Large-Area Near-Infrared Emission Enhancement on Single Upconversion Nanoparticles by Metal Nanohole Array.

Single lanthanide (Ln) ion doped upconversion nanoparticles (UCNPs) exhibit great potential for biomolecule sensing and counting. Plasmonic structures can improve the emission efficiency of single UCNPs by modulating the energy transferring process. Yet, achieving robust and large-area single UCNP emission modulation remains a challenge, which obstructs investigation and application of single UCNPs. Here, we present a strategy using metal nanohole arrays (NHAs) to achieve energy-transfer modulation on single UCNPs simultaneously within large-area plasmonic structures. By coupling surface plasmon polaritons (SPPs) with higher-intermediate state (1D2 → 3F3, 1D2 → 3H4) transitions, we achieved a remarkable up to 10-fold enhancement in 800 nm emission, surpassing the conventional approach of coupling SPPs with an intermediate ground state (3H4 → 3H6). We numerically simulate the electrical field distribution and reveal that luminescent enhancement is robust and insensitive to the exact location of particles. It is anticipated that the strategy provides a platform for widely exploring applications in single-particle quantitative biosensing.

Temporal compressive edge imaging enabled by a lensless diffuser camera.

Lensless imagers based on diffusers or encoding masks enable high-dimensional imaging from a single-shot measurement and have been applied in various applications. However, to further extract image information such as edge detection, conventional post-processing filtering operations are needed after the reconstruction of the original object images in the diffuser imaging systems. Here, we present the concept of a temporal compressive edge detection method based on a lensless diffuser camera, which can directly recover a time sequence of edge images of a moving object from a single-shot measurement, without further post-processing steps. Our approach provides higher image quality during edge detection, compared with the "conventional post-processing method." We demonstrate the effectiveness of this approach by both numerical simulation and experiments. The proof-of-concept approach can be further developed with other image post-processing operations or versatile computer vision assignments toward task-oriented intelligent lensless imaging systems.

Optomechanical entanglement affected by exceptional point in a WGM resonator system.

Entanglement of optical mode and mechanical mode plays a significant role for quantum information processing and memory. This type of optomechanical entanglement is always be suppressed by the mechanically dark-mode (DM) effect. However, the reason of the DM generation and how to control the bright-mode (BM) effect flexibly are still not resolved. In this letter, we demonstrate that the DM effect occurs at the exceptional point (EP) and it can be broken by changing the relative phase angle (RPA) between the nano scatters. We find that the optical mode and mechanical mode are separable at EPs but entangled when the RPA is tuned away from the EPs. Remarkably, the DM effect will be broken if the RPA away from EPs, resulting in the ground-state cooling of the mechanical mode. In addition, we prove that the chirality of the system can also influence the optomechanical entanglement. Our scheme can control the entanglement flexible merely depend on the relative phase angle, which is continuously adjustable and experimentally more feasible.

Strong antibunching effect under the combination of conventional and unconventional photon blockade.

Photon blockade (PB), an effective method of generating antibunching effect, is a critical way to construct a single photon source. The PB effect can be divided into conventional PB effect (CPB) and unconventional PB effect (UPB). Most studies focus on designing systems to successfully enhance CPB or UPB effect individually. However, CPB extremely depends on the nonlinearity strength of the Kerr materials to achieve strong antibunching effect while UPB relies on quantum interference beset with the high probability of the vacuum state. Here, we propose a method to utilize the relevance and complementarity of CPB and UPB to realize these two types simultaneously. We employ a hybrid Kerr nonlinearity two-cavity system. Because of the mutual assistance of two cavities, CPB and UPB can coexist in the system under certain states. In this way, for the same Kerr material, we reduce the value of the second-order correlation function due to CPB by three orders of magnitude without losing the mean photon number due to the presence of UPB, so the advantages of both PB effects are fully reflected in our system, which is a huge performance boost for single photons.

Multi-functional dual-path self-aligned polarization interference lithography.

