Calcium ion (Ca2+ ), an abundant species in the body, is a potential therapeutic ion with manageable side effects. However, the delivery of such a highly charged species represents a great challenge. Here, a nanosystem based on Au nanocages (AuNCs) and a phase-change material (PCM) for delivering calcium chloride (CaCl2 ) into cancer cells and thereby triggering cell death upon near-infrared (NIR) irradiation is demonstrated. In the absence of NIR irradiation, the nanosystem, denoted CaCl2 -PCM-AuNC, shows negligible cytotoxicity because the Ca2+ ions are fully encapsulated in a solid matrix. Upon NIR irradiation, the Ca2+ ions are swiftly released due to the melting of PCM matrix in response to photothermal heating. The sudden increase in intracellular Ca2+ causes disruption to the mitochondrial Ca2+ homeostasis and thus the loss of mitochondrial membrane potential, subsequently resulting in cell apoptosis. This nanosystem provides a new method for cancer treatment by tightly managing the intracellular concentration of a physiologically essential element.
Keywords: calcium ions; gold nanocages; intracellular release; phase change materials; photothermal therapy.
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