Open Cross-gap Gold Nanocubes with Strong, Large-Area, Symmetric Electromagnetic Field Enhancement for On-Particle Molecular-Fingerprint Raman Bioassays.

Plasmonic nanoparticles with an externally open nanogap can localize the electromagnetic (EM) field inside the gap and directly detect the target via the open nanogap with surface-enhanced Raman scattering (SERS). It would be beneficial to design and synthesize the open gap nanoprobes in a high yield for obtaining uniform and quantitative signals from randomly oriented nanoparticles and utilizing these particles for direct SERS analysis. Here, we report a facile strategy to synthesize open cross-gap (X-gap) nanocubes (OXNCs) with size- and EM field-tunable gaps in a high yield. The site-specific growth of Au budding structures at the corners of the AuNC using the principle that the Au deposition rate is faster than the surface diffusion rate of the adatoms allows for a uniform X-gap formation. The average SERS enhancement factor (EF) for the OXNCs with 2.6 nm X-gaps was 1.2 × 109, and the EFs were narrowly distributed within 1 order of magnitude for ∼93% of the measured OXNCs. OXNCs consistently displayed strong EM field enhancement on large particle surfaces for widely varying incident light polarization directions, and this can be attributed to the symmetric X-gap geometry and the availability of these gaps on all 6 faces of a cube. Finally, the OXNC probes with varying X-gap sizes have been utilized in directly detecting biomolecules with varying sizes without Raman dyes. The concept, synthetic method, and biosensing results shown here with OXNCs pave the way for designing, synthesizing, and utilizing plasmonic nanoparticles for selective, quantitative molecular-fingerprint Raman sensing and imaging applications.

The State of Use and Utility of Negative Controls in Pharmacoepidemiologic Studies.

Uses of real-world data in drug safety and effectiveness studies are often challenged by various sources of bias. We undertook a systematic search of the published literature through September 2020 to evaluate the state of use and utility of negative controls to address bias in pharmacoepidemiologic studies. Two reviewers independently evaluated study eligibility and abstracted data. Our search identified 184 eligible studies for inclusion. Cohort studies (115, 63%) and administrative data (114, 62%) were, respectively, the most common study design and data type used. Most studies used negative control outcomes (91, 50%), and for most studies the target source of bias was unmeasured confounding (93, 51%). We identified 4 utility domains of negative controls: 1) bias detection (149, 81%), 2) bias correction (16, 9%), 3) P-value calibration (8, 4%), and 4) performance assessment of different methods used in drug safety studies (31, 17%). The most popular methodologies used were the 95% confidence interval and P-value calibration. In addition, we identified 2 reference sets with structured steps to check the causality assumption of the negative control. While negative controls are powerful tools in bias detection, we found many studies lacked checking the underlying assumptions. This article is part of a Special Collection on Pharmacoepidemiology.

Synergistic Inclusion Effects of Hard Magnetic Nanorods on the Magnetomechanical Actuation of Soft Magnetic Microsphere-Based Polymer Composites.

The magnetomechanical actuation of micropillars is developed for the contactless manipulation of miniaturized actuators and microtextured surfaces. Anisotropic geometry of micropillars can significantly enhance the magnetic actuation compared with their isotropic counterparts by directional stress distributions. However, this strategy is not viable for triangular micropillars owing to insufficient anisotropy. In this study, a significant improvement in the magnetic actuation of triangular micropillars using composite magnetic particles is reported. A minute and optimal amount of hard magnetic gamma-ferrite nanorods are hybridized with soft magnetic iron microspheres to generate synergistic effects of magnetic coupling and percolation phenomenon on the magnetic actuation of polymer composites. The addition of 1 wt% face-centered cubic-phased gamma-ferrite nanorods suppresses the magnetic coupling interference of body-centered cubic-phased iron microspheres. Furthermore, the nanorods reduce the percolation threshold by participating in the percolation of the microspheres. A systematic compositional study on the magnetization and magnetorheological properties reveals that the coupling effect dominates the percolation effect at a low magnetic field, whereas the percolation effect governs the magnetic actuation at a high magnetic field. This hybrid approach can help in designing material constituents for effective magnetic actuators and robotic systems that can sensitively respond to an external magnetic field.

Programming Anisotropic Functionality of 3D Microdenticles by Staggered-Overlapped and Multilayered Microarchitectures.

