An Amphiphilic Molecule-Regulated Core-Shell-Solvation Electrolyte for Li-Metal Batteries at Ultra-Low Temperature.

Lithium metal batteries hold great promise for promoting energy density and operating at low temperatures, yet they still suffer from insufficient Li compatibility and slow kinetic, especially at ultra-low temperatures. Herein, we rationally design and synthesize a new amphiphilic solvent, 1,1,2,2-tetrafluoro-3-methoxypropane, for use in battery electrolytes. The lithiophilic segment is readily to solvate Li+ to induce self-assembly of the electrolyte solution to form a peculiar core-shell-solvation structure. Such unique solvation structure not only largely improves the ionic conductivity to allow fast Li+ transport and lower the desolvation energy to enable facile desolvation, but also leads to the formation of a highly robust and conductive inorganic SEI. The resulting electrolyte demonstrates high Li efficiency and superior cycling stability from room temperature to -40 °C at high current densities. Meanwhile, anode-free high-voltage cell retains 87 % capacity after 100 cycles.

Tuning the Solvent Alkyl Chain to Tailor Electrolyte Solvation for Stable Li-Metal Batteries.

1,2-Dimethoxyethane (DME) has been considered as the most promising electrolyte solvent for Li-metal batteries (LMBs). However, challenges arise from insufficient Li Coulombic efficiency (CE) and poor anodic stability associated with DME-based electrolytes. Here, we proposed a rational molecular design methodology to tailor electrolyte solvation for stable LMBs, where shortening the middle alkyl chain of the solvent could reduce the chelation ability, while increasing the terminal alkyl chain of the solvent could increase the steric hindrance, affording a diethoxymethane (DEM) solvent with ultra-weak solvation ability. When serving as a single solvent for electrolyte, a peculiar solvation structure dominated by contact ion pairs (CIPs) and aggregates (AGGs) was achieved even at a regular salt concentration of 1 m, which gives rise to anion-derived interfacial chemistry. This illustrates an unprecedentedly high Li||Cu CE of 99.1% for a single-salt single-solvent (non-fluorinated) electrolyte at ∼1 m. Moreover, this 1 m DEM-based electrolyte also remarkably suppresses the anodic dissolution of Al current collectors and significantly improves the cycling performance of high-voltage cathodes. This work opens up new frontiers in engineering electrolytes toward stable LMBs with high energy densities.

Tuning the Metal Ions of Prussian Blue Analogues in Separators to Enable High-Power Lithium Metal Batteries.

The Li dendrite issue is the major barrier that limits the implement of Li metal anode practically, especially at high current density. From the perspective of the nucleation and growth mechanism of the Li dendrite, we rationally develop a novel Prussian blue analogues (PBA)-derived separator, where tuning the metal ions bestows the PBAs with open metal site to confine anion movement and thereby afford a high Li+ transference number (0.78), and PBA with ordered micropores could act as an ionic sieve to selectively extract Li+ and thereby homogenize Li+ flux. This demonstrates a highly reversible Li plating/stripping cycling for 3000 h at a practically high current density (5.0 mA cm-2). Consequently, a high loading Li||LiFeO4 battery (∼10.0 mg cm-2) demonstrates ultralong cycling life at high current densities (∼5.1 mA cm-2). This work highlights the prospect of optimizing PBAs in regulating ion transport behavior to enable high-power Li metal batteries.

Electro-Enhanced Separation of Microsized Oil-in-Water Emulsions via Metallic Membranes: Performance and Mechanistic Insights.

