Session Overview |
Aqueous syntheses of multi-metallic nanostructures utilizing charge-transfer effect
1. Synthesis of nanoparticles and nanostructures * Anh T.N. Dao, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan Yuta Takeuchi, Kyushu University Hu-jun Lee, Kyushu University Hitoshi Kasai, Tohoku University, Japan Kenji Kaneko, Kyushu University In this report, Au@Ag core@shell NPs were successfully synthesized with uniform morphology and tunable size, composition and plasmonic property [1]. The synthesis is straightforward with citrate reduction and the products do not require complicated treatment process for further uses. In addition, Au@Ag core-shell NPs were demonstrated to have better chemical stability than pure Ag NPs and very high SERS activity [2]. Moreover, Ag in the shell also could suppress the galvanic replacement reaction allowing the formation of double shell (Au@Ag)@Au NPs without any defects or gaps in the structure. All these attractive aspects arise from the charge-transfer effect which has been shown to occur in the Au-Ag system. In this study, the intermediate Ag shell thickness is limited to the range where the charge transfer effect takes place, allowing the ability to create Au@Ag@Au NPs without significant alloying or defects in the structure [3]. |
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Au NPs to promote AgO-TiO2 prepared starting from jewellery industry wastewaters
1. Synthesis of nanoparticles and nanostructures Marta Stucchi, University of Milan, Italy Daniela Meroni, University of Milan, Italy Claudia Bianchi, University of Milan, Italy * Laura Prati, University of Milan, Italy Wastewaters from precious metal industries contain high amounts of noble metals, but their efficient recycling is hindered by the wastewater complex composition. Here, we propose an innovative approach for the efficient recovery of noble metals contained in these metal-enriched wastewaters as precursors for the synthesis of noble metal nanoparticles (NPs) and supported metal catalysts. Silver NPs were synthesized from Ag-enriched wastewater and then deposited on TiO2 to prepare photocatalysts. Then, further promotion of the photocatalytic activity of Ag-modified TiO2 was achieved by the addition of Au. STEM-EDS analyses proved that Au NPs were located on Ag or AgOx nanoparticles and the contact between the two metal-containing NPs results in charge transfer effects. The activity of the materials was then tested towards ethanol photodegradation under UV light: adding 0.5 wt.% Au NPs resulted in a promoted activity showing synergistic effects between Au and Ag. |
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Double-lattice packing of pentagonal gold bipyramids in supercrystals with triclinic symmetry
1. Synthesis of nanoparticles and nanostructures * Cyrille Hamon, Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, France Pentagonal packing is a long-standing issue and a rich mathematical topic, brought to the fore by recent progress in nanoparticle design. Gold pentagonal bipyramids combine five-fold symmetry and anisotropy and their section varies along the length. In this work, we obtain colloidal supercrystals of pentagonal gold bipyramids in a compact arrangement that generalizes the optimal packing of regular pentagons in the plane. Multimodal investigations reveal a two-particle unit cell with triclinic symmetry, a lower symmetry than that of the building blocks. Monte Carlo computer simulations show that this lattice achieves the densest possible packing. Going beyond pentagons, further simulations show an odd-even effect of the number of sides on the packing: odd-sided bipyramids are non-centrosymmetric and require the double-lattice arrangement to recover inversion symmetry. The crystalline order of the bipyramids results in a facet-dependent optical response, which is demonstrated by surface-enhanced Raman scattering spectroscopy. |
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Nanoparticles with chiroptical properties used in refractive index sensitivity
