Abstract
The quantum spin Hall effect lays the foundation for the topologically protected manipulation of waves, but is restricted to one-dimensional-lower boundaries of systems and hence limits the ...diversity and integration of topological photonic devices. Recently, the conventional bulk-boundary correspondence of band topology has been extended to higher-order cases that enable explorations of topological states with codimensions larger than one such as hinge and corner states. Here, we demonstrate a higher-order quantum spin Hall effect in a two-dimensional photonic crystal. Owing to the non-trivial higher-order topology and the pseudospin-pseudospin coupling, we observe a directional localization of photons at corners with opposite pseudospin polarizations through pseudospin-momentum-locked edge waves, resembling the quantum spin Hall effect in a higher-order manner. Our work inspires an unprecedented route to transport and trap spinful waves, supporting potential applications in topological photonic devices such as spinful topological lasers and chiral quantum emitters.
Precise control of solid-state elastic waves' mode content and coherence is of great use nowadays in reinforcing mechanical energy harvesting/storage, nondestructive material testing, wave-matter ...interaction, high sensitivity sensing, and information processing, etc. Its efficacy is highly dependent on having elastic transmission channels with lower loss and higher degree of freedom. Here, we demonstrate experimentally an elastic analog of the quantum spin Hall effects in a monolithically scalable configuration, which opens up a route in manipulating elastic waves represented by elastic pseudospins with spin-momentum locking. Their unique features including robustness and negligible propagation loss may enhance elastic planar-integrated circuit-level and system-level performance. Our approach promotes topological materials that can interact with solid-state phonons in both static and time-dependent regimes. It thus can be immediately applied to multifarious chip-scale topological phononic devices, such as path-arbitrary elastic wave-guiding, elastic splitters and elastic resonators with high-quality factors.
Topological insulators (TIs) can host an insulating gapped bulk with conducting gapless boundary states in lower dimensions than the bulk. To date, various kinds of classical wave TIs with gapless ...symmetry-protected boundary states have been discovered, promising for the efficient confinement and robust guiding of waves. However, for airborne sound, an acoustic analogue of a three-dimensional TI has not been achieved due to its spinless nature. Here, we experimentally demonstrate a three-dimensional topological acoustic crystal with pseudospins using bilayer chiral structures, in which multi-order topological bandgaps are generated step by step via elaborately manipulating the corresponding spatial symmetries. We observe acoustic analogues of 1st-order (two-dimensional gapless surface Dirac cones) and 2nd-order (one-dimensional gapless hinge Dirac dispersion) TIs in three dimensions, supporting robust surface or hinge sound transport. Based solely on spatial symmetry, our work provides a route to engineer the hierarchies of TIs and explore topological devices for three-dimensional spinless systems.
Stable and efficient guided waves are essential for information transmission and processing. Recently, topological valley-contrasting materials in condensed matter systems have been revealed as ...promising infrastructures for guiding classical waves, for they can provide broadband, non-dispersive and reflection-free electromagnetic/mechanical wave transport with a high degree of freedom. In this work, by designing and manufacturing miniaturized phononic crystals on a semi-infinite substrate, we experimentally realized a valley-locked edge transport for surface acoustic waves (SAWs). Critically, original one-dimensional edge transports could be extended to quasi-two-dimensional ones by doping SAW Dirac "semimetal" layers at the boundaries. We demonstrate that SAWs in the extended topological valley-locked edges are robust against bending and wavelength-scaled defects. Also, this mechanism is configurable and robust depending on the doping, offering various on-chip acoustic manipulation, e.g., SAW routing, focusing, splitting, and converging, all flexible and high-flow. This work may promote future hybrid phononic circuits for acoustic information processing, sensing, and manipulation.
Rational utilization of the rich light‐bio‐matter interplay taking place in single‐cell analysis represents a new technological direction in the field. The light‐fueled operation is expected to ...achieve advanced photoelectrochemical (PEC) single‐cell analysis with unknown possibilities. Here, a PEC nanoreactor capable of single‐cell sampling and near zero‐background Faradaic detection of intracellular microRNA (miR) is devised by the construction of a small reaction chamber accommodating the target‐triggered hybridization chain reaction for binding the metallointercalator of Ru(bpy)2(dppz)2+ as the signal reporter. Light stimulation of the dsDNA/metallointercalator adduct will induce the generation of photocurrents, underpinning a zero‐biased and near zero‐background PEC method toward Faradaic detection of non‐electrogenic miR at the single‐cell level. Using this nanotool, lower miR concentration in the near‐nucleus region than that in the main cytosol was revealed.
A photoelectrochemical nanoreactor was devised for single‐cell sampling and near zero‐background faradic detection of intracellular microRNA. This platform provided a new perspective for exploring light‐biomatter interplay toward single‐cell studies.
With reduced background and high sensitivity, photoelectrochemistry (PEC) may be applied as an intracellular nanotool and open a new technological direction of single‐cell study. Nevertheless, the ...present palette of single‐cell tools lacks such a PEC‐oriented solution. Here a dual‐functional photocathodic single‐cell nanotool capable of direct electroosmotic intracellular drug delivery and evaluation of oxidative stress is devised by engineering a target‐specific organic molecule/NiO/Ni film at the tip of a nanopipette. Specifically, the organic molecule probe serves simultaneously as the biorecognition element and sensitizer to synergize with p‐type NiO. Upon intracellular delivery at picoliter level, the oxidative stress effect will cause structural change of the organic probe, switching its optical absorption and altering the cathodic response. This work has revealed the potential of PEC single‐cell nanotool and extended the boundary of current single‐cell electroanalysis.
