Intelligent Hierarchical Targeting Near-Infrared Persistent Luminescence Nanosystem for Improved Nuclear Delivery and Simultaneous Visualization/Therapy of EBV-Associated Cancer

Epstein–Barr nuclear antigen 1 (EBNA1), a sequence-specific DNA binding protein of Epstein–Barr virus (EBV), is essential for viral genome replication and maintenance and is therefore an attractive target for the therapeutic intervention of EBV-associated cancers. Several EBNA1-specific inhibitors have demonstrated the ability to block EBNA1 function in vitro, but practical delivery strategies for these inhibitors in vivo are still lacking. Here, we report an intelligent hierarchical targeting theranostic nanosystem (denoted as mZGOCS@MnO2–P5) that integrates an azide (N3) terminal dual-targeting peptide (N3–P5), a tumor microenvironment-responsive degradable MnO2 nanosheet, and a mesoporous ZnGa2O4:Cr3+, Sn4+ near-infrared persistent luminescence (NIR-PL) nanosphere (mZGOCS). In our design, mZGOCS@MnO2–P5 enables primarily targeting of the EBV-specific oncoprotein LMP1 (an EBV-encoded transmembrane protein) via the LMP1 targeting motif within P5. Once internalized into cells, the MnO2 nanosheet would be degraded in the acidic and reducing tumor microenvironment, simultaneously releasing P5 and recovering the NIR-PL of ZnGa2O4:Cr3+, Sn4+ initially quenched by the MnO2 nanosheet, thereby providing an autofluorescence interference-free NIR-PL imaging signal for monitoring the delivery efficacy of P5. The released P5 can secondarily target EBNA1 via the EBNA1 binding motif, blocking its function and thus inhibiting the growth of EBV-positive tumors. The feasibility of our developed hierarchical targeting theranostic nanosystem is well demonstrated both in vitro and in vivo, highlighting the huge translational potential of mZGOCS@MnO2–P5 in EBV-associated cancer therapy.