Manufacturing sharp features is one of the most desired requirements for lithography. Here, we demonstrate a dual-path self-aligned polarization interference lithography (Dp-SAP IL) for fabricating periodic nanostructures, featuring high-steepness and high-uniformization. Meanwhile, it can manufacture quasicrystals with adjustable rotation symmetry. We reveal the change of the non-orthogonality degree under different polarization states and incident angles. We find that incident light's transverse electric (TE) wave results in high interference contrast at arbitrary incident angles, with a minimum contrast of 0.9328, that is, realizing the self-alignment of the polarization state of incident light and reflected light. We experimentally demonstrate this approach by fabricating a series of diffraction gratings with periods ranging from 238.3 nm to 851.6 nm. The steepness of each grating is greater than 85 degrees. Different from the traditional interference lithography system, Dp-SAP IL realizes a structure color using two mutually perpendicular and non-interference paths. One path is for the photolithography of patterns onto the sample, and the other path is for generating nanostructures on the patterns. Our technique showcases the feasibility of obtaining high contrast interference fringes by simply tuning the polarization, with the potential for cost-effective manufacturing of nanostructures such as quasicrystals and structure color.

Dual-mode adaptive-SVD ghost imaging.

In this paper, we present a dual-mode adaptive singular value decomposition ghost imaging (A-SVD GI), which can be easily switched between the modes of imaging and edge detection. It can adaptively localize the foreground pixels via a threshold selection method. Then only the foreground region is illuminated by the singular value decomposition (SVD) - based patterns, consequently retrieving high-quality images with fewer sampling ratios. By changing the selecting range of foreground pixels, the A-SVD GI can be switched to the mode of edge detection to directly reveal the edge of objects, without needing the original image. We investigate the performance of these two modes through both numerical simulations and experiments. We also develop a single-round scheme to halve measurement numbers in experiments, instead of separately illuminating positive and negative patterns in traditional methods. The binarized SVD patterns, generated by the spatial dithering method, are modulated by a digital micromirror device (DMD) to speed up the data acquisition. This dual-mode A-SVD GI can be applied in various applications, such as remote sensing or target recognition, and could be further extended for multi-modality functional imaging/detection.

Exploiting Dynamic Nonlinearity in Upconversion Nanoparticles for Super-Resolution Imaging.

Single-beam super-resolution microscopy, also known as superlinear microscopy, exploits the nonlinear response of fluorescent probes in confocal microscopy. The technique requires no complex purpose-built system, light field modulation, or beam shaping. Here, we present a strategy to enhance this technique's spatial resolution by modulating excitation intensity during image acquisition. This modulation induces dynamic optical nonlinearity in upconversion nanoparticles (UCNPs), resulting in variations of nonlinear fluorescence response in the obtained images. The higher orders of fluorescence response can be extracted with a proposed weighted finite difference imaging algorithm from raw fluorescence images to generate an image with higher resolution than superlinear microscopy images. We apply this approach to resolve single nanoparticles in a large area, improving the resolution to 132 nm. This work suggests a new scope for the development of dynamic nonlinear fluorescent probes in super-resolution nanoscopy.

Energy storage electrochromic devices in the era of intelligent automation.

The current intelligent automation society faces increasingly severe challenges in achieving efficient storage and utilization of energy. In the field of energy applications, various energy technologies need to be more intelligent and efficient to produce, store, transform and save energy. In addition, many smart electronic devices facing the future also require newer, lighter, thinner and even transparent multi-functional power supplies. The unique properties of electrochromic energy storage devices (ECESDs) have attracted widespread attention. In the field of energy applications, they have high potential value and competitiveness. This review focuses on the electrochromic basic principles, and the latest technological examples of ECESDs, which are related to materials and device structures. Simultaneously, this review makes a detailed comparison and summary of example performances. Moreover, the review compares the current mainstream energy storage devices: lithium batteries and supercapacitors, and the main challenges of ECESDs are discussed. Finally, the future development directions in the field of electrochromic energy storage are predicted.

