Regulating\nElectron Acceptor Unit to Construct Conjugated\nPolymer Probe for Raman Imaging of Tumor and Sentinel Lymph Nodes

Donor–acceptor (D-A) conjugated polymers have\nlarge Stokes\nshifts, high photostability, and good biocompatibility and thus are\nideal for use as Raman probes <i>in vivo</i>. However, few\nD–A conjugated polymers are used as Raman probes for Raman\nimaging due to their weak Raman signal intensity and intrinsic fluorescence\ninterference. Here, we developed a D–A conjugated polymer probe\n(CDT-TT) containing alternating cyclopentadithiophene-thienothiophene\nunits for Raman imaging of tumor and sentinel lymph nodes (SLNs).\nThe CDT-TT shows a strong Raman signal at 1389 cm<sup>–1</sup> without fluorescence and lipid background signal interference under\n785 nm near-infrared light. Moreover, the CDT-TT loaded nanoparticles\nrealized the accurate imaging of tumor cells and tumor tissues. In\naddition, a high-resolution margin imaging of <i>in situ</i> SLNs was acquired. Taken together, the established method is effective\nfor accurate Raman detection of tumors and SLNs, which may shed new\nlight on the development of D–A polymer Raman probes for clinical\nimaging.