With the development of nanomaterials and the increasing level of their complexity, there is a need for tools able to guide the management and evaluation of their toxicity. In the framework of European project HARMLESS, hybrid multi-component systems have been developed and will be tested in a safe by design approach (SbD). These nanomaterials consist of nanotubes high aspect ratio (HAR) covered by spherical metal nanoparticles. To be more precise, the nanotubes are alumino-silicate clays, called imogolites (Imo), easily synthesized by sol-gel methods. These nanotubes can be obtained with different level of complexity; the outer layer is made of alumina while either OH or CH3 group covers the inner core. One important characteristic of these tubes is their monodisperse pore size.The surface functionalization of these nanomaterials is (an effective approach) often applied to vary their versatile properties and enriching the range of potential applications. In particular, the external surface imogolites can be adjusted by using functionalization processes1 which have to be performed cautiously and demonstrations of imogolites decorated by Pt, Ag or Au nanoparticles have been reported. Our purpose was to obtain an advanced multi-constituent nanomaterial that is relevant for environmental applications and potentially respect the safe by design principle. In our study, Imogolites with an external surface functionalized by isotropic copper nanoparticles (Cu NPs) are synthesized and characterized by several techniques (SAXS, AFM, TEM, SEM, cryoTEM, UV-Vis, IR). The size and morphology of the Cu NPs can be modulated through two approaches: microwave irradiation and radiolysis. Our first results show that microwave irradiation produces spherical nanoparticles with optimum size of 40 nm, while radiolysis produce facetted particles of similar sizes. The characterization of those nanomaterials were discussed in relation with their reactivity.

Noble metal nanoparticles have been extensively studied because of the ease of their synthesis and the diverse structure – property relationships that they present. Specifically, optical properties can be tuned by modifying the nanoparticle composition, size, and shape. Gold nanoparticles (AuNPs) are particularly interesting because their surface plasmon resonance (SPR) can be tuned within almost the entire range of the visible spectrum. Additional modulation of optical properties can be achieved through the preparation of organized nanoparticle assemblies. In gold nanorings, the SPR band is determined not only by the properties of individual nanoparticles, but also by the ring diameter and interparticle coupling, making possible the modification of their optical properties by changing the ring dimensions. This is particularly useful because, using nanoparticles with a similar diameter, it is possible to assemble them to form nanorings with different SPR bands. Also, this versatility allows for post-synthesis modifications which makes these structures excellent candidates for the dynamic detection of different ions and molecules. The aim of this research is to develop and optimize a process that allows the easy and reproductible fabrication of gold nanorings to be used as plasmonic sensors. The procedure involves three main stages: AuNP synthesis, self-assembly of the nanoparticles around the hydrophobic domains of a block copolymer template followed by deposition on a solid substrate using the Langmuir-Blodgett (LB) technique, and finally growing the AuNPs after the deposition to attain the desired size to tune the SPR band. More specifically, thiol-capped AuNPs are mixed with poly(styrene)-b-poly(2-vinyl pyridine) (PS-b-P2VP) and spread at the air – water interface. The PS-b-P2VP self-assembles to form circular hydrophobic domains composed of aggregated PS surrounded by a corona of P2VP which spreads as a monolayer at the water surface. The organisation of the NPs within the block copolymer template is highly sensitive to their size. Particles with a diameter greater than 6 - 8 nm assemble within the PS domains whereas smaller particles (3 - 6 nm) spontaneously assemble at the periphery of the PS domains to form nanorings. The nanorings are then transferred to a glass substrate where further modifications are possible, such as increasing the nanoparticle diameter using a regrowth process. By controlling the growing conditions, AuNP size has been increased from 3 – 4 nm to 10 – 15 nm. The influence of different parameters such as the choice of reducing agent, reagent concentrations, stirring speed and temperature have been studied. To date, the best results are obtained when particles with initial diameters of around 4 nm are used in the self-assembly stage and their size is increased to around 10 nm after deposition by the reduction of Au(III) with ascorbic acid. However, maintaining a relatively narrow particle size distribution during the regrowth stage is still a challenge.