1. Synthesis of nanoparticles and nanostructures * Sergio Gómez-Graña, Universidade de Vigo, Spain Isabel Pastoriza-Santos, Universidade de Vigo, Spain Jorge Pérez-Juste, Universidade de Vigo, Spain Chirality is a molecule or structure property that is present in our daily life, and it can be from nano (conformation of small molecules) to macro (our hands or the shape of galaxies). Generally, enantiomers show similar physical properties, however, normally they have opposite optical properties, depending on how they are rotating the plane of polarization of an incident beam light. When an electromagnetic beam interacts with plasmonic nanoparticles, this generates a localized surface plasmon resonance (LSPR) with highly intense electromagnetic field at nanoparticles surface. Coupling the LSPR of achiral structures with chiral molecules, it is possible to increase and modify the chiroptical response of the hybrid nanomaterial. Chiral plasmonic nanostructures have been developed by assembly achiral plasmonic nanoparticles into chiral configurations by using chiral templates or chiral molecules.1 Recently, plasmonic nanoparticles with an intrinsic chirality have been achieved.2,3 In this context, we have developed one step synthesis of chiral-plasmonic nanoparticles by using achiral gold nanorods as seeds. We have studied the chirality evolution by HR-TEM as well as the chiral efficiency. Likewise, depending on the seed used, we are able to control and tune the CD response of the new chiral nanoparticles. Thanks to the layer by layer technique we have deposited on a glass substrate different layers of chiral nanoparticles and the chiroptical response have been evaluated. Moreover, taking advantage of the CD better efficiency than the LSPR, we have used the chiral substrates to develop a more efficient system to measure the refractive index sensitivity. |
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Optimizing the synthesis of gold nanotriangles by means of kinetic studies and transfer into microfluidic environment
* Ekaterina Podlesnaia, Leibniz Institute of Photonic Technologies, Germany Plasmonic nanoparticles have become well-known materials for rapidly developing optic and photonic technologies thanks to the peculiar optical properties [1]. Of vast interest are the shape anisotropic nanoparticles having edges, tips and corners which accumulate surface charges based on the near-field calculations [2-3]. Such structures also have a great potential in catalysis due to a high number of easily accessible, and hence catalytically very active, surface atoms on the mentioned edges [4]. However, anisotropic shapes are not thermodynamically favorable and can be only derived following fine and labor procedures the mechanisms of which have not been studied thoroughly yet [5-7]. Deeper research is required to describe the nanoparticle formation processes in order to optimize e.g. time and material consumption and improve the synthesis reproducibility. Online monitoring of the reaction mixture UV–Vis properties was utilized as a powerful tool to study the kinetics of the particle evolution at each synthesis step [8]. The obtained data correlated to the occurring chemical reactions, allowed to rationally determine the time intervals actually required for carrying out the procedure which led to its shortening from three days to one (Figure 1). Using UV–Vis spectroscopy and SEM imaging, the samples synthesized after the optimized protocol were compared with ones derived following the originally described preparation. The obtained data revealed no significant differences in such quality characteristics as shape yield and size distribution. Besides the practical interest of time consumption optimizing, this study represents an example of how characterization approaches can be utilized to determine the critical durations of key synthesis steps in order to improve the efficiency of nanoparticle production. A further optimization, such as low consumption of reagents and high reproducibility, becomes possible with implementing the microfluidic systems. These facilities are known to provide a very fast and efficient mixing with simple control of parameters which is also beneficial for improving the quality of the resulting material. However, the process kinetics change drastically with alteration of the environment, hence the current focus of the work is adapting the parameters to develop a protocol for the microfluidic synthesis of gold nanotriangles. |
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Recent Advances in the Characterization and Properties of Nanoporous Gold