Gastrodin relieves inflammation injury induced by lipopolysaccharides in MRC-5 cells by up-regulation of miR-103.

The beneficial function of gastrodin towards many inflammatory diseases has been identified. This study designed to see the influence of gastrodin in a cell model of chronic obstructive pulmonary disease (COPD). MRC-5 cells were treated by LPS, before which gastrodin was administrated. The effects of gastrodin were evaluated by conducting CCK-8, FITC-PI double staining, Western blot, qRT-PCR and ELISA. Besides this, the downstream effector and signalling were studied to decode how gastrodin exerted its function. And dual-luciferase assay was used to detect the targeting link between miR-103 and lipoprotein receptor-related protein 1 (LRP1). LPS induced apoptosis and the release of MCP-1, IL-6 and TNF-α in MRC-5 cells. Pre-treating MRC-5 cells with gastrodin attenuated LPS-induced cell damage. Meanwhile, p38/JNK and NF-κB pathways induced by LPS were repressed by gastrodin. miR-103 expression was elevated by gastrodin. Further, the protective functions of gastrodin were attenuated by miR-103 silencing. And LRP1 was a target of miR-103 and negatively regulated by miR-103. The in vitro data illustrated the protective function of gastrodin in LPS-injured MRC-5 cells. Gastrodin exerted its function possibly by up-regulating miR-103 and modulating p38/JNK and NF-κB pathways.

Supramolecular Self-Assembly in a Sub-micrometer Electrodic Cavity: Fabrication of Heat-Reversible π-Gel Memristor.

The use of biomimetic approaches toward the production of nonsolid yet functional architectures holds potential for the emergence of novel device concepts. Gels, in particular those obtained via self-assembly of π-conjugated molecules, are dynamic materials possessing unique (opto)electronic properties. Their adaptive nature imparts unprecedented responsivity to various stimuli. Hitherto, a viable device platform to electrically probe in situ a sol-gel transition is still lacking. Here we describe the fabrication of a sub-micrometer electrodic cavity, which enables low-voltage electrical operation of π-gels. Thanks to the in situ supramolecular self-assembly of the π-gelator occurring within the cavity, we conceived a novel gel-based memristor whose sol-gel transition is reversible and can be controlled via heating and dc bias. This work opens perspectives toward the fabrication of a novel generation of nonsolid multiresponsive devices.

Energy Transfer between Spatially Separated Entangled Molecules.

Light-matter strong coupling allows for the possibility of entangling the wave functions of different molecules through the light field. We hereby present direct evidence of non-radiative energy transfer well beyond the Förster limit for spatially separated donor and acceptor cyanine dyes strongly coupled to a cavity. The transient dynamics and the static spectra show an energy transfer efficiency approaching 37 % for donor-acceptor distances ≥100 nm. In such systems, the energy transfer process becomes independent of distance as long as the coupling strength is maintained. This is consistent with the entangled and delocalized nature of the polaritonic states.

Non-Radiative Energy Transfer Mediated by Hybrid Light-Matter States.

We present direct evidence of enhanced non-radiative energy transfer between two J-aggregated cyanine dyes strongly coupled to the vacuum field of a cavity. Excitation spectroscopy and femtosecond pump-probe measurements show that the energy transfer is highly efficient when both the donor and acceptor form light-matter hybrid states with the vacuum field. The rate of energy transfer is increased by a factor of seven under those conditions as compared to the normal situation outside the cavity, with a corresponding effect on the energy transfer efficiency. The delocalized hybrid states connect the donor and acceptor molecules and clearly play the role of a bridge to enhance the rate of energy transfer. This finding has fundamental implications for coherent energy transport and light-energy harvesting.

Ground-State Chemical Reactivity under Vibrational Coupling to the Vacuum Electromagnetic Field.

