ACS Nano最新文献

We introduce a method based on gold-assisted exfoliation for deterministic, large-area exfoliation of few-layer transition metal dichalcogenides with precise control of layer number N. This technique uses a hybrid gold tape to create (N - 1)-layer terraces on a bulk crystal. The terraces, along with a continuous monolayer below, are subsequently cleaved using uniform gold tape to yield N-layer regions. The high electronic quality of the material is confirmed through the fabrication of field-effect transistors (FETs) from exfoliated monolayer, bilayer, and trilayer MoS₂, which exhibit carrier mobilities of up to 160 cm² V^-1 s^-1. This exfoliation technique can be combined with stacking and atomic layer etching to create a versatile toolkit to achieve more complex structures, including moiré heterostructures. This work demonstrates a robust and scalable route to engineering high-quality, few-layer 2D materials for electronic and quantum devices.

Achieving precise control over chiral light-matter interactions at the nanometer-femtosecond scale, where both spatial and temporal limits are approached, remains a central challenge in nano- and quantum optics. This control is essential for next-generation ultracompact, ultrafast chiral photonic devices, but no method has realized both the construction and the active regulation of a localized chiroptical source within a single plasmonic nanoantenna. In this study, we report a strategy for creating and dynamically controlling a spatiotemporally localized chiroptical source via plasmonic eigenmode engineering in an achiral rectangular nanoantenna. With time-resolved photoemission electron microscopy, we directly image and analyze eigenmode dynamics and interference-induced near-field chirality across the space, time, and wavelength domains, revealing polarization-dependent hotspots in the nanoantenna. An interferometric pump-probe method further enables the on/off switching and near-field chirality reversal of the chiroptical photon source between nanoantenna corners with a sub-1.37 fs time delay between pump and probe pulses. This approach also yields a tunable superchiral photon source, providing a versatile platform for integrated ultrafast chiral nanophotonic applications.

When introduced into biological systems, the function and biodistribution of lipid nanoparticles (LNPs) are affected by the biomolecular coronas they acquire. Corona composition is determined by the biophysical and chemical properties of the particles and the contents of the biofluids. Polyethylene glycol (PEG) polymers, anchored using lipids that partition into LNPs during formulation, are key to LNP stability in circulation. It is, however, not well-studied how different PEG-lipid anchors, with different acyl chain lengths, headgroup/linker chemistries, and desorption rates (PEG "shedding" from nanoparticles) can affect corona composition and LNP function. Here, we examined how common PEG-lipid anchors affect (1) in vivo biodistribution in C57BL/6 mice, (2) corona content (using mass spectrometry-based proteomics), (3) LNP biophysical characteristics (using single-particle automated Raman trapping analysis (SPARTA^Ⓡ)), and (4) in vitro particle function (using cellular uptake and cargo delivery assays). Following nanoparticle formulation with clinically approved, commonly used PEG anchors, we found that the LNP biodistribution is strongly impacted, particularly in the liver, spleen, bone marrow, and lung. We then tested a wide range of lipid ratio combinations using high-throughput evaluation in vitro. Despite being minor LNP components (by molar ratio), the PEG-lipid anchors strongly impact the chemical characteristics, corona content, and particle function. These findings reveal structure-activity relationships between PEG-lipid anchor chemistry and functional LNP biodistribution, with implications for rational LNP design.

A high-quality topological insulator-superconductor (TI-SC) heterostructure with an atomically sharp and well-controlled interface is crucial for realizing topological superconductivity and a topological quantum qubit. In particular, many studies of TI-SC heterostructures have focused on inducing a superconducting gap in the TI layer via proximity effect, while the active manipulation of superconductivity in the SC layer remains largely unexplored. In this work, we fabricated TI/TiN heterostructures using highly air-stable, ultrathin TiN films as the SC layer and observed an interface-enhanced superconductivity that contrasts with the conventional proximity effect in the superconductor-normal metal interface. Band structure measurements reveal a consistent shift of the Dirac point with T_c enhancement. Interfacial charge transfer provides a plausible explanation for this shift based on the systematic analysis and is therefore a likely contributor to the observed T_c enhancement. First-principles calculations elucidate the charge transfer pathways, highlighting the critical role of the interfacial BiTe (BiSe) bilayer. Our results not only provide a tunable TI-SC hybrid system with robust superconductivity at ultrathin thickness but also offer a potential route for manipulating superconductivity in TI-SC heterostructures via interface engineering.

Atomically precise metal nanoclusters (NCs) have emerged as an important class of materials for optoelectronic applications, owing to their near-infrared-II (NIR-II) photoluminescence (PL) properties. To fully realize their applications, the PL quantum yield (PLQY) of NCs must be enhanced. In this regard, structure-property correlation studies are of critical importance. Herein, we report an alkynide-protected Au₂₀Ag₃₂ NC (charge neutral) protected by 36 ligands, including 12 Cl^- and 24 p-tert-butylphenylacetylide (^tBuPA^-). Structural analysis shows that the NC is a three-dimensional growth of a bi-icosahedral core. Theoretical analysis reproduces the experimental optical absorption spectral features. Interestingly, Au₂₀Ag₃₂ shows bright PL emission centered at 980 nm, with a PLQY of 30% in aerated and 33% in deaerated medium at room temperature, which is the highest among the reported NIR-II NCs. Furthermore, cryogenic PL measurements and transient absorption spectroscopy analysis reveal the PL mechanism, which involves both thermally activated delayed fluorescence (TADF) and phosphorescence (PH). This study is expected to motivate further research in expanding the Au-Ag nanoclusters and studying their high NIR-II emission.