1. Synthesis of nanoparticles and nanostructures Ayman El-Zoka, Max-Planck-Institut für Eisenforschung, Germany * Daniel Zeitler, University of Toronto, Canada Doug Perovic, University of Toronto, Canada Roger Newman, University of Toronto, Canada There is a substantial and growing literature on nanoporous gold (NPG), synthesized by a dealloying process. Dealloying is the selective electrolytic dissolution of less-noble elements from a homogeneous solid-solution alloy, such as AuCu or AuAg. The nanoporous structure results from the selective dissolution of Cu or Ag, and the diffusion of the remaining Au at the alloy-electrolyte interface. Ternary alloy variants include Pt, yielding NPG-Pt after dissolution of the least noble element. The mechanism by which trace amounts of Pt influence the evolution of nanoporosity is poorly understood. Atom probe tomography (APT) can provide sub-nanometer compositional analysis of the material, but the brittle nature and porous structure of NPG renders it unsuitable for this characterization method. Recently, atomic-scale analyses of the resulting nanomaterials were achieved by plating Cu into the pores and carrying out APT. Incorporation of Cu consolidates the structure, providing the mechanical stability needed for field evaporation and subsequent data reconstruction. 3D reconstructions yield details of the Au-rich ligament surfaces and Ag-rich cores in NPG. The role of Pt in retaining Ag during the dealloying process in NPG-Pt is also derived from the data. In situ STEM/SEM imaging of the thermal coarsening behaviour of NPG and NPG-Pt was also performed, revealing the impact of Pt on the mechanism and kinetics of ligament coalescence. An improved understanding of the microstructure and morphological transformations obtained here is aimed at realizing the potential of these nanomaterials as functional electrocatalysts. |
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Luminescence and Transition Rates of Excited States Study in Triple-decker Sandwich Gold-Metal Clusters: [M{[Au(-N3,C2-bzim)]3}2]BF4 with (M= Ag+, Cu+ and Au+)
12.Computational approaches, machine learning and artificial intelligence (AI) * Hassan Rabaa, UNT, United States Mohammad Omary, UNT, United States Rachid Valiev, Helsinki University, Finland Dage Sundholm, Helsinki University, Finland Computational study of the photophysical properties of the triple-decker sandwich gold-metal cluster: [M{[Au(m-N3,C2-bzim)]3}2]+ where (bzim) is 1-Benzylimidazolate, and M= Ag+, Cu+ and Au+. Rate constants for radiative and non-radiative transitions as well as the quantum yield of luminescence were calculated within the Herzberg–Teller approximation based on quantum mechanical principles. |
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Development of gold nanoparticle catalyst supported on Ni-Ti mixed metal oxides using layered double hydroxides
4. Catalysis * Ayu Takahashi, Tokyo Metropolitan University, Japan Akihiro Nakayama, Tokyo Metropolitan University, Japan Toru Murayama, Tokyo Metropolitan University, Japan Norihito Sakaguchi, Hokkaido University, Japan Tetsuya Shimada, Tokyo Metropolitan University, Japan Shinsuke Takagi, Tokyo Metropolitan University, Japan Tamao Ishida, Tokyo Metropolitan University, Japan Ni-Ti layered double hydroxides (LDHs) were deposited on SiO2 followed by calcination to obtain small Ni-Ti mixed metal oxide (MMO) crystals. Au was deposited onto Ni-Ti MMO/SiO2 by deposition-precipitation (DP) or onto Ni-Ti LDH/SiO2 by DP-urea followed by calcination to obtain Au/Ni-Ti MMO/SiO2. For CO oxidation, Au/Ni-Ti MMO/SiO2 (DP-urea) showed higher catalytic activity than Au/Ni-Ti MMO/SiO2 (DP). From XPS and CO-TPR measurements suggested that Au/Ni-Ti MMO/SiO2 (DP) had higher amount of Ni vacancies, while Au/Ni-Ti MMO/SiO2 (DP-urea) had more O vacancies. Thus, transformation LDH to MMO after deposition of Au efficiently generated O vacancies, resulting in high activity for CO oxidation. |
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Microwave-assisted base-free oxidation of glucose with H2O2 on Au-MnSBA-15 and Cu-MnSBA-15 mesoporous sieves
4. Catalysis * Izabela Sobczak, Adam Mickiewicz University, Poland Tsering Kowalska, Adam Mickiewicz University, Poland Magdalena Nowicka, Adam Mickiewicz University, Poland Maria Ziolek, Adam Mickiewicz University, Poland Glucose oxidation to gluconic acid is a very important process from the point of view of industrial applications. Recently, catalytic glucose oxidation with hydrogen peroxide have become a hot topic. Moreover, the application of microwave assisted heating to promote the oxidation is a promising alternative to conventional conditions. The aim of this work was to gain insights into the role of gold and copper present on MnSBA-15 surface (Mn as a source of acidity/basicity) in the base-free glucose oxidation with H2O2 using a microwave reactor. Au-MnSBA-15 was found as active and highly selective to gluconic acid, whereas Cu-MnSBA-15 sample was not selective. The different pathway of glucose oxidation on gold and copper catalysts has been proposed. |
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Plasmonic catalysis of different molecules on Au/Ag nanoarrays monitored by surface-enhanced Raman spectroscopy
