Adaptive design of mRNA-loaded extracellular vesicles for targeted immunotherapy of cancer.

The recent success of mRNA therapeutics against pathogenic infections has increased interest in their use for other human diseases including cancer. However, the precise delivery of the genetic cargo to cells and tissues of interest remains challenging. Here, we show an adaptive strategy that enables the docking of different targeting ligands onto the surface of mRNA-loaded small extracellular vesicles (sEVs). This is achieved by using a microfluidic electroporation approach in which a combination of nano- and milli-second pulses produces large amounts of IFN-γ mRNA-loaded sEVs with CD64 overexpressed on their surface. The CD64 molecule serves as an adaptor to dock targeting ligands, such as anti-CD71 and anti-programmed cell death-ligand 1 (PD-L1) antibodies. The resulting immunogenic sEVs (imsEV) preferentially target glioblastoma cells and generate potent antitumour activities in vivo, including against tumours intrinsically resistant to immunotherapy. Together, these results provide an adaptive approach to engineering mRNA-loaded sEVs with targeting functionality and pave the way for their adoption in cancer immunotherapy applications.

Determination of vanillin in different food samples by using SMM/Au@ZIF-67 electrochemical sensor.

Vanillin is a popular flavoring agent in many food products. Simple, fast, and reliable quantification of this compound is crucial for the food industry. In this work, we have developed a new electrochemical sensor for accurate detection of vanillin in various real samples. The composite electrode was made of sodium montmorillonite nanoclay (SMM) and gold nanoparticles modified ZIF-67 (Au@ZIF-67), in which SMM contributes to the large adsorption capacity of the analyte, ZIF-67 and SMM supply more sensing active sites, and gold nanoparticles provide high electrical conductivity. The sensing electrode was comprehensively characterized using Brunauer-Emmett-Teller, EDS, XRD, SEM, FTIR, and TEM, and its electrochemical behavior for determination of vanillin including the electrooxidation mechanism of vanillin and different parameters such as scan rate and pH value was investigated. The result revealed that a two electron-two proton process was involved in the electrooxidation of vanillin, which takes place more readily due to the lower potential on the surface of SMM/Au@ZIF-67/carbon paste electrode. The new composite electrode was also more sensitive to vanillin detection with an anodic peak current almost 2.6 times more than that of the bare electrode. A linear sensing concentration range was established between 1 and 1200 nM with a detection limit of 0. 3 nM and a limit of quantitation of 1 nM. For real samples, the sensor demonstrated excellent recovery rates and reliability that was comparable to the standard high-performance liquid chromatography method.

Redox Chemistry of the Subphases of α-CsPbI2Br and ß-CsPbI2Br: Theory Reveals New Potential for Photostability.

The logic in the design of a halide-mixed APb(I1−xBrx)3 perovskite is quite straightforward: to combine the superior photovoltaic qualities of iodine-based perovskites with the increased stability of bromine-based perovskites. However, even small amounts of Br doped into the iodine-based materials leads to some instability. In the present report, using first-principles computations, we analyzed a wide variety of α-CsPbI2Br and ß-CsPbI2Br phases, compared their mixing enthalpies, explored their oxidative properties, and calculated their hole-coupled and hole-free charged Frenkel defect (CFD) formations by considering all possible channels of oxidation. Nanoinclusions of bromine-rich phases in α-CsPbI2Br were shown to destabilize the material by inducing lattice strain, making it more susceptible to oxidation. The uniformly mixed phase of α-CsPbI2Br was shown to be highly susceptible towards a phase transformation into ß-CsPbI2Br when halide interstitial or halide vacancy defects were introduced into the lattice. The rotation of PbI4Br2 octahedra in α-CsPbI2Br allows it either to transform into a highly unstable apical ß-CsPbI2Br, which may phase-segregate and is susceptible to CFD, or to phase-transform into equatorial ß-CsPbI2Br, which is resilient against the deleterious effects of hole oxidation (energies of oxidation >0 eV) and demixing (energy of mixing <0 eV). Thus, the selective preparation of equatorial ß-CsPbI2Br offers an opportunity to obtain a mixed perovskite material with enhanced photostability and an intermediate bandgap between its constituent perovskites.