Natural sharkskin features staggered-overlapped and multilayered architectures of riblet-textured anisotropic microdenticles, exhibiting drag reduction and providing a flexible yet strong armor. However, the artificial fabrication of three-dimensional (3D) sharkskin with these unique functionalities and mechanical integrity is a challenge using conventional techniques. In this study, it is reported on the facile microfabrication of multilayered 3D sharkskin through the magnetic actuation of polymeric composites and subsequent chemical shape fixation by casting thin polymeric films. The fabricated hydrophobic sharkskin, with geometric symmetry breaking, achieves anisotropic drag reduction in frontal and backward flow directions against the riblet-textured microdenticles. For mechanical integrity, hard-on-soft multilayered mechanical properties are realized by coating the polymeric sharkskin with thin layers of zinc oxide and platinum, which have higher hardness and recovery behaviors than the polymer. This multilayered hard-on-soft sharkskin exhibits friction anisotropy, mechanical robustness, and structural recovery. Furthermore, coating the MXene nanosheets provides the fabricated sharkskin with a low electrical resistance of ≈5.3 Ω, which leads to high Joule heating (≈229.9 °C at 2.75 V). The proposed magnetomechanical actuation-assisted microfabrication strategy is expected to facilitate the development of devices requiring multifunctional microtextures.

Feasibility of artificial intelligence-driven interfractional monitoring of organ changes by mega-voltage computed tomography in intensity-modulated radiotherapy of prostate cancer.

PURPOSE: High-dose radiotherapy (RT) for localized prostate cancer requires careful consideration of target position changes and adjacent organs-at-risk (OARs), such as the rectum and bladder. Therefore, daily monitoring of target position and OAR changes is crucial in minimizing interfractional dosimetric uncertainties. For efficient monitoring of the internal condition of patients, we assessed the feasibility of an auto-segmentation of OARs on the daily acquired images, such as megavoltage computed tomography (MVCT), via a commercial artificial intelligence (AI)-based solution in this study. MATERIALS AND METHODS: We collected MVCT images weekly during the entire course of RT for 100 prostate cancer patients treated with the helical TomoTherapy system. Based on the manually contoured body outline, the bladder including prostate area, and rectal balloon regions for the 100 MVCT images, we trained the commercially available fully convolutional (FC)-DenseNet model and tested its auto-contouring performance. RESULTS: Based on the optimally determined hyperparameters, the FC-DenseNet model successfully auto-contoured all regions of interest showing high dice similarity coefficient (DSC) over 0.8 and a small mean surface distance (MSD) within 1.43 mm in reference to the manually contoured data. With this well-trained AI model, we have efficiently monitored the patient's internal condition through six MVCT scans, analyzing DSC, MSD, centroid, and volume differences. CONCLUSION: We have verified the feasibility of utilizing a commercial AI-based model for auto-segmentation with low-quality daily MVCT images. In the future, we will establish a fast and accurate auto-segmentation and internal organ monitoring system for efficiently determining the time for adaptive replanning.

Exploration of Tetrahydroisoquinoline- and Benzo[c]azepine-Based Sphingosine 1-Phosphate Receptor 1 Agonists for the Treatment of Multiple Sclerosis.

Because of the wide use of Fingolimod for the treatment of multiple sclerosis (MS) and its cardiovascular side effects such as bradycardia, second-generation sphingosine 1-phosphate receptor 1 (S1P1) agonist drugs for MS have been developed and approved by FDA. The issue of bradycardia is still present with the new drugs, however, which necessitates further exploration of S1P1 agonists with improved safety profiles for next-generation MS drugs. Herein, we report a tetrahydroisoquinoline or a benzo[c]azepine core-based S1P1 agonists such as 32 and 60 after systematic examination of hydrophilic groups and cores. We investigated the binding modes of our representative compounds and their molecular interactions with S1P1 employing recent S1P1 cryo-EM structures. Also, favorable ADME properties of our compounds were shown. Furthermore, in vivo efficacy of our compounds was clearly demonstrated with PLC and EAE studies. Also, the preliminary in vitro cardiovascular safety of our compound was verified with human iPSC-derived cardiomyocytes.

Strong coupling in plasmonic metal nanoparticles.