4. Catalysis * Shashank Gahlaut, Institute of Chemistry, University of Potsdam, Germany Ilko Bald, Institute of Chemistry, University of Potsdam, Germany Plasmonic materials have found their promising applications in most of the research domains in natural sciences and engineering. The metallic nanoparticles interact with the electromagnetic radiation through the collective electronic oscillations. Under some specific conditions, these oscillations resonate and generate very high intensity electromagnetic modes called surface plasmon resonance. After a series of events, these plasmons decay and the energy is transferred to the surrounding in the form of heat or electrons. This energy is enough to make various chemical reactions happen. The non-radiative decay leads to the generation of hot electrons in the metallic nanoparticles. We study the plasmonic induced chemical reactions like dimerization of molecules e.g. 4-Nitrothiophenol (4-NTP) and 4-Aminothiophenol (4-ATP) along with the dehalogenation in radiosensitizers e.g. Br-Adenine and Br-Guanine. SERS has been employed for in-situ monitoring the chemical reactions on the hot-spots in fabricated Au/Ag nanoarray substrates. Being an ultrasensitive detection tool, SERS not only investigates the reactions but also gives the information of the structural alteration of adsorbed molecules and the identification of the reaction product. For example, the plasmon induced dimerization of 4-NTP molecule on the silver nanorods array is monitored by time-dependent SERS as shown in the figure below. The decay in the SERS band at 1346 cm-1 (NO2 stretching vibrations in NTP) and increment in the 1444 cm-1 band corresponds to 4-4 dimercaptoazobenzene (DMAB) have been used to track the reaction. Moreover, the reactions were studied on gold nanoparticles array and the excitation wavelength and power dependent reaction kinetics is also elucidated. We also developed a suitable heterogeneous catalyst combining plasmonic metal (core) and semiconductor (shell) to enhance the catalytic activity of catalyst by supplying the hot carriers from the metal. This was demonstrated by the enhanced degradation rate of various dyes e.g., methylene blue, methyl orange etc. in presence of nano heterostructures. |
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Study on LAuCl catalysis using the P-ligand bearing pseudo-coordinative P=C
4. Catalysis * Shigekazu Ito, Tokyo Institute of Technology, Japan Catalytic functionality of the mononuclear AuCl complex of phosphanoxy-substituted phosphaalkenes Mes*P=C(Ph)-OP(R)Mes* (Mes* = 2,4,6-tri-tert-butylphenyl) is discussed. The presence of alcohol was requisite for the catalytic reactions, indicating the important role of the pseudo-coordinative P=C and the H-bond effect caused by the alcohol molecule. |
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Z-E Isomerization of Azobenzenes in Organic Solvents: Enhancement and Expansion into Red and Near-infrared Range Caused by Gold Nanorods
4. Catalysis * Nina Tarnowicz-Staniak, Wroclaw University of Science and Technology, Poland Marek Grzelczak, Centro de Física de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center, Spain Katarzyna Matczyszyn, Wroclaw University of Science and Technology, Poland Azobenzene-based light-responsive systems for advanced applications can benefit from elongating the Z-isomer lifetime or red-shifting both isomers' excitation wavelengths. This research aimed to investigate the influence of anisotropic gold nanoparticles of a rod-like shape on the Z-E isomerization of azobenzenes in their native organic solvents. The results indicate that the tuning of the optical properties of gold nanostructures can be used to tailor the excitation wavelength of the Z-E photoswitching process of azobenzenes. |
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A gold plasmonic antenna to optically generate ultrafast stationary magnetic fields at the nanoscale
* Mathieu Mivelle, Sorbonne Université / CNRS, France We theoretically demonstrate that a gold photonic nano-antenna, optimized by a genetic algorithm, allows, under high excitation power, to generate a pulse of stationary magnetic fields in the tesla range and at the nanoscale. |
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Coupling plasmonics and electrochemistry on hybrid gold nanostructures Towards plasmon-driven (electro)chemical transformations understandings