Gold nanorods are well known due to their distinct resonance modes, with the longitudinal mode being widely used in photothermal therapy, in exaltation spectroscopy/catalysis and in biodetection. Indeed, it is possible to exploit the change in frequency of the longitudinal mode to detect the capture of an analyte by a molecular probe immobilized on the nanoparticle. On the other hand, the transverse resonance mode of the nanorod is seldom used for this purpose due to a lower sensitivity to changes in refraction index ; furthermore, since this mode is mainly associated with the sides of the nanorods, analyte molecules captured on these facets do not contribute to the shift in resonance frequency of the longitudinal mode. This decreases the overall detection sensitivity and is most problematic for low analyte concentrations or when the association of the analyte with the capture probe is weak. In this work, we attempt to take advantage of the transverse mode and its associated facets by forming a silica shell anisotropically on the sides of the nanorods. This strategy allows to (1) attach probes only to the more sensitive ends of the nanorods, (2) use the transverse mode as a reference during measurements, and (3) add functionality to the nanostructure with the silica surface now available for further modification. The anisotropic growth of the silica shell using a Stöber protocol adapted for nanorods is performed by protecting the ends of the nanorods with a thiolated polyethylene oxide (PEO). This poster will present the relative merits of the various synthesis parameters for controlling the thickness and surface coverage of the silica shell.

Green hydrogen production by photocatalytic water splitting offers a promising way to solve environmental and energy issues. Modification of TiO2 surface with metal nanoparticles (NPs) leads to improve their photocatalytic activity. In particular, noble metal (Pt, Pd, Ag, Au) NPs have appeared as a very promising way to induce the photocatalytic activity of TiO2 and may allow the extension of the light absorption of wide band-gap semiconductors to the visible light due to the Localized Surface Plasmon Resonance (LSPR). Bimetallic NPs have attracted attention because they exhibit new solid-state properties which differ from their mono- and bimetallic Au-Pd NPs, which demonstrated to enhance the photocatalytic activity to generate hydrogen. The photocatalytsts were synthesized by chemical reduction methos using NaBH4 as strong reducing agent at room temperature. Bimetallic Au-Pd spherical NPs homogeneous in size, and well dispersed on Tio2 surface were obtained. The results showed a synergistic effect obtained with surface modification with Au-Pd bimetallic NPs, which present higher photocatalytic activity than their monometallic counterparts under UV-visible light irradiation. The photocatalysts were characterized High Resolution Transmission Electron Microscopy (HRTEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDS), Diffuse Reflectance Spectroscopy (DRS), X-Ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The charge carrier dynamics was studied by Time Resolved Microwave Conductivity (TRMC).

We have recently found that [PtAu24(SC2H4Ph)18]– (X–) with an icosahedral Pt@Au12 (7e) core was spontaneously formed via electron transfer (ET) from [PtAu24(SC2H4Ph)18]2– (X2–) to [PtAu24(SC2H4Ph)18]0 (X0) with Pt@Au12 (6e) and Pt@Au12 (8e) cores, respectively: X2– + X0 → 2X–. Since the ET reaction requires the overlap of the superatomic 1P orbitals of the Pt@Au12 cores of X2– and X0, it is expected that the thickness of the insulating layer affects the ET rates. We herein systematically investigated the rate constants for ET (kET) from [PtAu24(SCnH2n+1)18]2– (Xn2–) to [PtAu24(SCmH2m+1)18]0 (Xm0) as a function of the chain lengths of alkanethiolate ligands in the range of n, m = 2–16. We observed turnover behavior of the kET values as a function of the total chain length (n+m). Most notably, kET increases with increase in the n+m values (>12), implying that the ET probability increases with the elongation of the lifetime of the dimer intermediate (XnXm)2– due to stronger vdW interaction between the longer alkyl chains. This hypothesis was supported by the observation of (XnXm)2– by ESI-MS measurement of the mixture of Xn2– and Xm0.

E-waste is a growing problem with only a small fraction or devices getting recycled. These devices present both a potential environmental liability but also a resource opportunity for the precious metals such as gold they contain. To best deal with this, it is important to be able to profile the elements in these waste streams. To provide this information an accurate and quantitative assay is required that will allow for the detection of multiple elements and ideally have minimal sample preparation and processing requirements. To achieve this we have developed a neutron activation method that makes use of the waste neutrons produced by cyclotron during routine operation.