The ground-state deprotection of a simple alkynylsilane is studied under vibrational strong coupling to the zero-point fluctuations, or vacuum electromagnetic field, of a resonant IR microfluidic cavity. The reaction rate decreased by a factor of up to 5.5 when the Si-C vibrational stretching modes of the reactant were strongly coupled. The relative change in the reaction rate under strong coupling depends on the Rabi splitting energy. Product analysis by GC-MS confirmed the kinetic results. Temperature dependence shows that the activation enthalpy and entropy change significantly, suggesting that the transition state is modified from an associative to a dissociative type. These findings show that vibrational strong coupling provides a powerful approach for modifying and controlling chemical landscapes and for understanding reaction mechanisms.

The role of etching in the formation of Ag nanoplates with straight, curved and wavy edges and comparison of their SERS properties.

We investigate the role of etching in the formation of Ag nanoplates with different morphologies. By examining the reduction of AgNO3 with poly(vinyl pyrrolidone) in an aqueous solution under a hydrothermal condition, we confirm that etching plays an essential role in promoting the growth of Ag triangular nanoplates with straight edges at the expense of multiple twinned particles via Ostwald ripening. Once all the multiple twinned particles are gone, etching will continue at the corners of nanoplates, leading to the formation of enneahedral nanoplates with curved edges. When the nanoplates with straight edges are transferred into ethanol and subjected to a solvothermal treatment, we obtain nanoplates with wavy edges and sharp corners due to etching on the edges. A comparison study indicates that, at the same particle concentration, Ag nanoplates with wavy edges embraces a SERS enhancement factor at least 6 and 13 times stronger than those with straight and curved edges, respectively. The results from finite difference time domain calculations support our experimental observation that the sharp features on nanoplates with wavy edges are the most active sites for SERS.

High surface-enhanced Raman scattering performance of individual gold nanoflowers and their application in live cell imaging.

Molecular imaging techniques based on surface-enhanced Raman scattering (SERS) face a lack of reproducibility and reliability, thus hampering its practical application. Flower-like gold nanoparticles have strong SERS enhancement performance due to having plenty of hot-spots on their surfaces, and this enhancement is not dependent on the aggregation of the particles. These features make this kind of particle an ideal SERS substrate to improve the reproducibility in SERS imaging. Here, the SERS properties of individual flower-like gold nanoparticles are systematically investigated. The measurements reveal that the enhancement of a single gold nanoparticle is independent of the polarization of the excitation laser with an enhancement factor as high as 10(8) . After capping with Raman signal molecules and folic acid, the gold nanoflowers show strong Raman signal in the living cells, excellent targeting properties, and a high signal-to-noise ratio for SERS imaging.

CPLX2 Regulates Ferroptosis and Apoptosis Through NRF2 Pathway in Human Hepatocellular Carcinoma Cells.

Understanding the principle of regulated cell death (RCD) such as ferroptosis and apoptosis provides opportunities to overcome sorafenib resistance of HCC. Complexin II (CPLX2) is involved in calcium-dependent fusion of vesicles and plasma membrane, and recent studies showed CPLX2 is involved in cancer progression. However, the expression and function of CPLX2 are unclear in hepatocellular carcinoma (HCC). qPCR and western blotting assays were used to detect the levels of CPLX2. MTT and colony formation assays were used to detect cell viability. The contents of iron, ROS, MDA, and GSH were used to evaluate the function of CPLX2 on ferroptosis, while the flow cytometry and TUNEL assays were used to evaluate the role of CPLX2 on apoptosis. Our analysis showed CPLX2 is significantly upregulated in HCC, which predicts poor overall survival (OS), progression-free survival (PFS), relapse-free survival (RFS), and disease-specific survival (DSS) for patients with HCC. Further function enrichment analysis of genes related to CPLX2 showed CPLX2 is involved in the NRF2 pathway. Downregulation of CPLX2 can inhibit NRF2 expression and the transcription of its downstream genes, which confirms that CPLX2 is involved in NRF2 pathway. Cell viability assay showed that ferroptosis and apoptosis inhibitors can reverse the inhibition effect of CPLX2-knockdown on cell survival, respectively. And downregulation of CPLX2 significantly promotes the contents of iron, ROS, and MDA, while inhibiting the GSH level of HCC cell lysate, suggesting CPLX2 involved in ferroptosis. Moreover, downregulation of CPLX2 promotes the apoptosis of HCC cells by flow cytometry and TUNEL assay. And upregulation of NRF2 can partly reverse the inhibitory effect of CPLX2-downregulation on ferroptosis and apoptosis. Finally, we found downregulation of CPLX2 aggravates cell death induced by sorafenib. CPXL2 regulates ferroptosis and apoptosis through NRF2 pathway, and CPLX2 knockdown promotes cell death induced by sorafenib. CPLX2 might be an effective target for therapy patients with HCC.

