Erythrocyte membrane-camouflaged polymeric nanoparticles as a biomimetic delivery platform

Abstract

Efforts to extend nanoparticle residence time in vivo have inspired many strategies in particle surface modifications to bypass macrophage uptake and systemic clearance. Here we report a top-down biomimetic approach in particle functionalization by coating biodegradable polymeric nanoparticles with natural erythrocyte membranes, including both membrane lipids and associated membrane proteins for long-circulating cargo delivery. The structure, size and surface zeta potential, and protein contents of the erythrocyte membrane-coated nanoparticles were verified using transmission electron microscopy, dynamic light scattering, and gel electrophoresis, respectively. Mice injections with fluorophore-loaded nanoparticles revealed superior circulation half-life by the erythrocyte-mimicking nanoparticles as compared to control particles coated with the state-of-the-art synthetic stealth materials. Biodistribution study revealed significant particle retention in the blood 72 h following the particle injection. The translocation of natural cellular membranes, their associated proteins, and the corresponding functionalities to the surface of synthetic particles represents a unique approach in nanoparticle functionalization.

Fig. 1.

Schematics of the preparation process of the RBC-membrane-coated PLGA nanoparticles (NPs).

Fig. 2.

Structural characterization of the RBC-membrane-coated PLGA nanoparticles. (A) The nanoparticles were negatively stained with uranyl acetate and subsequently visualized with TEM. (B) DLS measurements of the size, PDI, and surface zeta potential of the nanoparticles over 14 d. (C) Scanning fluorescence microscopy images demonstrated the colocalization of the RBC membranes (visualized with green rhodamine-DMPE dyes) and polymeric cores (visualized with red DiD dyes) after being internalized by HeLa cells. The RBC-membrane-coated nanoparticles were incubated with HeLa cells for 6 h. The excess nanoparticles were washed out, and the cells were subsequently fixed for imaging.

Fig. 3.

Membrane protein retention, particle stability in serum, and the in vivo circulation time of the RBC-membrane-coated NPs. (A) Proteins in emptied RBCs, RBC-membrane-derived vesicles, and purified RBC-membrane-coated PLGA nanoparticles were solubilized and resolved on a polyacrylamide gel. (B) RBC-membrane-coated PLGA nanoparticles, PEG-coated lipid-PLGA hybrid nanoparticles, and bare PLGA nanoparticles were incubated in 100% fetal bovine serum and monitored for absorbance at 560 nm for 4 h. (C) DiD-loaded nanoparticles were injected intravenously through the tail vein of mice. At various time points blood was withdrawn intraorbitally and measured for fluorescence at 670 nm to evaluate the systemic circulation lifetime of the nanoparticles (n = 6 per group).

Fig. 4.

Biodistribution of the RBC-membrane-coated polymeric nanoparticles. Fluorescently labeled nanoparticles were injected intravenously into the mice. At each time point (24, 48, and 72 h respectively), the organs from a randomly grouped subset of mice were collected, homogenized, and quantified for fluorescence. (A) Fluorescence intensity per gram of tissue (n = 6 per group). (B) Relative signal per organ.