The study of strong coupling between light and matter has gained significant attention in recent years due to its potential applications in diverse fields, including artificial light harvesting, ultraefficient polariton lasing, and quantum information processing. Plasmonic cavities are a compelling alternative of conventional photonic resonators, enabling ultracompact polaritonic systems to operate at room temperature. This review focuses on colloidal metal nanoparticles, highlighting their advantages as plasmonic cavities in terms of their facile synthesis, tunable plasmonic properties, and easy integration with excitonic materials. We explore recent examples of strong coupling in single nanoparticles, dimers, nanoparticle-on-a-mirror configurations, and other types of nanoparticle-based resonators. These systems are coupled with an array of excitonic materials, including atomic emitters, semiconductor quantum dots, two-dimensional materials, and perovskites. In the concluding section, we offer perspectives on the future of strong coupling research in nanoparticle systems, emphasizing the challenges and potentials that lie ahead. By offering a thorough understanding of the current state of research in this field, we aim to inspire further investigations and advances in the study of strongly coupled nanoparticle systems, ultimately unlocking new avenues in nanophotonic applications.

Atomoxetine and Fluoxetine Activate AMPK-ACC-CPT1 Pathway in Human SH-SY5Y and U-87 MG Cells.

OBJECTIVE: Atomoxetine and fluoxetine are psychopharmacologic agents associated with loss of appetite and weight. Adenosine monophosphate-activated protein kinase (AMPK) is the cellular energy sensor that regulate metabolism and energy, being activated by fasting and inhibited by feeding in the hypothalamus. METHODS: Human brain cell lines (SH-SY5Y and U-87 MG cells) were used to study the outcome of atomoxetine and fluoxetine treatment in the activity of AMPK-acetyl-CoA carboxylase (ACC)- carnitine palmitoyl transferase 1 (CPT1) pathway and upstream regulation by calcium/calmodulin-dependent kinase kinase ß (CaMKKß) using immunoblotting and CPT1 enzymatic activity measures. RESULTS: Phosphorylation of AMPK and ACC increased significantly after atomoxetine and fluoxetine treatment in the first 30-60 minutes of treatment in the two cell lines. Activation of AMPK and inhibition of ACC was associated with an increase by 5-fold of mitochondrial CPT1 activity. Although the neuronal isoform CPT1C could be detected by immunoblotting, activity was not changed by the drug treatments. In addition, the increase in phospho-AMPK and phospho-ACC expression induced by atomoxetine was abolished by treatment with STO-609, a CaMKKß inhibitor, indicating that AMPK-ACC-CPT1 pathway is activated through CaMKKß phosphorylation. CONCLUSION: These findings indicate that at the cellular level atomoxetine and fluoxetine treatments may activate AMPK-ACC-CPT1 pathways through CaMKKß in human SH-SY5Y and U-87 MG cells.

Efficient Labeling of Vesicles with Lipophilic Fluorescent Dyes via the Salt-Change Method.

Fluorescent labeling allows for imaging and tracking of vesicles down to single-particle level. Among several options to introduce fluorescence, staining of lipid membranes with lipophilic dyes provides a straightforward approach without interfering with vesicle content. However, incorporating lipophilic molecules into vesicle membranes in an aqueous solution is generally not efficient because of their low water solubility. Here, we describe a simple, fast (<30 min), and highly effective procedure for fluorescent labeling of vesicles including natural extracellular vesicles. By adjusting the ionic strength of the staining buffer with NaCl, the aggregation status of DiI, a representative lipophilic tracer, can be controlled reversibly. Using cell-derived vesicles as a model system, we show that dispersion of DiI under low-salt condition improved its incorporation into vesicles by a factor of 290. In addition, increasing NaCl concentration after labeling induced free dye molecules to form aggregates, which can be filtered and thus effectively removed without ultracentrifugation. We consistently observed 6- to 85-fold increases in the labeled vesicle count across different types of dyes and vesicles. The method is expected to reduce the concern about off-target labeling resulting from the use of high concentrations of dyes.

Protection of Hearing Loss in Ototoxic Mouse Model Through SPIONs and Dexamethasone-Loaded PLGA Nanoparticle Delivery by Magnetic Attraction.