Investigation of size-dependent plasmonic and catalytic properties of metallic nanocrystals enabled by size control with HCl oxidative etching.

Particle size is one important parameter of nanocrystals that need to be tightly controlled, owing to its versatility for tailoring the properties and functions of nanocrystals towards various applications. In this article, oxidative etching by hydrogen chloride is employed as a tool to control the size of metallic nanocrystals. As a result of the size control, investigations into the size-dependent plasmonic and catalytic properties of metallic nanocrystals can be investigated. Given that the shape can be kept consistent when tuning the particle size in this system, it enables the systematic investigation of size-dependent properties free of the influence of other factors such as shape effect.

Fabrication of semiconductor-polymer compound nonlinear photonic crystal slab with highly uniform infiltration based on nano-imprint lithography technique.

We present a versatile technique based on nano-imprint lithography to fabricate high-quality semiconductor-polymer compound nonlinear photonic crystal (NPC) slabs. The approach allows one to infiltrate uniformly polystyrene materials that possess large Kerr nonlinearity and ultrafast nonlinear response into the cylindrical air holes with diameter of hundred nanometers that are perforated in silicon membranes. Both the structural characterization via the cross-sectional scanning electron microscopy images and the optical characterization via the transmission spectrum measurement undoubtedly show that the fabricated compound NPC samples have uniform and dense polymer infiltration and are of high quality in optical properties. The compound NPC samples exhibit sharp transmission band edges and nondegraded high quality factor of microcavities compared with those in the bare silicon PC. The versatile method can be expanded to make general semiconductor-polymer hybrid optical nanostructures, and thus it may pave the way for reliable and efficient fabrication of ultrafast and ultralow power all-optical tunable integrated photonic devices and circuits.

Manipulation of gold nanorods with dual-optical tweezers for surface plasmon resonance control.

Gold nanorods are too tiny to be manipulated using conventional mechanical methods. In this paper, we demonstrate the trapping, transferring, positioning and patterning of gold nanorods with dual-optical tweezers. The convenient manipulations are achieved by taking advantage of the longitudinal surface plasmon resonance of gold nanorods and the anisotropic optical trapping forces formed by two linearly polarized Gaussian beams. The trapped gold nanoparticles are positioned extremely firmly and quickly on a substrate compared with randomly dispersed ones. It is observed that gold nanorods show advantages over gold nanospheres with regard to positioning speed and stability. More importantly, versatile plasmon coupling effects have been achieved in some patterned nanorods.

Analysis of the Forward and Reverse Strongly Coupled States on the Nonradiative Energy Transfer Effect.

Nonradiative energy transfer (NRET) under light-matter strong coupling interaction provides an efficient method to achieve the ultralong-distance and ultrafast energy transfer, which is of significance in realizing remote control chemistry and the real-time dynamic research of biological macromolecules interaction and so on. Here we show that not only can the cavity mode first resonate with the donor to form a cascade hybrid light-matter states to drive energy transfer, when the cavity mode first resonates with the acceptor, it also can enhance the nonradiative energy transfer between the donor and the acceptor. Importantly, although these two strong coupling systems can enhance energy transfer, the polariton-mediated energy transfer mechanism behind these processes is different. By employing the quantum Tavis-Cummings theory, we calculate the time evolution of the mean photon number of each polariton state to analyze the energy transfer effect under different strongly coupled states.