Cell membrane camouflaged bismuth nanoparticles for targeted photothermal therapy of homotypic tumors

Bi nanoparticles (NPs) have been demonstrated as effective all-in-one type theranostic agent for imaging-guided photothermal therapy, but their applications have been limited by relatively low biocompatibility and target accumulation capacity. To address this issue, we report the camouflage of Bi NPs (size: ~42 ± 2 nm) by using the mouse colon cancer CT26 cells membrane (CT26 CCM). The camouflaging process confers the efficient coating of CCM shell layer with thickness of ~8 ± 2 nm on Bi NPs cores, which can be confirmed by TEM image, zeta potential and protein gel electrophoresis tests. Simultaneously, CCM shell has no side effects on the photoabsorption/photothermal effect. Importantly, Bi@CCM NPs retain significant features of CCM, including good biocompatibility and homologous targeting ability. When Bi@CCM dispersion was intravenously (i.v.) injected into mice, they exhibited higher blood circulation half-life (11.5 h, ~2.9 times) and accumulation amount (4.7 ± 0.56% ID/g, ~2.3 times) in homotypic CT26 tumor compared to those (4.0 h in blood and 2.03 ± 0.60% ID/g in tumor) from uncoated Bi NPs. After 808 nm laser irradiation, CT26 cancer cells could be effectively ablated after the photothermal therapy of high-accumulated Bi@CCM NPs, and then the tumor tends to be eradicated after 12 days. Thus, Bi NPs camouflaged with CT26 CCM have great potential for the targeted photothermal therapy of homotypic tumors.