Dissociation of carbon dioxide in atmospheric pressure microchannel plasma devices

Plasma discharge of carbon dioxide at atmospheric pressure was successfully demonstrated in microchannel plasma devices at breakdown voltages lower than 1 kVRMS. Optical emissions of molecular and ionic fragments of carbon dioxide were observed in emission spectra of visible wavelength range measured through a transparent dielectric coated with ITO electrode. Quantitative analysis by mass spectrometry derived the conversion rate of 2.40 ± 0.1 % and the energy efficiency of ~15 %. These results can be improved by modifying the device structures which leads to higher power loading and device packing density

Trends and perspectives in bio- and eco-friendly sustainable nanomaterial delivery systems through biological barriers

Many policies, including the European Green Deal, have been released to enhance global economic sustainability. Such policies require new materials to be sustainable, cost-effective, and safe for the fabrication of products that comply with regulations and are acceptable to consumers. In this context, the field of bionanomaterials has shifted toward developing green synthesis methods and the use of sustainable and eco-friendly materials. All these have to be considered for clinical applications along with other key issues and challenges in biomedical science including highly efficient targeted delivery of materials and chemicals with minimal toxicity and side effects. Here, we review the various types of inorganic and organic nanoparticles (NPs) used as the delivery vehicles to specific sites in human bodies, and discuss their advantageous properties and functions along with issues and limitations for clinical therapeutic applications. We summarized the strategies that can overcome both biological barriers such as the blood-brain barrier and harsh physiological conditions to realize clinically meaningful delivery systems, and introduced and discussed green synthesis methods for NPs and their environmental impacts. Finally, the perspectives on the biocompatibility, toxicity and environmental consequences of these NPs developed for biomedical applications are provided.N

Stabilization of colloidal crystals engineered with DNA

A postsynthetic method for stabilizing colloidal crystals programmed from DNA is developed. The method relies on Ag+ ions to stabilize the particle-connecting DNA duplexes within the crystal lattice, essentially transforming them from loosely bound structures to ones with very strong interparticle links. Such crystals do not dissociate as a function of temperature like normal DNA or DNA-interconnected superlattices, and they can be moved from water to organic media or the solid state, and stay intact. The Ag+-stabilization of the DNA bonds is accompanied by a nondestructive approximate to 25% contraction of the lattice, and both the stabilization and contraction are reversible with the chemical extraction of the Ag+ ions, by AgCl precipitation with NaCl. This synthetic tool is important, since it allows scientists and engineers to study such crystals in environments that are incompatible with structures made by conventional DNA programmable methods and without the influence of a matrix such as silica.11Nsciescopu

Time-Variable Chiroptical Vibrational Sum-Frequency Generation Spectroscopy of Chiral Chemical Solution

© 2021 American Chemical Society. All rights reserved.Vibrational sum-frequency generation (VSFG) spectroscopy, a surface-specific technique, was shown to be useful even for characterizing the vibrational optical activity of chiral molecules in isotropic bulk liquids. However, accurately determining the spectroscopic parameters is still challenging because of the spectral congestion of chiroptical VSFG peaks with different amplitudes and phases. Here, we show that a time-variable infrared-visible chiroptical three-wave-mixing technique can be used to determine the spectroscopic parameters of second-order vibrational response signals from chiral chemical liquids. For varying the delay time between infrared and temporally asymmetric visible laser pulses, we measure the chiral VSFG, achiral VSFG, and their interference spectra of bulk R-(+)-limonene liquid and perform a global fitting analysis for those time-variable spectra to determine their spectroscopic parameters accurately. We anticipate that this time-variable VSFG approach will be useful for developing nearly background-free chiroptical characterization techniques with enhanced spectral resolution.11Nsciescopu