Does environmental uncertainty of enterprises aggravate the accrual anomaly in the stock market? Evidence from China.

Enterprises do not exist independently of the external environment, so uncertainty affects their earnings volatility and exacerbates the information asymmetry between internal and external stakeholders. As a major manifestation of capital market mispricing, the accrual anomaly is caused by investors' functional fixation on total surplus under information asymmetry. Against this backdrop, taking A-share listed companies in China from 2007 to 2019 as our research objects, this study explores the impact of environmental uncertainty on the accrual anomaly based on the information asymmetry and investor irrationality perspective. We find that environmental uncertainty enterprises facing exacerbates the accrual anomaly in the Chinese stock market, and internal control quality, state ownership and the media coverage will affect this impact. Furthermore, this study shows that there are three factors playing the mediating role in the effect, accounting information quality, investment growth and the investor attention. The results show that environmental uncertainty exacerbates the accrual anomaly driven by information manipulation, empire building and investor irrationality. Improving investor irrationality behavior and restraining the self-interest behavior of managers can help alleviate the mispricing of accruals caused by information asymmetry in psychology.

Mechanical Properties and Strengthening Mechanism of Dredged Silty Clay Stabilized by Cement and Steel Slag.

The high moisture content and low strength of dredged soft soils result in significant difficulties in directly reutilizing them in engineering. Improving their mechanical properties effectively and achieving re-utilization with the maximum benefit in engineering is the key to disposing of dredged soils with high moisture content. This study investigated the influences of cement and steel slag ratio, moisture content, the maximum particle size of steel slag, and curing age on the compressive strength of dredged silty clay in a plastic flow state. The performance improvement of dredged silty clay stabilized with cement and steel slag was discussed by comparing to related previous studies. The strengthening mechanism of dredged soils stabilized with cement and steel slag was explored by microstructural observation. The results show that when the ratio of cement to steel slag was 9:6; namely, using steel slag to replace 40% of cement, the strength properties of dredged silty clay stabilized by cement and steel slag could ensure the minimum requirements of the project greater then 100 kPa, and their economics could achieve the best results. The finer the particle size of steel slag was, the better the stabilization effect was. The compressive strength of dredged silty clay stabilized by cement and steel slag with particle sizes of less than 0.075 mm was 1.06 times, 1.10 times, and 1.16 times that of 0.25 mm, 1 mm, and 2 mm and increased linearly over curing ages earlier than 28 days. The compressive strength of dredged silty clay stabilized by cement and steel slag cured for 28 days was 2.44 times, 1.59 times, and 1.36 times that of 3, 7, and 14 days, respectively. The evolution of microstructural characteristics showed that the internal pore sizes of dredged soil decreased the structural compactness increased significantly due to the formation of more calcium silicate hydrate and other agglomerated flocculent gel materials from the further reaction between steel slag and cement hydration products. The results of this study can provide technological parameters for the re-utilization of dredged soil stabilized with cement and steel slag.

Robust three-dimensional nanotube-in-micropillar array electrodes to facilitate size independent electroporation in blood cell therapy.

Blood is an attractive carrier for plasmid and RNA-based medicine in cell therapy. Electroporation serves as a favorable delivery tool for simple operation, quick internalization, minimum cell culture involvement, and low contamination risk. However, the delivery outcome of electroporation heavily depends on the treated cells such as their type, size, and orientation to the electric field, not ideal for highly heterogeneous blood samples. Herein, a new electroporation system was developed towards effective transfection to cells in blood regardless of their large diversity. By coupling replica molding and infiltration-coating processes, we successfully configured a three-dimensional electrode comprised of a polymer micropillar array on which carbon nanotubes (CNTs) are partially embedded. During electroporation, cells sag between micropillars and deform to form a conformal contact with their top and side surfaces. The implanted CNTs not only provide a robust conductive coating for polymer micropattern but also have their protruded ends face the cell membrane vertically everywhere with maximum transmembrane potential. Regardless of their largely varied sizes and random dispersion, both individual blood cell type and whole blood samples were effectively transfected with plasmid DNA (85% after 24 h and 95% after 72 h, or 2.5-3.0 folds enhancement). High-dose RNA probes were also introduced, which regulate better the expression levels of exogenous and endogenous genes in blood cells. Besides its promising performance on non-viral delivery routes to cell-related studies and therapy, the involved new fabrication method also provides a convenient and effective way to construct flexible electronics with stable micro/nano features on the surface.

