ACS Nanoscience Au最新文献

As the field of luminescence thermometry has matured, practical applications of luminescence thermometry techniques have grown in both frequency and scope. Due to the biocompatibility of most luminescent thermometers, many of these applications fall within the realm of biology. However, luminescence thermometry is increasingly employed beyond the biological realm, with expanding applications in areas such as thermal characterization of microelectronics, catalysis, and plasmonics. Here, we review the motivations, methodologies, and advances linked to nonbiological applications of luminescence thermometry. We begin with a brief overview of luminescence thermometry probes and techniques, focusing on those most commonly used for nonbiological applications. We then address measurement capabilities that are particularly relevant for these applications and provide a detailed survey of results across various application categories. Throughout the review, we highlight measurement challenges and requirements that are distinct from those of biological applications. Finally, we discuss emerging areas and future directions that present opportunities for continued research.

Niobium pentoxide (Nb₂O₅) is a promising negative electrode for sodium ion batteries (SIBs). By engineering the morphology and crystallinity of nanochanneled niobium oxides (NCNOs), the kinetic behavior and charge storage mechanism of Nb₂O₅ electrodes were investigated. Amorphous and crystalline NCNO samples were made by modulating anodization conditions (20–40 V and 140–180 °C) to synthesize nanostructures of varying pore sizes and wall thicknesses with identical chemical composition. The electrochemical energy storage properties of the NCNOs were studied, with the amorphous samples showing better overall rate performance than the crystalline samples. The enhanced rate performance of the amorphous samples is attributed to the higher capacitive contributions and Na-ion diffusivity analyzed from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT). It was found that the amorphous samples with smaller wall thicknesses facilitated improved kinetics. Among samples with similar pore size and wall thickness, the difference in their power performance stems from the crystallinity effect, which plays a more significant role in the resulting kinetics of the materials for Na-ion batteries.

Single unmodified biomolecules in solution can be observed and characterized by interferometric imaging approaches; however, Rayleigh scattering limits this to larger proteins (typically >30 kDa). We observe real-time image tracking of unmodified proteins down to 14 kDa using interference imaging enhanced by surface plasmons launched at an aperture in a metal film. The larger proteins show slower diffusion, quantified by tracking. When the diffusing protein is finally trapped by the nanoaperture, we perform complementary power spectral density and noise amplitude analysis, which gives information about the protein. This approach allows for rapid protein characterization with minimal sample preparation and opens the door to characterizing protein interactions in real time.

Materials referred to as “high entropy” contain a large number of elements randomly distributed on the lattice sites of a crystalline solid, such that a high configurational entropy is presumed to contribute significantly to their formation and stability. High temperatures are typically required to achieve entropy stabilization, which can make it challenging to synthesize colloidal nanoparticles of high entropy materials. Nonetheless, strategies are emerging for the synthesis of colloidal high entropy nanoparticles, which are of interest for their synergistic properties and unique catalytic functions that arise from the large number of constituent elements and their interactions. In this Perspective, we highlight the classes of materials that have been made as colloidal high entropy nanoparticles as well as insights into the synthetic methods and the pathways by which they form. We then discuss the concept of “high entropy” within the context of colloidal materials synthesized at much lower temperatures than are typically required for entropy to drive their formation. Next, we identify and address challenges and opportunities in the field of high entropy nanoparticle synthesis. We emphasize aspects of materials characterization that are especially important to consider for nanoparticles of high entropy materials, including powder X-ray diffraction and elemental mapping with scanning transmission electron microscopy, which are among the most commonly used techniques in laboratory settings. Finally, we share perspectives on emerging opportunities and future directions involving colloidal nanoparticles of high entropy materials, with an emphasis on synthesis, characterization, and fundamental knowledge that is needed for anticipated advances in key application areas.

The nanopore sensing method holds the promise of delivering a single molecule technology for identification of biological proteins, direct detection of post-translational modifications, and perhaps de novo determination of a protein’s amino acid sequence. The key quantity measured in such nanopore sensing experiments is the magnitude of the ionic current passing through a nanopore blocked by a polypeptide chain. Establishing a relationship between the amino acid sequence of a peptide fragment confined within a nanopore and the blockade current flowing through the nanopore remains a major challenge for realizing the nanopore protein sequencing. Using the results of all-atom molecular dynamics simulations, here we compare nanopore sequencing of DNA with nanopore sequencing of proteins. We then delineate the factors affecting the blockade current modulation by the peptide sequence, showing that the current can be determined by (i) the steric footprint of an amino acid, (ii) its interactions with the pore wall, (iii) the local stretching of a polypeptide chain, and (iv) the local enhancement of the ion concentration at the nanopore constriction. We conclude with a brief discussion of the prospects for purely computational prediction of the blockade currents.

Ligand dynamics plays a critical role in the chemical and biological properties of gold nanoparticles (AuNPs). In this study, ligands featuring hydrophobic alkanethiol interiors and hydrophilic shells were used to systematically examine the effects of ligand headgroups on the ligand dynamics. Solution nuclear magnetic resonance (NMR) spectroscopy provided quantitative insight into the monolayer ligand dynamics. Notably, the introduction of hydrophobic moieties to the cationic headgroups significantly decreased ligand conformational mobility; however, variations in hydrophobicity among these moieties had a limited effect on this reduction. Further examination of ligand dynamics under various physiological conditions, including ionic strength and temperature, showed that ligands bound to the AuNP surface become less conformationally mobile with an increase in ionic strength or decreasing temperature. This exploration of ligand dynamics provides insight into designing nanoparticles tailored to specific biological applications.

