Recent advance of physicochemical, structural properties, potential health benefits and application of bioactive macromolecules from Porphyra haitanensis: A review.

Porphyra haitanensis (P. haitanensis) belongs to the class Rhodophyta and the family Bangiaceae, which is a unique artificially cultivated seaweed in China, especially in the coastal areas of Fujian and Zhejiang province. P. haitanensis is rich in amino acids, mineral elements, proteins, polysaccharides, and trace elements, with proteins and polysaccharides being the main components. P. haitanensis proteins and polysaccharides have variety of biological activities, including antioxidant, anticancer, immunomodulatory, anti-allergic and anti-aging activities, among others. This review introduced and summarized the preparation, isolation and purification, phytochemistry and structural properties, and biological activities of P. haitanensis proteins and polysaccharide, as well as their biomedical and food applications. Furthermore, a thorough analysis of the current trends and perspectives on P. haitanensis bioactive macromolecules were highlighted and prospected. Hopefully, this review can provide a useful reference value for the development and application of P. haitanensis bioactive macromolecules in the field of biomedical and food in the future.

Coordination Chemistry and Reactivity of a Lewis Acidic Di-Zinc Framework Supported by Bisphenoxymethanone Ligands.

We present the synthesis, structural characterization, and reactivity studies of a tetra-zinc complex supported by the bisphenoxymethanone ligands and its transformation into various di-zinc architectures. Our findings highlight the potential of these complexes in molecular recognition, supramolecular chemistry, and catalysis.

Applications of Lightsheet Fluorescence Microscopy by High Numerical Aperture Detection Lens.

This Review explores the evolution, improvements, and recent applications of Light Sheet Fluorescence Microscopy (LSFM) in biological research using a high numerical aperture detection objective (lens) for imaging subcellular structures. The Review begins with an overview of the development of LSFM, tracing its evolution from its inception to its current state and emphasizing key milestones and technological advancements over the years. Subsequently, we will discuss various improvements of LSFM techniques, covering advancements in hardware such as illumination strategies, optical designs, and sample preparation methods that have enhanced imaging capabilities and resolution. The advancements in data acquisition and processing are also included, which provides a brief overview of the recent development of artificial intelligence. Fluorescence probes that were commonly used in LSFM will be highlighted, together with some insights regarding the selection of potential probe candidates for future LSFM development. Furthermore, we also discuss recent advances in the application of LSFM with a focus on high numerical aperture detection objectives for various biological studies. For sample preparation techniques, there are discussions regarding fluorescence probe selection, tissue clearing protocols, and some insights into expansion microscopy. Integrated setups such as adaptive optics, single objective modification, and microfluidics will also be some of the key discussion points in this Review. We hope that this comprehensive Review will provide a holistic perspective on the historical development, technical enhancements, and cutting-edge applications of LSFM, showcasing its pivotal role and future potential in advancing biological research.

Regulation of blood-brain barrier integrity by Dmp1-expressing astrocytes through mitochondrial transfer.

The blood-brain barrier (BBB) acts as the crucial physical filtration structure in the central nervous system. Here, we investigate the role of a specific subset of astrocytes in the regulation of BBB integrity. We showed that Dmp1-expressing astrocytes transfer mitochondria to endothelial cells via their endfeet for maintaining BBB integrity. Deletion of the Mitofusin 2 (Mfn2) gene in Dmp1-expressing astrocytes inhibited the mitochondrial transfer and caused BBB leakage. In addition, the decrease of MFN2 in astrocytes contributes to the age-associated reduction of mitochondrial transfer efficiency and thus compromises the integrity of BBB. Together, we describe a mechanism in which astrocytes regulate BBB integrity through mitochondrial transfer. Our findings provide innnovative insights into the cellular framework that underpins the progressive breakdown of BBB associated with aging and disease.

Significantly underestimated traffic-related ammonia emissions in Chinese megacities: Evidence from satellite observations during COVID-19 lockdowns.

Ammonia (NH3) plays an important role in the formation of atmospheric particulate matter, but the contribution of traffic-related emissions remains unclear, particularly in megacities with a large number of vehicles. Taking the opportunity of the stringent COVID-19 lockdowns implemented in Beijing and Shanghai in 2022, this study aims to estimate the traffic-related NH3 emissions in these two megacities based on satellite observations. Differences between urban and suburban areas during the lockdown and non-lockdown periods are compared. It was found that despite different dominating sources, the overall NH3 concentrations in urban and suburban areas were at a similar level, and the lockdown resulted in a more prominent decrease in urban areas, where traffic activities were most heavily affected. The traffic-related contribution to the total emission was estimated to be ∼30% in megacities, and ∼40% in urban areas, which are about 2-10 times higher than that in previous studies. The findings indicate that the traffic-related NH3 emissions have been significantly underestimated in previous studies and may play a more critical role in the formation of air pollution in megacities, especially in winter, when agricultural emissions are relatively low. This study highlights the importance of traffic-related NH3 emissions in Chinese megacities and the need to reassess the emissions and their impacts on air quality.

