Cobalt bisdicarbollides (COSANs) are inorganic boron-based anions that have been previously reported to permeate by themselves through lipid bilayer membranes, a propensity that is related to their superchaotropic character. We now introduce their use as selective and efficient molecular carriers of otherwise impermeable hydrophilic oligopeptides through both artificial and cellular membranes, without causing membrane lysis or poration at low micromolar carrier concentrations. COSANs transport not only arginine-rich but also lysine-rich peptides, whereas low-molecular-weight analytes such as amino acids as well as neutral and anionic cargos (phalloidin and BSA) are not transported. In addition to the unsubstituted isomers (known as ortho- and meta-COSAN), four derivatives bearing organic substituents or halogen atoms have been evaluated, and all six of them surpass established carriers such as pyrenebutyrate in terms of activity. U-tube experiments and black lipid membrane conductance measurements establish that the transport across model membranes is mediated by a molecular carrier mechanism. Transport experiments in living cells showed that a fluorescent peptide cargo, FITC-Arg₈, is delivered into the cytosol.

中文翻译：

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钴双二碳硼化物型金属碳硼烷簇阴离子作为阳离子肽跨膜和细胞内递送的离液载体

钴双二碳内酯 (COSAN) 是无机硼基阴离子，此前已报道其自身渗透通过脂质双层膜，这种倾向与其超离液特性有关。我们现在介绍它们作为不可渗透的亲水性寡肽通过人造膜和细胞膜的选择性和有效分子载体的用途，在低微摩尔载体浓度下不会引起膜裂解或穿孔。COSAN 不仅运输富含精氨酸的肽，还运输富含赖氨酸的肽，而不运输氨基酸等低分子量分析物以及中性和阴离子货物（鬼笔环肽和 BSA）。除了未取代的异构体（称为邻位和间位异构体）-COSAN），对四种带有有机取代基或卤素原子的衍生物进行了评估，所有六种衍生物在活性方面都超过了芘丁酸等现有载体。U 形管实验和黑色脂质膜电导测量表明，跨模型膜的运输是由分子载体机制介导的。活细胞中的转运实验表明，荧光肽货物 FITC-Arg ₈被递送到细胞质中。