Janus sand filter with excellent demulsification ability in separation of surfactant-stabilized oil/water emulsions: An experimental and molecular dynamics simulation study.

Developing efficient separation materials for surfactant-stabilized oil/water emulsions is of great importance while significantly challenging. In this work, a sand filter with Janus channels was prepared by simply mixing superhydrophilic and superhydrophobic quartz sand in a mass ratio of 1:1. Due to the imbalanced force of droplets in those Janus channels, better separation performance under gravity was achieved for both surfactant-stabilized oil-in-water and water-in-oil emulsions than the superhydrophilic or superhydrophobic sand filter alone. It also received high flux (1080.13 L m-2 h-1 for dichloroethane-in-water emulsion and 1378.07 L m-2 h-1 for water-in-dichloroethane emulsion) and high separation efficiency (99.80% for dichloroethane-in-water emulsion and 99.98% for water-in-dichloroethane emulsion). Molecular dynamics based computational work and experimental studies revealed that the Janus channels of mixed sand layer exhibited greater interaction energy with emulsion droplets for more efficient adsorption, resulting in better demulsification capability and separation performance. The as-prepared Janus sand filters retained excellent separation performance after 50 cycles of the stability test. Together with the needs on only cheap and easily accessible raw materials and its environmentally friendly preparation method, this Janus sand filtration process exhibits its great potential for the separation of surfactant-stabilized oil/water emulsions.

Self-Assembled pH-Sensitive Polymeric Nanoparticles for the Inflammation-Targeted Delivery of Cu/Zn-Superoxide Dismutase.

The use of superoxide dismutase (SOD) is currently limited by its short half-life, rapid plasma clearance rate, and instability. We synthesized a small library of biofriendly amphiphilic polymers that comprise methoxy poly(ethylene glycol)-poly(cyclohexane-1,4-diyl acetone dimethyleneketal) (mPEG-PCADK) and mPEG-poly((cyclohexane86.7%, 1,5-pentanediol13.3%)-1,4-diyl acetone dimethylene ketal) (PK3) for the targeted delivery of SOD. The novel polymers could self-assemble into micellar nanoparticles with favorable hydrolysis kinetics, biocompatibility, long circulation time, and inflammation-targeting effects. These materials generated a better pH-response curve and exhibited better hydrolytic kinetic behavior than PCADK and PK3. The polymers showed good biocompatibility with protein drugs and did not induce an acidic microenvironment during degradation in contrast to materials such as PEG-block-poly(lactic-co-glycolic acid) (PLGA) and PLGA. The SOD that contained reverse micelles based on mPEG2000-PCADK exhibited good circulation and inflammation-targeting properties. Pharmacodynamic results indicated exceptional antioxidant and anti-inflammatory activities in a rat adjuvant-induced arthritis model and a rat peritonitis model. These results suggest that these copolymers are ideal protein carriers for targeting inflammation treatment.

Electronic and optical properties of orthorhombic (CH3NH3)BX3 (B = Sn, Pb; X = F, Cl, Br, I) perovskites: a first-principles investigation.

