Design and Fabrication of a New Wearable Pressure Sensor for Blood Pressure Monitoring

In recent years, research into the field of materials for flexible sensors and fabrication techniques directed towards wearable devices has helped to raise awareness of the need for new sensors with healthcare applicability. Our goal was to create a wearable flexible pressure sensor that could be integrated into a clinically approved blood pressure monitoring device. The sensor is built from a microfluidic channel encapsulated between two polymer layers, one layer being covered by metal transducers and the other being a flexible membrane containing the microfluidic channel, which also acts as a sealant for the structure. The applied external pressure deforms the channel, causing changes in resistance to the microfluidic layer. Electrical characterization has been performed in 5 different configurations, using alternating current (AC) and (DC) direct current measurements. The AC measurements for the fabricated pressure sensor resulted in impedance values at tens of hundreds of kOhm. Our sensor proved to have a high sensitivity for pressure values between 0 and 150 mm Hg, being subjected to repeatable external forces. The novelty presented in our work consists in the unique technological flow for the fabrication of the flexible wearable pressure sensor. The proposed miniaturized pressure sensor will ensure flexibility, low production cost and ease of use. It is made of very sensitive microfluidic elements and biocompatible materials and can be integrated into a wearable cuffless device for continuous blood pressure monitoring.

Electrically programmable magnetoresistance in [Formula: see text]-based magnetic tunnel junctions

We report spin-dependent transport properties and I-V hysteresis characteristics in an [Formula: see text]-based magnetic tunnel junction (MTJ). The bipolar resistive switching and the magnetoresistances measured at high resistance state (HRS) and low resistance state (LRS) yield four distinctive resistive states in a single device. The temperature dependence of resistance at LRS suggests that the resistive switching is not triggered by the metal filaments within the [Formula: see text] layer. The role played by oxygen vacancies in [Formula: see text] is the key to determine the resistive state. Our study reveals the possibility of controlling the multiple resistive states in a single [Formula: see text]-based MTJ by the interplay of both electric and magnetic fields, thus providing potential applications for future multi-bit memory devices.

Insights into the Interfacial Effects in Heterogeneous Metal Nanocatalysts toward Selective Hydrogenation

Heterogeneous metal catalysts are distinguished by their structure inhomogeneity and complexity. The chameleonic nature of heterogeneous metal catalysts have prevented us from deeply understanding their catalytic mechanisms at the molecular level and thus developing industrial catalysts with perfect catalytic selectivity toward desired products. This Perspective aims to summarize recent research advances in deciphering complicated interfacial effects in heterogeneous hydrogenation metal nanocatalysts toward the design of practical heterogeneous catalysts with clear catalytic mechanism and thus nearly perfect selectivity. The molecular insights on how the three key components (i.e., catalytic metal, support, and ligand modifier) of a heterogeneous metal nanocatalyst induce effective interfaces determining the hydrogenation activity and selectivity are provided. The interfaces influence not only the H₂ activation pathway but also the interaction of substrates to be hydrogenated with catalytic metal surface and thus the hydrogen transfer process. As for alloy nanocatalysts, together with the electronic and geometric ensemble effects, spillover hydrogenation occurring on catalytically "inert" metal by utilizing hydrogen atom spillover from active metal is highlighted. The metal-support interface effects are then discussed with emphasis on the molecular involvement of ligands located at the metal-support interface as well as cationic species from the support in hydrogenation. The mechanisms of how organic modifiers, with the ability to induce both 3D steric and electronic effects, on metal nanocatalysts manipulate the hydrogenation pathways are demonstrated. A brief summary is finally provided together with a perspective on the development of enzyme-like heterogeneous hydrogenation metal catalysts.

3D DNA Nanostructures: The Nanoscale Architect

Structural DNA nanotechnology is a pioneering biotechnology that presents the opportunity to engineer DNA-based hardware that will mediate a profound interface to the nanoscale. To date, an enormous library of shaped 3D DNA nanostructures have been designed and assembled. Moreover, recent research has demonstrated DNA nanostructures that are not only static but can exhibit specific dynamic motion. DNA nanostructures have thus garnered significant research interest as a template for pursuing shape and motion-dependent nanoscale phenomena. Potential applications have been explored in many interdisciplinary areas spanning medicine, biosensing, nanofabrication, plasmonics, single-molecule chemistry, and facilitating biophysical studies. In this review, we begin with a brief overview of general and versatile design techniques for 3D DNA nanostructures as well as some techniques and studies that have focused on improving the stability of DNA nanostructures in diverse environments, which is pivotal for its reliable utilization in downstream applications. Our main focus will be to compile a wide body of existing research on applications of 3D DNA nanostructures that demonstrably rely on the versatility of their mechanical design. Furthermore, we frame reviewed applications into three primary categories, namely encapsulation, surface templating, and nanomechanics, that we propose to be archetypal shape- or motion-related functions of DNA nanostructures found in nanoscience applications. Our intent is to identify core concepts that may define and motivate specific directions of progress in this field as we conclude the review with some perspectives on the future.

UV response characteristics of mixed-phase MgZnO thin films with different structure distributions, high Iuv/Idark ratios, and fast speed MgZnO UV detectors with tunneling breakdown mechanisms

High-performance ultraviolet (UV) detectors with both high responses and fast speeds are hard to make on homogeneous crystal semiconductor materials. Here, the UV response characteristics of mixed-phase MgZnO thin films with different internal structure distributions are studied. The mixed-phase MgZnO-based detector with the given crystal composition has a high response at both deep UV light (96 A W-1 at 240 nm) and near UV light (80 A W-1 at 335 nm). Meanwhile, because of the quasi-tunneling breakdown mechanism within the device, the high-response UV detector also shows a fast response speed (tr = 0.11 μs) and recovery speed (td1 = 26 μs) at deep UV light, which is much faster than both low-response mixed-phase MgZnO-based UV detectors with other structure constitutions and reported high-response UV devices on homogenous crystal materials. The Idark of the device is just 4.27 pA under a 5 V bias voltage, so the signal-to-noise ratio of the device reached 23852 at 5.5 uW cm-2 235 nm UV light. The new quasi-tunneling breakdown mechanism is observed in some mixed-phase MgZnO thin films that contain both c-MgZnO and h-MgZnO parts, which introduce a high response, signal-to-noise ratio, and fast speed into mixed-phase MgZnO-based UV detectors at weak deep UV light.

