Se pu = Chinese journal of chromatography最新文献

Exosomes are nanoscale vesicles secreted by cells and are encapsulated in lipid bilayers. They play crucial roles in cell communication and are involved in a variety of physiological and pathological processes, including immune regulation, angiogenesis, and tumor initiation and metastasis. Exosomes carry a variety of biomolecules from maternal cells and are therefore important vehicles for discovering disease markers. Traditional detection methods only provide average cell-population information for a given sample and cannot establish clear relationships between the biological functions of exosomes and subtype owing to the significant heterogeneity associated with exosomes from different cell subsets. Therefore, characterizing exosomes at the single-cell and single-particle levels requires exosome specificities to be further explored and the characteristics of various exosome subtypes to be distinguished. Commonly used single-particle exosome characterization technologies include flow cytometry, super-resolution microscopy, atomic force microscopy, surface-enhanced Raman spectroscopy, proximity barcoding assay and MS. In this paper, we summarize recent advances in the separation and characterization of single-cell exosomes based on microfluidics and provide future applications prospects for emerging technologies (such as Olink proteomics, click chemistry, and molecular imprinting) for studying single-cell and single-particle exosomes.

Vesicles, are categorized as artificial (i.e., liposomes) or natural (i.e., extracellular vesicles (EVs)) and play significant roles in drug-delivery and biomarker-screening applications. Liposomes, as a representative form of artificial vesicle, are spherical lipid structures composed of one or more artificially synthesized phospholipid bilayers. Liposomes are highly biocompatible and bioavailable, very stable, and easily synthesized; hence, they are among the most commonly used and frequently applied nanocarriers in targeted drug-delivery systems (DDS). EVs are natural small membrane-bound vesicles actively secreted by cells and contain a variety of components, including nucleic acids, proteins, and lipids. They also serve as important mediators of intercellular communication. As the smallest EV subtype, with diameters of only 30-100 nm, exosomes contain unique biomolecules that are considered to be the fingerprints of the parent cells. In the pathological state, the content of exosomes will change; consequently, exosomes are potential disease-diagnosis biomarkers. Recent clinical trials have shown that exosomes are ideal nanocarriers in targeted drug-delivery therapies for a variety of diseases. Compared with traditional artificial liposomal carriers, exosomes display unique advantages and provide the DDS field with new possibilities. Liposomes and exosomes are receiving increasing levels of attention in the drug-delivery and biomarker-screening fields. This article introduces techniques for the preparation of liposomes, and the enrichment and separation of exosomes, and delves into research progress on their use in drug-delivery and biomarker-screening applications. Finally, challenges facing the use of liposomes and exosomes in clinical applications are discussed.

Exosomes form a subclass of extracellular vesicle that are secreted by most cells and found in nearly all body fluids, including blood, urine, saliva, amniotic fluid, and milk, as well as in various tissues and intercellular spaces. Exosomes have recently been recognized as crucial intercellular communication mediators, and an increasing number of studies have shown that exosomes are important liquid-biopsy tools that play irreplaceable roles in the diagnosis, prognosis, and treatment of diseases. The ability to isolate high-quality exosomes is a prerequisite for diagnosing and subsequently treating diseases in an accurate and repeatable manner. However, efficiently isolating exosomes from complex biological samples is challenging owing to their relatively low abundances and interference from non-vesicular macromolecules (such as cell debris and proteins). To date, various isolation techniques based on the physical, chemical, and biological characteristics of exosomes have been developed. Indeed, efficient affinity-interaction-based methods have recently overcome the limitations and drawbacks of traditional exosome isolation methods and are widely used in scientific research and clinical applications. This review focuses on exosome isolation and enrichment, and systematically reviews recent research progress on efficient isolation methods based on affinity interactions. Developmental prospects of exosome isolation and enrichment directions are analyzed with the aim of providing a reference for the construction and use of new exosome-isolation strategies.

