A Coupling-Induced Assembly Strategy for Constructing Artificial Shell on Mitochondria in Living Cells.

The strategy of in vivo self-assembly has been developed for improved enrichment and long-term retention of anticancer drug in tumor tissues. However, most self-assemblies with non-covalent bonding interactions are susceptible to complex physiological environments, leading to weak stability and loss of biological function. Here, we develop a coupling-induced assembly (CIA) strategy to generate covalently crosslinked nanofibers, which is applied for in situ constructing artificial shell on mitochondria. The oxidation-responsive peptide-porphyrin conjugate P1 is synthesized, which self-assemble into nanoparticles. Under the oxidative microenvironment of mitochondria, the coupling of thiols in P1 causes the formation of dimers, which is further ordered and stacked into crosslinked nanofibers. As a result, the artificial shell is constructed on the mitochondria efficiently through multivalent cooperative interactions due to the increased binding sites. Under ultrasound (US) irradiation, the porphyrin molecules in the shell produce a large amount of reactive oxygen species (ROS) that act on the adjacent mitochondrial membrane, exhibiting ~2-fold higher antitumor activity than nanoparticles in vitro and in vivo. Therefore, the mitochondria-targeted CIA strategy provides a novel perspective on improved sonodynamic therapy (SDT) and shows potential applications in antitumor therapies.

Performance Evaluation of a Nylon-like Polyester Tire Cord Combining the Characteristics of Nylon and Polyester.

A nylon-like polyester tire cord, which combined the characteristics of nylon and polyester tire cords, was designed as the carcass reinforcement material used to meet the increasing demands of the tire industry for performance and impact on the environment. Tires' carcass construction plays a crucial role in affecting handling performance and ride comfort. Small changes in the carcass component can lead to significant improvements in the total tire/vehicle performance. This study evaluated the performance of nylon-like polyester and nylon 6 motorcycle tires. The results showed that the nylon-like polyester tire passed all indoor tests, and post-cure inflation (PCI) could be eliminated, resulting in energy and cost savings. The rolling resistance coefficient of the nylon-like polyester tire was reduced by 6.8% compared to that of the nylon 6 control tire, which could save fuel and have a positive impact on the environment. Nylon-like polyester tire cord extracted from the experimental tire possessed a higher modulus compared to that of nylon 6 tire cord, which could lead to better handling and ride comfort performance. Morphological pictures showed that both nylon-like polyester and nylon 6 cords extracted from tires had a good rubber coverage and comparable adhesion properties.

A tert-Butyldiphenylsilyl-Containing Polyimide-Based Chemosensor for Sequential Detection of Fluoride Ions and Trace Water in Organic Solvents.

A tert-butyldiphenylsilyl-containing polyimide (PI-OSi) has been established as a colorimetric and ratiometric chemosensor for rapid detecting fluoride ions (F-). The UV-vis absorbance ratio value (A322/A288) of PI-OSi in a DMF solution displays a wide linear range change to F- concentrations with a detection limit (DL) value of 2.13 µM. Additionally, adding incremental amounts of F- to a DMF solution of PI-OSi shows an immediate color change to yellow and finally to green from colorless. More interestingly, the resulting PI-OSi plus F- system (PI-OSi·F) could detect trace water in DMF. The A292/A322 value of PI-OSi·F almost linearly increases with low water content, which suggests convenient quantitative sensing of trace water content in DMF. The DL value of PI-OSi·F for sensing water in DMF is determined to be 0.00149% (v/v). The solution color of PI-OSi·F returns to colorless when the water content increases, indicating that PI-OSi·F can conveniently estimate water content in DMF by naked-eye detection. The detection mechanisms confirmed by an 1H NMR study and a DFT calculation involve a F--induced desilylation reaction of PI-OSi to form phenolate anion followed by protonation with trace water. Finally, PI-OSi film was fabricated for the colorimetric detection of F- and water in CH3CN.

Recent advances in the intracellular delivery of macromolecule therapeutics.

Intracellular delivery of macromolecules is a critical procedure for biological research and drug discovery, including proteins, peptides, vaccines, antibodies and genes. The penetration of macromolecule therapeutics through the cell membrane to intracellular targets is a prerequisite for their biological activity, but most delivery systems rely on the endocytic pathway to enter the cell and confront an inability to escape from the lysosome. A profound understanding of the cellular internalization of transporting carriers can (i) optimize the design of drug delivery systems, (ii) maintain the biological activity of biomolecular drugs, (iii) improve the efficiency of intracellular macromolecule transport and release, (iv) bring new opportunities for the discovery of macromolecule therapeutics and treatment of refractory disease. This article summarizes the uptake pathway of intracellular delivery vehicles for macromolecule drugs, hoping to provide ideas and references for macromolecule therapeutics delivery systems.