OBP-functionalized/hybrid superparamagnetic nanoparticles for Candida albicans treatment

Infections caused by the opportunistic yeast Candida albicans are one of the major life threats for hospitalized and immunocompromised patients, as a result of antibiotic and long-term antifungal treatment abuse. Odorant binding proteins can be considered interesting candidates to develop systems able to reduce the proliferation and virulence of this yeast, because of their intrinsic antimicrobial properties and complexation capabilities toward farnesol, the major quorum sensing molecule of Candida albicans. In the present study, a hybrid system characterized by a superparamagnetic iron oxide core functionalized with bovine odorant binding protein (bOBP) was successfully developed. The nanoparticles were designed to be suitable for magnetic protein delivery to inflamed areas of the body. The inorganic superparamagnetic core was characterized by an average diameter of 6.5 ± 1.1 nm and a spherical shape. Nanoparticles were functionalized by using 11-phosphonoundecanoic acid as spacer and linked to bOBP via amide bonds, resulting in a concentration level of 26.0 ± 1.2 mg bOBP/g SPIONs. Finally, both the biocompatibility of the developed hybrid system and the fungistatic activity against Candida albicans by submicromolar OBP levels were demonstrated by in vitro experiments.

Silver nanoparticles obtained from Brazilian pepper extracts with synergistic anti-microbial effect: production, characterization, hydrogel formulation, cell viability, and in vitro efficacy

The synthesis of silver nanoparticles using plant extracts is known as a green approach, as it does not require the use of high pressure, energy, high temperature, or toxic chemicals. The approach makes use of plant extracts in a process called bioreduction, which is mediated by enzymes, proteins, amino acids, and metabolites found in bark, seed, and leaf extracts, transforming silver ions into metallic silver. This work aimed at developing silver nanoparticles (AgNPs) from Brazilian pepper, applying this green methodology. Hydroalcoholic extract of leaves of Schinus terebinthifolius Raddi was prepared and its concentration of polyphenols, tannins, and saponins quantified. The produced nanoparticles were characterized by UV-Vis spectroscopy, thermogravimetric analysis (TG), dynamic light scattering (DLS), and zeta potential (ZP). AgNPs were formulated in sodium alginate hydrogels to obtain a nano-based semi-solid formulation for skin application. The obtained silver nanoparticles of mean size between 350 and 450 nm showed no cytotoxicity against L929 mouse fibroblasts within the concentration range of 0.025 mg/mL and 10 mg/mL. Schinus terebinthifolius Raddi was found to enhance microbial inhibition against the tested strains, especially against gram-negative bacteria. Its potential use as an alternative to overcome bacterial resistance can be expected.

Nano-ghosts: Novel biomimetic nano-vesicles for the delivery of antisense oligonucleotides

Antisense oligonucleotides (ASOs) carry an enormous therapeutic potential in different research areas, however, the lack of appropriate carriers for their delivery to the target tissues is hampering their clinical translation. The present study investigates the application of novel biomimetic nano-vesicles, Nano-Ghosts (NGs), for the delivery of ASOs to human mesenchymal stem cells (MSCs), using a microRNA inhibitor (antimiR) against miR-221 as proof-of-concept. The integration of this approach with a hyaluronic acid-fibrin (HA-FB) hydrogel scaffold is also studied, thus expanding the potential of NGs applications in regenerative medicine. The study shows robust antimiR encapsulation in the NGs using electroporation and the NGs ability to be internalized in MSCs and to deliver their cargo while avoiding endo-lysosomal degradation. This leads to rapid and strong knock-down of miR-221 in hMSCs in vitro, both in 2D and 3D hydrogel culture conditions (>90% and > 80% silencing efficiency, respectively). Finally, in vivo studies performed with an osteochondral defect model demonstrate the NGs ability to effectively deliver antimiR to endogenous cells. Altogether, these results prove that the NGs can operate as stand-alone system or as integrated platform in combination with scaffolds for the delivery of ASOs for a wide range of applications in drug delivery and regenerative medicine.

Bottlebrush Copolymer as Surface Neutralizer for Vertical Alignment of Block Copolymer Nanodomains in Thin Films

Herein we designed bottlebrush copolymers for use as a neutral additive to block copolymer (BCP) thin films in which they are segregated to the interfaces via architectural effects and produce nonpreferential interfaces to induce perpendicular orientation of BCP microdomains. Two BCP systems were employed, a conventional poly(styrene-b-methyl methacrylate) (PS-b-PMMA) with relatively low χ and similar surface energies between blocks, and a high χ poly(styrene-b-methacrylic acid) (PS-b-PMAA) with distinct surface energies. The bottlebrushes, with either short side-chains of PS-r-PMMA or PS-r-PMAA random copolymers, were synthesized via ring-opening metathesis polymerization (ROMP). Remarkably, it was observed that the top and bottom interfaces of both BCP films were enriched with bottlebrush copolymers, regardless of the surface energy difference between blocks, hence, vertically oriented microdomains were achieved for both BCP systems. This can be attributed to the screening of polymer interactions by a good solvent during the spin-casting process, allowing architectural effects to play a role in surface segregation of bottlebrush copolymers, as confirmed by contact angle measurements and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). We believe that this concept can be further extended to various applications that require polymer films with functional surfaces.

Theoretical Study on Tuning Band Gap and Electronic Properties of Atomically Thin Nanostructured MoS2/Metal Cluster Heterostructures

Nano-heterostructures have attracted immense attention recently due to their remarkable interfacial properties determined by the heterointerface of different nanostructures. Here, using first-principles density functional theory (DFT) calculations, we examine what range the variable electronic properties such as the electronic band gap can be tuned by combining two dissimilar nanostructures consisting of atomically thin nanostructured MoS2 clusters with small silver and gold nanoparticles (Ag/Au NPs). Most interestingly, our calculations show that the electronic band gap of the nanostructured MoS2 cluster can be tuned from 2.48 to 1.58 and 1.61 eV, by the formation of heterostructures with silver and gold metal nanoclusters, respectively. This band gap is ideal for various applications ranging from flexible nanoelectronics to nanophotonics applications. Furthermore, the adsorption of H2 molecules on both nano-heterostructures is investigated, and the computed binding energies are found to be within the desirable range. The reported theoretical results provide inspiration for engineering various optoelectronic applications for nanostructured MoS2-based heterostructures.

A Low-Temperature Heat Output Photoactive Material-Based High-Performance Thermal Energy Storage Closed System

Designing and synthesizing photothermal conversion materials with better storage capacity, long-term stability as well as low temperature energy output capability is still a huge challenge in the area of photothermal storage. In this work, we report a brand new photothermal conversion material obtained by attaching trifluoromethylated azobenzene (Azo_F) to reduced graphene oxide (rGO). Azo_F-rGO exhibits outstanding heat storage density and power density up to 386.1 kJ·kg⁻¹ and 890.6 W·kg⁻¹, respectively, with a long half-life (87.7 h) because of the H-bonds based on high attachment density. Azo_F-rGO also exhibits excellent cycling stability and is equipped with low-temperature energy output capability, which achieves the reversible cycle of photothermal conversion within a closed system. This novel Azo_F-rGO complex, which on the one hand exhibits remarkable energy storage performance as well as excellent storage life span, and on the other hand is equipped with the ability to release heat at low temperatures, shows broad prospects in the practical application of actual photothermal storage.