Background: Ototoxicity currently has no available treatment other than medication withdrawal as soon as toxicity is suspected. The human inner ear organs have little potential for regeneration; thus, ototoxicity-induced hair cell injury is deemed permanent. Dexamethasone (Dexa) is a synthetic steroid analog that has significant potential for otoprotection in the treatment of various inner ear diseases; however, its low absorption into the inner ear prevents significant recovery of function. Nanoparticles facilitate targeted drug delivery, stabilize drug release, and increase half-life of the drug. Methods: This study aimed to develop poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded superparamagnetic iron oxide nanoparticles (SPIONs) and Dexa (PSD-NPs) to control localized drug delivery by magnetic attraction in the treatment of ototoxicity-induced hearing loss. PSD-NPs and without SPIONs (PD-NPs) were prepared using a nanoprecipitation method. Results: Using an inner ear simulating system, we confirmed that PSD-NPs has an otoprotective effect in organotypic culture that is enhanced by magnetic attraction. PSD-NPs delivered via intrabullar injection in a magnetic field penetrated the inner ear and prevented hearing loss progression to a greater degree than equivalent doses of Dexa or PSD-NPs alone (day 28: ototoxic: 80.0 ± 0.0 dB; Dexa 100: 60.0 ± 15.5 dB; PSD 100: 50.0 ± 8.2 dB; PSD 100 with magnet: 22.5 ± 5.0 dB; P < 0.05). The protective effects were confirmed in various in vivo and in vitro models of ototoxicity. Conclusion: Our findings suggest that SPIONs with Dexa and magnetic field application prevent the progression of ototoxicity-induced hearing loss through anti-apoptotic mechanisms in the inner ear.

Multimodal collective swimming of magnetically articulated modular nanocomposite robots.

Magnetically responsive composites can impart maneuverability to miniaturized robots. However, collective actuation of these composite robots has rarely been achieved, although conducting cooperative tasks is a promising strategy for accomplishing difficult missions with a single robot. Here, we report multimodal collective swimming of ternary-nanocomposite-based magnetic robots capable of on-demand switching between rectilinear translational swimming and rotational swimming. The nanocomposite robots comprise a stiff yet lightweight carbon nanotube yarn (CNTY) framework surrounded by a magnetic polymer composite, which mimics the hierarchical architecture of musculoskeletal systems, yielding magnetically articulated multiple robots with an agile above-water swimmability (~180 body lengths per second) and modularity. The multiple robots with multimodal swimming facilitate the generation and regulation of vortices, enabling novel vortex-induced transportation of thousands of floating microparticles and heavy semi-submerged cargos. The controllable collective actuation of these biomimetic nanocomposite robots can lead to versatile robotic functions, including microplastic removal, microfluidic vortex control, and transportation of pharmaceuticals.

On-Demand Dynamic Chirality Selection in Flower Corolla-like Micropillar Arrays.

Chiral morphology has been intensively studied in various fields including biology, organic chemistry, pharmaceuticals, and optics. On-demand and dynamic chiral inversion not only cannot be realized in most intrinsically chiral materials but also has mostly been limited to chemical or light-induced methods. Herein, we report reversible real-time magneto-mechanical chiral inversion of a three-dimensional (3D) micropillar array between achiral, clockwise, and counterclockwise chiral arrangements. Inspired by the flower corolla, achiral arrays of five and six radially arranged semicylindrical micropillars were employed as model systems to investigate the dynamic symmetry properties of arrays consisting of odd and even numbers of micropillars, respectively. Each micropillar underwent twisting actuation with a different twisting angle depending on the angle with the magnetic field direction and magnetic flux density, thereby collectively changing the chirality from the achiral to chiral state. Importantly, the morphological handedness of the micropillars was inverted within a few seconds by manipulating the direction of the magnetic field. A chiral morphology consisting of magnetically twisted micropillars was shape-fixed by the introduction of a polymeric binder. This binder could be simply washed off to return the shape-fixed twisted micropillars to their initial straight state. Magnetically programmable and reproducible 3D flower corolla-like micropillar arrays are expected to expand the potential of shape-reconfigurable devices that require real-time chiral manipulation in ambient environments.

Multi-Modal Locomotion of Caenorhabditis elegans by Magnetic Reconfiguration of 3D Microtopography.

Miniaturized untethered soft robots are recently exploited to imitate multi-modal curvilinear locomotion of living creatures that perceive change of surrounding environments. Herein, the use of Caenorhabditis elegans (C. elegans) is proposed as a microscale model capable of curvilinear locomotion with mechanosensing, controlled by magnetically reconfigured 3D microtopography. Static entropic microbarriers prevent C. elegans from randomly swimming with the omega turns and provide linear translational locomotion with velocity of ≈0.14 BL s-1 . This velocity varies from ≈0.09 (for circumventing movement) to ≈0.46 (for climbing) BL s-1 , depending on magnetic bending and twisting actuation coupled with assembly of microbarriers. Furthermore, different types of neuronal mutants prevent C. elegans from implementing certain locomotion modes, indicating the potential for investigating the correlation between neurons and mechanosensing functions. This strategy promotes a platform for the contactless manipulation of miniaturized biobots and initiates interdisciplinary research for investigating sensory neurons and human diseases.