Modified Fabrication of Perovskite-Based Composites and Its Exploration in Printable Humidity Sensors.

Organic perovskites are promising optoelectronic semiconductor materials with photoelectric applications. It is known that the luminescence of perovskites is highly sensitive to hydron molecules due to its low moisture resistance of crystal structure, indicating its potential application on humidity-sensing. Herein, a novel perovskite-based compound (PBC) with minimal defects was developed to promote the photoluminescence performance via optimization of the drying method and precursor constitutions. Perovskite materials with good structural integrity and enhanced fluorescence performance up to four times were obtained from supercritical drying. Moreover, the hydrophilic polymer matrix, polyethylene oxide (PEO), was added to obtain a composite of perovskite/PEO (PPC), introducing enhanced humidity sensitivity and solution processibility. These perovskite/PEO composites also exhibited long-term stability and manifold cycles of sensitivity to humidity owing to perovskite encapsulation by PEO. In addition, this precursor solution of perovskite-based composites could be fancily processed by multiple methods, including printing and handwriting, which demonstrates the potential and broaden the applications in architecture decoration, logos, trademarks, and double encryption of anti-fake combined with humidity.

Research progress on tumor hypoxia-associative nanomedicine.

Hypoxia at the solid tumor site is generally related to the unrestricted proliferation and metabolism of cancerous cells, which can cause tumor metastasis and aggravate tumor progression. Besides, hypoxia plays a substantial role in tumor treatment, and it is one of the main reasons that malignant tumors are difficult to cure and have a poor prognosis. On account of the tumor specific hypoxic environment, many hypoxia-associative nanomedicine have been proposed for tumor treatment. Considering the enhanced targeting effect, designing hypoxia-associative nanomedicine can not only minimize the adverse effects of drugs on normal tissues, but also achieve targeted therapy at the lesion site. Mostly, there can be three strategies for the treatment of hypoxic tumor, including improvement of hypoxic environment, hypoxia responsive drug release and hypoxia activated prodrug. The review describes the design principle and applications of tumor hypoxia-associative nanomedicine in recent years, and also explores its development trends in solid tumor treatment. Moreover, this review presents the current limitations of tumor hypoxia-associative nanomedicine in chemotherapy, radiotherapy, photodynamic therapy, sonodynamic therapy and immunotherapy, which may provide a reference for clinic translation of tumor hypoxia-associative nanomedicine.

Environmentally Friendly, Durably Waterproof, and Highly Breathable Fibrous Fabrics Prepared by One-Step Fluorine-Free Waterborne Coating.

Waterproof and breathable membranes (WBMs) have drawn broad attention due to their widespread applications in various scientific and industry fields. However, creating WBMs with environment-friendliness and high performance is still a critical and challenging task. Herein, an environmentally friendly fluorine-free WBM with high performance was prepared through electrospinning and one-step dip-coating technology. The fluorine-free waterborne hydroxyl acrylic resin (HAR) emulsion containing long hydrocarbon chains endowed the electrospun polyacrylonitrile/blocked isocyanate prepolymer (PAN/BIP) fibrous membranes with superior hydrophobicity; meanwhile, crosslinking agent BIP ensured strong chemical binding between hydrocarbon segments and fiber substrate. The as-prepared PAN/BIP@HAR fibrous membranes achieve ideal properties with waterproofness of 112.5 kPa and moisture permeability of 12.7 kg m-2 d-1, which are comparable to the existing high-performance fluorinated WBMs. Besides, the PAN/BIP@HAR membranes also display impressive tensile strength and durability. Significantly, the proposed technology was also applicable to other hydrophilic fiber substrates, such as cellulose acetate and polyamide 6. The successful synthesis of environmentally friendly, durably waterproof, and highly breathable PAN/BIP@HAR membranes not only opens a new avenue to materials design, but also provides promising candidates with tremendous potential in various areas.

Tailoring the Performances of Lead Halide Perovskite Devices with Electron-Beam Irradiation.