Unified Probability Distribution and Dynamics of Lead Contents in Human Erythrocytes Revealed by Single-Cell Analysis

Understanding the presence and dynamics of chemical pollutants in individual cells is fundamentally important for their trafficking, fate, and toxicity in humans. The presence of molecular components (i.e., proteins and mRNA) in individual cells of higher organisms is considered a stochastic event. The characteristics of chemical pollutants, as extrinsic compounds, in subpopulation of human cells on single-cell basis have not been explored yet. Here, we demonstrated the lead (Pb) content in individual mature erythrocytes (m-erythrocytes) of Pb-intoxicated patients, and healthy subjects exhibited a unified pattern in probability distribution (gamma distribution) and dynamics, despite being highly heterogeneous. The Pb content in individual m-erythrocytes decreased with the lifetime of m-erythrocytes. Meanwhile, the distribution and dynamics were found to be highly related to the Pb content in m-erythrocytes and was independent of patients and their status. This is the first study to analyze the distribution pattern of chemical pollutants at a single-cell level in higher organisms. This study sheds light on the molecular mechanism of Pb trafficking and fate in humans and the search for an efficient strategy to improve Pb excretion during Pb treatment.

Strain-dependent optical properties of the novel monolayer group-IV dichalcogenides SiS2semiconductor: a first-principles study

We studied the structural, electronic, and optical characters of SiS₂, a new type of group IV-VI two-dimensional semiconductor, in this article. We focused on monolayer SiS₂and its characteristic changes when different strains are applied on it. Results reveal that the monolayer SiS₂is dynamically stable when no strain is applied. In terms of electronic properties, it remains a semiconductor under applied strain within the range from -10% to 10%. Besides, its indirect band-gap is altered regularly after applying a strain, whereas different strains lead to various changing trends. As for its optical properties, it exhibits remarkable transparency for infrared and most visible light. Its main absorption and reflection regions lie in the blue and ultraviolet areas. The applied uniaxial strain causes its different optical properties along the armchair direction and zigzag direction. Moreover, the tensile strain could tune its optical properties more effectively than the compressive strain. When different strains are applied, the major changes are in blue and ultraviolet regions, but only minor changes can be found in infrared and visible regions. So its optical properties reveal good stability in infrared and visible regions. Therefore, SiS₂has a promising prospect in nano-electronic and nano-photoelectric devices.

Great Enhancement Effect of 20-40 nm Ag NPs on Solar-Blind UV Response of the Mixed-Phase MgZnO Detector

High-performance solar-blind UV detector with high response and fast speed is needed in multiple types of areas, which is hard to achieve in one device with a simple structure and device fabrication process. Here, the effects of Ag nanoparticles (NPs) with different sizes on UV response characteristics of the device are studied, the Ag NPs with different sizes that are made from a simple vacuum anneal method. Ag NPs with different sizes could modulate the peak response position of the mixed-phase MgZnO detector from near UV range (350 nm) to deep UV range (235 nm), and the enhancement effect of the Ag NPs on the UV response differs much with the crystal structure and the basic UV response of the MgZnO thin film. When high density 20-40 nm Ag NPs is induced, the deep UV (235 nm) response of the mixed-phase MgZnO detector is increased by 226 times, the I _uv/I _dark ratio of the modified device is increased by 17.5 times. The slight enhancement in UV light intensity from 20 to 40 nm Ag NPs induces multiple tunnel breakdown phenomena within the mixed-phase MgZnO thin film, which is the main reason for the abnormal great enhancement effect on deep UV response of the device, so the recovery speed of the modified device is not influenced. Therefore, Ag NPs with different sizes could effectively modulate the UV response peak position of mixed-phase MgZnO thin films, and the introduction of Ag NPs with high density and small size is a simple way to greatly increase the sensitivity of the mixed-phase MgZnO detector at deep UV light without decreasing the device speed.

Customizable Textile Sensors Based on Helical Core-Spun Yarns for Seamless Smart Garments

Most of the current sensors cannot meet the needs for seamless integration into the textile substrates of smart clothing and require improvements in terms of comfort and durability. Herein, smart textile-based sensors that have different sensing properties with integrated electronic elements were fabricated by knitting graphene-based helical conductive core-spun yarns. Such graphene-modified core-spun yarns are employed as building blocks of textile strain sensors, which showed high elasticity (ε > 300%), fast response time (120 ms), excellent reproducibility (over 10 000 cycles), wide sensing range (up to 100% strain), and low detection limit (0.3% strain). Thus, resistance-type strain sensors and capacitance-type pressure sensors composed of graphene-based smart fabric could be used to monitor large-scale limb movement and subtle human physiological signals. Such seamless smart textile-based fabric composed of superelastic helical conductive core-spun yarns shows great potential for fabricating an intelligent device to achieve real-time precise medicine and healthcare.

Synthetic heparan sulfate standards and machine learning facilitate the development of solid-state nanopore analysis

The application of solid-state (SS) nanopore devices to single-molecule nucleic acid sequencing has been challenging. Thus, the early successes in applying SS nanopore devices to the more difficult class of biopolymer, glycosaminoglycans (GAGs), have been surprising, motivating us to examine the potential use of an SS nanopore to analyze synthetic heparan sulfate GAG chains of controlled composition and sequence prepared through a promising, recently developed chemoenzymatic route. A minimal representation of the nanopore data, using only signal magnitude and duration, revealed, by eye and image recognition algorithms, clear differences between the signals generated by four synthetic GAGs. By subsequent machine learning, it was possible to determine disaccharide and even monosaccharide composition of these four synthetic GAGs using as few as 500 events, corresponding to a zeptomole of sample. These data suggest that ultrasensitive GAG analysis may be possible using SS nanopore detection and well-characterized molecular training sets.

Catalytically active and thermally stable core-shell gold-silica nanorods for CO oxidation

Deactivation based on sintering phenomena is one of the most costly issues for the industrial application of metal nanoparticle catalysts. To address this drawback, mesoporous silica encapsulation is reported as a promising strategy to stabilize metallic nanoparticles towards use in high temperature catalytic applications. These protective shells provide significant structural support to the nanoparticles, while the mesoporosity allows for efficient transport of the reactants to the catalytically active surface of the metallic nanoparticle in the core. Here, we extend the use of gold nanorods with mesoporous silica shells by investigating their stability in the CO oxidation reaction as an example of high temperature gas phase catalysis. Gold nanorods were chosen as the model system due to the availability of a simple, high yield synthesis method for both the metallic nanorods and the mesoporous silica shells. We demonstrate the catalytic activity of gold nanorods with mesoporous silica shells at temperatures up to 350 °C over several cycles, as well as the thermal stability up to 500 °C, and compare these results to surfactant-stabilized gold nanorods of similar size, which degrade, and lose most of their catalytic activity, before reaching 150 °C. These results show that the gold nanorods protected by the mesoporous silica shells have a significantly higher thermal stability than surfactant-stabilized gold nanorods and that the mesoporous silica shell allows for stable catalytic activity with little degradation at high temperatures.