Orthogonal Chemical Modification of Template-Synthesized Nanostructures with DNA

Very few chemical strategies for the selective functionalization of nanostructures have been developed despite their potential for controlling high-order assembly processes. We report a novel approach for the selective chemical functionalization and localized assembly of one-dimensional nanostructures (rods), based upon the systematic activation (DNA functionalization) and passivation (self-assembled monolayers) of specific surface sites through the use of orthogonal chemical reactions on electrochemically grown metal nanorod arrays in porous anodic aluminum oxide templates. The ability to orthogonally functionalize the ends or the side of a nanorod, as well as the gaps between two rods, with different DNA strands allows one to synthesize nanostructure assemblies that would be difficult to realize any other way and that could ultimately be utilized for making a wide variety of device architectures

Direct Observation of Plasmon-Induced Interfacial Charge Separation in Metal/Semiconductor Hybrid Nanostructures by Measuring Surface Potentials

Plasmon-induced interfacial charge separation (PICS) is one of the key processes responsible for the improved conversion efficiencies of energy-harvesting devices that incorporate metal nanostructures. In this Letter, we reveal a mechanism of PICS by visualizing (with nanometer-scale resolution) and characterizing plasmon–exciton coupling between <i>p</i>-type poly­(pyrrole) (PPy) nanowires (NWs) and Ag nanoparticles (NPs) using light-irradiated Kelvin probe force microscopy (KPFM). Under blue-light irradiation, the Ag NPs are expected to donate electrons to the PPy NWs via a hot electron injection process. However, in this Letter, we observe that under blue-light irradiation the plasmonically and excitonically excited electrons in the semiconductor back-transfer to the metal. The PICS in this system can be explained by comparing it with a similar one where Au NPs are attached to <i>n</i>-type ZnO NWs; we observed a net electron transfer from the Au NPs to the ZnO NWs (an upward band bending is formed at the interface of the two materials, presumably obstructing electron back-transfer). Indeed, energy band matching between the metal and the semiconductor components of hybrid nanostructures influences PICS pathways. These experimental findings and our proposed mechanism consistently explain the PICS occurring in the PPy NW-Ag NP system with important implications on explaining their cooperative optoelectronic activities

DNA‐ and Field‐Mediated Assembly of Magnetic Nanoparticles into High‐Aspect Ratio Crystals

Under an applied magnetic field, superparamagnetic Fe3O4 nanoparticles with complementary DNA strands assemble into crystalline, pseudo-1D elongated superlattice structures. The assembly process is driven through a combination of DNA hybridization and particle dipolar coupling, a property dependent on particle composition, size, and interparticle distance. The DNA controls interparticle distance and crystal symmetry, while the magnetic field leads to anisotropic crystal growth. Increasing the dipole interaction between particles by increasing particle size or external field strength leads to a preference for a particular crystal morphology (e.g., rhombic dodecahedra, stacked clusters, and smooth rods). Molecular dynamics simulations show that an understanding of both DNA hybridization energetic and magnetic interactions is required to predict the resulting crystal morphology. Taken together, the data show that applied magnetic fields with magnetic nanoparticles can be deliberately used to access nanostructures beyond what is possible with DNA hybridization alone.11Nsciescopu

Mussel-Inspired Anchoring of Polymer Loops That Provide Superior Surface Lubrication and Antifouling Properties.

We describe robustly anchored triblock copolymers that adopt loop conformations on surfaces and endow them with unprecedented lubricating and antifouling properties. The triblocks have two end blocks with catechol-anchoring groups and a looping poly(ethylene oxide) (PEO) midblock. The loops mediate strong steric repulsion between two mica surfaces. When sheared at constant speeds of ∼2.5 μm/s, the surfaces exhibit an extremely low friction coefficient of ∼0.002-0.004 without any signs of damage up to pressures of ∼2-3 MPa that are close to most biological bearing systems. Moreover, the polymer loops enhance inhibition of cell adhesion and proliferation compared to polymers in the random coil or brush conformations. These results demonstrate that strongly anchored polymer loops are effective for high lubrication and low cell adhesion and represent a promising candidate for the development of specialized high-performance biomedical coatings