Iron phosphide (FeP) nanoparticles have excellent properties such as fast charge transfer kinetics, high electrical conductivity, and high stability, making them a promising catalyst for hydrogen evolution reaction (HER). A challenge to the wide use of iron phosphide nanomaterials for this application is the available synthesis protocols that limit control over the resulting crystalline phase of the product. In this study, we report a method for synthesizing FeP through a solution-based process. Here, we use iron oxyhydroxide (β-FeOOH) as a cost-effective, environmentally friendly, and air-stable source of iron, along with tri-n-octylphosphine (TOP) as the phosphorus source and solvent. FeP is formed in a nanobundle morphology in the solution phase reaction at a temperature of 320 °C. The materials were characterized by pXRD and transmission electron microscopy (TEM). The optimization parameters evaluated to produce the phosphorus-rich FeP phase included the reaction rate, time, amount of TOP, and reaction temperature. Mixtures of Fe₂P and FeP phases were obtained at shorter reaction times and slow heating rates (4.5 °C /min), while longer reaction times and faster heating rates (18.8 °C/min) favored the formation of phosphorus-rich FeP. Overall, the reaction lever that consistently yielded FeP as the predominant crystalline phase was a fast heat rate.

We report the effects of screening capacity, surface roughness, and interfacial epitaxy of the bottom electrodes on the polarization switching, domain wall (DW) roughness, and ferroelectric Curie temperature (T_C) of PbZr_0.2Ti_0.8O₃ (PZT)-based free-standing membranes. Singe crystalline 10–50 nm (001) PZT and PZT/La_0.67Sr_0.33MnO₃ (LSMO) membranes are prepared on Au, correlated oxide LSMO, and two-dimensional (2D) semiconductor MoS₂ base layers. Switching the polarization of PZT yields nonvolatile current modulation in the MoS₂ channel at room temperature, with an on/off ratio of up to 2 × 10⁵ and no apparent decay for more than 3 days. Piezoresponse force microscopy studies show that the coercive field E_c for the PZT membranes varies from 0.75 to 3.0 MV cm^–1 on different base layers and exhibits strong polarization asymmetry. The PZT/LSMO membranes exhibit significantly smaller E_c, with the samples transferred on LSMO showing symmetric E_c of about −0.26/+0.28 MV cm^–1, smaller than that of epitaxial PZT films. The DW roughness exponent ζ points to 2D random bond disorder dominated DW roughening (ζ = 0.31) at room temperature. Upon thermal quench at progressively higher temperatures, ζ values for PZT membranes on Au and LSMO approach the theoretical value for 1D random bond disorder (ζ = 2/3), while samples on MoS₂ exhibits thermal roughening (ζ = 1/2). The PZT membranes on Au, LSMO, and MoS₂ show T_C of about 763 ± 12, 725 ± 25, and 588 ± 12 °C, respectively, well exceeding the bulk value. Our study reveals the complex interplay between the electrostatic and mechanical boundary conditions in determining ferroelectricity in free-standing PZT membranes, providing important material parameters for the functional design of PZT-based flexible nanoelectronics.

Micro- and nanoscopic particles that swim autonomously and self-assemble under the influence of chemical fuels and external fields show promise for realizing systems capable of carrying out large-scale, predetermined tasks. Different behaviors can be realized by tuning swimmer interactions at the individual level in a manner analogous to the emergent collective behavior of bacteria and mammalian cells. However, the limited toolbox of weak forces with which to drive these systems has made it difficult to achieve useful collective functions. Here, we review recent research on driving swimming and particle self-organization using acoustic fields, which offers capabilities complementary to those of the other methods used to power microswimmers. With either chemical or acoustic propulsion (or a combination of the two), understanding individual swimming mechanisms and the forces that arise between individual particles is a prerequisite to harnessing their interactions to realize collective phenomena and macroscopic functionality. We discuss here the ingredients necessary to drive the motion of microscopic particles using ultrasound, the theory that describes that behavior, and the gaps in our understanding. We then cover the combination of acoustically powered systems with other cross-compatible driving forces and the use of ultrasound in generating collective behavior. Finally, we highlight the demonstrated applications of acoustically powered microswimmers, and we offer a perspective on the state of the field, open questions, and opportunities. We hope that this review will serve as a guide to students beginning their work in this area and motivate others to consider research in microswimmers and acoustic fields.

Altering the physical and chemical properties of a layered material through intercalation has emerged as a unique strategy toward tunable applications. In this work, we demonstrate a wet chemical method to intercalate titanium, hafnium, and zirconium into 2D layered nanomaterials. The metals are intercalated using bis-tetrahydrofuran metal halide complexes. Metal intercalation is demonstrated in nanomaterials of Bi₂Se₃, Si₂Te₃, MoO₃, and GeS. This strategy intercalates, on average, 3 atm % or less of Hf, Ti, and Zr that share charge with the host nanomaterial. This methodology is used to chemochromically alter MoO₃ from transparent white to dark blue.