Lead halide perovskites have generated considerable interest in solar cell, sensor, and electronics applications. While great focus has been placed on (CH3NH3)PbI3, an organic-inorganic hybrid perovskite, comparatively little work has been done to understand some of its existing crystal phases and analogous materials after substituting with Sn and/or other halogens in the framework. Here, first-principles density functional theory calculations are performed to comprehensively evaluate the electronic and optical properties of (CH3NH3)BX3 (B = Sn, Pb; X = F, Cl, Br, I) in a low-temperature orthorhombic phase. Bulk modulus, electronic structures, and several optical properties of these perovskite systems are further calculated. The obtained results are first confirmed by comparing with existing perovskite systems in literature. The shifting trends on those physical properties when extending to other barely studied systems of (CH3NH3)BX3 is further revealed. The band gap of these perovskites is found to decrease when varying halogen anion in "X" sites from F to I, and/or substituting Pb cations with Sn in "B" sites. Notably, the less toxic Sn-containing perovskites, (CH3NH3)SnI3 in particular, display higher absorption coefficients in the visible light range than their Pb-containing counterparts. An orthorhombic (CH3NH3)PbF3 is predicted to exist at low temperature, and adsorb strongly UV energy. Our systematical examination efforts on the two groups of perovskites provide valuable physical insights in these materials, and the accompanied new findings warrant further investigation on such subjects.

Splitting Tensile Strength of Cement Soil Reinforced with Basalt Fibers.

Due to low splitting tensile strength, cement soil is more likely to experience dry shrinkage and cracking in practical engineering. In this study, the mixing procedure of the cement soil reinforced with basalt fibers was investigated; the influences of cement content, curing time, basalt fiber content and length on the splitting tensile strength of the cement soil reinforced with basalt fibers were studied; and the correlation of the splitting tensile strength vs. the compressive strength of the cement soil reinforced with basalt fibers was discussed. The contribution of basalt fibers on performance improvement of the cement soil was also addressed based on the microstructural analysis and the toughening mechanism exposition. Results indicate that the best mixing method for the cement soil reinforced with basalt fibers is to mix the muddy silty clay with basalt fibers first, then with cement slurry. The increase of cement content and curing time can improve the splitting tensile strength of the cement soil effectively. The splitting tensile strength of the cement soil increases first and then decreases with the content and length of basalt fibers. The optimal content and length of basalt fibers for the cement soil are 0.4% and 12 mm, respectively. The relationship between the splitting tensile strength and the compressive strength of the cement soil reinforced with basalt fibers can be described as a linear relationship with the correlation coefficient of 0.245 and the determination coefficient of 0.990. The contribution of basalt fibers on the toughening mechanisms of cement soil shows that the fiber-matrix interaction would be the dominant effect to control the tensile strength of the soil-cement-fiber composites. The results of this study can provide a reference for the design and application of cement soil reinforced with basalt fibers in actual engineering.

Microfluidic Electroporation Coupling Pulses of Nanoseconds and Milliseconds to Facilitate Rapid Uptake and Enhanced Expression of DNA in Cell Therapy.

Standard electroporation with pulses in milliseconds has been used as an effective tool to deliver drugs or genetic probes into cells, while irreversible electroporation with nanosecond pulses is explored to alter intracellular activities for pulse-induced apoptosis. A combination treatment, long nanosecond pulses followed by standard millisecond pulses, is adopted in this work to help facilitate DNA plasmids to cross both cell plasma membrane and nuclear membrane quickly to promote the transgene expression level and kinetics in both adherent and suspension cells. Nanosecond pulses with 400-800 ns duration are found effective on disrupting nuclear membrane to advance nuclear delivery of plasmid DNA. The additional microfluidic operation further helps suppress the negative impacts such as Joule heating and gas bubble evolution from common nanosecond pulse treatment that lead to high toxicity and/or ineffective transfection. Having appropriate order and little delay between the two types of treatment with different pulse duration is critical to guarantee the effectiveness: 2 folds or higher transfection efficiency enhancement and rapid transgene expression kinetics of GFP plasmids at no compromise of cell viability. The implementation of this new electroporation approach may benefit many biology studies and clinical practice that needs efficient delivery of exogenous probes.

Cell Size-Specific Transfection by Micropillar Array Electroporation.

In this study, we reported a new micropillar array electroporation (MAE) platform to accomplish large-scale, size-specific DNA and RNA delivery to mammalian cells for nanomedicine. By introducing well-patterned micropillar array on the electrode surface, the number of micropillars each cell faces varies with the surface area of cell membrane or the size of cells. In this way, cell size-specific electroporation is conveniently done on a large population of cells in despite of their random locations between the two electrodes. The enhancement of this MAE system on the delivery of DNA and RNA probes without sacrifice of cell viability is demonstrated with an average increase of 2.5 to 3-fold on the transfection efficiency of DNA plasmids and additional knockdown of the targeted protein 10-55% more in siRNA delivery when compared to that using a commercial electroporation system. This MAE system works like many single cell electroporation are carried out in parallel, showing potential to bridge the gap between single cell electrophysiology study and in vitro electroporation to a large population of cells.