Lead halide perovskites are intensively studied in past few years due to their potential applications in optoelectronic devices such as solar cells, photodetectors, light-emitting diodes (LED), and lasers. In addition to the rapid developments in material synthesis and device fabrication, it is also very interesting to postsynthetically control the optical properties with external irradiations. Here, the influences of very low energy (10-20 keV) electron beam of standard electron beam lithography are experimentally explored on the properties of lead halide perovskites. It is confirmed that the radiolysis process also happens and it can selectively change the photoluminescence, enabling the direct formation of nanolaser array, microsized light emitter array, and micropictures with an electron beam writer. Interestingly, it is found that discontinuous metallic lead layers are formed on the top and bottom surfaces of perovskite microplate during the radiolysis process, which can act as carrier conducting layers and significantly increase the photocurrent of perovskite photodetector by a factor of 217%. By using the electron beam with low energy to modify the perovskite, this method promises to shape the emission patterns for micro-LED with well-preserved optical properties and improves the photocurrent of photodetector.

Miscellaneous Lasing Actions in Organo-Lead Halide Perovskite Films.

Lasing actions in organo-lead halide perovskite films have been heavily studied in the past few years. However, due to the disordered nature of synthesized perovskite films, the lasing actions are usually understood as random lasers that are formed by multiple scattering. Herein, we demonstrate the miscellaneous lasing actions in organo-lead halide perovskite films. In addition to the random lasers, we show that a single or a few perovskite microparticles can generate laser emissions with their internal resonances instead of multiple scattering among them. We experimentally observed and numerically confirmed whispering gallery (WG)-like microlasers in polygon shaped and other deformed microparticles. Meanwhile, owing to the nature of total internal reflection and the novel shape of the nanoparticle, the size of the perovskite WG laser can be significantly decreased to a few hundred nanometers. Thus, wavelength-scale lead halide perovskite lasers were realized for the first time. All of these laser behaviors are complementary to typical random lasers in perovskite film and will help the understanding of lasing actions in complex lead halide perovskite systems.

Room temperature three-photon pumped CH3NH3PbBr3 perovskite microlasers.

Hybrid lead halide perovskites have made great strides in next-generation light-harvesting and light emitting devices. Recently, they have also shown great potentials in nonlinear optical materials. Two-photon absorption and two-photon light emission have been thoroughly studied in past two years. However, the three-photon processes are rarely explored, especially for the laser emissions. Here we synthesized high quality CH3NH3PbBr3 perovskite microstructures with solution processed precipitation method and studied their optical properties. When the microstructures are pumped with intense 1240 nm lasers, we have observed clear optical limit effect and the band-to-band photoluminescence at 540 nm. By increasing the pumping density, whispering-gallery-mode based microlasers have been achieved from CH3NH3PbBr3 perovskite microplate and microrod for the first time. This work demonstrates the potentials of hybrid lead halide perovskites in nonlinear photonic devices.

Integrated photonic power divider with arbitrary power ratios.

Integrated optical power splitters are one of the fundamental building blocks in photonic integrated circuits. Conventional multimode interferometer-based power splitters are widely used as they have reasonable footprints and are easy to fabricate. However, it is challenging to realize arbitrary split ratios, especially for multi-outputs. In this Letter, an ultra-compact power splitter with a QR code-like nanostructure is designed by a nonlinear fast search method. The highly functional structure is composed of a number of freely designed square pixels with the size of 120×120 nm which could be either dielectric or air. The light waves are scattered by a number of etched squares with optimized locations, and the scattered waves superimpose at the outputs with the desired power ratio. We demonstrate 1×2 splitters with 1:1, 1:2, and 1:3 split ratios, and a 1×3 splitter with the ratio of 1:2:1. The footprint for all the devices is only 3.6×3.6 µm. Well-controlled split ratios are measured for all the cases. The measured transmission efficiencies of all the splitters are close to 80% over 30 nm wavelength range.

Construction of a Fish-like Robot Based on High Performance Graphene/PVDF Bimorph Actuation Materials.

Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish-like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene-PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene-based materials at a macro scale.

Large-Scale and Defect-Free Silicon Metamaterials with Magnetic Response.

All-dielectric metamaterials offer a potential low-loss alternative to plasmonic metamaterials at optical frequencies. Here, we experimentally demonstrate a silicon based large-scale magnetic metamaterial, which is fabricated with standard photolithography and conventional reactive ion etching process. The periodically arrayed silicon sub-wavelength structures possess electric and magnetic responses with low loss in mid-infrared wavelength range. We investigate the electric and magnetic resonances dependencies on the structural parameters and demonstrate the possibility of obtaining strong dielectric-based magnetic resonance through a broad band range. The optical responses are quite uniform over a large area about 2 × 2 cm(2). The scalability of this design and compatibility fabrication method with highly developed semiconductor devices process could lead to new avenues of manipulating light for low-loss, large-area and real integrated photonic applications.

