Plasmonics Devoted to Photocatalytic Applications in Liquid, Gas, and Biological Environments

Plasmonic nanomaterials have emerged in the last years as a very interesting option for many photocatalytic processes. Their localized surface plasmon resonance (LSPR) brings in some unique properties that overcome some of the drawbacks associated with traditional photocatalysis based on semiconductors. Even when in its infancy, many advances have been made in the field, mainly related to the synthesis of new structures with the capabilities of light absorption in the whole solar spectrum. A great number of reactions have been attempted using nanoplasmonic materials. In this chapter, we present the most recent advances made in the field of plasmonic photocatalysis comprising an introductory section to define the main types of plasmonic nanomaterials available, including the most recently labeled alternatives. Following with the major areas of catalytic application, a second section of the chapter has been devoted to liquid-phase reactions for the treatment of pollutants and a selection of organic reactions to render added-value to chemicals under mild conditions. The third part of the chapter addresses two specific applications of nanoplasmonic photocatalysts in gas-phase reactions involving the remediation of volatile organic compounds and the transformation of carbon dioxide into valuable energy-related chemicals. Finally, a fourth section of the chapter introduces the most recent applications of plasmonics in biochemical processes involving the regulation of cofactor molecules and their mimetic behavior as potential enzyme-like surrogates

Silver-Copper Oxide Heteronanostructures for the Plasmonic-Enhanced Photocatalytic Oxidation of n-Hexane in the Visible-NIR Range

Volatile organic compounds (VOCs) are recognized as hazardous contributors to air pollution, precursors of multiple secondary byproducts, troposphere aerosols, and recognized contributors to respiratory and cancer-related issues in highly populated areas. Moreover, VOCs present in indoor environments represent a challenging issue that need to be addressed due to its increasing presence in nowadays society. Catalytic oxidation by noble metals represents the most effective but costly solution. The use of photocatalytic oxidation has become one of the most explored alternatives given the green and sustainable advantages of using solar light or low-consumption light emitting devices. Herein, we have tried to address the shortcomings of the most studied photocatalytic systems based on titania (TiO2) with limited response in the UV-range or alternatively the high recombination rates detected in other transition metal-based oxide systems. We have developed a silver-copper oxide heteronanostructure able to combine the plasmonic-enhanced properties of Ag nanostructures with the visible-light driven photoresponse of CuO nanoarchitectures. The entangled Ag-CuO heteronanostructure exhibits a broad absorption towards the visible-near infrared (NIR) range and achieves total photo-oxidation of n-hexane under irradiation with different light-emitting diodes (LEDs) specific wavelengths at temperatures below 180 °C and outperforming its thermal catalytic response or its silver-free CuO illuminated counterpart

Recent advances in the design and photocatalytic enhanced performance of gold plasmonic nanostructures decorated with non-titania based semiconductor hetero-nanoarchitectures

Plasmonic photocatalysts combining metallic nanoparticles and semiconductors have been aimed as versatile alternatives to drive light-assisted catalytic chemical reactions beyond the ultraviolet (UV) regions, and overcome one of the major drawbacks of the most exploited photocatalysts (TiO2 or ZnO). The strong size and morphology dependence of metallic nanostructures to tune their visible to near-infrared (vis-NIR) light harvesting capabilities has been combined with the design of a wide variety of architectures for the semiconductor supports to promote the selective activity of specific crystallographic facets. The search for efficient heterojunctions has been subjected to numerous studies, especially those involving gold nanostructures and titania semiconductors. In the present review, we paid special attention to the most recent advances in the design of gold-semiconductor hetero-nanostructures including emerging metal oxides such as cerium oxide or copper oxide (CeO2 or Cu2O) or metal chalcogenides such as copper sulfide or cadmium sulfides (CuS or CdS). These alternative hybrid materials were thoroughly built in past years to target research fields of strong impact, such as solar energy conversion, water splitting, environmental chemistry, or nanomedicine. Herein, we evaluate the influence of tuning the morphologies of the plasmonic gold nanostructures or the semiconductor interacting structures, and how these variations in geometry, either individual or combined, have a significant influence on the final photocatalytic performance

High-radiance LED-driven fluidized bed photoreactor for the complete oxidation of n-hexane in air

