Construction and Properties of Strong Near‐IR Absorption Photosensitizers

Abstract

The design of near‐infrared photosensitizers with high photodynamic and photothermal synergistic therapeutic properties is of great significance for tumor therapy. In this study, An‐cyclic‐BDP with excellent near‐infrared absorption (ε = 1.94 × 105 m−1 cm−1 at 804 nm) is prepared using a dual strategy of twisted π‐conjugated system induction (T‐π‐CSI) and spin‐orbit charge transfer (SOCT). Theoretical calculations, steady‐state and transient absorption spectra are used to investigate the intrinsic regulatory mechanisms between molecular structure and intersystem crossing (ISC) capacity. The results indicate that the application of the T‐π‐CSI and SOCT approach can be superimposed to increase ISC capacity and the triplet lifetime of An‐cyclic‐BDP (τ = 2961 ps). Electron paramagnetic resonance (EPR) results confirm that An‐cyclic‐BDP has the ability to generate hydroxyl radical (·OH) and singlet oxygen (1O2). Furthermore, the calculated 1O2 yield of An‐cyclic‐BDP is found to be 13%. The experimental results of the photothermal conversion indicates that An‐cyclic‐BDP exhibits a photothermal conversion efficiency of up to 48%. In vitro cell experiments demonstrate that An‐cyclic‐BDP‐NPs, constructed by encapsulating An‐cyclic‐BDP with DSPE‐mPEG2000, exhibit excellent biocompatibility and tumor cell‐killing ability. Therefore, the strong near‐IR absorption photosensitizer prepared in this study exhibits significant potential for application in the area of photodynamic and photothermal synergistic therapy.