Fluorescent liposomal nanoparticles containing oxidized [5]CPP-nanohoop aggregates

Cycloparaphenylenes (CPPs) have garnered widespread attention from various fields due to their high molecular symmetry and unique topology characteristics. However, the non-fluorescence properties and low water-solubility of small CPPs have obstructed their use in bio-related applications. Here, we prepared an oxidized product (named Oxi- [5]CPP) and found its new physiochemical property that shows a stable and bright blue fluorescence. As Oxi- [5]CPP still exhibited low water-solubility, we produced Lip- [5]CPP, which has high water-solubility by forming liposomal nanoparticles. Lip- [5]CPP had non-cytotoxicity at concentrations of up to 40 μM in HeLa cells and demonstrated remarkable imaging capability. The capability of a two-photon imaging probe was also confirmed by observing the two-photon emission characteristics of Lip- [5]CPP. This work can serve as a guide within the field of basic research of CPP and for the development of new bio-imaging probes.