This work presents a highly efficient photo-reactor configuration for VOC abatement. It consists of a fluidized bed made of commercial, easy to fluidize, transparent borosilicate glass beads coated with commercial TiO2 nanoparticles (0.15–2.3 wt% loadings). Herein, we demonstrate that the use of high-radiance/low consumption UV-LEDs as irradiation sources with a deeper light penetration under fluidizing conditions facilitates the photocatalytic response to achieve the complete oxidation of VOCs. The role of different parameters such as catalyst loading and irradiation power have been thoroughly studied and evaluated to maximize the full combustion of n-hexane. Under the high radiance (up to 2200 mW/cm2) conditions used the bed heats significantly (up to 190 °C), although this did not have an effect on the conversions reached, which depended solely on the wavelength and power used. The productivity of the photoreactor tested and the space velocity used were around 5.25 × 10-2 mol/g·h and 12000 h-1 respectively

The genome sequence of the emerging common midwife toad virus identifies an evolutionary intermediate within ranaviruses

Worldwide amphibian population declines have been ascribed to global warming, increasing pollution levels, and other factors directly related to human activities. These factors may additionally be favoring the emergence of novel pathogens. In this report, we have determined the complete genome sequence of the emerging common midwife toad ranavirus (CMTV), which has caused fatal disease in several amphibian species across Europe. Phylogenetic and gene content analyses of the first complete genomic sequence from a ranavirus isolated in Europe show that CMTV is an amphibian-like ranavirus (ALRV). However, the CMTV genome structure is novel and represents an intermediate evolutionary stage between the two previously described ALRV groups. We find that CMTV clusters with several other ranaviruses isolated from different hosts and locations which might also be included in this novel ranavirus group. This work sheds light on the phylogenetic relationships within this complex group of emerging, disease-causing viruses. © 2012, American Society for Microbiology.Peer Reviewe

Complete genome sequence of the European sheatfish virus

Viral diseases are an increasing threat to the thriving aquaculture industry worldwide. An emerging group of fish pathogens is formed by several ranaviruses, which have been isolated at different locations from freshwater and seawater fish species since 1985.We report the complete genome sequence of European sheatfish ranavirus (ESV), the first ranavirus isolated in Europe, which causes high mortality rates in infected sheatfish (Silurus glanis) and in other species. Analysis of the genome sequence shows that ESV belongs to the amphibian- like ranaviruses and is closely related to the epizootic hematopoietic necrosis virus (EHNV), a disease agent geographically confined to the Australian continent and notifiable to the World Organization for Animal HealthThis work was supported by grant AGL 2009-08711 from the Spanish Ministerio de Ciencia e Innovación. Alberto López-Bueno and Carla Mavian are recipients of Ramón y Cajal and Formación de Personal Investigador fellowships, respectively, from the same institutio

The genome sequence of the emerging common midwife toad virus identifies an evolutionary intermediate within ranaviruses

Worldwide amphibian population declines have been ascribed to global warming, increasing pollution levels, and other factors directly related to human activities. These factors may additionally be favoring the emergence of novel pathogens. In this report, we have determined the complete genome sequence of the emerging common midwife toad ranavirus (CMTV), which has caused fatal disease in several amphibian species across Europe. Phylogenetic and gene content analyses of the first complete genomic sequence from a ranavirus isolated in Europe show that CMTV is an amphibian-like ranavirus (ALRV). However, the CMTV genome structure is novel and represents an intermediate evolutionary stage between the two previously described ALRV groups. We find that CMTV clusters with several other ranaviruses isolated from different hosts and locations which might also be included in this novel ranavirus group. This work sheds light on the phylogenetic relationships within this complex group of emerging, disease-causing viruses.This work was supported by grant AGL 2009-08711 from the Spanish Ministerio de Ciencia e Innovación. Alberto López-Bueno and Carla Mavián are recipients of the Ramón y Cajal and Formación del Personal Investigador fellowships, respectively, from the same institutio

Novel polyomavirus and papillomavirus detected in gilthead seabream infected by lymphocystis disease virus