Conventional separation membranes suffer from evitable fouling and flux decrease for water treatment applications. Herein, a novel protocol of electro-enhanced membrane separation is proposed for the efficient treatment of microsized emulsions (∼1 µm) by rationally designing robust electroresponsive copper metallic membranes, which could mitigate oil fouling and coenhance permeance (from ∼1026 to ∼2516 L·m-2·h-1·bar-1) and rejection (from ∼87 to ∼98%). High-flux Cu membranes exhibit superior ductility and electrical conductivity, enabling promising electroactivity. Separation performance and the fouling mechanism were studied under different electrical potentials and ionic strengths. Application of negative polarization into a large-pore (∼2.1 µm) Cu membrane is favorable to not only almost completely reject smaller-sized oil droplets (∼1 µm) but also achieve antifouling and anticorrosion functions. Moreover, surfactants around oil droplets might be redistributed due to electrostatic repulsion, which effectively enhances the steric hindrance effect between neighboring oil droplets, mitigating oil coalescence and consequently membrane fouling. Furthermore, due to the screening effect of surfactants, the presence of low-concentration salts increases the adsorption of surfactants at the oil-water interface, thus preventing oil coalescence via decreasing oil-water interfacial tension. However, under high ionic strengths, the fouling mechanism converts from cake filtration to a complete blocking model due to the reduced electrostatic repulsion between the Cu membrane and oil droplets. This work would provide mechanistic insights into electro-enhanced antifouling for not only oil emulsion separation but also more water treatment applications using rationally designed novel electroresponsive membranes.

Distribution, Biotransformation, Pharmacological Effects, Metabolic Mechanism and Safety Evaluation of Platycodin D: A Comprehensive Review.

Platycodonis Radix (Jiegeng), the dried root of Platycodon grandiflorum, is a traditional herb used as both medicine and food. Its clinical application for the treatment of cough, phlegm, sore throat, pulmonary and respiratory diseases has been thousands of years in China. Platycodin D is the main active ingredient in Platycodonis Radix, which belongs to the family of pentacyclic triterpenoid saponins because it contains an oleanolane type aglycone linked with double sugar chains. Modern pharmacology has demonstrated that Platycodin D displays various biological activities, such as analgesics, expectoration and cough suppression, promoting weight loss, anti-tumor and immune regulation, suggesting that Platycodin D has the potential to be a drug candidate and an interesting target as a natural product for clinical research. In this review, the distribution and biotransformation, pharmacological effects, metabolic mechanism and safety evaluation of Platycodin D are summarized to lay the foundation for further studies.

Concentrated Electrolytes Widen the Operating Temperature Range of Lithium-Ion Batteries.

The operating temperatures of commercial lithium-ion batteries (LIBs) are generally restricted to a narrow range of -20 to 55 °C because the electrolyte is composed of highly volatile and flammable organic solvents and thermally unstable salts. Herein, the use of concentrated electrolytes is proposed to widen the operating temperature to -20 to 100 °C. It is demonstrated that a 4.0 mol L-1 LiN(SO2 F)2 /dimethyl carbonate electrolyte enables the stable charge-discharge cycling of a graphite anode and a high-capacity LiNi0.6 Co0.2 Mn0.2 O2 cathode and the corresponding full cell in a wide temperature range from -20 to 100 °C owing to the highly thermal stable solvation structure of the concentrated electrolyte together with the robust and Li+ -conductive passivation interphase it offered that alleviate various challenges at high temperatures. This work demonstrates the potential for the development of safe LIBs without the need for bulky and heavy thermal management systems, thus significantly increasing the overall energy density.

Three-Dimensional (3D) Nanostructured Skeleton Substrate Composed of Hollow Carbon Fiber/Carbon Nanosheet/ZnO for Stable Lithium Anode.

The practical applications of Li metal batteries (LMBs) have long been limited by the obstacles of low Coulombic efficiency (CE) and formation of dendrites on Li metal electrode. Herein, we demonstrated the synthesis of a novel three-dimensional (3D) nanostructured skeleton substrate composed of nitrogen-doped hollow carbon fiber/carbon nanosheets/ZnO (NHCF/CN/ZnO) using 2-methylimidazole (2-MIZ)-coated 3D cloth as a scaffold. The mechanism of formation of this novel hierarchical structure was investigated. The multilayered hierarchical structure and abundant lithiophilic nucleation sites of the substrate provide a stable environment for the deposition and stripping of lithium metal, thus preventing the generation of lithium dendrites. Consequently, the lithium anode based on the NHCF/CN/ZnO current collector demonstrated an excellent Coulombic efficiency of 96.47% after 400 cycles at 0.5 mA cm-2. The prepared NHCF/CN/ZnO/Li electrode also showed outstanding cycling performance of over 800 h and an ultralow voltage hysteresis of less than 30 mV in a symmetric cell at 5 mA cm-2 and 5 mAh cm-2. Even at a high loading of the cathode with 10.4 mg cm-2, the full cell of NHCF/CN/ZnO/Li anode with LiFePO4 can also work very well. Our work offers a path toward the facial preparation of 3D hierarchical structure for high-performance lithium metal batteries.

