Dual-emitting nanocomposites for oxygen-carrying capacity analysis and boosted singlet oxygen generation in stored red blood cells

We combined the unique natural oxygen transporting function of red blood cells (RBCs) with photosensitive nanocomposites to create biomaterials with strong singlet oxygen ( 1 O 2 ) generation. During cold storage for a long time, structural changes to RBCs may occur, which reduce their oxygen carrying capacity. The nanocomposite developed herein featured dual emission characteristic, which enabled evaluation of the status of the RBCs. On the basis of energy transfer from the conjugated polymer to iridium(III) complexes, the formed nanocomposites show intense, long-lived and oxygen-sensitive emission. When modified with 1,2-distearoyl- sn -glycero-3-phosphoethanolamine- N -[methoxy(polyethyleneglycol)-2000], the nanocomposites non-invasively entered RBCs through hydrophobic interactions . We measured the quenching effect of oxygen on the emission of the iridium(III) complexes. The differential fluorescent signals and fluorescence lifetime images indicated the storage history of the RBCs. RBCs in good condition stored oxygen. When engineered with nanocomposites, RBCs generated large amounts of cytotoxic 1 O 2 upon irradiation. These decorated RBCs might serve as a new kind of photosensitive biomaterial.