6. Plasmonics (fundamentals, engineering and systems) * Vincent Wieczny, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France Denis Château, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France Michel Pellarin, Institut Lumière-Matière, France Christophe Morel, Institut Lumière-Matière, France Frédéric Chaput, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France Stéphane Parola, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France Emmanuel Cottancin, Institut Lumière-Matière, France Christophe Bucher, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France Frédéric Lerouge, Laboratoire de Chimie de l'Ecole Normale Supérieure de Lyon, France In the past few years, gold nanomaterials demonstrated the great ability to activate local (electro)chemical transformations under plasmonic control. However, the underlying mechanisms implicating hot charge carriers remain poorly investigated. The use of electrochemical characterization tools recently offered new insights to access fundamental hot carrier features with the possibility to correlate electronic energy in gold nanoparticles and electrode potential. In that context, the possibility to apply an electrochemical control on nanostructures under photophysical irradiation appears as an interesting parameter to expand the feasibility and understandings of plasmon-driven electrochemical reactions. The present study focuses on broadening the diversity of nanoparticle shapes as well as the diversity of molecular redox systems to open new opportunities of exploring charge transfer at a specific location on the nanosystems, thanks to innovative plasmonic electrodes characterized through electrochemical and spectroscopic measurements. |
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Nonlinear Optical Response of Thin Film Amorphous Gold Nanoparticle Layers
6. Plasmonics (fundamentals, engineering and systems) * Navid Daryakar, Friedrich Schiller University of Jena, Germany Christin David, Friedrich Schiller University of Jena, Germany The nonlinear optical response in thin films containing gold nanoparticles was investigated. The nonlinear Maxwell-Garnett theory was used to obtain the effective third order nonlinear susceptibility of the amorphous layers. In the nonlinear regime, the optical response is modified and the dependence on various system parameters such as fill fraction, layer thickness, illumination conditions and laser intensity were studied and compared to experimental results. |
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A new class of antimicrobial coordination compounds: antibacterial and antibiofilm activity of [AuIII(N^N)X2]PF6 complexes (N^N = 2,2'-bipyridine and 1,10-phenanthroline derivatives, X = Cl, Br)
8. Biomedical applications of gold: in vivo applications and technologies, injectable nanoparticles and pharmacology * Anna Pintus, Università degli Studi di Cagliari, Italy The haxafluorophosphate salts of gold(III) dihalocomplexes belonging to the class [Au(N^N)X2]PF6 (N^N = 2,2'-bipyridine and 1,10-phenanthroline derivatives, X = Cl, Br) were synthesized, characterized, and tested for their antimicrobic properties against different bacterial species. Structure-property relationships were elucidated by cross analyzing the data from the experimental and theoretical characterization of the complexes and the results of the biological tests. |
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Gold as a modifier in creation of multi-functionalize silk protein-based nanomedicines
8. Biomedical applications of gold: in vivo applications and technologies, injectable nanoparticles and pharmacology * Anh T.N. Dao, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan Hitoshi Kasai, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan For the last few decades, drug delivery technologies have been intensively involved nanotechnology to advance the creation of multifunctional drug carriers, and often employed in combination cancer therapy, in which it can accomplish targeting a tumor, delivering therapeutic molecules, imaging and monitoring drug response. Many models were built and tested; still the challenge is at the choice of the appropriate materials and the facilitation of carrier preparation to achieve both safety and efficacy. Reflecting such needs, silk protein was chosen to provide a biodegradable and biocompatible matrix for dispersing noble metallic nanoparticle, as a modifier, and drug molecule, as a therapeutic agent. Such system with controllable structures and compositions can be an advanced type of drug carriers and further contribute to the improvement of cancer therapy. |
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How do surface properties of nanoparticles influence their biological behavior? A model study using polymer-grafted gold nanoparticles and in situ SAXS technique
