Blood Circulation-Prolonging Peptides for Engineered Nanoparticles Identified via Phage Display.

Sustaining blood retention for theranostic nanoparticles is a big challenge. Various approaches have been attempted and have demonstrated some success but limitations remain. We hypothesized that peptides capable of increasing blood residence time for M13 bacteriophage, a rod-shaped nanoparticle self-assembled from proteins and nucleic acids, should also prolong blood circulation for engineered nanoparticles. Here we demonstrate the feasibility of this approach by identifying a series of blood circulation-prolonging (BCP) peptides through in vivo screening of an M13 peptide phage display library. Intriguingly, the majority of the identified BCP peptides contained an arginine-glycine-aspartic acid (RGD) motif, which was necessary but insufficient for the circulation-prolonging activity. We further demonstrated that the RGD-mediated specific binding to platelets was primarily responsible for the enhanced blood retention of BCP1. The utility of the BCP1 peptide was demonstrated by fusion of the peptide to human heavy-chain ferritin (HFn), leading to significantly improved pharmacokinetic profile, enhanced tumor cell uptake and optimum anticancer efficacy for doxorubicin encapsulated in the HFn nanocage. Our results provided a proof-of-concept for an innovative yet simple strategy, which utilizes phage display to discover novel peptides with the capability of substantially prolonging blood circulation for engineered theranostic nanoparticles.