Self-driven immune checkpoint blockade and spatiotemporal-sensitive immune response monitoring in acute myeloid leukemia using an all-in-one turn-on bionanoprobe

Immune checkpoint (ICP) blockade (ICB) is one of the most promising immunotherapies for acute myeloid leukemia (AML). However, owing to their heterogeneity, AML cells may cause uncoordinated metabolic fluxes and heterogeneous immune responses, inducing the release of a spatiotemporally sensitive immune response marker. Timely and in situ detection of immune responses in ICB therapy is important for therapeutic strategy adjustment. Herein, we constructed an all-in-one nanoprobe for self-driving ICB and simultaneously detecting an immune response in the same AML cell in vivo, thus enabling accurate evaluation of heterogenetic immune responses in living AML mice without additional drug treatment or probe processes. The nature-inspire polydopamine (PDA) nanoparticles loaded with an ICP blocker were targeted to the leukocyte immunoglobulin like receptor B4 (a new ICP) of AML cells to induce the release of immune response marker granzyme B (GrB). The PDA nanoparticles were additionally paired with carbon-derived graphene quantum dots (GQDs) to construct a full-organic ‘turn-on’ bionanoprobe that can transfer fluorescence resonance energy for GrB detection. This multifunctional nanoprobe was validated for triggering ICB therapy and monitoring the changes of GrB levels in real-time both in vitro and in vivo. The organic nanoprobe showed excellent permeability and retention in tumor cells and high biocompatibility in vivo. This bionanoprobe orderly interacted with the upstream ICP molecules and downstream signal molecule GrB, thereby achieving in situ immune response signals within the therapeutic efficacy evaluation window.