A simple therapeutic nanoplatform in the second near-infrared window for synergistic phototherapy

It is considerably meaningful to fabricate a second near-infrared spectral region (NIR-II, 1000–1700 nm) responsive theranostic nanoplatform simultaneously possessing good stability and biocompatibility for efficient and safe cancer treatment. In this work, as a flexible strategy, an intelligent nanoplatform was prepared by using water-soluble cyclic oligosaccharides α-cyclodextrin (α-CD) to load photosensitizer Chlorin e6 (Ce6) onto Fe 3 O 4 @Cu 2−x S core−shell nanoparticles (NPs). The as-synthesized Fe 3 O 4 @Cu 2−x S-Ce6/α-CD NPs are ultrasmall (≈5 nm) and aqueously dispersible, which offer both biocompatibility and renal clearance. Resultly, the obtained Fe 3 O 4 @Cu 2−x S-Ce6/α-CD NPs feature remarkable absorption in the second near-infrared region (NIR-II), which can provide advantages of large penetration depth and high photothermal conversion efficiency (η = 67.88%). Additionally, the introduction of Ce6 can trigger the generation of 1 O 2 under visible light irradiation. Therefore, it provides the proof-of-concept application of functional materials in photodynamic and photothermal combination cancer therapy.