SG)13) with GSH reduced spine density, whereas larger gold nanoclusters (Au25(SG)18) with the same ligand did not. Thus, assessment of dendritic morphology, spine densities can reveal subtler changes of neural cells than cell death when exposed to nanoparticles, including AuNPs.},

note = {PMID: 30691378},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nano9030457,

title = {Catenane Structures of Homoleptic Thioglycolic Acid-Protected Gold Nanoclusters Evidenced by Ion Mobility-Mass Spectrometry and DFT Calculations},

author = {Clothilde Comby-Zerbino and Martina Perić and Franck Bertorelle and Fabien Chirot and Philippe Dugourd and Vlasta Bonačić-Koutecký and Rodolphe Antoine},

url = {https://www.mdpi.com/2079-4991/9/3/457},

doi = {10.3390/nano9030457},

issn = {2079-4991},

year  = {2019},

date = {2019-01-01},

journal = {Nanomaterials},

volume = {9},

number = {3},

abstract = {Thiolate-protected metal nanoclusters have highly size- and structure-dependent physicochemical properties and are a promising class of nanomaterials. As a consequence, for the rationalization of their synthesis and for the design of new clusters with tailored properties, a precise characterization of their composition and structure at the atomic level is required. We report a combined ion mobility-mass spectrometry approach with density functional theory (DFT) calculations for determination of the structural and optical properties of ultra-small gold nanoclusters protected by thioglycolic acid (TGA) as ligand molecules, Au10(TGA)10. Collision cross-section (CCS) measurements are reported for two charge states. DFT optimized geometrical structures are used to compute CCSs. The comparison of the experimentally- and theoretically-determined CCSs allows concluding that such nanoclusters have catenane structures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/rcm.8204,

title = {Direct determination of molecular weight distribution of calf-thymus DNAs and study of their fragmentation under ultrasonic and low-energy infrared irradiations. A charge detection mass spectrometry investigation},

author = {Mohammad A Halim and Franck Bertorelle and Tristan Doussineau and Rodolphe Antoine},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/rcm.8204},

doi = {https://doi.org/10.1002/rcm.8204},

year  = {2019},

date = {2019-01-01},

journal = {Rapid Communications in Mass Spectrometry},

volume = {33},

number = {S1},

pages = {35-39},

abstract = {Rationale Calf-thymus (CT-DNA) is widely used as a binding agent. The commercial samples are known to be “highly polymerized DNA” samples. CT-DNA is known to be fragile in particular upon ultrasonic wave irradiation. Degradation products could have dramatic consequences on its bio-sensing activity, and an accurate determination of the molecular weight distribution and stability of commercial samples is highly demanded. Methods We investigated the sensitivity of charge detection mass spectrometry (CDMS), a single-molecule MS method, both with single-pass and ion trap CDMS (“Benner” trap) modes to the determination of the composition and stability (under multiphoton IR irradiation) of calf-thymus DNAs. We also investigated the changes in molecular weight distributions in the course of sonication by irradiating ultrasonic waves to CT-DNA. Results We report, for the first time, the direct molecular weight (MW) distribution of DNA sodium salt from calf-thymus revealing two populations at high (~10 MDa) and low (~3 MDa) molecular weights. We evidence a transition between the high-MW to the low-MW distribution, confirming that the low-MW distribution results from degradation of CT-DNA. Finally, we report also IRMPD experiments carried out on trapped single-stranded linear DNAs from calf-thymus allowing extraction of their activation energy for unimolecular dissociation. Conclusions We show that single-pass CDMS is a direct, efficient and accurate MS-based approach to determine the composition of calf-thymus DNAs. Furthermore, ion trap CDMS allows us to evaluate the stability (both under multiphoton IR irradiation and in the course of sonication by irradiating ultrasonic wave) of calf-thymus DNAs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.nanolett.8b02717,

title = {Mechanical Vibrations of Atomically Defined Metal Clusters: From Nano- to Molecular-Size Oscillators},

author = {Paolo Maioli and Tatjana Stoll and Huziel E Sauceda and Israel Valencia and Aude Demessence and Franck Bertorelle and Aurélien Crut and Fabrice Vallée and Ignacio L Garzón and Giulio Cerullo and Natalia Del Fatti},

