Responses of assembled structures of block polyelectrolytes to electrostatic interaction strength.

In this paper, the responses of assembled behaviors of block polyelectrolytes (PEs) to the strength of electrostatic interactions are studied through molecular dynamic simulations. The results show that the assembled structures closely depend on the electrostatic strength. It should be noted that PE coacervation can outweigh the nucleation of hydrophobic blocks and invert the micelle structures at strong electrostatic strengths, leading to the formation of inverted micelles of PE cores and hydrophobic coronas. In the poor solvent condition for neutral block, diverse anisotropic micelles are presented; candy-like conventional micelles of hydrophobic cores and PE patches coexist with inverted candy-like micelles of PE cores and hydrophobic patches and with Janus micelles of semi-neutral aggregate and semi-PE cluster in the presence of divalent and trivalent counterions. The formation of conventional or inverted micelle is largely determined by the type of micellar fusion, which results from the nucleation competition between electrostatic correlation and hydrophobic interaction. The merge of micelles mediated by hydrophobic attraction leads to conventional hydrophobic cores, and the fusion induced by electrostatic correlations results in PE cores micelles. At strong electrostatic strengths, the PE chains exhibit rich conformations at trivalent counterions, ranging from a fully collapsed state to a rod-like state, and parallel alignment of PE chains is found.

Phosphoprotein dynamics of interacting T cells and tumor cells by HySic.

Functional interactions between cytotoxic T cells and tumor cells are central to anti-cancer immunity. However, our understanding of the proteins involved is limited. Here, we present HySic (hybrid quantification of stable isotope labeling by amino acids in cell culture [SILAC]-labeled interacting cells) as a method to quantify protein and phosphorylation dynamics between and within physically interacting cells. Using co-cultured T cells and tumor cells, we directly measure the proteome and phosphoproteome of engaged cells without the need for physical separation. We identify proteins whose abundance or activation status changes upon T cell:tumor cell interaction and validate our method with established signal transduction pathways including interferon γ (IFNγ) and tumor necrosis factor (TNF). Furthermore, we identify the RHO/RAC/PAK1 signaling pathway to be activated upon cell engagement and show that pharmacologic inhibition of PAK1 sensitizes tumor cells to T cell killing. Thus, HySic is a simple method to study rapid protein signaling dynamics in physically interacting cells that is easily extended to other biological systems.

Development and validation of an improved QuEChERS method for the extraction of semi-volatile organic compounds (SVOCs) from complex soils.

In order to achieve rapid, sensitive, and high-throughput determination of typical semi-volatile organic compounds (SVOCs) in soil samples, a method for the rapid determination of 63 SVOCs in soil was developed by optimizing and improving the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction technique in conjunction with gas chromatography-mass spectrometry (GC-MS) analysis. A small amount of soil sample (5.0 g) was vortexed with 10 mL of a mixture of acetone and n-hexane (V/V = 1 : 1) for 2 min, followed by rapid vortex purification and centrifugation using a mixture of copper powder and octadecylsilane (C18) dispersant. The resulting supernatant was then purified through a 0.22 µm filter membrane. The results showed that the 63 SVOCs exhibited good linear relationships within the concentration range of 100-5000 µg L-1, with correlation coefficients (R2) above 0.99. The method detection limit (MDL = 3.3 Sy/m) was lower than 0.050 mg kg-1. At a spike concentration of 1 mg kg-1, the recovery rates of the 63 SVOCs were almost above 70% (n = 7). Compared with the rapid solvent extraction (ASE) method specified in US EPA 3545 standard, this method reduced the organic solvent usage by 14 times and significantly shortened the operation time. Furthermore, this method did not involve any transfer or concentration steps of the extractant during the experimental process, reducing the exposure time of toxic compounds and providing support for the principles of green analytical chemistry. Moreover, in the detection of most compounds in the same batch of contaminated soil, the extraction results obtained by QuEChERS were superior to those obtained by the ASE method, providing evidence for the practical application of this method. This method is rapid, simple, accurate, requires a small sample volume, and causes minimal environmental pollution. It provides a high-throughput detection method for the rapid screening of SVOCs in soil.

Optimized Suspension Trapping Method for Phosphoproteomics Sample Preparation.

A successful mass spectrometry-based phosphoproteomics analysis relies on effective sample preparation strategies. Suspension trapping (S-Trap) is a novel, rapid, and universal method of sample preparation that is increasingly applied in bottom-up proteomics studies. However, the performance of the S-Trap protocol for phosphoproteomics studies is unclear. In the existing S-Trap protocol, the addition of phosphoric acid (PA) and methanol buffer creates a fine protein suspension to capture proteins on a filter and is a critical step for subsequent protein digestion. Herein, we demonstrate that this addition of PA is detrimental to downstream phosphopeptide enrichment, rendering the standard S-Trap protocol suboptimal for phosphoproteomics. In this study, the performance of the S-Trap digestion for proteomics and phosphoproteomics is systematically evaluated in large-scale and small-scale samples. The results of this comparative analysis show that an optimized S-Trap approach, where trifluoroacetic acid is substituted for PA, is a simple and effective method to prepare samples for phosphoproteomics. Our optimized S-Trap protocol is applied to extracellular vesicles to demonstrate superior sample preparation workflow for low-abundance, membrane-rich samples.