Supported gold nanoclusters can show high catalytic activity when dispersed on oxide surfaces, while bulk gold is inert [1]. Recently, it has been discovered that single-atom catalysts, consisting of isolated metal atoms dispersed on surfaces, could enhance some catalytic reactions in comparison with the corresponding supported nanoparticle [2]. Likewise, two dimensional materials have been intensively investigated mainly due to their potential applications in catalysis, transistors, batteries and chemical sensing. In particular, it has been theoretically predicted that graphene-like tin carbide (SnC) two-dimensional monolayer is a stable, indirect-gap semiconductor [3-5]. In this work, the interactions between oxygen molecule O2 with pristine and gold-decorated tin carbide monolayers were investigated by using spin-polarized density functional calculations, within the generalized gradient approximation. The results indicate that O2 is adsorbed, with an energy of 0.95 eV, on the pristine SnC nanosheet in a configuration where one oxygen atom is close to a carbon atom and the other one is close to a tin atom, respectively. There is a large electronic charge transfer from the SnC monolayer to the O2 molecule, which enlarges the molecule internal bond, indicating an activation towards a peroxo-like state. Also, a gold adatom can strongly bind to the SnC monolayer over a C atom leading to a stable decorated nanosheet. Furthermore, when O2 interacts with this Au adatom, it is spontaneously dissociated with an energy gain of 1.84 eV and where the final adsorption configuration consists of each oxygen atom located on the top of different tin atoms but sharing the gold one. Hence, the Au-2DSnC could be contemplated as a potential single-atom catalyst for chemical reactions involving the dissociation of O2, such as the oxidation of CO. This work was supported by UNAM-PAPIIT IN109320 and IPN-SIP 2020-2093, 2021-0236. Computational resources were given through Project LANCAD-UNAM-DGTIC-180. [1] J.A. van Bokhoven et al., J. Phys. Chem. C 111, 9245 (2007) https://doi.org/10.1021/jp070755t. [2] J. Li et al., Chem. Rev. 120, 11699 (2020) https://doi.org/10.1021/acs.chemrev.0c01097 [3] H. Sahin et al., Phys. Rev. B 80, 155453 (2009) https://doi.org/10.1103/PhysRevB.80.155453 155453 [4] T.-Y. Lü et al., J. Mater. Chem. 22, 10062 (2012) https://doi.org/10.1039/C2JM30915G [5] Y. Mogulkoc et al., J. Chem. Phys. Solids 111, 458 (2017) https://doi.org/10.1016/j.jpcs.2017.08.036

In this work, monolayers containing silver nanocubes and gold nanoparticles are used to generate hot electrons. The generated hot electrons are used to reduce halogenated thiophenols to thiophenol and 4,4-biphenyldithiol. The hot electrons generated by silver and gold monolayered substrates are compared against the hot electrons generated by gold monolayered substrates and silver monolayered substrates. The reduction reactions is monitored using surface enhanced Raman spectroscopy (SERS).

The proof of the concept of a new, one step and safe by design process to synthesize metal-polymer nanocomposites thin films on a large surface is presented. It is based on the injection of an aerosol of a solution of metal (gold) salts dissolved in a polymerisable solvent (isopropanol or ethyl lactate) into an argon atmospheric pressure (AP) dielectric barrier discharge (DBD). The main novelty of this PECVD (Plasma Enhanced Chemical Vapor Deposition) method resides in the fact that the nanoparticles are formed in situ, inside the plasma reactor, in the gas phase. Consequently, the nanoparticle synthesis and deposition is concomitant with the solvent polymerization used to produce the matrix, which makes it possible to obtain homogeneous layers of non-agglomerated nanoparticles (NPs) with high NPs density. A large range of thin film morphology and plasmonic properties are obtained.

