Carbon nano onions (CNOs) are carbonaceous nanostructures composed of multiple concentric shells of fullerenes. These cage-within-cage structures remain as one of the most exciting and fascinating carbon forms, along with graphene and its derivatives, due to their unique chemical and physical properties. Their exceptional biocompatibility and biosafety make them an attractive choice in a wide range of areas, including biological systems. This nanomaterial displays low toxicity, high dispersity in aqueous solutions (upon surface functionalization), and high pharmaceutical efficiency. Even though CNOs were discovered almost simultaneously along with carbon nanotubes (CNTs), their potential in biomedical applications still appears unrealized. The existence of CNOs is equally important, just like any other carbon nanostructures such as CNTs and fullerenes, because they display the ability of carbon to form another unique nanostructure with wonderful properties. Therefore, this mini-review summarizes recent studies geared towards developing CNOs for various biomedical applications, including sensing, drug delivery, imaging, tissue engineering, and as a therapeutic drug. It concludes by discussing other potential applications of this unique nanomaterial.

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碳纳米洋葱在生物医学领域的应用：最新进展和挑战

碳纳米洋葱（CNOs）是由富勒烯的多个同心壳组成的含碳纳米结构。这些笼中笼结构由于其独特的化学和物理特性，与石墨烯及其衍生物一起，仍是最令人兴奋和令人着迷的碳形式之一。它们出色的生物相容性和生物安全性使其成为包括生物系统在内的广泛领域的有吸引力的选择。这种纳米材料显示出低毒性，在水溶液中具有较高的分散性（根据表面功能化）以及较高的制药效率。即使CNO与碳纳米管（CNT）几乎同时被发现，但它们在生物医学应用中的潜力仍未实现。CNO的存在同样重要，就像任何其他碳纳米结构（例如CNT和富勒烯）一样，因为它们显示出碳形成具有独特性能的另一个独特纳米结构的能力。因此，本小型综述总结了针对开发用于各种生物医学应用的CNO的最新研究，这些生物医学应用包括传感，药物递送，成像，组织工程以及作为治疗药物。最后讨论了这种独特的纳米材料的其他潜在应用。