* Marine Le Goas, Université de Montréal, Canada Tom Roussel, CEA, France Fabienne Testard, CEA, France Xavier Banquy, Université de Montréal, Canada Geraldine Carrot, CEA, France Jean-Philippe Renault, CEA, France Despite profuse literature and promising results, very few cancer nanomedicines have been successfully translated to the clinic. This gap can be partly explained because the biological behavior of nanoparticles, such as their ability to diffuse in tumors or their in vivo stability, is not well understood. Here, we determined the relation between the surface properties of nanoparticles and their biological behavior via the systematic study of a library of polymer-grafted gold nanoparticles. We also developed in situ tools based on small-angle X-ray scattering (SAXS), to enable nanoparticle characterization in biologically relevant environments. |
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Improving systemic radiotherapy with radioenhancing gold nanoparticles
8. Biomedical applications of gold: in vivo applications and technologies, injectable nanoparticles and pharmacology * Marine Le Goas, Université de Montréal, Canada Béatrice Cambien, Université Côte d'Azur, France Geraldine Carrot, CEA, France Jean-Philippe Renault, CEA, France Radiotherapy is widely used for cancer treatment but suffers from side effects due to the irradiation of healthy surrounding tissues. Hence, the use of tumor-located radioenhancers is a promising way to improve the efficacy of radiotherapy. Multiple radioenhancing nanoparticles have been developed, but most studies have only dealt with external beam radiotherapy. This study establishes a proof of concept for a clinically relevant approach combining gold nanoparticles with systemic radiotherapy. |
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Maghemite nanoflowers: multifunctional biodegradable nanocarriers for a better targeting of gold nanoparticles
8. Biomedical applications of gold: in vivo applications and technologies, injectable nanoparticles and pharmacology * Inaya Dabaja, UTINAM UMR 6213, France The combination of magnetic resonance imaging (MRI) with positron emission tomography (PET) in the same imaging session is interesting because it allows to combine the outstanding sensitivity of PET and the high resolution of MRI. In order to have a probe suited for both types of imaging, we have recently developed gold nanoparticles coated with two different organic chelators: TADOTAGA (DOTAGA: chelator of gadolinium ion for MRI) and TA(NODAGA-Lys-NH2) (NODAGA: chelator of copper-64 for PET). These gold nanoparticles (core size: 3nm, hydrodynamic diameter: 6-10 nm) were produced by reducing gold salt in the presence of both types of dithiolated chelators. However, the potential of these gold nanoparticles is not entirely exploited because of a too rapid renal clearance. Therefore, we investigated different methods for postponing renal clearance, which is required for non-biodegradable nanoparticles. One of the strategies we explored rests on the grafting of the gold nanoparticles onto biodegradable iron oxide (maghemite -Fe2O3) nanoflowers which are expected to behave as carriers for targeting atherosclerotic plaques. The immobilization of the gold nanoparticles onto iron oxide nanoflowers was ensured by the modification of the gold nanoparticles using hydrocaffeic acid. The biodistribution of the nanoflowers decorated with the gold nanoparticles was monitored by simultaneous PET/MR imaging after intravenous injection to healthy mice and to mice with atherosclerotic plaques in aorta and their behavior was compared with the one of free gold nanoparticles (i.e. the same gold nanoparticles but not grafted to nanoflowers). From the data collected by imaging, we deduced that the gold nanoparticles are less quickly removed from body when they are grafted to the nanoflowers in comparison to free (i.e. non-supported) gold nanoparticles. Moreover, we observed that the atherosclerotic plaques are better targeted by the gold nanoparticles when the latter are carried by the nanoflowers. |
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PEGylated gold nanoparticles: synthesis, characterization and biodistribution studies