Receptor Ligand-Free Mesoporous Silica Nanoparticles: A Streamlined Strategy for Targeted Drug Delivery across the Blood-Brain Barrier.

Mesoporous silica nanoparticles (MSNs) represent a promising avenue for targeted brain tumor therapy. However, the blood-brain barrier (BBB) often presents a formidable obstacle to efficient drug delivery. This study introduces a ligand-free PEGylated MSN variant (RMSN25-PEG-TA) with a 25 nm size and a slight positive charge, which exhibits superior BBB penetration. Utilizing two-photon imaging, RMSN25-PEG-TA particles remained in circulation for over 24 h, indicating significant traversal beyond the cerebrovascular realm. Importantly, DOX@RMSN25-PEG-TA, our MSN loaded with doxorubicin (DOX), harnessed the enhanced permeability and retention (EPR) effect to achieve a 6-fold increase in brain accumulation compared to free DOX. In vivo evaluations confirmed the potent inhibition of orthotopic glioma growth by DOX@RMSN25-PEG-TA, extending survival rates in spontaneous brain tumor models by over 28% and offering an improved biosafety profile. Advanced LC-MS/MS investigations unveiled a distinctive protein corona surrounding RMSN25-PEG-TA, suggesting proteins such as apolipoprotein E and albumin could play pivotal roles in enabling its BBB penetration. Our results underscore the potential of ligand-free MSNs in treating brain tumors, which supports the development of future drug-nanoparticle design paradigms.

A Bis-Cyclopentadienyl Ligand-Supported Di-Iron Trihydride Motif as a Synthon for Access to Heterobimetallic Trinuclear Complexes.

Herein, we report the synthesis of a flexible bis-cyclopentadienyl ligand L (the doubly deprotonated form of H2L (1,3-bis(2,4-di-tert-butylcyclopentadienyldimethylsilyl)benzene)), demonstrating its ability to stabilize a series of di-iron hydrido complexes. Notably, this ligand facilitates the isolation of an unprecedented anionic cyclopentadienyl ligand-supported di-iron trihydride complex, LFe2(µ-H)3Li(THF) (2), functioning as a synthon for the [Fe2(µ-H)3]- core and providing access to heterobimetallic complexes 4-6 with coinage metals.

Synthesis of Benzo[c]cinnolinium Salts from 2-Azobiaryls by Copper(II) or Electrochemical Oxidation.

Synthesis of benzo[c]cinnolinium salts by copper(II)-promoted or electrochemical oxidation of 2-azobiaryls is described. A variety of diversely functionalized benzo[c]cinnolinium salts were easily constructed by this strategy with excellent functional group tolerance and high efficiency. An interesting fluorescence centered at 571 nm is revealed by a benzo[c]cinnolinium salt with electron push-pull substitutions. The mechanism is proposed to go through single-electron transfer driven by oxidant and intramolecular cyclization via nucleophilic addition, followed by an anion exchange.

Mechanical overload-induced release of extracellular mitochondrial particles from tendon cells leads to inflammation in tendinopathy.

Tendinopathy is one of the most common musculoskeletal diseases, and mechanical overload is considered its primary cause. However, the underlying mechanism through which mechanical overload induces tendinopathy has not been determined. In this study, we identified for the first time that tendon cells can release extracellular mitochondria (ExtraMito) particles, a subtype of medium extracellular particles (mEPs), into the environment through a process regulated by mechanical loading. RNA sequencing systematically revealed that oxygen-related reactions, extracellular particles, and inflammation were present in diseased human tendons, suggesting that these factors play a role in the pathogenesis of tendinopathy. We simulated the disease condition by imposing a 9% strain overload on three-dimensional mouse tendon constructs in our cyclic uniaxial stretching bioreactor. The three-dimensional mouse tendon constructs under normal loading with 6% strain exhibited an extended mitochondrial network, as observed through live-cell confocal laser scanning microscopy. In contrast, mechanical overload led to a fragmented mitochondrial network. Our microscopic and immunoblot results demonstrated that mechanical loading induced tendon cells to release ExtraMito particles. Furthermore, we showed that mEPs released from tendon cells overloaded with a 9% strain (mEP9%) induced macrophage chemotaxis and increased the production of proinflammatory cytokines, including IL-6, CXCL1, and IL-18, from macrophages compared to mEP0%, mEP3%, and mEP6%. Partial depletion of the ExtraMito particles from mEP9% by magnetic-activated cell sorting significantly reduced macrophage chemotaxis. N-acetyl-L-cysteine treatment preserved the mitochondrial network in overloaded tendon cells, diminishing overload-induced macrophage chemotaxis toward mEP9%. These findings revealed a novel mechanism of tendinopathy; in an overloaded environment, ExtraMito particles convey mechanical response signals from tendon cells to the immune microenvironment, culminating in tendinopathy.