Background & Objectives: Currently, systemic drugs injections reach tumor sites only to a very limited extent and, as a result, high doses, relative to the patient’s needs, are administered, causing harmful side effects and excessive toxicities [1]. The new implementations of nanoparticles in the medical field offer new strategies to vectorize an active substance in diseased cells. This work is focused on the development of nanohybrids based on titanate nanotubes (TiONts) to fight against prostate cancer by intratumoral (IT) injection, which is the second most frequently diagnosed cancer and the fifth leading cause of cancer death in men worldwide [2]. Their uncommon morphology allows them to be internalized more easily into cells without inducing cytotoxicity while producing a radiosensitizing effect [3]. In literature, the use of TiONts as carriers of therapeutic molecules such as docetaxel (TiONts-DTX) into prostate tumor showed nanohybrid ability to remain inside the tumor and tumor growth after irradiation was significantly slowed in mice receiving TiONts-DTX compared to mice receiving free DTX [1]. Encouraged by these results, it was necessary to further improve the in vivo radiosensitizing effect of these nanohybrids into tumor prostate by immobilizing DTDTPA-modified gold nanoparticles (Au@DTDTPA NPs), which appear to be attractive for image-guided radiotherapy, are biologically well-tolerated and exhibit low toxicity [4]. Methods & Results: TiONts are synthesized by a hydrothermal process. To develop the custom-engineered nanohybrids, the surface of TiONts is coated beforehand with a siloxane and coupled with both Au@DTDTPA NPs and a heterobifunctional polymer (PEG3000) to significantly improve suspension stability and biocompatibility of TiONts for biomedical applications. The pre-functionalized surface of this scaffold has reactive sites to graft DTX (TiONts-AuNPs-PEG3000-DTX). This novel combination, aimed at retaining the AuNPs inside the tumor via TiONts, is able to enhance the radiation effect. Nanohybrids are extensively characterized and detectable by SPECT/CT imaging through grafted Au@DTDTPA NPs, radiolabeled with 111In. In vitro results showed that nanohybrids have a substantial cytotoxic activity on human PC-3 prostate adenocarcinoma cells, in contrast to initial nanohybrids without DTX. Biodistribution studies demonstrated that these novel nanocarriers are retained within the tumor for at least 20 days on mice PC-3 xenografted tumors after IT injection, further delaying tumor growth upon irradiation. Conclusion: The combination of Au@DTDTPA NPs with TiONts overcomes some limitations by (i) maintaining of nanotubes on site thanks to the design of nanohybrids compared to circulating nanovectors, (ii) improving the efficiency of nanohybrids in IT, and (iii) allowing combined injection of nanohybrids with radioactive iodine seeds during brachytherapy. Finally, the AuNPs grafting onto TiONts, associated with anticancer agents, paves the way to the combination of tumor retention, radiosensitization, and chemotherapy in the same entity, and appears to be a new, attractive, and versatile platform for the prostate cancer treatment. [1] Mirjolet, C. et al., International Journal of Nanomedicine, 2017, 12, 6357–6364. [2] Rawla, P., World Journal of Oncology, 2019, 10, 63–89. [3] Mirjolet, C. et al., Radiotherapy and Oncology, 2013, 108 (1), 136-142. [4] Loiseau, A. et al., Cancers, 2019, 11, 1962.

The potential applications of gold nanoparticles (NPs) for nanomedicine and biosystem imaging have strongly increased. However, few cancer nanodrugs have been successfully translated into clinical use. Among the various nanomedicine-based treatments, photothermal therapy is an extremely promising method in oncology, suitable for the treatment of solid, localized, and shallow tumors. The use of plasmonic particles-generated hyperthermia allows targeted removal of the tumor without creating significant peripheral toxicity, which constitutes a great benefit for the patient compared to chemotherapy. However, the stability of plasmonic particles in a biological environment is unpredictable, which limits their photothermal efficiency and hinders their translation to the clinic. The colloidal stability of plasmonic NPs is ensured by organic surface ligands that can be degraded or undergo exchange with molecules naturally present in vivo. This can, in turn, change the surface properties (and therefore affect the targeting ability) and/or alter the core of the NP (dissolution, aggregation, reorganization). Understanding the mechanisms responsible for this instability and developing strategies to ensure the stability of plasmonic NPs in biological environments, to increase the therapeutic efficacy of photothermal treatments is needed. Dynamic Differential Microscopy (DDM), a versatile technique can characterize the dynamics of particles (and therefore their size) in a large variety of samples, from biological media to cells or living zebrafish larvae. DDM can be used to follow ligand exchange on the surface of NPs. Different ligand exchange conditions were studied, varying both the initial and incoming ligands (polymers, proteins). All the measurements carried out make it possible to follow the evolution of the surface chemistry in very different media.