Nanodiamond-Enhanced Nanofiber Separators for High-Energy Lithium-Ion Batteries.

Current lithium-ion battery separators made from polyolefins such as polypropylene and polyethylene generally suffer from low porosity, low wettability, and slow ionic conductivity and tend to perform poorly against heat-triggering reactions that may cause potentially catastrophic issues, such as fire. To overcome these limitations, here we report that a porous composite membrane consisting of poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers functionalized with nanodiamonds (NDs) can realize a thermally resistant, mechanically robust, and ionically conductive separator. We critically reveal the role of NDs in the polymer matrix of the membrane to improve the thermal, mechanical, crystalline, and electrochemical properties of the composites. Taking advantages of these characteristics, the ND-functionalized nanofiber separator enables high-capacity and stable cycling of lithium cells with LiNi0.8Mn0.1Co0.1O2 (NMC811) as the cathode, much superior to those using conventional polyolefin separators in otherwise identical cells.

Research progress of bio-slurry remediation technology for organic contaminated soil.

Bio-slurry remediation technology, as a controllable bioremediation method, has the significant advantage of high remediation efficiency and can effectively solve the problems of high energy consumption and secondary pollution of traditional organic pollution site remediation technology. To further promote the application of this technology in the remediation of organically polluted soil, this paper summarizes the importance and advantages of bio-slurry remediation technology compared with traditional soil remediation technologies (physical, chemical, and biological). It introduces the technical infrastructure and its technological processes. Then, various factors that may affect its remediation performance are discussed. By analyzing the applications of this technology to the remediation of typical organic pollutant-(polycyclic aromatic hydrocarbons(PAHs), polychlorinated biphenyls(PCBs), total petroleum hydrocarbons(TPH), and pesticide) contaminated sites, the following key features of this remediation technology are summarised: (1) the technology has a wide range of applications and can be used in a versatile way in the remediation projects of various types of organic-contaminated soil sites such as in clay, sand, and high organic matter content soil; (2) the technology is highly controllable. Adjusting environmental parameters and operational conditions, such as nutrients, organic carbon sources (bio-stimulation), inoculants (bio-augmentation), water-to-soil ratio, etc., can control the remediation process, thus improving the restoration performance. To sum up, this bio-slurry remediation technology is an efficient, controllable and green soil remediation technology that has broad application prospects.

Self-assembly of amphiphilic polyelectrolytes in trivalent salt solution.

Multivalent salt plays important roles in polyelectrolyte (PE) systems. Some special effects, such as ion mediated electrostatic correlation and reentrant condensation can be induced in the presence of multivalent salt. In this work, the self-assembly behaviors of diblock PEs in trivalent salt solutions are mainly investigated by molecular dynamics (MD) simulations, and partial results are qualitatively verified by experiments. The electrostatic correlation between PE chains and trivalent counterions is first enhanced with the increase of salt concentration, and then the large complexes of co-ions and trivalent counterions reduce the correlation at the excessive salt regime. Therefore, the electrostatic correlation mediated by trivalent ions shows a non-monotonic dependence on salt content. It should be noted that one-dimensional chain-like and two-dimensional planar network supra-micellar structures are obtained at different concentrations of PEs. It is the strong electrostatic correlation mediated by trivalent counterions that leads to the cross-linking of micelles, and homogeneous spherical micelles rather than anisotropic micelles are used as building blocks. Both of these supra-micellar structures predicted by simulations are qualitatively confirmed by experiments, and a micron sized long polymer chain and planar networks of inter-connected micelles are demonstrated in transmission electron microscopy (TEM) images. Reentrant behavior of the assembled micelles is demonstrated at a lower polymer concentration. The transitions from a dispersed micellar phase to a fully phase separated phase (where all the copolymer chains aggregate into one micelle to precipitate out of the solution) and to the re-dissolution of micelles are displayed with an increase in trivalent salt. The non-monotonic dependence of electrostatic correlation on the salt content is well displayed by the four states of the assembled micelles: (i) dispersed micelles, (ii) a single micelle comprising of all copolymer chains, (iii) micellar complex, and (iv) re-dispersed micelles. Our analysis may provide guidance for cross-linking of isotropic micelles into superstructures.

Affinity-based protein profiling to reveal targets of puerarin involved in its protective effect on cardiomyocytes.