Protein and lipid expansion microscopy with trypsin and tyramide signal amplification for 3D imaging.

Expansion microscopy, whereby the relative positions of biomolecules are physically increased via hydrogel expansion, can be used to reveal ultrafine structures of cells under a conventional microscope. Despite its utility for achieving super-resolution imaging, expansion microscopy suffers a major drawback, namely reduced fluorescence signals caused by excessive proteolysis and swelling effects. This caveat results in a lower photon budget and disfavors fluorescence imaging over a large field of view that can cover an entire expanded cell, especially in 3D. In addition, the complex procedures and specialized reagents of expansion microscopy hinder its popularization. Here, we modify expansion microscopy by deploying trypsin digestion to reduce protein loss and tyramide signal amplification to enhance fluorescence signal for point-scanning-based imaging. We name our new methodology TT-ExM to indicate dual trypsin and tyramide treatments. TT-ExM may be applied for both antibody and lipid staining. TT-ExM displayed enhanced protein retention for endoplasmic reticulum and mitochondrial markers in COS-7 cell cultures. Importantly, TT-ExM-based lipid staining clearly revealed the complex 3D membrane structures in entire expanded cells. Through combined lipid and DNA staining, our TT-ExM methodology highlighted mitochondria by revealing their DNA and membrane structures in cytoplasm, as well as the lipid-rich structures formed via phase separation in nuclei at interphase. We also observed lipid-rich chromosome matrices in the mitotic cells. These high-quality 3D images demonstrate the practicality of TT-ExM. Thus, readily available reagents can be deployed in TT-ExM to significantly enhance fluorescence signals and generate high-quality and ultrafine-resolution images under confocal microscopy.

Unraveling the Adhesion Behavior of Different Cell Lines on Biomimetic PEDOT Interfaces: The Role of Surface Morphology and Antifouling Properties.

The poly(3,4-ethylenedioxythiophene) (PEDOT) interface, renowned for its biocompatibility and intrinsic conductivity, holds substantial potential in biosensing and cellular modulation. Through strategic functionalization, PEDOT derivatives can be adaptable for multifaceted applications. Notably, integrating phosphorylcholine (PC) groups into PEDOT, mimicking the hydrophilic headgroups from cell membranes, confers exceptional antifouling properties on the coating. This study systematically investigated biomolecule interactions with distinct forms of PEDOT, incorporating variations in surface modifications and structure. Zwitterionic PEDOT-PC was electropolymerized on smooth and nanostructured surfaces using various feeding ratios in electrolytes to finely control the antifouling properties of the interface. Precise electropolymerization conditions governed the attainment of smooth and nanostructured filamentous surfaces. The study employed a quartz crystal microbalance with dissipation (QCM-D) to assess protein binding behavior. Bovine serum albumin (BSA), lysozyme (LYZ), cytochrome c (cyt c), and fibronectin (FN) were used to evaluate their binding affinities for PEDOT films. FN, a pivotal extracellular matrix component, was included for connecting to cell adhesion behavior. Furthermore, the cellular adhesion behaviors on PEDOT interfaces were evaluated. Three cell lines─MG-63 osteosarcoma, HeLa cervical cancer, and fibroblast NIH/3T3 were examined. The presence of PC moieties significantly altered the adhesive response, including the number of attached cells, their morphologies, and nucleus shrinkage. MG-63 cells exhibited the highest tolerance for PC moieties. A feeding ratio of PEDOT-PC exceeding 70% resulted in cell apoptosis. This study contributes to understanding biomolecule adsorption on PEDOT surfaces of diverse morphologies and degrees of the antifouling moiety. Meanwhile, it also sheds light on the responses of various cell types.

Silane-modified hydroxyapatite nanoparticles incorporated into polydioxanone/poly(lactide-co-caprolactone) creates a novel toughened nanocomposite with improved material properties and in vivo inflammatory responses.

