Theranostic nanoprobes integrated with dual-modal imaging and therapeutic functions, such as photodynamic therapy (PDT), have exhibited significant potency in cancer treatments due to their high imaging accuracy and non-invasive advantages for cancer elimination. However, biocompatibility and highly efficient accumulation of these nanoprobes in tumor are still unsatisfactory for clinical application. In this study, a photosensitizer -loaded magnetic nanobead with surface further coated with a layer of cancer cell membrane (SSAP-Ce6@CCM) was designed to improve the biocompatibility and cellular uptake and ultimately achieve enhanced MR/NIR fluorescence imaging and PDT efficacy. Compared with similar nanobeads without CCM coating, SSAP-Ce6@CCM showed significantly enhanced cellular uptake, as evidenced by Prussian blue staining, confocal laser scanning microscopy (CLSM) and flow cytometric analysis. Consequently, SSAP-Ce6@CCM displayed a more distinct MR/NIR imaging ability and more obvious photo-cytotoxicity towards cancer cells under 670 nm laser irradiation. Furthermore, the enhanced PDT effect benefited from the surface coating of cancer cell membrane was demonstrated in SMMC-7721 tumor-bearing mice through tumor growth observation and tumor tissue pathological examination. Therefore, this CCM-disguised nanobead that integrated the abilities of MR/NIR fluorescence dual-modal imaging and photodynamic therapy might be a promising theranostic platform for tumor treatment.

HIGHLIGHTS • A narrow bandgap electron donor-acceptor (D-A) semiconducting polymer nanoparticle (SPN) coated with red blood cell membrane (RBCM) for photoacoustic imaging and photothermal therapy. • The D-A structure endows SPN with excellent near-infrared absorbance, high photothermal conversion ability, and good photothermal stability. • The RBCM endows SPN with good biocompatibility, prolonged blood circulation, and improved tumor accumulation, while the small size structure endows SPN with deep tumor penetration and rapid clearance from body.