Conjugated Oligomer‐Based NIR‐II Chemiluminescence Nanosensor for In Vivo Imaging

Abstract Chemiluminescence imaging has become a promising optical imaging method because of its advantages such as no excitation source and minimal background autofluorescence. However, chemiluminescent nanosensors with second near‐infrared (NIR‐II) window emission are rarely reported. Here, a NIR‐II chemiluminescence nanosensor OLBB‐CLS is designed by adopting the CRET (chemiluminescence resonance energy transfer) – FRET (fluorescent resonance energy transfer) combined strategy, which consists of OFBTL, BTD540‐C 8 , BBTD725‐C 8 and DSPE‐PEG 2000 . OFBTL, a chemiluminescent conjugated oligomer with D‐A‐D (donor‐acceptor‐donor) molecular structure, acts as a chemiluminescent probe of 1 O 2 and the donor of CRET. BTD540‐C 8 , as an energy receptor of CRET and an energy donor of FRET, can absorb the energy of chemiluminescence and transfer the energy to NIR‐II molecule BBTD725‐C 8 , thus producing NIR‐II fluorescence. Notably, there is a great overlap between the chemiluminescence spectrum of OFBTL and the absorption spectrum of BTD540‐C 8 , enabling efficient CRET between them. Also, an excellent overlap occurs between the emission spectrum of BTD540‐C 8 and the absorption spectrum of BBTD725‐C 8 , allowing effective FRET. The nanosensor OLBB‐CLS demonstrates remarkable biosafety and can achieve in vivo NIR‐II chemiluminescent imaging for ROS‐related disease with a high signal‐to‐noise ratio. This study paves the way for the design of NIR‐II chemiluminescence probes for in vivo imaging.