Potential therapeutic agents to COVID-19: An update review on antiviral therapy, immunotherapy, and cell therapy

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in December 2020 and coronavirus disease 19 (COVID-19) was later announced as pandemic by the World Health Organization (WHO). Since then, several studies have been conducted on the prevention and treatment of COVID-19 by potential vaccines and drugs. Although, the governments and global population have been attracted by some vaccine production projects, the presence of SARS-CoV-2-specific antiviral drugs would be an urge necessity in parallel with the efficient preventive vaccines. Various nonspecific drugs produced previously against other bacterial, viral, and parasite infections were recently evaluated for treating patients with COVID-19. In addition to therapeutic properties of these anti-COVID-19 compounds, some adverse effects were observed in different human organs as well. Not only several attentions were paid to antiviral therapy and treatment of COVID-19, but also nanomedicine, immunotherapy, and cell therapy were conducted against this viral infection. In this review study, we planned to introduce the present and potential future treatment strategies against COVID-19 and define the advantages and disadvantages of each treatment strategy.

Water-Soluble Carbon Dots in Cigarette Mainstream Smoke: Their Properties and the Behavioural, Neuroendocrinological, and Neurotransmitter Changes They Induce in Mice

BACKGROUND

It is well known that smoking is harmful to health; however, it can also ameliorate anxiety. To date, it is unclear whether any nanoparticles found in cigarette mainstream smoke (CS) contribute to this effect.

AIM

The aim of this study was to assess the particle composition of CS to identify novel anti-anxiety components.

METHODS

Carbon dots (CDs) from CS (CS-CDs) were characterised using high-resolution transmission electron microscopy, Fourier-transform infrared, ultraviolet, fluorescence, X-ray photoelectron spectroscopy, X-ray diffraction and high-performance liquid chromatography. The anti-anxiety effects of CS-CDs in mouse models were evaluated and confirmed with the elevated plus maze and open-field tests.

RESULTS

The quantum yield of CS-CDs was 13.74%, with a composition of C, O, and N. In addition, the surface groups contained O-H, C-H, C=O, C-N, N-H, C-O-C, and COO- bonds. Acute toxicity testing revealed that CS-CDs had low in vitro and in vivo toxicity within a certain concentration range. The results of the elevated plus maze and open-field tests showed that CS-CDs had a significant anti-anxiety effect and a certain sedative effect in mice. The mechanism of these effects may be related to the decrease in glutamate levels and promotion of norepinephrine production in the mouse brain, and the decrease in dopamine in mouse serum due to CS-CDs.

CONCLUSION

CS-CDs may have anti-anxiety and certain sedative effects. This study provides a new perspective for a more comprehensive understanding of the components, properties, and functions of CS. Furthermore, it offers a novel target for the development of smoking cessation treatments, such as nicotine replacement therapy.

Epoxy-matrix polyaniline/p-phenylenediamine-functionalised graphene oxide coatings with dual anti-corrosion and anti-fouling performance

This research work reports on the anti-corrosion and anti-fouling properties of epoxy (E) coatings reinforced with polyaniline (PANI)/p-phenylenediamine-functionalised graphene oxide (PGO) composites. The mass ratio of graphene oxide/p-phenylenediamine in any PGO was assumed to be 1 : 1, but different PANI-PGO composites containing various loadings of PGO were prepared. An ultrasonic-assisted in situ polymerization method was employed to produce PANI-PGO at low temperature (0 °C). Several analytical and microscopical techniques, i.e., Fourier-transfer infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), were used to confirm that PANI-PGO composites were successfully synthesized. The epoxy-based coatings (E/PANI-PGO (x), x = 0.05-0.4 g) were applied by brushing them onto carbon steel substrates, which exhibited dual anti-corrosion and anti-fouling performance. Electrochemical impedance spectroscopy (EIS) results show that E/PANI-PGO (0.2) has the highest corrosion resistance (8.87 × 10⁶ Ω cm²) after 192 h of immersion in 3.5 wt% NaCl amongst all the coatings compared with neat epoxy (1.00 × 10⁴ Ω cm²) and E/PANI (6.82 × 10³ Ω cm²). Efficient antifouling performance at the macroscopic level under simulated marine conditions was observed for the epoxy-based PANI-PGO coatings with a range of PGO compositions, in particular for the 0.1 and 0.2 g PGO coatings.

Spreading Dynamics of a Precursor Film of Ionic Liquid or Water on a Micropatterned Polyelectrolyte Brush Surface

Time evolution of the microscopic wetting velocity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or water on a micrometer-scale line-patterned surface with a poly(3-sulfopropyl methacrylate) brush and a hydrophobic perfluoroalkyl monolayer was precisely measured by direct observation using optical microscopy and a selective dyeing method over a long period (178 days). When a liquid droplet was placed on the dyed line-patterned brush surface, the liquid penetrated and spread into the polymer brush layer, forming a precursor thin film that extended beyond the macroscopic contact line. The elongation proceeded in two stages by an adiabatic process followed by a diffusive process. The elongation distance X increased with time in proportion to t^2.6 for water and t^0.81 for EMI-TFSI during the adiabatic process. In a diffusive process, the advancing velocity of the precursor film was markedly reduced to be expressed as X ∝ t^0.66 for water and X ∝ t^0.21 for EMI-TFSI, indicating that the diffusive process was affected by the energy dissipation of the wetting system. The high viscosity and the strong molecular interaction of EMI-TFSI with the polymer brush gave a large entropy change during the wetting process to result in a slower spreading velocity.

On the Role and Applications of Electron Magnetic Resonance Techniques in Surface Chemistry and Heterogeneous Catalysis

Abstract

Some relevant aspects of Electron Paramagnetic Resonance (EPR) applied to the fields of surface chemistry and heterogeneous catalysis are illustrated in this perspective paper that aims to show the potential of these techniques in describing critical features of surface structures and reactivity. Selected examples are employed covering distinct aspects of catalytic science from morphological analysis of surfaces to detailed descriptions of chemical bonding and catalytic sites topology. In conclusions the pros and cons related to the acquisition of EPR instrumentations in an advanced laboratory of surface chemistry and heterogeneous catalysis are briefly considered.

