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"Song, Han"
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Hydrophobicity of arginine leads to reentrant liquid-liquid phase separation behaviors of arginine-rich proteins
Intrinsically disordered proteins rich in cationic amino acid groups can undergo Liquid-Liquid Phase Separation (LLPS) in the presence of charge-balancing anionic counterparts. Arginine and Lysine are the two most prevalent cationic amino acids in proteins that undergo LLPS, with arginine-rich proteins observed to undergo LLPS more readily than lysine-rich proteins, a feature commonly attributed to arginine’s ability to form stronger cation-π interactions with aromatic groups. Here, we show that arginine’s ability to promote LLPS is independent of the presence of aromatic partners, and that arginine-rich peptides, but not lysine-rich peptides, display re-entrant phase behavior at high salt concentrations. We further demonstrate that the hydrophobicity of arginine is the determining factor giving rise to the reentrant phase behavior and tunable viscoelastic properties of the dense LLPS phase. Controlling arginine-induced reentrant LLPS behavior using temperature and salt concentration opens avenues for the bioengineering of stress-triggered biological phenomena and drug delivery systems.
Arginine-rich proteins display reentrant LLPS behavior with changes in salt and temperature due to the hydrophobicity of arginine. Controlling the reentrant LLPS behavior opens avenues for the bioengineering and drug delivery fields.
Journal Article
Synthesis of high-entropy alloy nanoparticles on supports by the fast moving bed pyrolysis
High-entropy alloy nanoparticles (HEA-NPs) are important class of materials with significant technological potential. However, the strategies for synthesizing uniformly dispersed HEA-NPs on granular supports such as carbon materials, γ-Al
2
O
3
, and zeolite, which is vital to their practical applications, are largely unexplored. Herein, we present a fast moving bed pyrolysis strategy to immobilize HEA-NPs on granular supports with a narrow size distribution of 2 nm up to denary (MnCoNiCuRhPdSnIrPtAu) HEA-NPs at 923 K. Fast moving bed pyrolysis strategy ensures the mixed metal precursors rapidly and simultaneously pyrolyzed at high temperatures, resulting in nuclei with a small size. The representative quinary (FeCoPdIrPt) HEA-NPs exhibit high stability (150 h) toward hydrogen evolution reaction with high mass activity, which is 26 times higher than the commercial Pt/C at an overpotential of 100 mV. Our strategy provides an improved methodology for synthesizing HEA-NPs on various supports.
The large-scale application of extremely small, high-entropy alloy nanoparticles is limited by the phase separation and immobilization. Here, the authors develop a general method of fast-moving bed pyrolysis, uniformly dispersing high-entropy alloy nanoparticles on various granular supports.
Journal Article
Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity
The concept of point of darkness has received much attention for biosensing based on phase-sensitive detection and perfect absorption of light. The maximum phase change is possible at the point of darkness where the reflection is almost zero. To date, this has been experimentally realized using different material systems through the concept of topological darkness. However, complex nanopatterning techniques are required to realize topological darkness. Here, we report an approach to realize perfect absorption and extreme phase singularity using a simple metal-dielectric multilayer thin-film stack. The multilayer stack works on the principle of an asymmetric Fabry–Perot cavity and shows an abrupt phase change at the reflectionless point due to the presence of a highly absorbing ultrathin film of germanium in the stack. In the proof-of-concept phase-sensitive biosensing experiments, we functionalize the film surface with an ultrathin layer of biotin-thiol to capture streptavidin at a low concentration of 1 pM.
Optical sensors generally rely on abrupt phase changes to detect the presence of an analyte, but oftentimes they require complex nanostructures. Here, Sreekanth et al. use a simple asymmetric thin-film multilayer stack to demonstrate a point of darkness and phase singularity to develop a sensitive biosensor.
Journal Article
Influence of polyethylene-microplastic on environmental behaviors of metals in soil
Microplastics (MPs) in terrestrial ecosystems have attracted increasing attention all over the world. The adsorption-desorption behavior and bioavailability of metals in soil would affect its toxicity to organisms. However, the influences of MPs on adsorption-desorption behavior between metals and soil as well as bioavailability of metals in soils are scarcely investigated. Herein, different percentage (0, 0.1%, 1%, 10%) of polyethylene-microplastic (PE-MP) were thoroughly mixed into the soil to investigate the impacts of PE-MP on adsorption-desorption and bioavailability of metals (Zn
2+
, Pb
2+
) in the soil. A series of characterization were carried out to determine the change of PE-MP before and after adsorption to investigate the mechanisms. When MP100 (average size: 129 μm) content in soil increased to 10%, the adsorption capacities of soil with Pb
2+
and Zn
2+
were 3.73 and 4.56 mg/g, respectively, which were significantly (
p
< 0.05) lower than that of pure soil. When MP300 (average size: 293 μm) content in soil increased to 10%, the extraction fraction of Zn
2+
and Pb
2+
from soil by diethylenetriaminepentaacetic acid reached 12.35% and 23.96%, respectively, which were significantly (
p
< 0.05) higher than that of pure soil, indicating high concentration (10%) of MPs in soil would decrease the adsorption capability of soil to metals and increase the mobility of metals in terrestrial environment. However, when MPs content in soil was 0.1%, the extraction fraction of Zn
2+
and Pb
2+
showed no significant difference with that of pure soil, indicating that actual MPs in soil is unlikely to bring significant influence on metal bioavailability.