8. Biomedical applications of gold: in vivo applications and technologies, injectable nanoparticles and pharmacology * Inaya Dabaja, UTINAM - UMR6213 - CNRS, France Gold nanoparticles are one of the most promising multifunctional metal nanoparticles in nanomedicine owing to their large palette of tunable properties which paves the way to medical applications combining imaging and remotely controlled therapy. First, gold is a biocompatible metal with exceptional chemical stability. Moreover, this element is characterized by high atomic number (Z=79) and density, allowing it to strongly absorb X rays. In this context, we developed radiosensitizing gold nanoparticles which exhibit a promising potential for radiotherapy guided by magnetic resonance imaging (MRI) and/or by nuclear imaging (SPECT, PET). The follow-up of these gold nanoparticles by MRI is ensured by the ability of the organic shell to form stable complexes with gadolinium ions (for MRI) and radioisotopes for SPECT (In-111) or TEP (68Ga, 64Cu…). For achieving a longstanding immobilization of these ions of interest for medical imaging, the gold core is coated by highly hydrophilic macrocyclic chelators (TAPEGnDOTAGA, with n=0,4,11-(O-CH2-CH2) units). The reduction of the gold salt in presence of these chelators provides whatever n ultra-small gold nanoparticles Au@TAPEGnDOTAGA (core < 3 nm, hydrodynamic diameter 6-10 nm). This protocol, which relies on PEGylated macrocycles, is appealing since it does not require the post-functionalization of nanoparticles with PEG chains, unlike the traditional PEGylation route. Two models were used to test PEGylated nanoparticles in vivo. The first study of the biodistribution of different types of nanoparticles has shown that the length of the PEG chain influences the in vivo behavior of intravenously injected nanoparticles in healthy mice. The second preliminary study was focused on the radiotherapeutic potential of these PEGylated macrocyclic chelators coated gold nanoparticles. Radiotherapy was performed after administration of Au@TAPEGnDOTAGA nanoparticles on chicken embryos with human glioblastomas initiated from the U87 cell line. This study showed the anti-metastatic effect of PEGylated gold nanoparticles. |
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Non-invasive Point-of-care nanobiosensing of cervical cancer as an auxiliary to pap-smear test
9. Biomedical applications of gold: sensors and devices * Mitali Basak, INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI, India Dipankar Bandyopadhyay, INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI, India Cervical cancer (CaCx) is presently one the most common forms of carcinoma among women. Nearly 2.8 billion females aged ~15 years or older are at risk of developing this dreaded disease. Till date, the available techniques, such as pap-smear test1, Lugol’s iodine test (VILI)2, acetone treatment (VIA)2 on cervix among others, for cervical cancer detection in women is painful, invasive, and not instant. The need for painless and non-invasive cervical cancer detection has vital societal importance and the present study works in the same line. Precisely, this work was based on plasmonic gold nanoparticle (Au NP) based portable detection of cervical cancer from urine sample of the patient. A potential cancer antigen (Ag), Protein-Phosphatase-1-gamma-2 (PP1ϒ2) with a restricted expression in testis and sperms was identified as a biomarker specific to cervical cancer (CaCx). Detection of this novel cancer biomarker antigen (NCB-Ag) in human urine opened up the possibility of non-invasive detection of CaCx to supplement the dreaded and invasive Pap-smear test. Absorption based colorimetric response of an assembly of Au NPs was employed for the quantitative, non-invasive, and point-of-care-testing (POCT) of CaCx in the urine. In order to fabricate the immunosensor, Au NPs of sizes ~5–20 nm have been chemically modified with a linker, 3,3'-di-thio-di-propionic-acid-di(n-hydroxy-succinimide-ester) (DTSP) to attach the antibody (Ab) specific to the NCB-Ag. An in-house prototype has been assembled by integrating a light emitting diode (LED) of a narrow range wavelength in one side of a cuvette in which the reaction has been performed while a sensitive photodetector to the other side to transduce the transmitted signal associated with the loading of NCB-Ag in the Ab-DTSP-Au NPs composite. Interestingly, the addition of Ag to the composite of Ab-DTSP-Au NPs leads to a significant change of absorption along with hypsochromic shift due to localized surface plasmon resonance (LSPR) phenomenon, which originates from the specific epitope-paratope interaction between the NCB-Ag and Ab-DTSP-Au NPs. The variations in the absorbance and wavelength shift during such attachments of different concentrations of NCB-Ag on the Ab-DTSP-Au NPs composite were employed as a calibration to identify NCB-Ag in human urine. The proposed immunosensing platform was tested against other standard proteins to ensure non-interference alongside proving the proof-for-specificity of the NCB detection. Furthermore, real patient samples were also tested and the same shows high efficacy of cervical cancer screening. A huge number of sample tests and device optimization bears the potential of developing a useful POCT device for cervical cancer detection. References: 1. Koss, L. G. J. J., The Papanicolaou test for cervical cancer detection: a triumph and a tragedy. 1989, 261 (5), 737-743. 2. Sankaranarayanan, R.; Wesley, R.; Thara, S.; Dhakad, N.; Chandralekha, B.; Sebastian, P.; Chithrathara, K.; Parkin, D. M.; Nair, M. K. J. I. J. o. C., Test characteristics of visual inspection with 4% acetic acid (VIA) and Lugol's iodine (VILI) in cervical cancer screening in Kerala, India. 2003, 106 (3), 404-408. |