Graphic Abstract

The Era of Nanomaterials: A Safe Solution or a Risk for Marine Environmental Pollution?

In recent years, the application of engineered nanomaterials (ENMs) in environmental remediation gained increasing attention. Due to their large surface area and high reactivity, ENMs offer the potential for the efficient removal of pollutants from environmental matrices with better performances compared to conventional techniques. However, their fate and safety upon environmental application, which can be associated with their release into the environment, are largely unknown. It is essential to develop systems that can predict ENM interactions with biological systems, their overall environmental and human health impact. Until now, Life-Cycle Assessment (LCA) tools have been employed to investigate ENMs potential environmental impact, from raw material production, design and to their final disposal. However, LCA studies focused on the environmental impact of the production phase lacking information on their environmental impact deriving from in situ employment. A recently developed eco-design framework aimed to fill this knowledge gap by using ecotoxicological tools that allow the assessment of potential hazards posed by ENMs to natural ecosystems and wildlife. In the present review, we illustrate the development of the eco-design framework and review the application of ecotoxicology as a valuable strategy to develop ecosafe ENMs for environmental remediation. Furthermore, we critically describe the currently available ENMs for marine environment remediation and discuss their pros and cons in safe environmental applications together with the need to balance benefits and risks promoting an environmentally safe nanoremediation (ecosafe) for the future.

Trans-illumination intestine projection imaging of intestinal motility in mice

Functional intestinal imaging holds importance for the diagnosis and evaluation of treatment of gastrointestinal diseases. Currently, preclinical imaging of intestinal motility in animal models is performed either invasively with excised intestines or noninvasively under anesthesia, and cannot reveal intestinal dynamics in the awake condition. Capitalizing on near-infrared optics and a high-absorbing contrast agent, we report the Trans-illumination Intestine Projection (TIP) imaging system for free-moving mice. After a complete system evaluation, we performed in vivo studies, and obtained peristalsis and segmentation motor patterns of free-moving mice. We show the in vivo typical segmentation motor pattern, that was previously shown in ex vivo studies to be controlled by intestinal pacemaker cells. We also show the effects of anesthesia on motor patterns, highlighting the possibility to study the role of the extrinsic nervous system in controlling motor patterns, which requires unanesthetized live animals. Combining with light-field technologies, we further demonstrated 3D imaging of intestine in vivo (3D-TIP). Importantly, the added depth information allows us to extract intestines located away from the abdominal wall, and to quantify intestinal motor patterns along different directions. The TIP system should open up avenues for functional imaging of the GI tract in conscious animals in natural physiological states.

EA-Directing Formamidinium-Based Perovskite Microwires with A-Site Doping

One recent development to improve optoelectronic properties of perovskites is to use a larger cation for multication engineering. The chain-like ethylammonium (EA) [(C2H5)NH3]+ cation is more likely to form a one-dimensional perovskite structure; however, there is no remarkable evidence in this connection. Therefore, in this work, for the first time, the EA cation as an alternative cation was introduced into FAPbBr3 cubic crystals to explore the stabilities and optoelectronic properties of mixed FA x EA(1-x)PbBr3 perovskites. The results indicate that replacing FA with EA is a more effective way to realize band gap tuning and morphology transformation between the cubic shape and microwires. The tuned band gap of perovskite is due to the variation of Pb-Br-Pb angles induced by the insertion of the larger EA cation. We highlight that this work provides new physical insights into the correlation between the engineering of organic cations and the formation of perovskite microwires and the tunable band gap. This observation will help us to find new ways to grow perovskite microwires and subsequently study the optoelectronic performance of low-dimensional perovskites devices.

Occupational Exposure to Carbon Nanotubes and Carbon Nanofibres: More Than a Cobweb

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are erroneously considered as singular material entities. Instead, they should be regarded as a heterogeneous class of materials bearing different properties eliciting particular biological outcomes both in vitro and in vivo. Given the pace at which the industrial production of CNTs/CNFs is increasing, it is becoming of utmost importance to acquire comprehensive knowledge regarding their biological activity and their hazardous effects in humans. Animal studies carried out by inhalation showed that some CNTs/CNFs species can cause deleterious effects such as inflammation and lung tissue remodeling. Their physico-chemical properties, biological behavior and biopersistence make them similar to asbestos fibers. Human studies suggest some mild effects in workers handling CNTs/CNFs. However, owing to their cross-sectional design, researchers have been as yet unable to firmly demonstrate a causal relationship between such an exposure and the observed effects. Estimation of acceptable exposure levels should warrant a proper risk management. The aim of this review is to challenge the conception of CNTs/CNFs as a single, unified material entity and prompt the establishment of standardized hazard and exposure assessment methodologies able to properly feed risk assessment and management frameworks.

Optimizing interferences of DUV lithography on SOI substrates for the rapid fabrication of sub-wavelength features

Scalable fabrication of Si nanowires with a critical dimension of about 100 nm is essential to a variety of applications. Current techniques used to reach these dimensions often involve e-beam lithography or deep-UV (DUV) lithography combined with resolution enhancement techniques. In this study, we report the fabrication of <150 nm Si nanowires from SOI substrates using DUV lithography (λ = 248 nm) by adjusting the exposure dose. Irregular resist profiles generated by in-plane interference under masking patterns of width 800 nm were optimized to split the resulting features into twin Si nanowires. However, masking patterns of micrometre size or more on the same photomask does not generate split features. The resulting resist profiles are verified by optical lithography computer simulation based on Huygens-Fresnel diffraction theory. Photolithography simulation results validate that the key factors in the fabrication of subwavelength nanostructures are the air gap value and the photoresist thickness. This enables the parallel top-down fabrication of Si nanowires and nanoribbons in a single DUV lithography step as a rapid and inexpensive alternative to conventional e-beam techniques.

