No abstract

Organic radicals can potentially play important roles in functional materials owing to an unpaired electron, but they are usually highly reactive and difficult to use. Therefore, stabilization of organic radicals is important. Among organic radicals, carbon‐centered radicals are promising because of their trivalent nature, which enables structural diversity and elaborate designs, but they are also less stable because of the reactivities towards carbon–carbon bond formation and atmospheric oxygen. Recently, stable carbon‐centered radicals across diverse molecular platforms have been increasingly explored. This Minireview highlights these newly explored, stable carbon‐centered radicals, with a focus on porphyrinoid‐stabilized radicals because of their remarkable spin delocalization abilities.

Extracellular vesicles (EVs) including exosomes and microvesicles have attracted considerable attention in the fields of cell biology and medicine. For a better understanding of EVs and further exploration of their applications, the development of analytical methods for biological nanovesicles has been required. In particular, considering the heterogeneity of EVs, methods capable of measuring individual vesicles are desired. Here, we report that on-chip immunoelectrophoresis can provide a useful method for the differential protein expression profiling of individual EVs. Electrophoresis experiments were performed on EVs collected from the culture supernatant of MDA-MB-231 human breast cancer cells using a measurement platform comprising a microcapillary electrophoresis chip and a laser dark-field microimaging system. The zeta potential distribution of EVs that reacted with an anti-human CD63 (exosome and microvesicle marker) antibody showed a marked positive shift as compared with that for the normal immunoglobulin G (IgG) isotype control. Thus, on-chip immunoelectrophoresis could sensitively detect the over-expression of CD63 glycoproteins on EVs. Moreover, to explore the applicability of on-chip immunoelectrophoresis to cancer diagnosis, EVs collected from the blood of a mouse tumor model were analyzed by this method. By comparing the zeta potential distributions of EVs after their immunochemical reaction with normal IgG, and the anti-human CD63 and anti-human CD44 (cancer stem cell marker) antibodies, EVs of tumor origin circulating in blood were differentially detected in the real sample. The result indicates that the present method is potentially applicable to liquid biopsy, a promising approach to the low-invasive diagnosis of cancer.

This review discusses pillar[n]arene-based MIMs such as rotaxanes, catenanes, polyrotaxanes, single-component mechanically self-locked molecules, and supramolecular polymers.

Extracellular vesicles including exosomes have the potential to be used in therapeutic and diagnostic applications. Towards the noninvasive diagnosis of prostate cancer using urinary exosomes, technical challenges lie in developing precise methods of analyzing exosomes. Previously, we developed an on-chip microcapillary electrophoresis (µCE) system equipped with a laser dark-field microscope. The zeta potential of exosomes of cancer cells was found to be larger than that of normal cells. In this study, the zeta potential of exosomes of normal and cancer prostate cells was evaluated using this system after treating with sialidase. The large negative charge of cancer exosomes was found to be due to the large amount of sialic acids. These results suggest that an on-chip µCE system is useful for the accurate evaluation of events that occur on the exosome surfaces at the single-particle level and promising for the prescreening of prostate cancer exosomes without the need for labeling.