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Surface/cell interactions via surface functionalization: bactericidal protection and realization of biocomponents
9. Biomedical applications of gold: sensors and devices * Marion Stalet, Université de Sherbrooke, Institut interdisciplinaire d'innovation technologique - Équipe Biophotonique et Optoéletronique, Canada Michael Canva, LN2 - Université de Sherbrooke, Institut interdisciplinaire d'innovation technologique - Équipe Biophotonique et Optoéletronique, Canada Background. Microbial proliferation in human environments has been one major public health concern for years. Nosocomial and implants infections represent 3,500 to 9,000 deaths per year in France1 especially due to pathogens antibiotic resistance. To effectively fight against these micro-organisms, it is crucial to develop surfaces limiting adhesion and proliferation in its early stages. In the recent years, two main types of methods providing antimicrobial properties to materials have been studied: chemical functionalization using bioactive or anti-adhesive agents2 and physical micro- and nanostructuring, often inspired by natural surfaces such as cicada wings.3 Objectives. The main objective of this PhD is to study the synergy of these two approaches, as it has been little considered. By doing so, it could be possible to get rid of some drawbacks that single approaches may experience, such as chemical degradation, cytotoxicity and biological waste accumulation onto the surfaces. Methods. The antimicrobial activities of single and combined approaches are quantified and compared using microbiological characterization as well as Surface Plasmon Resonance imaging (SPRi) to better understand interactions between the micro-organisms and the engineered surfaces. Gold coated glass is used as the substrate of study to allow SPRi characterization. First, antimicrobial peptides (AMP) functionalization is explored, as they are promising candidates for tackling a wide range of micro-organisms.4 As AMP activity can be greatly modified by several immobilization parameters, peptide orientation and linker length impacts are investigated. For micro and nanofabrication different bioinspired nanostructurations known to have antifouling and antimicrobial properties5 are considered with various morphological parameters such as the aspect ratio, sharpness, density, order. Finally, the two approaches are combined and characterized. Results. A first AMP functionalization using Self-Assembled Monolayer (SAM) of Magainin I and LL-37 was tested to study the impact immobilization parameters on antimicrobial efficiency. A microbiological characterization protocol was developed to assess surface efficiency in reducing bacteria adhesion, viability and growth. The results indicated no significative difference regarding both peptides orientation, but the greatest efficiency was achieved for Magainin I with the short linker. All functionalization demonstrated better efficiency in reducing adhesion (up to 98%) than the bare surface and surface coated with PEG (90% reduction). Regarding the physical structuration, an electrodeposition protocol was developed using gold salts to create nanospikes onto surfaces. This method presents the advantages of being cheap, fast and able to structure in one step rather large samples compared to classical fabrication methods such as lithography. Discussion and conclusion. The parameters of electrodeposition such as precursor concentration, deposition time and applied potential needs to be investigated to study their impact on nanostructures morphology and antimicrobial efficiency. This method present great potential for antimicrobial surfaces but also for SPR, as these structures could be used to optimize detection. It can also be combined with other fabrication techniques to create double-level structures with great self-cleaning properties. For the combination of functionalization and nanostructuration, multiple parameters such as solvent type, AMP concentration and regioselective functionalization should be optimized to create a panel of efficient and durable antibacterial surfaces |