Cellulose as an Inert Scaffold in Plasmon-Assisted Photoregeneration of Cofactor Molecules

Plasmonic nanoparticles exhibit excellent light-harvesting properties in the visible spectral range, which makes them a convenient material for the conversion of light into useful chemical fuel. However, the need for using surface ligands to ensure colloidal stability of nanoparticles inhibits their photochemical performance due to the insulating molecular shell hindering the carrier transport. We show that cellulose fibers, abundant in chemical functional groups, can serve as a robust substrate for the immobilization of gold nanorods, thus also providing a facile way to remove the surfactant molecules. The resulting functional composite was implemented in a bioinspired photocatalytic process involving dehydrogenation of sodium formate and simultaneous photoregeneration of cofactor molecules (NADH, nicotinamide adenine dinucleotide) using visible light as an energy source. By systematic screening of experimental parameters, we compare photocatalytic and thermocatalytic properties of the composite and evaluate the role of palladium cocatalyst.M.G. acknowledges funding from the Spanish MINECO (grant MAT2013-49375-EXP) and the BBVA Foundation "Primera convocatoria de ayudas fundacion BBVA a investigadores, innovadores y creadores culturales". N.T.-S. acknowledges the support from the BioTechNan (NCBiR) program of interdisciplinary PhD studies at Wroclaw University of Science and Technology as well as the support from the Photonics and Bionanotechnology Association (PhoBiA). The work was also financed by a statutory activity subsidy from the Polish Ministry of Science and Higher Education for the Faculty of Chemistry of Wroclaw University of Science and Technology. S.V. D. and V. P. acknowledge the support by the Spanish Ministry of Science, Innovation, and Universities (project BIO2017-88030-R), Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency grant no. MDM-2017-0720

Statistical thermodynamics in reversible clustering of gold nanoparticles. A first step towards nanocluster heat engines

A statistical thermodynamics variational criterion is propounded to study thermal hysteresis in reversible clustering of gold (Au) nanoparticles. Experimentally, a transient equilibrium mapping analysis is employed to characterize it thermodynamically, further measurements being performed at the nanostructural and electrochemical levels (UV-Vis-NIR spectra, SLS/SAXS, zeta potential). Theoretically, it is successfully interpreted as a thermodynamic cycle, prompting that nanoclusters has potential to produce useful work from heat and paving the way to nanoclustering heat engines. By taking into account the virial expansion of hysteretic pressure, an entropy measure is deduced for a dilute system with given virial coefficients. This allows us to figure out the role of relevant interparticle potential parameters (i.e. surface potential, nanoparticle size, Debye's length, Hamaker energy) in both isothermal and isochoric variations at the onset of hysteresis. Application to spherical Au nanoparticles in watery salt solution (NaCl) is developed when an ad-hoc (DLVO) pairwise potential governs the second virial coefficient at the nanoscale. In particular, the variational criterion predicts a pressure drop between heating and cooling paths which is likely at the base of some energy redistribution (e.g. ordering/restructuring of electric double layers). We found an integrating factor that is able to numerically predict the existence of a critical value for the initial salt concentration maximizing the hysteretic area, and the effect of nanoparticle size on the cycle extent.A.A. and A.I acknowledge the Grant PID2021-123438NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, as well as financial support of Eusko Jaurlaritza, code: IT-1566-22 and from the IKUR Strategy. A. I. thanks MICINN for a Personal Técnico de Apoyo contract (PTA2017-14359-I). Correspondence of one of the authors (S.A.M.) with Dezső Boda (IASK/UP - Hungary) is kindly acknowledged. This work was supported by grant PID2019-111772RB-I00 funded by MCIN/AEI/ 10.13039/501100011033

Robust Rules for Optimal Colorimetric Sensing Based on Gold Nanoparticle Aggregation