A hybrid system with highly enhanced graphene SERS for rapid and tag-free tumor cells detection.

By dint of unique physical/chemical properties and bio-compatibility, graphene can work as a building block for a SERS substrate and open up a unique platform for tumor cells detection with high sensitivity. Herein we demonstrate a facile system with highly enhanced surface enhanced Raman spectroscopy of graphene (G-SERS). The system consists of a reduced graphene oxide (rGO) sandwiched by silver and gold nanostructures. Due to the ultrasmall thickness of rGO, the inter-coupling between Ag and Au nanoparticles is precisely controlled and the local field enhancement has been improved to more than 70 times. Associated with the unique chemical mechanism of rGO, the hybrid system has been utilized to identify tumor cells without using any biomarkers. We believe this research will be important for the applications of rGO in cancer screening.

Wafer-scale metamaterials for polarization-insensitive and dual-band perfect absorption.

Mid-infrared (IR) perfect absorbers have great potential in practical applications such as biomedical sensing and thermal energy and have been successfully demonstrated in a number of plasmonic metallic nanostructures. However, all the experimental realizations of perfect absorbers are strongly dependent on nanofabrication techniques, which usually require high costs and a long time to fabricate a wafer scale device. Here we propose and experimentally demonstrate a wafer scale, polarization independent, wide angle, and dual-band IR perfect absorber. By fabricating double "E"-shaped metallic structures on a ZnSe coated gold film, a dual-band metamaterial absorber has been uniformly realized on a 2'' silicon wafer. Two absorption peaks have been realized at 18 and 27 THz, which are well consistent with the designs. We believe that our research will boost the applications of metamaterial perfect absorbers.

Single Nanoparticle Detection Using Far-field Emission of Photonic Molecule around the Exceptional Point.

Highly sensitive, label-free detection methods have important applications in fundamental research and healthcare diagnostics. To date, the detection of single nanoparticles has remained largely dependent on extremely precise spectral measurement, which relies on high-cost equipment. Here, we demonstrate a simple but very nontrivial mechanism for the label-free sizing of nanoparticles using the far-field emission of a photonic molecule (PM) around an exceptional point (EP). By attaching a nanoparticle to a PM around an EP, the main resonant behaviors are strongly disturbed. In addition to typical mode splitting, we find that the far-field pattern of the PM is significantly changed. Taking a heteronuclear diatomic PM as an example, we demonstrate that a single nanoparticle, whose radius is as small as 1 nm to 7 nm, can be simply monitored through the variation of the far-field pattern. Compared with conventional methods, our approach is much easier and does not rely on high-cost equipment. In addition, this research will illuminate new advances in single nanoparticle detection.

Three-dimensionally bonded spongy graphene material with super compressive elasticity and near-zero Poisson's ratio.

It is a challenge to fabricate graphene bulk materials with properties arising from the nature of individual graphene sheets, and which assemble into monolithic three-dimensional structures. Here we report the scalable self-assembly of randomly oriented graphene sheets into additive-free, essentially homogenous graphene sponge materials that provide a combination of both cork-like and rubber-like properties. These graphene sponges, with densities similar to air, display Poisson's ratios in all directions that are near-zero and largely strain-independent during reversible compression to giant strains. And at the same time, they function as enthalpic rubbers, which can recover up to 98% compression in air and 90% in liquids, and operate between -196 and 900 °C. Furthermore, these sponges provide reversible liquid absorption for hundreds of cycles and then discharge it within seconds, while still providing an effective near-zero Poisson's ratio.

Enhanced second-harmonic generation from nonlinear optical metamagnetics.

We present a numerical simulation of second-harmonic generation (SHG) from a nonlinear magnetic metamaterial. By inserting a second-order nonlinear material in the high local field area of magnetic metamaterial, which consists of periodic arrays of paired thin silver strips, the convertion efficiency of SHG has been significantly enhanced by almost four orders of magnitude. The corresponding field patterns and further studies on dependance between SHG and symmetry of nonlinear crystal show that the increase of the conversion efficiency is attributed to the local field enhancement caused by the magnetic resonnance of the structure. Our researches provide an additional way to further improve the optical nonlinearity in nanostructures.

Multichannel and repeatable self-healing of mechanical enhanced graphene-thermoplastic polyurethane composites.

A novel self-healing material, which was fabricated using few-layered graphene (FG) and thermoplastic polyurethane (TPU) via a facile method, not only exhibits a mechanical enhanced property, but also can be repeatedly healed by various methods including infrared (IR) light, electricity and electromagnetic wave with healing efficiencies higher than 98%.