Erythrocyte Membrane Is an Alternative Coating to Polyethylene Glycol for Prolonging the Circulation Lifetime of Gold Nanocages for Photothermal Therapy

TLDR

Gold nanocages (AuNCs) have tunable near‑infrared absorption and high photothermal conversion efficiency, but their short blood circulation lifetime limits tumor uptake and in vivo applications. The study aims to overcome this limitation by cloaking AuNCs with red blood cell membranes to create a natural stealth coating. RBC membranes are fused onto the AuNC surface, preserving the nanocages’ porous, hollow structure while providing colloidal stability and stealth properties. RBC‑coated AuNCs retain photothermal activity, selectively ablate cancer cells in vitro, exhibit markedly prolonged circulation and tumor uptake in mice, and achieve 100 % survival over 45 days, demonstrating enhanced efficacy for photothermal therapy.

Abstract

Gold nanocages (AuNCs), which have tunable near-infrared (NIR) absorption and intrinsically high photothermal conversion efficiency, have been actively investigated as photothermal conversion agents for photothermal therapy (PTT). The short blood circulation lifetime of AuNCs, however, limits their tumor uptake and thus in vivo applications. Here we show that such a limitation can be overcome by cloaking AuNCs with red blood cell (RBC) membranes, a natural stealth coating. The fusion of RBC membranes over AuNC surface does not alter the unique porous and hollow structures of AuNCs, and the resulting RBC-membrane-coated AuNCs (RBC-AuNCs) exhibit good colloidal stability. Upon NIR laser irradiation, the RBC-AuNCs demonstrate in vitro photothermal effects and selectively ablate cancerous cells within the irradiation zone as do the pristine biopolymer-stealth-coated AuNCs. Moreover, the RBC-AuNCs exhibit significantly enhanced in vivo blood retention and circulation lifetime compared to the biopolymer-stealth-coated counterparts, as demonstrated using a mouse model. With integrated advantages of photothermal effects from AuNCs and long blood circulation lifetime from RBCs, the RBC-AuNCs demonstrate drastically enhanced tumor uptake when administered systematically, and mice that received PPT cancer treatment modulated by RBC-AuNCs achieve 100% survival over a span of 45 days. Taken together, our results indicate that the long circulating RBC-AuNCs may facilitate the in vivo applications of AuNCs, and the RBC-membrane stealth coating technique may pave the way to improved efficacy of PPT modulated by noble metal nanoparticles.