The interface tissue between bone and soft tissues, such as tendon and ligament (TL), is highly prone to injury. Although different biomaterials have been developed for TL regeneration, few address the challenges of the TL-bone interface. Here, we aim to develop novel hybrid nanocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL), and hydroxyapatite (HA) nanoparticles suitable for TL-bone interface repair. Nanocomposites, containing 3-10% of both unmodified and chemically modified hydroxyapatite (mHA) with a silane coupling agent. We then explored biocompatibility through in vitro and in vivo studies using a subcutaneous mouse model. Through different characterisation tests, we found that mHA increases tensile properties, creates rougher surfaces, and reduces crystallinity and hydrophilicity. Morphological observations indicate that mHA nanoparticles are attracted by PDO rather than LCL phase, resulting in a higher degradation rate for mHA group. We found that adding the 5% of nanoparticles gives a balance between the properties. In vitro experiments show that osteoblasts' activities are more affected by increasing the nanoparticle content compared with fibroblasts. Animal studies indicate that both HA and mHA nanoparticles (10%) can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. In summary, this work highlights the potential of PDO/LCL/HA nanocomposites as an excellent biomaterial for TL-bone interface tissue engineering applications.

Enantioselective Synthesis of Nabscessin C.

Enantioselective synthesis of nabscessin C (1), an aminocyclitol amide with antimicrobial activity, is reported. Starting from myo-inositol, (+)-nabscessin C was synthesized in 12 isolation steps. Desymmetrization of 2-deoxygenated 4,6-dibenzylinositol was achieved using lipase from porcine pancreas (PPL), and the stereochemistry was established by X-ray crystallography. This method has the potential for synthesizing other cyclitol-derived compounds.

Estimating DNA-Binding Specificities of Transcription Factors Using SELEX-Seq.

Here we provide an updated protocol for the Systematic Evolution of Ligands followed by massively parallel sequencing (SELEX-seq) method to study protein-DNA interaction specificities. This in vitro method is used to characterize DNA-binding specificities of transcription factors (TFs). The procedure is based on cycles of immunoprecipitation of protein-DNA complexes, starting with a randomized DNA library of defined fragment length, followed by massively parallel sequencing. The updated protocol includes aspects of experimental design and procedure as well as basic instructions on data analysis.

Photosalience and Thermal Phase Transitions of Azobenzene- and Crown Ether-Based Complexes in Polymorphic Crystals.

Stimuli-responsive molecular crystals have attracted considerable attention as promising smart materials with applications in various fields such as sensing, actuation, and optoelectronics. Understanding the structure-mechanical property relationships, however, remains largely unexplored when it comes to functionalizing these organic crystals. Here, we report three polymorphic crystals (Forms A, B, and C) formed by the non-threaded complexation of a dibenzo[18]crown-6 (DB18C6) ether ring and an azobenzene-based ammonium cation, each exhibiting distinct thermal phase transitions, photoinduced deformations, and mechanical behavior. Structural changes on going from Form A to Form B and from Form C to Form B during heating and cooling, respectively, are observed by single-crystal X-ray crystallography. Form A shows photoinduced reversible bending, whereas Form B exhibits isotropic expansion. Form C displays uniaxial negative expansion with a remarkable increase of 44% in thickness under photoirradiation. Force measurements and nanoindentation reveal that the soft crystals of Form A with a low elastic modulus demonstrate a significant photoresponse, attributed to the non-threaded molecular structure, which permits flexibility of the azobenzene unit. This work represents a significant advance in the understanding of the correlation between structure-thermomechanical and structure-photomechanical properties necessary for the development of multi-stimulus-responsive materials with tailored properties.

Sertoli cell-derived extracellular vesicles traverse the blood-testis barrier and deliver miR-24-3p inhibitor into germ cells improving sperm mobility.

Asthenozoospermia, characterized by poor sperm motility, is a common cause of male infertility. Improving energy metabolism and alleviating oxidative stress through drug regimens are potential therapeutic strategies. In this study, we observed upregulated miR-24-3p levels in asthenozoospermia spermatozoa, contributing to energy metabolism disorder and oxidative stress by reducing GSK3ß expression. Thus, reducing miR-24-3p levels using drugs is expected to improve sperm motility. The blood-testis barrier (BTB) protects the testis from xenobiotics and drugs. In this study, we found that Sertoli cell-derived small extracellular vesicles (SC-sEV) can traverse the BTB and enter germ cells. We successfully loaded miR-24-3p inhibitor into SC-sEV, creating the nano-drug SC-sEV@miR-24-3p inhibitor, which effectively delivers miR-24-3p inhibitor into germ cells. In a gossypol-induced mouse asthenozoospermia model, administration of SC-sEV@miR-24-3p inhibitor significantly improved sperm motility, in vitro fertilization success, and blastocyst formation rates. As anticipated, it also improved the litter size of asthenozoospermia mice. These results suggest that SC-sEV@miR-24-3p inhibitor holds promise as a potential clinical treatment for asthenospermia.