Flow micropillar array electroporation to enhance size specific transfection to a large population of cells.

Despite serving as a popular non-viral delivery approach, electroporation carries several drawbacks in its current configurations. We developed a Flow Micropillar-array Electroporation (FME) system to wisely regulate an important transmembrane-determining factor, namely cell size variations among individual cells, to achieve effective transfection. In FME, cells flow through a slit-type microfluidic channel on which carbon electrodes with well-patterned micropillar array texture are integrated as the top and bottom wall. Gravity helps bring cells to the micropillar array surface so that the permeable area on cells in different size populations is specified by their size regardless their random location fact. Without sacrificing cell viability, we demonstrate this FME concept by delivering DNA plasmids to several mammalian cell lines with obvious transfection enhancement when compared to a commercial system (K562: 3.0 folds; A549: 3.3 folds; HeLa: 1.8 folds, COS7: 1.7 folds; 293T: 2.9 folds; mES: 2.5 folds). Moreover, carbon-based electrodes are less expensive, more durable, and convenient for integration with a microfluidic setup which enables rapid and massive transfection capability that many therapeutic application needs. The success of FME may benefit many emerging biological studies and clinical practice that requires effective transfection to a large population of cells in limited processing time.

Room Temperature Synthesis of All Inorganic Lead-Free Zero-Dimensional Cs4SnBr6 and Cs3KSnBr6 Perovskites.

Lead halide perovskites are excellent candidates for photoelectronic and photovoltaic applications, but the toxicity from lead is extremely concerning. Recently, Sn-based zero-dimensional lead-free perovskites synthesized using solid-state reaction techniques have become a new focus in the field. Here, we report a simple room temperature antisolvent method for the synthesis of all inorganic lead-free green emissive Cs4SnBr6 (emission at 524 nm) and cyan emissive Cs3KSnBr6 (emission at 500 nm) zero-dimensional perovskites. Their photoluminescence quantum yields reach 20% and 35%, respectively. In addition, they maintain their emission for 46 and 55 h in the air, respectively, compared to only 5 min of CsSnBr3. This method provides a convenient way to do the research and apply these highly emissive perovskites.

Strong Blue Emission from Sb3+-Doped Super Small CsPbBr3 Nanocrystals.

Colloidal lead halide perovskite nanocrystals (NCs) have high tunability in the visible light region and high photoluminescence quantum yields (PL QYs) for green and red emissions, but bright blue emission is still a challenge. Super small CsPbBr3 perovskite NCs emit blue light around 460 nm with a narrow peak width, and they do not have the problem of phase separation like their Cl-Br counterparts. However, the blue emission from super small CsPbBr3 NCs easily becomes green over time, and their PL QY is still low. The doping of Sb3+ ions successfully reduced the surface energy, improved the lattice energy, passivated the defect states below the band gap, eventually boosted the PL QY of blue emission to 73.8%, and resulted in better spectral stability even at elevated temperatures in solution (40-100 °C). Its CIE coordinates were (0.14, 0.06), which are close to the primary blue color (0.155, 0.070) according to the NTSC TV color standard.

A nitrogen-doped PtSn nanocatalyst supported on hollow silica spheres for acetic acid hydrogenation.

A novel PtSn/NHSS bimetallic catalyst with N-doped hollow silica spheres as the support was synthesized for the gas-phase hydrogenation of acetic acid to ethanol. Its specific activity was 30% higher than that of PtSn/SiO2 due to the enhanced surface exposure of Pt active sites, induced by the strong interaction between Pt and N.

Excitation wavelength independent visible color emission of carbon dots.