Journal Article
Measurement of dielectric properties of cells at single-cell resolution using electrorotation
Dielectric properties of a cell are biophysical properties of high interest for various applications. However, measuring these properties accurately is not easy, which can be exemplified by the large variations in reported dielectric properties of the same cell types. This paper presents a method for measuring the dielectric properties of cells at high frequency, especially lipid-producing microalgae, at single-cell resolution, by integrating an electrorotation-based dielectric property measurement method with a negative dielectrophoretic (nDEP) force-based single-cell trapping method into a single device. In this method, a four-electrode nDEP structure was used to trap a single cell in an elevated position in the center of another four-electrode structure that can apply electrorotational force. By measuring the speed of cell rotation under different applied electrorotation frequencies and fitting the results into a theoretical core–shell cell model, the dielectric properties of cells, including membrane capacitance and cytoplasm conductivity, could be obtained. This system was applied to measure the dielectric properties of lipid-accumulating microalga Chlamydomonas reinhardtii strain Sta6 by applying an electrorotation signal of up to 100 MHz. By utilizing a broad frequency range and expanding the measurement spectra to a high frequency region, increased accuracy in fitting the dielectric parameters to a theoretical model was possible, especially the cytoplasm conductivity. The developed method can be used in various applications, such as screening microalgae based on their lipid production capabilities, separating cells of different dielectric properties, identifying different cell types, as well as conducting basic biophysical analyses of cellular properties.
Journal Article
Inhibition of the NLRP3-inflammasome prevents cognitive deficits in experimental autoimmune encephalomyelitis mice via the alteration of astrocyte phenotype
ABSTRACT
Multiple sclerosis (MS) is a chronic disease that is characterized by demyelination and axonal damage in the central nervous system. Cognitive deficits are recognized as one of the features of MS, and these deficits affect the patients’ quality of life. Increasing evidence from experimental autoimmune encephalomyelitis (EAE), the animal model of MS, has suggested that EAE mice exhibit hippocampal impairment and cognitive deficits. However, the underlying mechanisms are still unclear. The NLRP3 inflammasome is a key contributor to neuroinflammation and is involved in the development of MS and EAE. Activation of the NLRP3 inflammasome in microglia is fundamental for subsequent inflammatory events. Activated microglia can convert astrocytes to the neurotoxic A1 phenotype in a variety of neurological diseases. However, it remains unknown whether the NLRP3 inflammasome contributes to cognitive deficits and astrocyte phenotype alteration in EAE. In this study, we demonstrated that severe memory deficits occurred in the late phase of EAE, and cognitive deficits were ameliorated by treatment with MCC950, an inhibitor of the NLRP3 inflammasome. In addition, MCC950 alleviated hippocampal pathology and synapse loss. Astrocytes from EAE mice were converted to the neurotoxic A1 phenotype, and this conversion was prevented by MCC950 treatment. IL-18, which is the downstream of NLRP3 inflammasome, was sufficient to induce the conversion of astrocytes to the A1 phenotype through the NF-κB pathway. IL-18 induced A1 type reactive astrocytes impaired hippocampal neurons through the release of complement component 3 (C3). Altogether, our present data suggest that the NLRP3 inflammasome plays an important role in cognitive deficits in EAE, possibly via the alteration of astrocyte phenotypes. Our study provides a novel therapeutic strategy for hippocampal impairment in EAE and MS.
Journal Article
Conocybe Section Pilosellae in China: Reconciliation of Taxonomy and Phylogeny Reveals Seven New Species and a New Record
Conocybe belongs to the Bolbitiaceae. The morphological classification and molecular phylogenetics of Conocybe section Pilosellae are not in agreement. In this study, based on the specimens from China, we investigated the sect. Pilosellae and identified 17 species, including 7 new species: Conocybe pilosa, with a densely hairy pileus and stipe; C. reniformis, with reniform spores; C. ceracea, with waxy dehydration of the lamellae; C. muscicola, growing on moss; C. sinobispora, with two-spored basidia; C. hydrophila, with a hygrophanous pileus; C. rufostipes, growing on dung with a brown stipe; and C. pseudocrispa, one new record for China. A key was compiled for the sect. Pilosellae in China. Here, the sect. Pilosellae, and new species and records from China are morphologically described and illustrated. Maximum likelihood and Bayesian analyses were performed using a combined nuc rDNA internal transcribed spacer region (ITS) and nuc 28S rDNA (nrLSU), and translation elongation factor 1-alpha (tef1-α) dataset to reconstruct the relationships of this section. We found that the sect. Pilosellae was the basal clade of Conocybe, and its evolutionary features may shed light on the characteristics of Conocybe. By integrating morphological classification and phylogenetic analysis, we explored the possible phylogenetic relationships among the species of the sect. Pilosellae in China.
Journal Article
A two-dimensional mid-infrared optoelectronic retina enabling simultaneous perception and encoding
Infrared machine vision system for object perception and recognition is becoming increasingly important in the Internet of Things era. However, the current system suffers from bulkiness and inefficiency as compared to the human retina with the intelligent and compact neural architecture. Here, we present a retina-inspired mid-infrared (MIR) optoelectronic device based on a two-dimensional (2D) heterostructure for simultaneous data perception and encoding. A single device can perceive the illumination intensity of a MIR stimulus signal, while encoding the intensity into a spike train based on a rate encoding algorithm for subsequent neuromorphic computing with the assistance of an all-optical excitation mechanism, a stochastic near-infrared (NIR) sampling terminal. The device features wide dynamic working range, high encoding precision, and flexible adaption ability to the MIR intensity. Moreover, an inference accuracy more than 96% to MIR MNIST data set encoded by the device is achieved using a trained spiking neural network (SNN).
Designing an infrared machine vision system that can efficiently perceive, convert, and process a massive amount of data remains a challenge. Here, the authors present a retina-inspired 2D optoelectronic device based on van der Waals heterostructure that can perform the data perception and spike-encoding simultaneously for night vision, sensing, spectroscopy, and free-space communications.
Journal Article