Lanthanide-Doped Upconversion-Linked Immunosorbent Assay for the Sensitive Detection of Carbohydrate Antigen 19-9

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted considerable attention in detection of biological analytes and bioimaging owing to their superior optical properties, including high photochemical stability, sharp emission bandwidth, large anti-Stokes shifts, and low toxicity. In this work, we fabricated UCNP-linked immunosorbent assay (ULISA) for the sensitive detection of carbohydrate antigen 19-9 (CA19-9). The design is based on amino-functionalized SiO₂-coated Gd-doped NaYF₄:Yb³⁺,Er³⁺ upconversion nanoparticles (UCNPs@SiO₂-NH₂) as a direct background-free luminescent reporter; a secondary anti-IgG antibody (Ab₂) was conjugated to the surface of UCNPs@SiO₂-NH₂ (UCNP-Ab₂), and UCNP-Ab₂ was used for specific targeting of CA19-9. The UCNPs were well characterized by TEM, SEM, XRD, FT-IR, and UV-vis. The detection process was similar to enzyme-linked immunosorbent assay (ELISA). UCNPs were used as signal transducer to replace the color compounds for an enzyme-mediated signal amplification step. An anti-CA19-9 primary antibody (Ab₁) was fixed for capturing the CA19-9, and the fluorescence signal was obtained from the specific immunoreaction between UCNP-Ab₂ and CA19-9. Under optimum conditions, this ULISA shows sensitive detection of CA19-9 with a dynamic range of 5-2,000 U/ml. The ULISA system shows higher detection sensitivity and wider detection range compared with the traditional ELISA for CA19-9 detection. This strategy using UCNPs as signal transducer may pave a new avenue for the exploration of rare doped UCNPs in ELISA assay for clinical applications in the future.

Synthesis and Properties of Strongly Quantum-Confined Cesium Lead Halide Perovskite Nanocrystals

ConspectusSemiconducting metal halide perovskite (MHP) nanocrystals have emerged as an important new class of materials as the source of photons and charges for various applications that can outperform many other semiconductor nanocrystals utilized for the same purposes. However, the majority of the studies of MHP nanocrystals focused on weakly or nonconfined systems, where the quantum confinement giving rise to various size-dependent and confinement-enhanced photophysical properties cannot be explored readily. This was partially due to the challenge in producing strongly quantum-confined MHP nanocrystals, since the traditional kinetic control approach was less effective for the size control. Recent synthetic progress in MHP nanocrystals utilizing the equilibrium-based size control achieved the precise control of quantum confinement with high ensemble uniformity, enabling the exploration of the unique properties of MHP nanocrystals under strong quantum confinement. In this Account, we review the recent progress made in the synthesis of strongly quantum-confined cesium lead halide nanocrystals and investigation of the properties of exciton modified by strong quantum confinement. The main body of this Account discusses the key results of the research in this field in two separate sections. Section 2 describes the thermodynamic equilibrium-based synthesis method to control the size of cesium lead halide perovskite quantum dots in strongly confined regime. Size control in anisotropic nanocrystals with one- and two-dimensional quantum confinement is also discussed. Section 3 covers the following three topics that highlight the effects of quantum confinement on various spectroscopic properties of excitons in cesium lead halide perovskite nanocrystals: (1) Size-dependent absorption cross section of cesium lead halide quantum dots; (2) confinement effect on exciton fine structure and access to the dark exciton exhibiting intense and long-lived photoluminescence; (3) activation of forbidden exciton transition via dynamic lattice distortion by the photoexcited charge carriers enhanced by quantum confinement. The impact of strong quantum confinement goes beyond the properties of excitons covered in this Account and is expected to expand the functionality of MHP nanocrystals as the source of photons and charges. For instance, realization of the possible enhancement of photon down- and upconversion and hot carrier generation via quantum confinement will further increase the usefulness of strongly confined MHP nanocrystals in their applications.

Colloidal Nanostructures of Transition-Metal Dichalcogenides

ConspectusLayered transition-metal dichalcogenides (TMDs) are intriguing two-dimensional (2D) compounds where metal and chalcogen atoms are covalently bonded in each monolayer, and the monolayers are held together by weak van der Waals forces. Distinct from graphene, which is chemically inert, layered TMDs exhibit a wide range of electronic, optical, catalytic, and magnetic properties dependent upon their compositions, crystal structures, and thicknesses, which make them fundamentally and technologically important. TMD nanostructures are traditionally synthesized using gas-phase chemical deposition methods, which are typically limited to small-scale samples of substrate-bound planar materials. Colloidal synthesis has emerged as an alternative synthesis approach to enable the scalable synthesis of free-standing TMDs. The judicious selection of precursors, solvents, and capping ligands together with the optimization of synthesis parameters such as concentrations and temperatures leads to the fabrication of colloidal TMD nanostructures exhibiting tunable properties. In addition, understanding the formation and transformation of TMD nanostructures in solution contributes to the discovery of important structure-function relationships, which may be extendable to other anisotropic systems.In this Account, we summarize recent progress in the colloidal synthesis, characterization, and applications of TMD nanostructures with tunable compositions, structures, and thicknesses. On the basis of the preparation of Mo- and W-based disulfide, diselenide, and ditelluride nanostructures, we discuss examples of phase engineering where various metastable TMD compounds can be directly accessed at low temperatures in solution. We also analyze the chemistry involved in broadly tuning the composition across the MoSe₂-WSe₂, WS₂-WSe₂, and MoTe₂-WTe₂ solid solutions as well as atomic-level microscopic characterization and the resulting composition-tunable properties. We then highlight how the high densities of defects in the colloidally synthesized TMD nanostructures enable unique catalytic properties, including their ability to facilitate the selective hydrogenation of substituted nitroarenes using molecular hydrogen. Finally, using this library of colloidal TMD nanostructures as substrates, we discuss the pathways by which noble metals deposit onto them in solution. We highlight the importance of the relative strengths of the interfacial metal-chalcogen bonds in determining the sizes and morphologies of the deposited noble metal components. These synthesis capabilities for colloidal TMD nanostructures, which have been generalized to a library of composition-tunable phases, enable new systematic studies of structure-property relationships and chemical reactivity in this important class of 2D materials.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

A perfusable, multifunctional epicardial device improves cardiac function and tissue repair

Despite advances in technologies for cardiac repair after myocardial infarction (MI), new integrated therapeutic approaches still need to be developed. In this study, we designed a perfusable, multifunctional epicardial device (PerMed) consisting of a biodegradable elastic patch (BEP), permeable hierarchical microchannel networks (PHMs) and a system to enable delivery of therapeutic agents from a subcutaneously implanted pump. After its implantation into the epicardium, the BEP is designed to provide mechanical cues for ventricular remodeling, and the PHMs are designed to facilitate angiogenesis and allow for infiltration of reparative cells. In a rat model of MI, implantation of the PerMed improved ventricular function. When connected to a pump, the PerMed enabled targeted, sustained and stable release of platelet-derived growth factor-BB, amplifying the efficacy of cardiac repair as compared to the device without a pump. We also demonstrated the feasibility of minimally invasive surgical PerMed implantation in pigs, demonstrating its promise for clinical translation to treat heart disease.