url = {https://doi.org/10.1021/acs.nanolett.8b02717},

doi = {10.1021/acs.nanolett.8b02717},

year  = {2018},

date = {2018-01-01},

journal = {Nano Letters},

volume = {18},

number = {11},

pages = {6842-6849},

abstract = {Acoustic vibrations of small nanoparticles are still ruled by continuum mechanics laws down to diameters of a few nanometers. The elastic behavior at lower sizes (<1–2 nm), where nanoparticles become molecular clusters made by few tens to few atoms, is still little explored. The question remains to which extent the transition from small continuous-mass solids to discrete-atom molecular clusters affects their specific low-frequency vibrational modes, whose period is classically expected to linearly scale with diameter. Here, we investigate experimentally by ultrafast time-resolved optical spectroscopy the acoustic response of atomically defined ligand-protected metal clusters Aun(SR)m with a number n of atoms ranging from 10 to 102 (0.5–1.5 nm diameter range). Two periods, corresponding to fundamental breathing- and quadrupolar-like acoustic modes, are detected, with the latter scaling linearly with cluster diameters and the former taking a constant value. Theoretical calculations based on density functional theory (DFT) predict in the case of bare clusters vibrational periods scaling with size down to diatomic molecules. For ligand-protected clusters, they show a pronounced effect of the ligand molecules on the breathing-like mode vibrational period at the origin of its constant value. This deviation from classical elasticity predictions results from mechanical mass-loading effects due to the protecting layer. This study shows that clusters characteristic vibrational frequencies are compatible with extrapolation of continuum mechanics model down to few atoms, which is in agreement with DFT computations.},

note = {PMID: 30247927},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acsomega.8b02615,

title = {Isomeric Effect of Mercaptobenzoic Acids on the Synthesis, Stability, and Optical Properties of Au25(MBA)18 Nanoclusters},

author = {Franck Bertorelle and Isabelle Russier-Antoine and Clothilde Comby-Zerbino and Fabien Chirot and Philippe Dugourd and Pierre-François Brevet and Rodolphe Antoine},

url = {https://doi.org/10.1021/acsomega.8b02615},

doi = {10.1021/acsomega.8b02615},

year  = {2018},

date = {2018-01-01},

journal = {ACS Omega},

volume = {3},

number = {11},

pages = {15635-15642},

abstract = {We report a simple size focusing, two-step “bottom-up” protocol to prepare water-soluble Au25(MBA)18 nanoclusters, using the three isomers of mercaptobenzoic acids (p/m/o-MBA) as capping ligands and Me3NBH3 as a mild reducing agent. The relative stability of the gas-phase multiply deprotonated Au25(MBA)18 ions was investigated by collision-induced dissociation. This permitted us to evaluate the possible isomeric effect on the Au–S interfacial bond stress. We also investigated their optical properties. The absorption spectra of Au25(MBA)18 isomers were very similar and showed bands at 690, 470, and 430 nm. For all Au25(MBA)18 isomeric clusters, no measurable one-photon excited fluorescence under UV–vis light was found, in neither solid- nor solution-state. The two-photon excited emission spectra and first hyperpolarizabilities of the clusters were also determined. The results are discussed in terms of the possible isomeric effect on excitations within the metal core and the possibility of charge transfer excitations from the ligands to the metal nanocluster.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{C8NR00660A,

title = {pH-Induced transformation of ligated Au25 to brighter Au23 nanoclusters},

author = {Magdalena Waszkielewicz and Joanna Olesiak-Banska and Clothilde Comby-Zerbino and Franck Bertorelle and Xavier Dagany and Ashu K Bansal and Muhammad T Sajjad and Ifor D W Samuel and Zeljka Sanader and Miroslawa Rozycka and Magdalena Wojtas and Katarzyna Matczyszyn and Vlasta Bonacic-Koutecky and Rodolphe Antoine and Andrzej Ozyhar and Marek Samoc},

url = {http://dx.doi.org/10.1039/C8NR00660A},

doi = {10.1039/C8NR00660A},

year  = {2018},

date = {2018-01-01},

journal = {Nanoscale},

volume = {10},

pages = {11335-11341},

publisher = {The Royal Society of Chemistry},

abstract = {Thiolate-protected gold nanoclusters have recently attracted considerable attention due to their size-dependent luminescence characterized by a long lifetime and large Stokes shift. However, the optimization of nanocluster properties such as the luminescence quantum yield is still a challenge. We report here the transformation of Au25Capt18 (Capt labels captopril) nanoclusters occurring at low pH and yielding a product with a much increased luminescence quantum yield which we have identified as Au23Capt17. We applied a simple method of treatment with HCl to accomplish this transformation and we characterized the absorption and emission of the newly created ligated nanoclusters as well as their morphology. Based on DFT calculations we show which Au nanocluster size transformations can lead to highly luminescent species such as Au23Capt17.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.jpcc.8b03550,

title = {Nonlinear Refraction and Absorption of Ag29 Nanoclusters: Evidence for Two-Photon Absorption Saturation},

author = {Albert S Reyna and Isabelle Russier-Antoine and Franck Bertorelle and Emmanuel Benichou and Philippe Dugourd and Rodolphe Antoine and Pierre-François Brevet and Cid B de Araújo},