Carbon dots (CDs) usually emit a strong blue light and excitation wavelength dependent long wavelength lights. This significantly limits their applications because one has to use a series of different excitation light sources to get different colors and the long wavelength emissions are usually very weak. We found that one type of CDs synthesized from p-phenylenediamine could emit various long wavelength lights (green to red) independent of the excitation wavelength when dispersed in different solvents. The photoluminescence quantum yields of the same CDs were 10-35% in different solvents for different color emissions. Based on this solvent-color effect, we further mixed the same CDs with different polymers to form solid CD films for various color emissions, and these film emissions were also excitation wavelength independent. Multicolor LEDs were demonstrated with the same CDs in solution and solid film states for color displays.

Size Specific Transfection to Mammalian Cells by Micropillar Array Electroporation.

Electroporation serves as a promising non-viral gene delivery approach, while its current configuration carries several drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here we developed a new micropillar array electroporation (MAE) platform to advance the electroporation-based delivery of DNA and RNA probes into mammalian cells. By introducing well-patterned micropillar array texture on the electrode surface, the number of pillars each cell faces varies with its plasma membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently carried out, contributing to a 2.5~3 fold increase on plasmid DNA transfection and an additional 10-55% transgene knockdown with siRNA probes, respectively. The delivery efficiency varies with the number and size of micropillars as well as their pattern density. As MAE works like many single cell electroporation are carried out in parallel, the electrophysiology response of individual cells is representative, which has potentials to facilitate the tedious, cell-specific protocol screening process in current bulk electroporation (i.e., electroporation to a large population of cells). Its success might promote the wide adoption of electroporation as a safe and effective non-viral gene delivery approach needed in many biological research and clinical treatments.

Manufacturing a nanowire-based sensing system via flow-guided assembly in a microchannel array template.

A novel flow-guided assembly approach is presented to accurately align and position nanowire arrays in pre-defined locations with high throughput and large-scale manufacturing capability. In this approach, a polymer solution is first filled in an array of microfluidic channels. Then a gas flow is introduced to blow out most of the solution while pushing a little leftover against the channel wall for assembly into polymer nanowires. In this way, highly ordered nanowires are conveniently aligned in the flow direction and patterned along both sides of the microchannels. In this study, we demonstrated this flow-guided assembly process by producing millimetre-long nanowires across a 5 × 12 mm area in the same orientation and with basic 'I-shape', 'T-shape', and 'cross' patterns. The assembled polymer nanowires were further converted to conductive carbon nanowires through a standard carbonization process. After being integrated into electronic sensors, high sensitivity was found in model protein sensing tests. This new nanowire manufacturing approach is anticipated to open new doors to the fabrication of nanowire-based sensing systems and serve as good manufacturing practice for its simplicity, low cost, alignment reliability, and high throughput.

Gold nanoparticles enhanced electroporation for mammalian cell transfection.

Electroporation figured prominently as an effective nonviral gene delivery approach for its balance on the transfection efficiency and cell viability, no restrictions of probe or cell type, and operation simplicity. The commercial electroporation systems have been widely adopted in the past two decades while still carry drawbacks associated with the high applied electric voltage, unsatisfied delivery efficiency, and/or low cell viability. By adding highly conductive gold nanoparticles (AuNPs) in electroporation solution, we demonstrated enhanced electroporation performance (i.e., better DNA delivery efficiency and higher cell viability) on mammalian cells from two different aspects: the free, naked AuNPs reduce the resistance of the electroporation solution so that the local pulse strength on cells was enhanced; targeting AuNPs (e.g., Tf-AuNPs) were brought to the cell membrane to work as virtual microelectrodes to porate cells with limited area from many different sites. The enhancement was confirmed with leukemia cells in both a commercial batch electroporation system and a home-made flow-through system using pWizGFP plasmid DNA probes. Such enhancement depends on the size, concentration, and the mixing ratio of free AuNPs/Tf-AuNPs. An equivalent mixture of free AuNPs and Tf-AuNPs exhibited the best enhancement with the transfection efficiency increased 2-3 folds at minimum sacrifice of cell viability. This new delivery concept, the combination of nanoparticles and electroporation technologies, may stimulate various in vitro and in vivo biomedical applications which rely on the efficient delivery of nucleic acids, anticancer drugs, or other therapeutic materials.