Single-Atom Gadolinium Anchored on Graphene Quantum Dots as a Magnetic Resonance Signal Amplifier

A single-atom metal doped on carbonaceous nanomaterials has attracted increasing attention due to its potential applications as high-performance catalysts. However, few studies focus on the applications of such nanomaterials as nanotheranostics for simultaneous bioimaging and cancer therapy. Herein, it is pioneeringly demonstrated that the single-atom Gd anchored onto graphene quantum dots (SAGd-GQDs), with dendrite-like morphology, was successfully prepared. More importantly, the as-fabricated SAGd-GQDs exhibits a robustly enhanced longitudinal relaxivity (r₁ = 86.08 mM^-1 s^-1) at a low Gd³⁺ concentration of 2 μmol kg^-1, which is 25 times higher than the commercial Gd-DTPA (r₁ = 3.44 mM^-1 s^-1). In vitro and in vivo studies suggest that the obtained SAGd-GQDs is a highly potent and contrast agent to obtain high-definition MRI, thereby opening up more opportunities for future precise clinical theranostics.

Waveguide integrated hot electron bolometer for classical and quantum photonics

The development of performant integrated detectors, which are sensitive to quantum fluctuations of coherent light, are strongly desired to realize a scalable and determinist photonic quantum processor based on continuous variables states of light. Here, we investigate the performance of hot electron bolometers (HEBs) fabricated on top of a silicon-on-insulator (SOI) photonic circuit showing responsivities up to 8600 V/W and a record noise equivalent temperature of 1.1 dB above the quantum limit. Thanks to a detailed analysis of the noise sources of the waveguide integrated HEB, we estimate 14.8 dBV clearance between the shot noise and electrical noise with just 1.1µW of local oscillator power. The full technology compatibility with superconducting nanowire single photon detectors (SNSPDs) opens the possibility of nonclassical state engineering and state tomography performed within the same platform, enabling a new class of optical quantum processors.

Caffeic acid protects mice pancreatic islets from oxidative stress induced by multi-walled carbon nanotubes (MWCNTs)

Increasing applications of carbon nanotubes (CNTs) indicate the necessity to examine their toxicity. According to previous studies, CNTs caused oxidative stress that impaired β-cell functions and reduced insulin secretion. Our previous study indicated that single-walled carbon nanotubes (SWCNTs) could induce oxidative stress in pancreatic islets. However, there is no study on the effects of multi-walled carbon nanotubes (MWCNTs) on islets and β-cells. Therefore, the present study aims to evaluate effects of MWCNTs on the oxidative stress of islets and the protective effects of caffeic acid (CA) as an antioxidant. The effects of MWCNTs and CA on islets were investigated using MTT assay, reactive oxygen species (ROS), malondialdehyde (MDA), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), the content of glutathione (GSH) and mitochondrial membrane potential (MMP) and insulin secretion measurements. The lower viability of islet cells was dose-dependent due to the exposure to MWCNTs according to the MTT assay. Further studies revealed that MWCNTs decreased insulin secretion and MMP, induced ROS creation, increased the MDA level, and decreased activities of SOD, GSH-Px, CAT, and content of GSH. Furthermore, the pretreatment of islets with CA returned the changes. These findings indicated that MWCNTs might induce the oxidative stress of pancreatic islets occurring diabetes and protective CA effects that were mediated by the augmentation of the antioxidant defense system of islets. Our research suggested the necessity of conducting further studies on effects of MWCNTs and CA on the diabetes.

Systematic evaluation of CdSe/ZnS quantum dots toxicity on the reproduction and offspring health in male BALB/c mice

Increased applications of quantum dots (QDs) in the biomedical field have aroused attention for their potential toxicological effects. Although numerous studies have been carried out on the toxicity of QDs, their effects on reproductive and development are still unclear. In this study, we systematically evaluated the male reproductive toxicity and developmental toxicity of CdSe/ZnS QDs in BALB/c mice. The male mice were injected intravenously with CdSe/ZnS QDs at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively, and the survival status, biodistribution of QDs in testes, serum sex hormone levels, histopathology, sperm motility and acrosome integrity was measured on Day 1, 7, 14, 28 and 42 after injection. On Day 35 after treatment, male mice were housed with non-exposed female mice, and then offspring number, body weight, organ index and histopathology of major organs, blood routine and biochemical tests of offspring were measured to evaluate the fertility and offspring health. The results showed that CdSe/ZnS QDs could rapidly distribute in the testis, and the fluorescence of QDs could still be detected on Day 42 post-injection. QDs had no adverse effect on the structure of testis and epididymis, but high-dose QDs could induce apoptosis of Leydig cells in testis at an early stage. No significant differences in survival of state, body weight organ index of testis and epididymis, sex hormones levels, sperm quality, sperm acrosome integrity and fertility of male mice were observed in QDs exposed groups. However, the development of offspring was obviously influenced, which was mainly manifested in the slow growth of offspring, changes in organ index of main organs, and the abnormality of liver and kidney function parameters. Our findings revealed that CdSe/ZnS QDs were able to cross the blood-testis barrier (BTB), produce no discernible toxic effects on the male reproductive system, but could affect the healthy growth of future generations to some extent. In view of the broad application prospect of QDs in biomedical fields, our findings might provide insight into the biological safety evaluation of the reproductive health of QDs.

Influence of the Thermomechanical Characteristics of Low-Density Polyethylene Substrates on the Thermoresistive Properties of Graphite Nanoplatelet Coatings

Morphological, structural, and thermoresistive properties of films deposited on low-density polyethylene (LDPE) substrates are investigated for possible application in flexible electronics. Scanning and transmission electron microscopy analyses, and X-ray diffraction measurements show that the films consist of overlapped graphite nanoplatelets (GNP) each composed on average of 41 graphene layers. Differential scanning calorimetry and dynamic-mechanical-thermal analysis indicate that irreversible phase transitions and large variations of mechanical parameters in the polymer substrates can be avoided by limiting the temperature variations between −40 and 40 °C. Electrical measurements performed in such temperature range reveal that the resistance of GNP films on LDPE substrates increases as a function of the temperature, unlike the behavior of graphite-based materials in which the temperature coefficient of resistance is negative. The explanation is given by the strong influence of the thermal expansion properties of the LDPE substrates on the thermo-resistive features of GNP coating films. The results show that, narrowing the temperature range from 20 to 40 °C, the GNP on LDPE samples can work as temperature sensors having linear temperature-resistance relationship, while keeping constant the temperature and applying mechanical strains in the 0–4.2 × 10−3 range, they can operate as strain gauges with a gauge factor of about 48.