url = {https://doi.org/10.1021/acs.jpcc.8b03550},

doi = {10.1021/acs.jpcc.8b03550},

year  = {2018},

date = {2018-01-01},

journal = {The Journal of Physical Chemistry C},

volume = {122},

number = {32},

pages = {18682-18689},

abstract = {We report the nonlinear absorption and refraction of Ag29 nanocluster aqueous suspensions using the open and closed aperture Z-scan method at 532 nm. The stoichiometry of the atomically precise silver nanoclusters has been determined by mass spectrometry, and their formula is Ag29DHLA12 where the ligand is dihydrolipoic acid (DHLA). Using different concentration of nanoclusters, we observe beyond the expected linear absorption saturation and nonlinear absorption a clear saturation of the nonlinear absorption, a feature so far not described for nanoclusters. The nonlinear refraction is also determined and exhibits a regular behavior with a negative n2 value. A figure of merit is discussed in view of potential applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{SOLEILHAC2018283,

title = {Sizing protein-templated gold nanoclusters by time resolved fluorescence anisotropy decay measurements},

author = {Antonin Soleilhac and Franck Bertorelle and Rodolphe Antoine},

url = {https://www.sciencedirect.com/science/article/pii/S138614251730999X},

doi = {https://doi.org/10.1016/j.saa.2017.12.025},

issn = {1386-1425},

year  = {2018},

date = {2018-01-01},

journal = {Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy},

volume = {193},

pages = {283-288},

abstract = {Protein-templated gold nanoclusters (AuNCs) are very attractive due to their unique fluorescence properties. A major problem however may arise due to protein structure changes upon the nucleation of an AuNC within the protein for any future use as in vivo probes, for instance. In this work, we propose a simple and reliable fluorescence based technique measuring the hydrodynamic size of protein-templated gold nanoclusters. This technique uses the relation between the time resolved fluorescence anisotropy decay and the hydrodynamic volume, through the rotational correlation time. We determine the molecular size of protein-directed AuNCs, with protein templates of increasing sizes, e.g. insulin, lysozyme, and bovine serum albumin (BSA). The comparison of sizes obtained by other techniques (e.g. dynamic light scattering and small-angle X-ray scattering) between bare and gold clusters containing proteins allows us to address the volume changes induced either by conformational changes (for BSA) or the formation of protein dimers (for insulin and lysozyme) during cluster formation and incorporation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{comby2018structural,

title = {Structural insights into glutathione-protected gold Au 10- 12 (SG) 10- 12 nanoclusters revealed by ion mobility mass spectrometry},

author = {Clothilde Comby-Zerbino and Franck Bertorelle and Fabien Chirot and Philippe Dugourd and Rodolphe Antoine},

url = {https://doi.org/10.1140/epjd/e2018-90133-8},

doi = {10.1140/epjd/e2018-90133-8},

year  = {2018},

date = {2018-01-01},

journal = {The European Physical Journal D},

volume = {72},

number = {8},

pages = {1--5},

publisher = {Springer},

abstract = {Gold nanoclusters protected by ligands present well-defined compositions and tunable structures, which builds a solid basis for correlation between structures and properties. We report a combined ion mobility-mass spectrometry approach for the analysis of ultra-small gold nanoclusters protected by glutathione (SG) as ligand molecules, Au10−12(SG)10−12. Collision cross section (CCS) measurements are reported for different charge states for Au10(SG)10, Au11(SG)11 and Au12(SG)12 nanoclusters. Computational calculations, at the PM7 semi-empirical level of theory, are performed to optimize geometrical structures and use them to compute CCS. The comparison of the experimentally and theoretically determined CCS allows drawing conclusions on the structural changes, in particular partial unfolding of SG ligands, upon charging.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bertorelle_2017,

title = {Bulky Counterions: Enhancing the Two-Photon Excited Fluorescence of Gold Nanoclusters},

author = {Franck Bertorelle and Christophe Moulin and Antonin Soleilhac and Clothilde Comby-Zerbino and Philippe Dugourd and Isabelle Russier-Antoine and Pierre-François Brevet and Rodolphe Antoine},

url = {http://dx.doi.org/10.1002/cphc.201701186},

doi = {10.1002/cphc.201701186},

issn = {1439-4235},

year  = {2017},

date = {2017-12-01},

journal = {ChemPhysChem},

volume = {19},

number = {2},

pages = {165–168},

publisher = {Wiley},

abstract = {Increasing fluorescence quantum yields of ligand-protected gold nanoclusters has attracted wide research interest. The strategy consisting in using bulky counterions has been found to dramatically enhance the fluorescence. In this communication, we push forward this concept to the nonlinear optical regime. We show that by an appropriate choice of bulky counterions and of solvent, a 30-fold increase in two-photon excited fluorescence (TPEF) signal at ~600 nm for gold nanoclusters can be obtained. This would correspond to a TPEF cross section in the range of 0.1 to 1 GM.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}