Outer membrane vesicles (OMVs) are 20-400 nm in size, membrane-bound, and secreted by gram-negative bacteria. OMVs play important roles in processes such as toxin delivery and immune evasion. Although many studies have revealed the critical roles played by OMVs, their heterogeneity has limited our ability to attain a comprehensive understanding of their protein compositions and functions. Therefore, studying the compositions of heterogeneous OMVs subpopulations and their biological functions is important. Herein, we used ultracentrifugation combined with density-gradient centrifugation and quantitative proteomics to systematically separate, characterize, and comprehensively analyze OMVs secreted by Escherichia coli DH5α and Pseudomonas aeruginosa PAO1. First, crude OMVs extracts from both strains were obtained by ultracentrifugation and subjected to iodixanol density-gradient centrifugation to afford six fractions each. DH5α-OMVs and PAO1-OMVs particle-size distributions were then determined via nanoparticle tracking analysis, with average particle sizes of 131.0-161.0 and 140.0-169.0 nm determined for the two subpopulation, respectively. Vesicles were observed to have classical chattel structures by transmission electron microscopy. OMVs subpopulation distributions in the density-gradated fractions were determined by silver staining and protein immunoblotting, which also identified F1a-F4a and F1b-F5b as the effective DH5α-OMVs and PAO1-OMVs subpopulation fractions, respectively. We then identified 2388 and 905 proteins from the DH5α-OMVs and PAO1-OMVs subpopulation, respectively, and used k-means clustering and gene ontology (GO) enrichment analyses to reveal the heterogeneities of the various density subpopulations in terms of biological functions, such as energy metabolism, material transport and ribosome synthesis. Comparative analysis of the E. coli DH5α-OMVs and P. aeruginosa PAO1-OMVs subpopulations finally revealed that they exhibit different functional characteristics, despite sharing commonalities in their basic OMVs functions. The F1a DH5α-OMVs subpopulation was found to be enriched for functions related to amino-acid metabolism and protein synthesis, while the F2b PAO1-OMVs subpopulation exhibited significant biomolecule synthesis functions. This study revealed that bacterial OMVs subpopulations have distinct biological functions, which in turn provides a new theoretical basis for understanding the pathogenic mechanisms of bacteria and their interactions with the host, thereby expanding their biological applications.

Exosomes play crucial intercellular-communication roles and regulate various cellular physiological processes. They are considered potential biomarkers for the early diagnosis of cancers and other diseases. Therefore, detecting and isolating exosomes with specific functions has significant clinical implications. Moreover, the development of low-cost, highly sensitive recognition elements for identifying exosomes is essential for advancing early disease diagnosis and treatment. Nucleic acid aptamers are single-stranded DNA or RNA molecules capable of specifically binding to targets and are produced through the systematic evolution of ligands by exponential enrichment (SELEX) technique. Such aptamers are highly stable, chemically synthesizable, exhibit high affinities and specificities, and are applicable to a broad range of targets, which endow them with unique advantages. Currently, aptamers that target exosomes have been used in a variety of research fields, including cell imaging, drug delivery, and disease diagnosis and treatment. However, selecting aptamers that precisely identify specific exosomes is significantly challenging owing to the complex structures of exosome and their heterogeneity. Consequently, obtaining high-performance aptamers requires efficient screening techniques. This review first summarizes the functions and selection strategies of key targets for exosome-aptamer screening. Furthermore, it outlines the main methods and techniques currently used to screen exosome aptamers, which includes five screening techniques: magnetic bead-SELEX, microfluidic-SELEX, nitrocellulose-SELEX, cell-SELEX, and capillary electrophoresis-SELEX. The separation principles, advantages, limitations, and the latest applications of these techniques are discussed in detail. The review finally addresses current challenges associated with selecting exosome aptamers and provides insight into future research directions.

Exosomes are nano-sized, lipid bilayer vesicles secreted by cells. They carry essential bioactive molecules, such as proteins, nucleic acids, and lipids, and are widely present in bodily fluids including blood and cerebrospinal fluid. Exosomes transfer bioactive molecules to target cells through various mechanisms, including endocytosis, ligand-receptor interactions, or direct membrane fusion, and play crucial roles in intercellular communication, including facilitating intercellular information exchange, maintaining nerve-cell function, participating in immune responses, and providing nutritional support. Exosomes significantly promote signal transmission and intercellular communication in the central nervous system and are involved in the pathogenesis and development of diseases by participating in the spread of pathological proteins, regulating neuroinflammation, and the deposition of pathological proteins. Therefore, exosomes play key roles in the occurrence and development of neurodegenerative diseases, and their contents, especially proteins and miRNAs, are specific for given pathological and physiological states and are relatively stable during extraction and analysis. Hence, exosomes are ideal tools for diagnosing diseases, staging their courses, and assisting prognosis. This article further explores exosomes derived from blood, saliva, urine, and cerebrospinal fluid as potential diagnostic biomarkers for neurodegenerative diseases. As natural drug-delivery systems, exosomes have the advantages of biocompatibility, ability to cross biological barriers, target specificity, stability, and containing natural therapeutic molecules, which can effectively improve the precision and efficacy of drug delivery and reduce side effects, making them an ideal carrier for delivering drugs to the central nervous system. Therefore, exosomes hold great potential in the diagnosis and treatment of central nervous system diseases. This article systematically reviews the latest advances in exosome research directed toward specific neurodegenerative diseases, focusing on their roles played in disease pathogenesis, progression, diagnosis, and treatment, with the aim of providing theoretical support and a reference for the early diagnosis and treatment of these diseases.