Sodium- and Potassium-Hydrate Melts Containing Asymmetric Imide Anions for High-Voltage Aqueous Batteries.

Aqueous Na- or K-ion batteries could virtually eliminate the safety and cost concerns raised from Li-ion batteries, but their widespread applications have generally suffered from narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems of Na and K salts with asymmetric imide anions, we discovered, for the first time, room-temperature hydrate melts for Na and K systems, which are the second and third alkali metal hydrate melts reported since the first discovery of Li hydrate melt by our group in 2016. The newly discovered Na- and K- hydrate melts could significantly extend the potential window up to 2.7 and 2.5 V (at Pt electrode), respectively, owing to the merit that almost all water molecules participate in the Na+ or K+ hydration shells. As a proof-of-concept, a prototype Na3 V2 (PO4 )2 F3 |NaTi2 (PO4 )3 aqueous Na-ion full-cell with the Na-hydrate-melt electrolyte delivers an average discharge voltage of 1.75 V, that is among the highest value ever reported for all aqueous Na-ion batteries.

3D Microstructured Scaffolds to Support Photoreceptor Polarization and Maturation.

Blinding disorders of the outer retina involve dysfunction and degeneration of photoreceptors. One potential approach to treat these forms of blindness is to repopulate the outer retina via a simple bolus injection of donor photoreceptors. However, this may not be ideal due to the highly polarized organization of photoreceptors that include apical light sensing photopigments and basal axon terminals. Furthermore, bolus injections create uncertainty with regard to the area, density, and retention of donor cells. Here, a novel and robust microfabrication process is developed to create 3D, micrometer-sized complex structures in ultrathin and biocompatible elastomer films (nonbiodegradable polydimethylsiloxane and biodegradable poly(glycerol-sebacate)) that can serve as polarizable photoreceptor delivery scaffolds, consisting of an array of cup-shaped photoreceptor capture wells that funnel into a microchannel. This "wine glass" scaffold design promotes efficient capture of human pluripotent stem-cell-derived photoreceptor cell bodies and guidance of basal axon extensions, ultimately achieving a uniform level of organization and polarization that is not possible with bolus injections or previously described scaffolds. In addition to future therapeutic applications, our scaffold design and materials provide a platform to generate reproducible and scalable in vitro models of photoreceptor-based diseases.

Neuroendocrine Tumor-Targeted Upconversion Nanoparticle-Based Micelles for Simultaneous NIR-Controlled Combination Chemotherapy and Photodynamic Therapy, and Fluorescence Imaging.

Although neuroendocrine tumors (NETs) are slow growing, they are frequently metastatic at the time of discovery and no longer amenable to curative surgery, emphasizing the need for the development of other treatments. In this study, multifunctional upconversion nanoparticle (UCNP)-based theranostic micelles are developed for NET-targeted and near-infrared (NIR)-controlled combination chemotherapy and photodynamic therapy (PDT), and bioimaging. The theranostic micelle is formed by individual UCNP functionalized with light-sensitive amphiphilic block copolymers poly(4,5-dimethoxy-2-nitrobenzyl methacrylate)-polyethylene glycol (PNBMA-PEG) and Rose Bengal (RB) photosensitizers. A hydrophobic anticancer drug, AB3, is loaded into the micelles. The NIR-activated UCNPs emit multiple luminescence bands, including UV, 540 nm, and 650 nm. The UV peaks overlap with the absorption peak of photocleavable hydrophobic PNBMA segments, triggering a rapid drug release due to the NIR-induced hydrophobic-to-hydrophilic transition of the micelle core and thus enabling NIR-controlled chemotherapy. RB molecules are activated via luminescence resonance energy transfer to generate 1O2 for NIR-induced PDT. Meanwhile, the 650 nm emission allows for efficient fluorescence imaging. KE108, a true pansomatostatin nonapeptide, as an NET-targeting ligand, drastically increases the tumoral uptake of the micelles. Intravenously injected AB3-loaded UCNP-based micelles conjugated with RB and KE108-enabling NET-targeted combination chemotherapy and PDT-induce the best antitumor efficacy.

