Host-rotaxanes with oligomeric axles are intracellular transport agents.

Polymeric macromolecules are promising drug delivery devices with endocytotic properties that need to be resolved. Host-rotaxanes (HRs) also deliver materials into cells but require improved in vivo targeting capacity. Combining the targeting properties of nanoparticles with the transport function of HRs may improve drug efficacy. Our prototype HR (HR 1) has a short axle and is an efficient transporter. Here, we have constructed HRs that contain an oligo(ethylene glycol) (HR 2) or an oligoalkyl (HR 3) axle with the future goal of combining them with nanoparticles. HR 2 more efficiently delivers Fl-peptides into ovarian cancer cells than HR 3 and, in most cases, than HR 1. HR 2 appears to possess the appropriate balance between water solubility and lipophilicity to be an efficient transporter along with a suitable structure for incorporation into a larger nanoparticle.