We present herein the development of a new technique, based on plasmonic labeling of live cells before fixation to improve the reliability of cytopathology diagnosis. This cost-effective and sensitive methodology is based on the optical properties of spectrally distinct metallic nanoparticles (NPs), in this case gold and gold-silver alloy NPs, conjugated with specific antibodies to target specific antigens. We believe that the excellent stability and biocompatibility of these nanoparticles, as well as the very strong signal that they scatter, make these new biomarkers extremely efficient. The overall methodology includes all steps, from accurate synthesis of nanoparticles with controlled size and composition to visualization of cytopathological samples decorated with plasmonic biomarkers, including functionalization strategies to turn plasmonic markers into plasmonic biomarkers. The visualization approach for immunoplasmonic microscopy (IPM) has been adapted in order to be compatible with existing hardware in pathology laboratories. It consists in a multispectral side-illumination darkfield microscopy that stands out from standard strategies for plasmonic visualization by its simplicity. In addition to providing an excellent contrast for nanoparticles located on cellular membranes, it offers the possibility to build an extremely compact module, adaptable to any microscope. The presented method can provide an easy routine for immunoplasmonic labeling of cythopathological samples in order to improve the reliability of cancer diagnosis.

Currently, more than 90% of ophthalmic drugs are administered by eye drops. However, the passage of drugs through the cornea is the main obstacle to their therapeutic action in the eye. The percentage of active products available in the anterior chamber of the eye, behind the cornea, is less than 0.02%. This nanotechnology is a drug carrier based on gold nanoparticles. Much research is underway to develop mucoadhesive drug carriers for these diseases to improve drug delivery in eye drops. However, everyone has a different ocular mucin composition and some eye diseases also alter the ocular mucosa. Therefore, the development of a molecular platform for the sensitive and selective determination of mucins present on the ocular surface would allow for an efficient improvement in the diagnosis in certain cases, and in the treatment of ocular diseases by proposing the most suitable drug carrier for everyone

Among all the point-of-care devices that have been developed over the past years, Lateral-flow Immunoassays (LFIAs) are probably the most widely used. Indeed, LFIAs combine all the POC features such as easy read-out signal (naked eye observation), low cost and ease of use. Gold nanoparticles (AuNPs) are classically used as colorimetric reporters in LFIAs. However, current LFIAs possess a poor sensitivity (around µM) compared to ELISAs (pM to nM). To address this issue, we envisaged the use of a colorimetric reporter with better optical properties than AuNPs, silver nanostructures (AgNPs) such as spheres or triangular nanoplates. Indeed, these latter also exhibit a LSPR band in the visible region but with an extinction coefficient at least one order of magnitude higher than classical AuNPs, acting as better colorimetric reporters. If AgNPs represent thus better candidates than AuNPs for the design of LFIAs, their use has however been scarcely reported in the literature due to their poor chemical and colloidal stabilities. An efficient strategy for the building of robust and thin organic interface on various surfaces consists in using calix[4]arene-tetradiazonium salts. Indeed, these molecular platforms can be irreversibly and strongly grafted on surfaces through the reduction of their diazonium groups. We have adapted this calixarene-based coating technology to produce ultra-stable AgNPs, much more stable than most of the commercially available AgNPs, that can be easily manipulated and conjugated to biomolecules such as proteins. As proof-of-concept, these calixarene-coated AgNPs were used as colorimetric reporters in LFIAs to detect different biomolecules of great medical interests (eg. SARS-Cov-2 antibodies, see Figure 1). Our results highlight that the use of AgNPs allows, with 10 times less particles, to decrease 10-fold the limit of detection in comparison to standard AuNPs while using model samples, i.e. target spiked in buffer. Furthermore, due to the extreme stability of these AgNPs, the biomolecules could be detected in complex media such as human plasma or cell lysate and even in clinical samples. Our findings are of general interest for the diagnosis field as it could pave the way to the development of improved LFIA-type applications using silver nanostructures.