Spurred by outstanding optical properties, chemical stability, and facile bioconjugation, plasmonic metals have become the first-choice materials for optical signal transducers in biosensing. While the design rules for surface-based plasmonic sensors are well-established and commercialized, there is limited knowledge of the design of sensors based on nanoparticle aggregation. The reason is the lack of control over the interparticle distances, number of nanoparticles per cluster, or multiple mutual orientations during aggregation events, blurring the threshold between positive and negative readout. Here we identify the geometrical parameters (size, shape, and interparticle distance) that allow for maximizing the color difference upon nanoparticle clustering. Finding the optimal structural parameters will provide a fast and reliable means of readout, including unaided eye inspection or computer vision.J.L.M.-P., N.Z., and J.A. acknowledge financial support from Spanish MICIN/AE/DOI 10.13039/501100004837, Reg. No. PID2019-107432GB-I00 and from the Department of Education of the Basque Government under Project IT1526-22. M.G. acknowledges Euskampus Foundation for financial support (Resilience COVID19). This work received computational support from DIPC's HPC cluster ATLAS, operated by DIPC Supercomputing Center

On-demand reversible switching of the emission mode of individual semiconductor quantum emitters using plasmonic metasurfaces

The field of quantum technology has been rapidly expanding in the past decades, yielding numerous applications as quantum information, quantum communication and quantum cybersecurity. The central building block for these applications is a quantum emitter (QE), a controllable source of single photons or photon pairs. Semiconductor QEs such as perovskite nanocrystals (PNCs) and semiconductor quantum dots (QDs) have been demonstrated to be a promising material for pure single-photon emission, and their hybrids with plasmonic nanocavities may serve as sources of photon pairs. Here we have designed a system in which individual quantum emitters and their ensembles can be traced before, during, and after the interaction with the external plasmonic metasurface in controllable way. Upon coupling the external plasmonic metasurface to the array of QEs, the individual QEs switch from single-photon to photon-pair emission mode. Remarkably, this method does not affect the chemical structure and composition of the QEs, allowing them to return to their initial state after decoupling from the plasmonic metasurface. By employing this approach, we have successfully demonstrated the reversible switching of the ensemble of individual semiconductor QEs between single-photon and photon pair emission modes. This significantly broadens the potential applications of semiconductor QEs in quantum technologies

Plasmonic supercrystals

For decades, plasmonic nanoparticles have been extensively studied due to their extraordinary properties, related to localized surface plasmon resonances. A milestone in the field has been the development of the so-called seed-mediated growth method, a synthetic route that provided access to an extraordinary diversity of metal nanoparticles with tailored size, geometry and composition. Such a morphological control came along with an exquisite definition of the optical response of plasmonic nanoparticles, thereby increasing their prospects for implementation in various fields. The susceptibility of surface plasmons to respond to small changes in the surrounding medium or to perturb (enhance/quench) optical processes in nearby molecules, has been exploited for a wide range of applications, from biomedicine to energy harvesting. However, the possibilities offered by plasmonic nanoparticles can be expanded even further by their careful assembly into either disordered or ordered structures, in 2D and 3D. The assembly of plasmonic nanoparticles gives rise to coupling/hybridization effects, which are strongly dependent on interparticle spacing and orientation, generating extremely high electric fields (hot spots), confined at interparticle gaps. Thus, the use of plasmonic nanoparticle assemblies as optical sensors have led to improving the limits of detection for a wide variety of (bio)molecules and ions. Importantly, in the case of highly ordered plasmonic arrays, other novel and unique optical effects can be generated. Indeed, new functional materials have been developed via the assembly of nanoparticles into highly ordered architectures, ranging from thin films (2D) to colloidal crystals or supercrystals (3D). The progress in the design and fabrication of 3D supercrystals could pave the way toward next generation plasmonic sensors, photocatalysts, optomagnetic components, metamaterials, etc. In this Account, we summarize selected recent advancements in the field of highly ordered 3D plasmonic superlattices. We first analyze their fascinating optical properties for various systems with increasing degrees of complexity, from an individual metal nanoparticle through particle clusters with low coordination numbers to disordered self-assembled structures and finally to supercrystals. We then describe recent progress in the fabrication of 3D plasmonic supercrystals, focusing on specific strategies but without delving into the forces governing the self-assembly process. In the last section, we provide an overview of the potential applications of plasmonic supercrystals, with a particular emphasis on those related to surface-enhanced Raman scattering (SERS) sensing, followed by a brief highlight of the main conclusions and remaining challenges.Agencia Estatal de Investigación | Ref. MAT2017-86659-RMinisterio de Economía, Industria y Competitividad | Ref. MAT2016-77809-

