Recent advances and challenges in the recovery and purification of cellular exosomes

Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.     

Size,Charge, and Stability of Fully Serine‐Based Catanionic Vesicles: Towards Versatile Biocompatible Nanocarriers

Vesicles based on mixed cationic and anionic surfactants (catanionic vesicles) offer a number of advantageous colloidal features over conventional lipid‐based vesicles, namely spontaneity in formation, long‐term stability, and easy modulation of size and charge. If biocompatibility is added through rational design of the chemical components, the potential for biorelated applications further emerges. Here, we report for the first time on two catanionic vesicle systems in which both ionic amphiphiles are derivatized from the same amino acid—serine—with the goal of enhancing aggregate biocompatibility. Phase behavior maps for a mixture with chain length symmetry, 12Ser/12‐12Ser, and another with asymmetry, 16Ser/8‐8Ser, are presented, for which regions of vesicles, micelles, and coexisting aggregates are identified. For the asymmetric mixture, detailed phase behavior and microstructure characterization have been carried out based on surface tension, light microscopy, cryo‐SEM, cryo‐TEM, and dynamic light scattering analysis. Vesicles are found with tunable mean size, pH, and zeta potential. Changes in aggregate shape with varying composition and the effect of preparation methods and aging on vesicle features and stability have been investigated in detail. The results are discussed in the light of self‐assembly models and related catanionic systems reported before. A versatile system of robust vesicles is thus presented for potential applications.     

Extracellular Matrix Proteins Involved in Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases and characterized by cognitive and memory impairments. Emerging evidence suggests that the extracellular matrix (ECM) in the brain plays an important role in the etiology of AD. It has been detected that the levels of ECM proteins have changed in the brains of AD patients and animal models. Some ECM components, for example, elastin and heparan sulfate proteoglycans, are considered to promote the upregulation of extracellular amyloid-beta (Aβ) proteins. In addition, collagen VI and laminin are shown to have interactions with Aβ peptides, which might lead to the clearance of those peptides. Thus, ECM proteins are involved in both amyloidosis and neuroprotection in the AD process. However, the molecular mechanism of neuronal ECM proteins on the pathophysiology of AD remains elusive. More investigation of ECM proteins with AD pathogenesis is needed, and this may lead to novel therapeutic strategies and biomarkers for AD.     

Double-Layered Plasmonic–Magnetic Vesicles by Self-Assembly of Janus Amphiphilic Gold–Iron(II,III) Oxide Nanoparticles

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double-layered plasmonic–magnetic vesicle assembled from Janus amphiphilic Au-Fe₃O₄ NPs grafted with polymer brushes of different hydrophilicity on Au and Fe₃O₄ surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au-Fe₃O₄ NPs in opposite direction, and the orientation of Au or Fe₃O₄ in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers.     

Controlled Release of Hepatocyte Growth Factor from MPEG‐b‐(PCL‐ran‐PLLA) Diblock Copolymer for Improved Vocal Fold Regeneration

An in situ‐forming gel system comprised of diblock copolymer formed from polyethylene glycol (PEG) and polycaprolactone (PCL) {MPEG‐b‐(PCL‐ran‐PLLA)} could be used in controlled drug delivery for tissue remodeling. The purpose of this study is to demonstrate favorable vocal folds (VF) regeneration by using MPEG‐b‐(PCL‐ran‐PLLA) diblock copolymers (C97L3; CL/LA ratio 97:3) incorporating hepatocyte growth factor (HGF). Gradual release of HGF from C97L3 is detected and biochemical properties of released HGF are maintained. A scar is made with microscissors on both VFs in 32 rabbits, followed by injection of HGF‐only, C97L3‐only, or HGF‐C97L3 composite gel in the left side VF, while the right side VF is left untreated. In vivo fluorescence live imaging system demonstrates that C97L3 enables the sustained release of injected HGF in the scarred VF for 12 weeks. The histological analysis shows increased glycosaminoglycan including hyaluronic acid accumulation and decreased collagen deposition. Videokymographic analysis shows more favorable vibrations of HGF‐C97L3 treated VF mucosa, compared to other treatment groups. In conclusion, the controlled HGF release helps to regulate extracellular matrix synthesis, and leads to the eventual functional improvement of the scarred VF.

     

凝胶渗透色谱-气相色谱-离子阱质谱法测定桔梗原药和当归提取物中101种农药残留

建立了凝胶渗透色谱（GPC）-气相色谱-离子阱质谱同时检测桔梗原药和当归提取物中101种农药残留的分析方法。方法采用乙腈超声辅助提取桔梗原药和当归提取物,浓缩提取液至近干后用乙酸乙酯-环己烷（1∶1, v/v）复溶,采用凝胶渗透色谱法（选取40 cm长、内径20 mm的凝胶渗透色谱柱）对样品进行净化,弃去前段含脂类、色素等杂质的流出液,收集17~30 min洗脱液并旋转蒸发浓缩至近干,甲苯1 mL定容上机。选用DB-5MS毛细管色谱柱分离待测物,通过离子阱质谱实现对101种农药残留的高效检测。方法通过优化前处理条件和离子阱二级质谱参数,有效降低了复杂中药基质对待测化合物的干扰,最大限度提高了样品中农药的定量准确性和回收率,101种农药3水平添加的平均回收率为58.3%~108.9%,每个添加水平10次独立重复测定的相对标准偏差为0.4%~16.5%,检出限（LOD）范围为0.2~40.0 μg/kg,可满足当前韩国、日本、欧洲规定的最大残留限量（maximum residue limits, MRLs）要求。方法具有操作简单快速、灵敏度高、重复性好等特点,凝胶渗透色谱技术的应用克服了固相萃取小柱净化容量不足的弊端,离子阱技术的应用可以进一步排除共流出基体杂质的干扰,提高定量和定性的准确性,检测效果优于常用的气相色谱-质谱法,是对中药中同时分析多种农药残留检测方法的有益补充。     

非平衡溶剂化新理论在有机染料电子光谱中的应用

总结了非平衡溶剂化新理论和在量子化学软件Q-Chem中基于含时密度泛函理论(TD-DFT)实现溶剂效应下计算电子吸收和发射光谱的数值解方法.采用该方法计算了染料敏化太阳能电池(DSSCs)中三苯胺型有机染料■在真空和乙腈溶剂中的电子结构与光谱性质,研究发现,π共轭桥上碳碳双键的个数和溶剂效应会促进光电转换.