Objective: To construct a novel nanoplatform GNS@CaCO3/Ce6-NK by loading the CaCO3-coated gold nanostars (GNSs) with Chlorin e6 molecules (Ce6) into human peripheral blood mononuclear cells (PBMCs)-derived NK cells for tumor targeted therapy.

Methods: GNS@CaCO3/Ce6 nanoparticles were prepared and characterized by TEM and UV-vis. The cell surface markers and cytokines secretion of NK cells before and after loading the GNS@CaCO3/Ce6 nanoparticles were detected by Flow Cytometry (FCM) and ELISA. Effects of the GNS@CaCO3/Ce6-NK cells on A549 cancer cells was determined by FCM and CCK-8. Intracellular fluorescent signals of GNS@CaCO3/Ce6-NK cells were detected via Confocal laser scanning microscopic (CLSM) and FCM at different time points. Intracellular ROS generation of GNS@CaCO3/Ce6-NK cells under laser irradiation were examined by FCM. The distribution of GNS@CaCO3/Ce6-NK in A549 tumor-bearing mice were observed by fluorescence imaging and PA imaging. The combination therapy of GNS@CaCO3/Ce6-NK under laser irradiation were investigated on tumor-bearing mice.

Results: The coated CaCO3 shell on the surface of GNSs exhibited prominent delivery and protection effect of Ce6 during the cellular uptake process. The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells possessed bimodal functions of fluorescence imaging and photoacoustic imaging. The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells could actively target tumor tissues with the enhanced photothermal/photodynamic therapy and immunotherapy.

Conclusions: The GNS@CaCO3/Ce6-NK shows effective tumor-targeting ability and prominent therapeutic efficacy toward lung cancer A549 tumor-bearing mice. Through fully utilizing the features of GNSs and NK cells, this new nanoplatform provides a new synergistic strategy for enhanced photothermal/photodynamic therapy and immunotherapy in the field of anticancer development in the near future.

Keywords: Gold nanostars; immunotherapy; natural killer cells; photodynamic therapy; photothermal therapy.