Natural products are an important source of new drugs. Some of them may be used directly in clinical settings without further structural modification. One of these directly used natural products is puerarin (Pue), which protects cardiomyocytes against oxidative stress and high glucose stress. Although Pue has been used in clinics for many years, its direct binding targets involved in the protection of cardiomyocytes are not yet fully understood. Here, we reported that Pue could prevent cardiomyocytes from apoptosis under H2O2 and high glucose conditions. Based on affinity-based protein profiling methods, we synthesized an active Pue probe (Pue-DA) with a photosensitive crosslinker to initiate a biological orthogonal reaction. Because of the steric hindrance of Pue-DA, two conformational isomers (syn and anti) unequivocally existed in the probe, and these transformed into one isomer when the probe was heated at 60 °C. We confirmed that the alkylation was on the 7-position phenol group of Pue. Mass spectroscopy revealed that Pue-DA can bind with three proteins, namely CHAF1B, UBE2C, and UBE2T. Finally, cellular thermal shift assay showed that Pue has the ability to stabilize CHAF1B stabilization. The knock-down of CHAF1B reduced the protective effect of Pue on cardiomyocytes. In conclusion, Pue protects cardiomyocytes from apoptosis through binding with CHAF1B.

Mechanisms of Transformation of Bulk Aluminum-Lithium Alloys to Aluminum Metal-Organic Nanowires.

Fabrication and applications of lightweight, high load-bearing, thermally stable composite materials would benefit greatly from leveraging the high mechanical strength of ceramic nanowires (NWs) over conventional particles or micrometer-scale fibers. However, conventional synthesis routes to produce NWs are rather expensive. Recently we discovered a novel method to directly convert certain bulk bimetallic alloys to metal-organic NWs at ambient temperature and pressure. This method was demonstrated by a facile transformation of polycrystalline aluminum-lithium (AlLi) alloy particles to aluminum alkoxide NWs, which can be further transformed to mechanically robust aluminum oxide (Al2O3) NWs. However, the transformation mechanisms have not been clearly understood. Here, we conducted advanced materials characterization (via electron microscopy and nuclear magnetic resonance spectroscopies) and chemo-mechanical modeling to elucidate key physical and chemical mechanisms responsible for NWs formation. We further demonstrated that the content of Li metal in the AlLi alloy could be reduced to about 4 wt % without compromising the success of the NWs synthesis. This new mechanistic understanding may open new avenues for large-scale, low-cost manufacturing of NWs and nanofibers for a broad range of composites and flexible ceramic membranes.

Super-quenched Molecular Probe Based on Aggregation-Induced Emission and Photoinduced Electron Transfer Mechanisms for Formaldehyde Detection in Human Serum.

Energy transfer between fluorescent dyes and quenchers is widely used in the design of light-up probes. Although dual quenchers are more effective in offering lower background signals and higher turn-on ratios than one quencher, such probes are less explored in practice as they require both quenchers to be within the proximity of the fluorescent core. In this contribution, we utilized intramolecular motion and photoinduced electron transfer (PET) as quenching mechanisms to build super-quenched light-up probes based on fluorogens with aggregation-induced emission. The optimized light-up probe possesses negligible background and is able to detect not only free formaldehyde (FA) but also polymeric FA, with an unprecedented turn-on ratio of >4900. We envision that this novel dual quenching strategy will help to develop various light-up probes for analyte sensing.

Caspase-1 Specific Light-Up Probe with Aggregation-Induced Emission Characteristics for Inhibitor Screening of Coumarin-Originated Natural Products.

Caspase-1 is a key player in pyroptosis and inflammation. Caspase-1 inhibition is found to be beneficial to various diseases. Coumarin-originated natural products have an anti-inflammation function, but their direct inhibition effect to caspase-1 remains unexplored. To evaluate their interactions, the widely used commercial coumarin-based probe (Ac-YVAD-AMC) is not suitable, as the background signal from coumarin-originated natural products could interfere with the screening results. Therefore, fluorescent probes using a large Stokes shift could help solve this problem. In this work, we chose the fluorophore of tetraphenylethylene-thiophene (TPETH) with aggregation-induced emission characteristics and a large Stokes shift of about 200 nm to develop a molecular probe. Bioconjugation between TPETH and hydrophilic peptides (DDYVADC) through a thiol-ene reaction generated a light-up probe, C1-P3. The probe has little background signal in aqueous media and exerts a fluorescent turn-on effect in the presence of caspase-1. Moreover, when evaluating the inhibition potency of coumarin-originated natural products, the new probe could generate a true and objective result but not for the commercial probe (Ac-YVAD-AMC), which is evidenced by HPLC analysis. The quick light-up response and accurate screening results make C1-P3 very useful in fundamental study and inhibitior screening toward caspase-1.