A composite generator film impregnated with cellulose nanocrystals for enhanced triboelectric performance.

A novel polydimethylsiloxane (PDMS)/cellulose nanocrystal flake (CNCF) composite triboelectric nanogenerator (CTG) using CNCFs as effective dielectrics exhibited a 10-times-enhanced triboelectric performance compared with its pure PDMS counterpart. Positive charges generated on the surface of the CNCFs during cyclic compression boosted electron transfer and induced extra charges. The CTG exhibited an instantaneous output power (density) of 1.65 mW (0.76 mW cm-2) under continuous operation.

Synthesis of polyvinyl alcohol/cellulose nanofibril hybrid aerogel microspheres and their use as oil/solvent superabsorbents.

Superhydrophobic and crosslinked poly(vinyl alcohol) (PVA)/cellulose nanofibril (CNF) aerogel microspheres were prepared via a combination of the water-in-oil (W/O) emulsification process with the freeze-drying process, followed by thermal chemical vapor deposition of methyltrichlorosilane. The oil phase and the cooling agent were judiciously selected to ensure that the frozen ice microspheres can be easily separated from the emulsion system. The silanized microspheres were highly porous with a bulk density ranging from 4.66 to 16.54mg/cm(3). The effects of the solution pH, stirring rate, and emulsifier concentration on the morphology and microstructure of the aerogel microspheres were studied. The highly porous structure of the ultralight aerogel microspheres demonstrated an ultrahigh crude oil absorption capacity (up to 116 times its own weight). This study provides a novel approach for the large-scale preparation of polymeric aerogel microspheres with well-controlled particle sizes that can be used for various applications including oil and chemical spill/leak clean-up.

Flexible Infrared Responsive Multi-Walled Carbon Nanotube/Form-Stable Phase Change Material Nanocomposites.

Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-stable phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm(2), respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-stable phase transitions occurring in the PCM matrix due to MWCNT's excellent photoabsorption and thermal conversion capabilities, which subsequently affected the thickness of the interfacial PCM between adjacent conductive MWCNTs and thus the electron tunneling efficiency between the MWCNTs. Our findings suggest that these unique MWCNT/PCM nanocomposites offer promising new options for high-performance and flexible optoelectronic devices, including thermal imaging, IR sensing, and optical communication.

High-performance green flexible electronics based on biodegradable cellulose nanofibril paper.

Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.

Poly(vinyl alcohol)/cellulose nanofibril hybrid aerogels with an aligned microtubular porous structure and their composites with polydimethylsiloxane.

Superhydrophobic poly(vinyl alcohol) (PVA)/cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and contact angle measurements. The structure of the aerogels fully filled with polydimethylsiloxane (PDMS) was confirmed by SEM and optical microscopy. The mechanical properties of the resulting PDMS/aerogel composites were examined using both compressive and tensile tests. The compressive and tensile Young's moduli of the fully filled PDMS/aerogel composites were more than 2-fold and 15-fold higher than those of pure PDMS. This study provides a novel alternative approach for preparing high performance polymer nanocomposites with a bicontinuous structure.

Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors.

A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4/poly(vinyl alcohol) (PVA) gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors were fabricated without any binders, current collectors, or electroactive additives. Because of the porous structure of the CNF/RGO/CNT aerogel electrodes and the excellent electrolyte absorption properties of the CNFs present in the aerogel electrodes, the resulting flexible supercapacitors exhibited a high specific capacitance (i.e., 252 F g(-1) at a discharge current density of 0.5 A g(-1)) and a remarkable cycle stability (i.e., more than 99.5% of the capacitance was retained after 1000 charge-discharge cycles at a current density of 1 A g(-1)). Furthermore, the supercapacitors also showed extremely high areal capacitance, areal power density, and energy density (i.e., 216 mF cm(-2), 9.5 mW cm(-2), and 28.4 µWh cm(-2), respectively). In light of its excellent electrical performance, low cost, ease of large-scale manufacturing, and environmental friendliness, the CNF/RGO/CNT aerogel electrodes may have a promising application in the development of flexible energy-storage devices.