Cell-derived vesicles from adipose-derived mesenchymal stem cells ameliorate irradiation-induced salivary gland cell damage.

Introduction: Salivary gland (SG) damage is commonly caused by aging, irradiation, and some medications, and currently, no damage modifying agent is available. However, cell therapy based on mesenchymal stem cells (MSCs) has been proposed as a therapeutic modality for irradiated SGs. Therefore, we administered cell-derived vesicles (CDVs) of adipose-derived mesenchymal stem cells (ADMSCs) to irradiated SG cells to investigate their radioprotective effects in vitro. Methods: The artificial CDVs were obtained from ADMSC by tangential flow filtration (TFF) purification and ultracentrifugation. Cultured human SG epithelial cells were exposed to 2, 5 or 15 Gy of 4 MV X-rays produced by a linear accelerator. The effects of ADMSC-CDVs on SG epithelial cells damaged by irradiation were tested by proliferation activity, transepithelial electrical resistance (TEER), and amylase activity. Results: Exposure to penetrating radiation inhibited the proliferation of SG epithelial cells, but the radiation intensity required to reduce the proliferation of human submandibular gland epithelial cells (hSMGECs) was greater than required for other SG cells. ADMSC-CDVs restored the proliferative ability of SG epithelial cells reduced by irradiation, and the proliferation capacities of irradiated human parotid gland epithelial cells (hPGECs) and human sublingual gland epithelial cells (hSLGECs) were increased by administering ADMSC-CDVs to non-irradiated SG epithelial cells. Furthermore, amylase activity in irradiated hPGECs, hSMGECs, and hSLGECs was lower than in non-irradiated controls. However, amylase ability was restored in all by ADMSC-CDV treatment. Also, TEER was diminished by irradiation in hPGECs, hSMGECs, and hSLGECs and restored by ADMSC-CDV administration. Conclusion: Overall, our findings demonstrate that ADMSC-CDVs have potent radioprotective effects on irradiated SG cells.

Modeling the Health and Economic Burden of Chronic Obstructive Pulmonary Disease in China From 2020 to 2039: A Simulation Study.

OBJECTIVES: Despite a growing prevalence of respiratory diseases in recent decades in China, limited evidence is available on the health and economic burden of chronic obstructive pulmonary disease (COPD). We estimated the 20-year health and economic burden of COPD in China from 2020 to 2039. METHODS: We created a probabilistic dynamic open-cohort Markov model of COPD for the Chinese population aged ≥40 years. Projections of population growth and urbanization rates were obtained from the United Nations Population Division. Other parameter inputs including smoking prevalence, COPD prevalence and severity distributions, disease-related costs, and utility weights were obtained from the most recent published literature. We modeled number of COPD patients, excess mortality due to COPD, exacerbations, COPD-attributable losses of quality-adjusted life-years, and direct and indirect COPD costs over the 20 years. RESULTS: The number of COPD patients was projected to increase from 88.3 million in 2020 to 103.3 million in 2039. The projected total losses of quality-adjusted life-years and the excess mortality due to COPD were, respectively, estimated to be 253.6 million and 3.9 million over the 20 years. The projected 20-year total discounted direct and indirect costs of COPD were, respectively, $3.1 trillion and $360.5 billion. The projected health and economic burden was higher in males and urban areas. CONCLUSIONS: COPD is projected to inflict a substantial burden to the society and the health care system in China. Effective strategies for prevention and early management of COPD are needed to mitigate the forthcoming disease burden.

A simple and sensitive HPLC-FL method for bioanalysis of velpatasvir, a novel hepatitis C virus NS5A inhibitor, in rat plasma: Investigation of factors determining its oral bioavailability.

Velpatasvir is a novel inhibitor of hepatitis C virus nonstructural protein 5A that received US Food and Drug Administration approval for the treatment of patients with chronic hepatitis C virus genotypes 1-6. In the present study, a sensitive bioanalytical method for velpatasvir was developed using high-performance liquid chromatography coupled with a fluorescence detector system, which was applied to elucidate the factors determining the oral bioavailability and disposition of velpatasvir. This method offered sufficient sensitivity, with a lower limit of quantification of 0.5 ng/mL, which is comparable to previously reported methods using liquid chromatography coupled with tandem mass spectrometry. Velpatasvir exhibited low oral bioavailability, moderate intestinal permeability, and significant biliary excretion in rats. It was also found to be significantly metabolized in the liver, with a low-to-moderate extraction ratio; however, its intestinal metabolism and enterohepatic circulation did not occur. Thus, our present results demonstrate that the oral bioavailability of velpatasvir is primarily dependent on gut absorption and hepatic first-pass metabolism. The fractions of velpatasvir dose unabsorbed from the gut and eliminated by the liver before reaching the systemic circulation following oral administration were estimated to be 32.8%-58.6% and 4.74%-30.54% of the oral dose, respectively. To our knowledge, this is the first systematic study to investigate the contributory roles of biopharmaceutical and pharmacokinetic factors on the oral bioavailability of velpatasvir, together with a new bioanalytical method for velpatasvir.