Strontium titanate (SrTiO3) mesoporous coatings for enhanced strontium delivery and osseointegration on bone implants

The incorporation of strontium (Sr) in titania enhances surface bioactivity and has a positive effect on pre-osteoblastic cell attachment, proliferation, and differentiation. Strontium titanate mesoporous films (SrTiMFs) with 30% pore volume and a 20% Sr molar content have been prepared by the evaporation induced self-assembly method. SrTiMFs display a large internal surface area available for exchange of Sr, which is released in cell media up to 44% within the first 8 h. SrTiMFs improve attachment of MC3T3-E1 pre-osteoblastic cells, which show larger filopodia and more elongated features than cells attached to plain mesoporous titania films (MTFs). SrTiMFs also display improved cell proliferation and differentiation rates indicating that overall Sr incorporation into mesoporous titania coatings can lead to enhanced osseointegration during the early stages of bone tissue formation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bordoni, Andrea Veronica. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez, Angel. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Coy, Emerson. Adam Mickiewicz University. Nanobiomedical Centre; PoloniaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Antibacterial mesoporous titania films with embedded gentamicin and surface modified with bone morphogenetic protein 2 to promote osseointegration in bone implants

Novel approaches are needed to avoid bacterial infections following implant surgery. Here the use of mesoporous titania films (MTFs) for gentamicin loading and delivery and the surface functionalization of MFTs with human recombinant bone morphogenetic protein 2 (hrBMP-2) are discussed. Gentamicin is incorporated into the MTF pores by immersion of the porous materials in gentamicin solution while hrBMP-2 is adsorbed on top of the MTF. Contact angle and X-ray photoelectron spectroscopy measurements are performed to prove gentamicin loading and hrBMP-2 functionalization. An initial burst release of gentamicin takes place in physiological media followed by a prolonged release that lasts weeks. Such a release profile is highly appealing for bone implants where a high concentration of antibiotics is necessary during implant surgery while a lower antibiotic concentration is needed until tissue is regenerated. The MTFs loaded with gentamicin and functionalized with hrBMP-2 are effective against Staphylococcus aureus colonization, and the presence of hrBMP-2 enhances MC3T3-E1 preosteoblastic cell attachment, proliferation, and differentiation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Centro de Investigación Cooperativa en Biomateriales; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coy, Emerson. Adam Mickiewicz University; PoloniaFil: Liu, Hui. Chinese Academy of Sciences; República de ChinaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Wang, Guocheng. Chinese Academy of Sciences; República de ChinaFil: Angelome, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Delcea, Mihaela. University of Greifswald; AlemaniaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Strong coupling effects in hybrid plexitonic systems

Trabajo presentado a la 3rd International Conference on Applications of Optics and Photonics, celebrado en Faro (Portugal) del 8 al 12 de mayo de 2017.We investigated the interactions between localized plasmons in gold nanorods and excitons in J-aggregates and were able to track an anticrossing behavior of the hybridized modes both in the extinction and in the photoluminescence spectra of this hybrid system. We identified the nonlinear optical behavior of this system by transient absorption spectroscopy. Finally using magnetic circular dichroism spectroscopy we showed that nonmagnetic organic molecules exhibit magneto-optical response due to binding to a plasmonic nanoparticles. In our experiments we also studied the effect of detuning as well as the effect of off- and on resonance excitation on the hybrid states.We acknowledge financial support from Project Fis2016.80174-P (PLASMOQUANTA) from MINECO (Ministerio de Economía y Competitividad). L.L.-M. acknowledges funding from the European Research Council (ERC Advanced Grant 267867, Plasmaquo). This study was supported by the Ministry of Education and Science of the Russian Federation, grant no. 14.Y26.31.0011.Peer Reviewe