Metal–Polymer Heterojunction in Colloidal-Phase Plasmonic Catalysis

[EN] Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD+ to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal-polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD+ reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity.This work was supported by grant PID2019-111772RB-I00 funded by MCIN/AEI/10.13039/501100011033 and grant IT 1254-19 funded by Basque Government. The authors acknowl- edge the financial support of the European Commission (EUSMI, Grant 731019). S.B. is grateful to the European Research Council (ERC-CoG-2019 815128). The authors acknowledge the contributions by Dr. Adrian Pedrazo Tardajos related to sample support and electron microscopy experiments

Chemotermally fueled transient self-assembly of gold nanoparticles

Resumen del póster presentado a la XXXVIII Reunión Bienal de la Real Sociedad Española de Química, celebrada en el Palacio de Congresos de Granada, del 27 de junio al 30 de junio de 2022.Inspired by biology, the field of supramolecular self-assembly evolved over the years from thermodynamical equilibrium structures towards dissipative assemblies, where molecular building blocks assemble out-of-equilibrium for the time being of fuel consumption. These dissipative assemblies in nature fulfill actions like transport, movement, and catalysis among others. More recently, controlling transient states of nanoparticles using chemical fuel is an emerging field for the creation of active matter, and gives the possibility to exploit new materials with unusual and adaptive properties (e.g. optical, electrical, mechanical). Examples in literature are still rare, due to difficulties of bridging different length scales with the fuel being on the molecular and building blocks on the nanoscopic scale. We report here on coupling a chemothermal cycloaddition reaction with thermosensitive DNA-coated gold nanoparticles[2] (AuDNA) (Figure 1: Coupling chemothermal reaction cycle with thermosensitive DNA coated gold nanoparticles). AuDNA undergo transient redispersion for the time of heat production by the exothermic reaction. After the excessive heat dissipates, AuDNA spontaneously cluster due to DNA rehybridization. Through adjusting the amount of fuel added, different transient states could be accessed as well as their lifetime could be controlled. To the best of our knowledge, this is the first example of coupling thermosensitive nano building blocks with a chemical reaction cycle. Our results expand the existing list of nanoscale constructs sensitive to the outcome of a chemical reaction.Peer reviewe

Coupling reversible clustering of DNA-coated gold nanoparticles with chemothermal cycloaddition reaction

Stimuli-responsive, optically-active colloidal systems are convenient signal transducers capable of monitoring environmental changes at the nanoscale. We report on the coupling of chemo-thermal cycloaddition reaction with temperature-sensitive, DNA-coated gold nanoparticles. We found that the concentration of chemical fuel, dictating the temperature of the mixture, is a primary ingredient in controlling the extent of the reversible clustering of gold nanoparticles. Our results show that rational coupling of chemical and colloidal systems can open up new possibilities in tracking the change of local temperature using aggregation/redispersion of nanoparticles.This work was supported by grant PID2019-111772RB-I00 funded by MCIN/AEI/10.13039/501100011033.Peer reviewe

Bioinspired lipid coated porous particle as inhalable carrier with pulmonary surfactant adhesion and mucus penetration

There is an urgent need for novel inhalable drug carriers to fight respiratory infections. Lipid-coated mesoporous silica particles (LC-MSPs) combine the biocompatibility of lipids with the aerosolization properties of micronized low-density MSPs. In this study, the abundant lung surfactant phospholipid dipalmitoylphosphatidylcholine (DPPC) was used to coat disordered MSPs by means of two methods: vesicle fusion (VF) and spray-drying (SD). FT-IR and TGA analyses indicated the presence of the lipid coating, while SEM images revealed spherical particles with a smooth, homogenous surface and no detectable lipid aggregates. Both the VF and SD methods resulted in full phospholipid coverage on the outer silica surface (>100 %). However, the VF method produced a more homogeneous coating across particles and achieved a higher lipid content compared to SD (7.0 vs 3.0 % w/w). The resulting LC-MSPs exhibited favorable aerosolization properties, enabling efficient pulmonary delivery of clofazimine, a lipophilic antitubercular drug. The DPPC coating promoted interaction with endogenous lung surfactant, which enhanced the dispersion of the particles in the alveolar environment and significantly increased drug dissolution (from 35 to 75 %). Lipid coating significantly enhances particle adhesion and penetration across the human bronchial mucus layer and into the underlying tissue. Overall, our study presents a refined formulation strategy using phospholipid-coated MSPs as a single-component dry powder carrier, offering targeted lung deposition, enhanced drug dissolution, mucoadhesion, and tissue penetration

Metal-polymer heterojunction in colloidal-phase plasmonic catalysis

[Image: see text] Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD(+) to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal–polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD(+) reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity

Metal–Polymer Heterojunction in Colloidal-Phase Plasmonic Catalysis

Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD+ to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal–polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD+ reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity

Metal–Polymer Heterojunction in Colloidal-Phase Plasmonic Catalysis

Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD+ to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal–polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD+ reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity

Supramolecular chemistry in solution and solid–gas interfaces: synthesis and photophysical properties of monocolor and bicolor fluorescent sensors for barium tagging in neutrinoless double beta decay

Translation of photophysical properties of fluorescent sensors from solution to solid–gas environments via functionalized surfaces constitutes a challenge in chemistry. In this work, we report on the chemical synthesis, barium capture ability and photophysical properties of two families of monocolor and bicolor fluorescent sensors. These sensors were prepared to capture barium cations that can be produced in neutrinoless double beta decay of Xe-136. These sensors incorporate crown ether units, two different fluorophores, aliphatic spacers of different lengths, and a silatrane linker that forms covalent bonds with indium tin oxide (ITO) surfaces. Both species shared excellent Ba2+ binding abilities. Fluorescent monocolor indicators (FMIs), based on naphthyl fluorophores, showed an off–on character in solution controlled by photoinduced electron transfer. Fluorescent bicolor indicators (FBIs), based on benzo[a]imidazo[5,1,2-cd] fluorophores, exhibited a significant change in their emission spectra on going from the free to the barium-bound state. Both FMIs and FBIs showed similar photophysics in solution and on ITO. However, their performance on ITO was found to be attenuated, but not fully extinguished, with respect to the values obtained in solution, both in terms of intensity and selectivity between the free and Ba2+-bound states. Despite this issue, improved performance of the FBIs based on confocal microscopy of the directly attached molecules was observed. These selective FMI and FBI chemosensors installed on tailor-made functionalized surfaces are promising tools to capture the barium cations produced in the double beta decay of Xe-136. The identification of this capture would boost the sensitivity of the experiments searching for the Xe-136-based neutrinoless double beta decay, as backgrounds would be almost totally suppressed.Financial support for this work was provided by the European Research Council (ERC) under the European's Union Horizon 2020 research and innovation programme (H2020 ERC-SyG 951281), by the Spanish Ministerio de Ciencia, Innovación y Universidades (Grant PID2023-151549NB-I00, funded by MICIU/AEI/10.13039/501100011033 and by FEDER, EU) and by the Gobierno Vasco/Eusko Jaurlaritza (GV/EJ, Grant IT-1553-22). The authors thank the SGI/IZO-SGIker of the UPV/EHU and the DIPC for the generous allocation of analytical and computational resources. Technical assistance for confocal microscopy from Achucarro Basque Center for Neuroscience-Imaging Facility (UPV/EHU Scientific Park, Spain) is gratefully acknowledged