Lymphocystis disease virus (LCDV), a member of the genus Lymphocystivirus, family Iridoviridae, is the etiological agent of the lymphocystis disease (LCD), a common pathology that has been described in more than 150 different fish species worldwide. Direct sequencing of the virome of lymphocystis lesions from affected gilthead seabream (Sparus aurata) was used to obtain the complete genome sequence of a new LCDV species, named LCDV-Sa, that is the largest vertebrate iridovirus sequenced to date. This approach allowed us to assemble the full-length circular genomes of two previously unknown viruses, tentatively identified as members of the Polyomaviridae and Papillomaviridae families, and named Sparus aurata polyomavirus 1 (SaPyV1) and Sparus aurata papillomavirus 1 (SaPV1), respectively. SaPyV1 genome is a circular 7,299-bp-long DNA with a 52.1% GC content, and contains five nonoverlapping ORFs carried on opposite DNA strands in an organization reminiscent to that found in polyomaviruses. Phylogenetic analyses based on the amino acid sequence of the large T antigen and the VP1 proteins revealed that SaPyV1 clustered with the other currently available polyomavirus-like full-length genomes obtained from fish. SaPV1 genome corresponds to a circular 5,748-bp-long DNA and has a GC content of 39.5%. Although this genome is smaller than that of previously described papillomaviruses (about 8 kbp), it presents a typical papillomavirus organization, with seven ORFs carried on the same strand. Similarity searches identified distant orthologues of the early E1 and E2 proteins involved in replication and transcription, and late structural proteins L1 and L2. Furthermore, one of the others ORFs encodes a small protein (52 amino acids) that contains both a pRB binding domain (LXCXE) and a C-terminal PDZ class 2 binding motif, with are elements typically present in the longer E7 and E6 proteins found in most known papillomaviruses. The conserved genomic organization, the similarity of the main proteins, and the phylogenetical analysis, based on the amino acid sequence of the L1 protein, support that SaPV1 is the first member of the Papillomaviridae family described in fish. Epizootic surveys carried out in gilthead seabream farms in the Mediterranean area showed that LCD is frequently associated with the concurrent appearance of one or both of the new viruses, 98.3% of diseased fish being positive for SaPyV1 and/or SaPV1. In LCDV-infected asymptomatic fish, SaPyV1 and/or SaPV1 were detected in 32.1% of the animals analysed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Anisotropic Au-ZnO photocatalyst for the visible-light expanded oxidation of n-hexane

In this work we present a novel metal-semiconductor heterostructure that contains triangular and prism-shaped plasmonic gold nanostructures directly synthesized and assembled onto ZnO nanostructures. Spatially-resolved (SR) high-resolution electron energy loss spectroscopy (EELS) at the local (sub-nanometer scale) level confirmed the field enhancement of the local electromagnetic fields in the surroundings of the triangular and prism-shaped Au nanostructures and in the interfacial junction between Au and ZnO. Different LED excitation sources have been systematically selected in the whole UV–vis-NIR range to evaluate the photocatalytic response of the Au-ZnO heterostructures towards the oxidation of n-hexane, selected as a model VOC present in indoor environments. The Au-ZnO exhibits visible expanded photo-response with the more energetic interband and intraband electrons and the higher LED irradiation wavelengths and it is able to outperform its ZnO plain counterpart.Financial support from the European Research Council (ERC Advanced Grant CADENCE number 742684) is gratefully acknowledged. We also acknowledge the support from CIBER-BBN and MINECO (Spain) with project CTQ2016-79419-R. R.A. acknowledges funding from the Spanish Ministerio de Ciencia, Innovación y Universidades (project grant MAT2016-79776-P (AEI/FEDER, UE)) and from the European Union H2020 program “ESTEEM3” (823717).Peer reviewe

Use of triplet excited states for the study of drug binding to human and bovine serum albumins

[EN] The triplet excited states of (S)- and (R)-flurbiprofen (FBP) have been used as reporters for the microenvironments experienced within the binding sites of human and bovine serum albumins. Regression analysis of triplet decay provides valuable information on the degree of protection that these excited states are afforded from attack by a second FBP molecule, oxygen, or other reagents. The multiexponential fitting of these decays can be satisfactorily correlated with the distribution of the drug among the two binding sites and its presence as the noncomplexed form in the bulk solution. This assignment has been confirmed by using (S)-ibuprofen or capric acid as selective site II replacement probes. Triplet lifetimes and site occupancy are sensitive to the type of serum albumin employed (human versus bovine). Finally, the binding behaviour of (S)- and (R)-FBP exhibits little stereoselectivity.Financial support from the MCYT (CTQ2004-03811) and the Generalitat Valenciana (GV06/099) isgratefully acknowledged. I.V. and C.J.B. thank “Ministerio de Educación y Ciencia” for a fellowship.Vayá Pérez, I.; Bueno Alejo, CJ.; Jiménez Molero, MC.; Miranda Alonso, MÁ. (2006). Use of triplet excited states for the study of drug binding to human and bovine serum albumins. ChemMedChem. 1(9):1015-1020. https://doi.org/10.1002/cmdc.200600061S101510201