Regulating Electron Acceptor Unit to Construct Conjugated Polymer Probe for Raman Imaging of Tumor and Sentinel Lymph Nodes

Donor-acceptor (D-A) conjugated polymers have large Stokes shifts, high photostability, and good biocompatibility and thus are ideal for use as Raman probes <i>in vivo</i>. However, few D-A conjugated polymers are used as Raman probes for Raman imaging due to their weak Raman signal intensity and intrinsic fluorescence interference. Here, we developed a D-A conjugated polymer probe (CDT-TT) containing alternating cyclopentadithiophene-thienothiophene units for Raman imaging of tumor and sentinel lymph nodes (SLNs). The CDT-TT shows a strong Raman signal at 1389 cm^-1 without fluorescence and lipid background signal interference under 785 nm near-infrared light. Moreover, the CDT-TT loaded nanoparticles realized the accurate imaging of tumor cells and tumor tissues. In addition, a high-resolution margin imaging of <i>in situ</i> SLNs was acquired. Taken together, the established method is effective for accurate Raman detection of tumors and SLNs, which may shed new light on the development of D-A polymer Raman probes for clinical imaging.