An integrated photocathodic nanotool was fabricated for dual‐functional intracellular drug delivery and evaluation of cellular oxidative stress in single live cell.
Single‐cell protein therapeutics is expected to promote our in‐depth understanding of how a specific protein with a therapeutic dosage treats the cell without population averaging. However, it has ...not yet been tackled by current single‐cell nanotools. We address this challenge by the use of a double‐barrel nanopipette, in which one lumen was used for electroosmotic cytosolic protein delivery and the other was customized for ionic evaluation of the consequence. Upon injection of protein DJ‐1 through the delivery lumen, upregulation of the antioxidant protein could protect neural PC‐12 cells against oxidative stress from phorbol myristate acetate exposure, as deduced by targeting of the cytosolic hydrogen peroxide by the detecting lumen. The nanotool developed in this study for single‐cell protein therapeutics provides a perspective for future single‐cell therapeutics involving different therapeutic modalities, such as peptides, enzymes and nucleic acids.
Electrochemical single‐cell protein therapeutics was devised with an engineered θ‐nanopipette and exemplified by protein DJ‐1 enabled neuroprotection. Upon DJ‐1 injection through the delivery lumen, upregulation of the antioxidant protein could protect neural PC‐12 cells against oxidative stress from phorbol myristate acetate exposure, as deduced by targeting of the cytosolic H2O2 by the detecting lumen.
Single‐cell epigenetics is envisioned to decipher manifold epigenetic phenomena and to contribute to our accurate knowledge about basic epigenetic mechanisms. Engineered nanopipette technology has ...gained momentum in single‐cell studies; however, solutions to epigenetic questions remain unachieved. This study addresses the challenge by exploring N6‐methyladenine (m6A)‐bearing deoxyribozyme (DNAzyme) confined within a nanopipette for profiling a representative m6A‐modifying enzyme, fat mass and obesity‐associated protein (FTO). Electroosmotic intracellular extraction of FTO could remove the m6A and cause DNAzyme cleavage, leading to the altered ionic current signal. Because the cleavage can release a DNA sequence, we simultaneously program it as an antisense strand against FTO‐mRNA, intracellular injection of which has been shown to induce early stage apoptosis. This nanotool thus features the dual functions of studying single‐cell epigenetics and programmable gene regulation.
An integrated iontronic nanotool was developed for the study of single‐cell epigenetics and programmable gene regulation. With the nanotool, an N6‐methyladenine (m6A)‐modified deoxyribozyme (DNAzyme) was used for profiling a representative m6 A‐modifying enzyme, fat mass and obesity‐associated protein (FTO), which also released a DNA sequence that could be programmed as an antisense strand against intracellular FTO‐mRNA.
Though significant advances are made in the arena of single‐cell electroanalysis, quantification of intracellular amino acids of human cells remains unsolved. Exemplified by l‐histidine (l‐His), this ...issue is addressed by a practical electrochemical nanotool synergizing the highly accessible nanopipette with commercially available synthetic DNAzyme. The fabricated nanotools are screened before operation of a single‐use manner, and the l‐His‐provoked cleavage of the DNA molecules can be sensibly transduced by the ionic current rectification response, the intrinsic property of nanopipette governed by its interior surface charges. Regional distribution of cytosolic l‐His level in human cells is electrochemically quantified for the first time, and time‐dependent drug treatment effects are further revealed. This work unveils the possibility of electrochemistry for quantification of cytosolic amino acids of a spatial‐ and time‐based manner and ultimately enables a better understanding of amino acid‐involved events in living cells.
The solution‐to‐electrochemical single‐cell analysis of intracellular amino acids is achieved by integrating nanopipette with specific DNAzyme and exemplified by targeting l‐histidine. It allowed minimally invasive detection with high sensitivity and selectivity. Drug treatment is also probed of a spatial‐ and time‐based manner.
Coherent phonon transfer via high‐quality factor (Q) mechanical resonator strong coupling has garnered significant interest. Yet, the practical applications of these strongly coupled resonator ...devices are largely constrained by their vulnerability to fabrication defects. In this study, topological strong coupling of gigahertz frequency surface acoustic wave (SAW) resonators with lithium niobate is achieved. The nanoscale grooves are etched onto the lithium niobate surface to establish robust SAW topological interface states (TISs). By constructing phononic crystal (PnC) heterostructures, a strong coupling of two SAW TISs, achieving a maximum Rabi splitting of 22 MHz and frequency quality factor product fQm of ≈1.2 × 1013 Hz, is realized. This coupling can be tuned by adjusting geometric parameters and a distinct spectral anticrossing is experimentally observed. Furthermore, a dense wavelength division multiplexing device based on the coupling of multiple TISs is demonstrated. These findings open new avenues for the development of practical topological acoustic devices for on‐chip sensing, filtering, phonon entanglement, and beyond.
The strong coupling of topological surface acoustic wave resonators with a large Rabi splitting and a high‐quality factor operating at gigahertz frequencies based on a single‐crystal lithium niobate acoustic‐electric integrated system is realized. The coupling resonators are prepared by etching nanoscale grooves on the surface of lithium niobate. Then dense wavelength division multiplexers based on multiresonator coupling are also demonstrated.
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