Lasing Action from Quasi-Propagating Modes.

Band edges at the high symmetry points in reciprocal space of periodic structures hold special interest in materials engineering for their high density of states. In optical metamaterials, standing waves found at these points have facilitated lasing, bound-states-in-the-continuum, and Bose-Einstein condensation. However, because high symmetry points by definition are localized, properties associated with them are limited to specific energies and wavevectors. Conversely, quasi-propagating modes along the high symmetry directions are predicted to enable similar phenomena over a continuum of energies and wavevectors. Here, quasi-propagating modes in 2D nanoparticle lattices are shown to support lasing action over a continuous range of wavelengths and symmetry-determined directions from a single device. Using lead halide perovskite nanocrystal films as gain materials, lasing is achieved from waveguide-surface lattice resonance (W-SLR) modes that can be decomposed into propagating waves along high symmetry directions, and standing waves in the orthogonal direction that provide optical feedback. The characteristics of the lasing beams are analyzed using an analytical 3D model that describes diffracted light in 2D lattices. Demonstrations of lasing across different wavelengths and lattice designs highlight how quasi-propagating modes offer possibilities to engineer chromatic multibeam emission important in hyperspectral 3D sensing, high-bandwidth Li-Fi communication, and laser projection displays.

In-Bi Electrocatalyst for the Reduction of CO2 to Formate in a Wide Potential Window.

The CO2 atmospheric concentration level hit the record at more than 400 ppm and is predicted to keep increasing as the dependence on fossil fuels is inevitable. The CO2 electrocatalytic conversion becomes an alternative due to its environmental and energy-friendly properties and benign operation condition. Lately, bimetallic materials have drawn significant interest as electrocatalysts due to their distinct properties, which the parents' metal cannot mimic. Herein, the indium-bismuth nanosphere (In16Bi84 NS) was fabricated via the facile liquid-polyol technique. The In16Bi84 NS exhibits exceptional performance for CO2 reduction to formate, with the faradaic efficiency (FE) approaching ∼100% and a corresponding partial current density of 14.1 mA cm-2 at -0.94 V [vs the reversible hydrogen electrode (RHE)]. Furthermore, the FE could be maintained above 90% in a wide potential window (-0.84 to -1.54 V vs the RHE). This superior performance is attributed to the tuned electronic properties induced by the synergistic interaction between In and Bi, enabling the intermediates to be stably adsorbed on the catalyst surface to generate more formate ions.

Light-Matter Interactions in Hybrid Material Metasurfaces.

This Review focuses on the integration of plasmonic and dielectric metasurfaces with emissive or stimuli-responsive materials for manipulating light-matter interactions at the nanoscale. Metasurfaces, engineered planar structures with rationally designed building blocks, can change the local phase and intensity of electromagnetic waves at the subwavelength unit level and offers more degrees of freedom to control the flow of light. A combination of metasurfaces and nanoscale emitters facilitates access to weak and strong coupling regimes for enhanced photoluminescence, nanoscale lasing, controlled quantum emission, and formation of exciton-polaritons. In addition to emissive materials, functional materials that respond to external stimuli can be combined with metasurfaces to engineer tunable nanophotonic devices. Emerging metasurface designs including surface-functionalized, chemically tunable, and multilayer hybrid metasurfaces open prospects for diverse applications, including photocatalysis, sensing, displays, and quantum information.

Interfacial engineering of plasmonic nanoparticle metasurfaces.

SignificanceMolecules interacting with metallic nanostructures can show tunable exciton-plasmon coupling, ranging from weak to strong. One factor that influences the interactions is the spatial organization of the molecules relative to the localized plasmon-enhanced electromagnetic fields. In this work, we show that the arrangement of aromatic dye molecules can be tuned within plasmonic hotspots by interfacial engineering of nanoparticle surfaces. By controlling the local chemical and physical interactions, we could modulate lasing thresholds. Surface-functionalized plasmonic metasurfaces open prospects for programmable light-matter interactions at the nanoscale.