Multilayer 2D germanium phosphide (GeP) infrared phototransistor

Layered two-dimensional (2D) materials with broadband photodetection capability have tremendous potential in the design and engineering of future optoelectronics devices. To date, studies of 2D semiconductors are actively focused on graphene, black phosphorus, and black arsenic phosphorus as attractive candidates. So far, however, novel group IV-V 2D semiconductors (e.g., GeAs and SiAs) have not been extensively explored for broad-band optoelectronics applications. Here, we report a high-performance multilayered 2D GeP gate-tunable photodetector that operates at a short-wavelength infrared (SWIR) regime. With a back-gate device geometry, a p-type behavior is observed at room temperature. Furthermore, a broadband spectral response from UV to optical communication wavelengths is detected. Under a nanowatt-level illumination, a peak responsivity of 25.5 A/W at λ = 1310 nm is achieved with detectivity of ∼ 1×10¹¹ cm.Hz^1/2.W^-1 at a source-drain bias of -5 V and medium gate voltage bias of -30 V. Additionally, the devices show a relatively low dark current of 40-250 nA for device area in the range of 50-600 µm² and excellent stability and reproducibility. Our work demonstrates the potential of 2D GeP as an alternative mid-infrared material with broad optical tunability suitable for optical communication and low-light-level detection applications.

Surface-enhanced Raman scattering by the composite structure of Ag NP-multilayer Au films separated by Al2O3

In the present study, a nanoparticle-multilayer metal film substrate was presented with silver nanoparticles (Ag NPs) assembled on a multilayer gold (Au) film by employing alumina (Al₂O₃) as a spacer. The SERS performance of the proposed structures was determined. It was suggested that the SERS effect was improved with the increase in the number of layers, which was saturated at four layers. The SERS performance of the structures resulted from the mutual coupling of multiple plasmon modes [localized surface plasmons (LSPs), surface plasmon polaritons (SPPs), as well as bulk plasmon polaritons (BPPs)] generated by the Ag NP-multilayer Au film structure. Furthermore, the electric field distribution of the hybrid system was studied with COMSOL Multiphysics software, which changed in almost consistency with the experimentally achieved results. For this substrate, the limit of detection (LOD) was down to 10^-13 M for the rhodamine 6G (R6G), and the proposed SERS substrate was exhibited prominently quantitatively detected capability and high reproducibility. Moreover, a highly sensitive detection was conducted on toluidine blue (TB) molecules. As revealed from the present study, the Ag NP-multilayer Au film structure can act as a dependable SERS substrate for its sensitive molecular sensing applications in the medical field.

Liquid crystal integrated metadevice for reconfigurable hologram displays and optical encryption

The ultimate goal of metasurface research in recent years is to apply metasurface to reality applications and improve the performance compared to its counterpart, namely conventional optical elements with the same function. Inspired by the application of electrically addressing spatial light modulator (EA-SLM) and based on the binary holographic algorithm, here we propose a reconfigurable metadevice integrated with the nematic liquid crystal (NLC). The smart metadevice directly uses the subwavelength antennas as the main contributor to the phase accumulation instead of the NLC layer. By applying different electrical modulation patterns on the NLC, the metadevice can realize the function of dynamic holographic display as traditional SLMs but features in smaller size, higher resolution and lager field of view. In addition, we improved the existing computer-generated hologram algorithm to generate three holograms with quantitative correlation and also propose a new optical encryption method based on our metadevice. The encryption method needs four elements in total to decrypt and can fully meets the requirements of the various encrypted content. We believe such metadevice paves the way for the new generation of micro-optical display and optical encryption devices.

Tailoring anisotropic absorption in a borophene-based structure via critical coupling

The research of two-dimensional (2D) materials with atomic-scale thicknesses and unique optical properties has become a frontier in photonics and electronics. Borophene, a newly reported 2D material, provides a novel building block for nanoscale materials and devices. We present a simple borophene-based absorption structure to boost the light-borophene interaction via critical coupling in the visible wavelengths. The proposed structure consists of borophene monolayer deposited on a photonic crystal slab backed with a metallic mirror. The numerical simulations and theoretical analysis show that the light absorption of the structure can be remarkably enhanced as high as 99.80% via critical coupling mechanism with guided resonance, and the polarization-dependent absorption behaviors are demonstrated due to the strong anisotropy of borophene. We also examine the tunability of the absorption behaviors by adjusting carrier density and lifetime of borophene, air hole radius in the slab, the incident angle and polarization angle. The proposed absorption structure provides novel access to the flexible and effective manipulation of light-borophene interactions in the visible and shows a good prospect for the future borophene-based electronic and photonic devices.

Small Extracellular Vesicles: A Novel Avenue for Cancer Management

Extracellular vesicles are small membrane particles derived from various cell types. EVs are broadly classified as ectosomes or small extracellular vesicles, depending on their biogenesis and cargoes. Numerous studies have shown that EVs regulate multiple physiological and pathophysiological processes. The roles of small extracellular vesicles in cancer growth and metastasis remain to be fully elucidated. As endogenous products, small extracellular vesicles are an ideal drug delivery platform for anticancer agents. However, several aspects of small extracellular vesicle biology remain unclear, hindering the clinical implementation of small extracellular vesicles as biomarkers or anticancer agents. In this review, we summarize the utility of cancer-related small extracellular vesicles as biomarkers to detect early-stage cancers and predict treatment outcomes. We also review findings from preclinical and clinical studies of small extracellular vesicle-based cancer therapies and summarize interventional clinical trials registered in the United States Food and Drug Administration and the Chinese Clinical Trials Registry. Finally, we discuss the main challenges limiting the clinical implementation of small extracellular vesicles and recommend possible approaches to address these challenges.

Impacts of Mechanical Stiffness of Bacteriophage-Loaded Hydrogels on Their Antibacterial Activity

The elaboration of efficient hydrogel-based materials with antimicrobial properties requires a refined control of defining their physicochemical features, which includes mechanical stiffness, so as to properly mediate their antibacterial activity. In this work, we design hydrogels consisting of polyelectrolyte multilayer films for the loading of T4 and φX174 bacteria-killing viruses, also called bacteriophages. We investigate the antiadhesion and bactericidal performances of this biomaterial against Escherichia coli, with a specific focus on the effects of chemical cross-linking of the hydrogel matrix, which, in turn, mediates the hydrogel stiffness. Depending on the latter and on phage replication features, it is found that the hydrogels loaded with the bacteria-killing viruses make both contact killing (targeted bacteria are those adhered at the hydrogel surface) and release killing (planktonic bacteria are the targets) possible with ca. 20-80% efficiency after only 4 h of incubation at 25 °C as compared to cases where hydrogels are free of viruses. We further demonstrate the lack of dependence of virus diffusion within the hydrogel and of the maximal viral storage capacity on the hydrogel mechanical properties. In addition to the evidenced bacteriolytic activity of the phages loaded in the hydrogels, the antimicrobial property of the phage-loaded materials is shown to be partly controlled by the chemistry of the hydrogel skeleton and, more specifically, by the mobility of the peripheral free polycationic components, known for their ability to weaken and permeabilize membranes of bacteria, the latter then becoming "easier" targets for the viruses.