Small-Molecule Photostabilizing Agents are Modifiers of Lipid Bilayer Properties

AbstractSmall-molecule photostabilizing or protective agents (PAs) provide essential support for the stability demands on fluorescent dyes in single-molecule spectroscopy and fluorescence microscopy. These agents are employed also in studies of cell membranes and model systems mimicking lipid bilayer environments, but there is little information about their possible effects on membrane structure and physical properties. Given the impact of amphipathic small molecules on bilayer properties such as elasticity and intrinsic curvature, we investigated the effects of six commonly used PAs—cyclooctatetraene (COT), para-nitrobenzyl alcohol (NBA), Trolox (TX), 1,4-diazabicyclo[2.2.2]octane (DABCO), para-nitrobenzoic acid (pNBA), and n-propyl gallate (nPG)—on bilayer properties using a gramicidin A (gA)-based fluorescence quench assay to probe for PA-induced changes in the gramicidin monomer↔dimer equilibrium. The experiments were done using fluorophore-loaded large unilamellar vesicles that had been doped with gA, and changes in the gA monomer↔dimer equilibrium were assayed using a gA channel-permeable fluorescence quencher (Tl+). Changes in bilayer properties caused by, e.g., PA adsorption at the bilayer/solution interface that alter the equilibrium constant for gA channel formation, and thus the number of conducting gA channels in the large unilamellar vesicle membrane, will be detectable as changes in the rate of Tl+ influx—the fluorescence quench rate. Over the experimentally relevant millimolar concentration range, TX, NBA, and pNBA, caused comparable increases in gA channel activity. COT, also in the millimolar range, caused a slight decrease in gA channel activity. nPG increased channel activity at submillimolar concentrations. DABCO did not alter gA activity. Five of the six tested PAs thus alter lipid bilayer properties at experimentally relevant concentrations, which becomes important for the design and analysis of fluorescence studies in cells and model membrane systems. We therefore tested combinations of COT, NBA, and TX; the combinations altered the fluorescence quench rate less than would be predicted assuming their effects on bilayer properties were additive. The combination of equimolar concentrations of COT and NBA caused minimal changes in the fluorescence quench rate

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

Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations

In-Situ Deposition of Plasmonic Gold Nanotriangles and Nanoprisms onto Layered Hydroxides for Full-Range Photocatalytic Response towards the Selective Reduction of p-Nitrophenol

In this work, we present photocatalysis as a greener alternative to conventional catalysis where harsh reaction conditions, temperature and/or pressure are needed. Photodegradation of organic pollutants is a cost-effective, eco-friendly solution for the decontamination of water and air, and is a field that has been continuously growing over the last decade. Plasmonic metal nanoparticles absorb light irradiation that is transferred to the chemical reaction in a different fashion. Furthermore, plasmonic nanostructures can be combined with other materials, such as semiconductors or a basic support, to create hybrid systems capable of overcoming certain challenges that photocatalysis is facing nowadays and to expand the photocatalytic response towards the whole visible-near infrared (Vis-NIR) ranges. The main objective of this work has been to in-situ synthesize plasmonic anisotropic gold nanoparticles onto hydrotalcite (HT) and calcined hydrotalcite (CHT) supports by way of a sequential deposition-reduction (DR) process and to evaluate their efficiency as heterogeneous catalysts towards the selective oxidation of p-nitrophenol (hereafter 4-NP), a well-known model contaminant, either in the absence or the presence of full-range light irradiation sources (LEDs) spanning the whole UV-Vis-NIR range. Special attention has been paid to the optimization of the catalyst preparation parameters, including the pH and the concentration of reducing and stabilizing agents. Interestingly, the use of thermally modified hydrotalcites has enabled a strong metal-support interaction to induce the preferential formation of triangular-shaped Au nanoparticles with ca. 0.8 wt.% loading while increasing the colloidal stability and surface area of the catalyst with respect to the commercial untreated HT supports

Chapter 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

Chapter 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

Rebuilding lives, recreating dreams: A case study of the coping, resilience and quality of life of five resettled families

This study aims to know the changes that took place when the families moved to a resettlement area and the effects of these changes for family members. It also aims to know the various coping strategies that the family and family members use in order to adjust to their new environment. Lastly, it looks at the resilience and the quality of life of the families. A case study was conducted for each of the five families that are currently living in resettlement areas---two families from National Housing Authority Northville 3, Meycauayan, Bulacan and three families from Gawad Kalinga - Baseco. Each family that was given a semi-structured interview consisted of a father, a mother and a child. Results show that the significant changes were the change in the environment and the change in social activity. The effects of these changes include feelings of stability, security, accomplishment and identity. Coping strategies revolve around working harder, openly communicating with each other and for those in the Baseco resettlement area, having faith in God