A blood circulation-prolonging peptide anchored biomimetic phage-platelet hybrid nanoparticle system for prolonged blood circulation and optimized anti-bacterial performance

Phage therapy holds great promise for resolving the ever-worsening crisis of antibiotic resistance, but it also faces many challenges. One of the issues hampering phage therapy is the short blood residence time of bacteriophages. We have previously identified, through in vivo phage display, a blood circulation-prolonging peptide (BCP1) that was capable of significantly prolonging the blood retention time of a doxorubicin-loaded human ferritin nanocage, leading to enhanced therapeutic efficacy against tumors. Herein, we aimed to extend the application of BCP1 to anti-bacterial phage therapy. Methods: A genetically engineered M13 phage, BCP1-BGL, that displayed the BCP-1 peptide and expressed the restriction endonuclease Bgl II, was constructed. Taking advantage of the fact that BCP1 harbors an RGD motif (a three amino-acid sequence Arg-Gly-Asp with the ability to bind to integrins) and exerts its circulation-prolonging activity primarily through interaction with platelets, we further designed and fabricated a biomimetic phage-platelet hybrid nanoparticle (PPHN) via the physical binding of the BCP1-BGL phage to the platelet membrane nanoparticles derived via a repeated freeze-thaw procedure. A series of experiments in vitro and in vivo were conducted to reveal the long circulation and anti-bacterial capacities of BCP1-BGL phages and PPHNs. Results: The resulting PPHNs possessed a hydrodynamic size of 368 nm in deionized water, with each spherical membranous nanoparticle harboring approximately 12 rod-shaped phage particles stably bound to its surface. PPHNs, which were superior to the BCP1-BGL phages that displayed significantly prolonged anti-bacterial action in vivo against Escherichia coli infection, exhibited further extended blood retention time and optimal anti-bacterial performance in both the prophylactic and treatment approaches. Conclusion: Our work demonstrated a novel strategy in engineering biomimetic phage-based nanoparticles with improved blood retention and anti-bacterial performance and may have implications in phage therapy.