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-C₈, BBTD725-C₈ and DSPE-PEG₂₀₀₀. OFBTL, a chemiluminescent conjugated oligomer with D-A-D (donor-acceptor-donor) molecular structure, acts as a chemiluminescent probe of ¹O₂ and the donor of CRET. BTD540-C₈, 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-C₈, thus producing NIR-II fluorescence. Notably, there is a great overlap between the chemiluminescence spectrum of OFBTL and the absorption spectrum of BTD540-C₈, enabling efficient CRET between them. Also, an excellent overlap occurs between the emission spectrum of BTD540-C₈ and the absorption spectrum of BBTD725-C₈, 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.