Graphene/phase change material nanocomposites: light-driven, reversible electrical resistivity regulation via form-stable phase transitions.

Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-stable phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-stable PCM. The reversible phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mechanical properties. Such photoresponsive materials have many potential applications, including flexible electronics.

Drug-loaded nanoparticles induce gene expression in human pluripotent stem cell derivatives.

Tissue engineering and advanced manufacturing of human stem cells requires a suite of tools to control gene expression spatiotemporally in culture. Inducible gene expression systems offer cell-extrinsic control, typically through addition of small molecules, but small molecule inducers typically contain few functional groups for further chemical modification. Doxycycline (DXC), a potent small molecule inducer of tetracycline (Tet) transgene systems, was conjugated to a hyperbranched dendritic polymer (Boltorn H40) and subsequently reacted with polyethylene glycol (PEG). The resulting PEG-H40-DXC nanoparticle exhibited pH-sensitive drug release behavior and successfully controlled gene expression in stem-cell-derived fibroblasts with a Tet-On system. While free DXC inhibited fibroblast proliferation and matrix metalloproteinase (MMP) activity, PEG-H40-DXC nanoparticles maintained higher fibroblast proliferation levels and MMP activity. The results demonstrate that the PEG-H40-DXC nanoparticle system provides an effective tool to controlling gene expression in human stem cell derivatives.

Image-guided and tumor-targeted drug delivery with radiolabeled unimolecular micelles.

Unimolecular micelles formed by dendritic amphiphilic block copolymers poly(amidoamine)-poly(L-lactide)-b-poly(ethylene glycol) conjugated with anti-CD105 monoclonal antibody (TRC105) and 1,4,7-triazacyclononane-N, N', N-triacetic acid (NOTA, a macrocyclic chelator for (64)Cu) (abbreviated as PAMAM-PLA-b-PEG-TRC105) were synthesized and characterized. Doxorubicin (DOX), a model anti-cancer drug, was loaded into the hydrophobic core of the unimolecular micelles formed by PAMAM and PLA via physical encapsulation. The unimolecular micelles exhibited a uniform size distribution and pH-sensitive drug release behavior. TRC105-conjugated unimolecular micelles showed a CD105-associated cellular uptake in human umbilical vein endothelial cells (HUVEC) compared with non-targeted unimolecular micelles, which was further validated by cellular uptake in CD105-negative MCF-7 cells. In 4T1 murine breast tumor-bearing mice, (64)Cu-labeled targeted micelles exhibited a much higher level of tumor accumulation than (64)Cu-labeled non-targeted micelles, measured by serial non-invasive positron emission tomography (PET) imaging and confirmed by biodistribution studies. These unimolecular micelles formed by dendritic amphiphilic block copolymers that synergistically integrate passive and active tumor-targeting abilities with pH-controlled drug release and PET imaging capabilities provide the basis for future cancer theranostics.

Polyvinyl alcohol-cellulose nanofibrils-graphene oxide hybrid organic aerogels.

Hybrid organic aerogels consisting of polyvinyl alcohol (PVA), cellulose nanofibrils (CNFs), and graphene oxide nanosheets (GONSs) were prepared using an environmentally friendly freeze-drying process. The material properties of these fabricated aerogels were measured and analyzed using various characterization techniques including compression testing, scanning electron microscopy, thermogravimetric (TGA) analysis, Brunauer-Emmet-Teller (BET) surface area analysis, and contact angle measurements. These environmentally friendly, biobased hybrid organic aerogels exhibited a series of desirable properties including a high specific compressive strength and compressive failure strain, ultralow density and thermal conductivity, good thermal stability, and moisture resistance, making them potentially useful for a broad range of applications including thermal insulation.