One-Pot Ultrafast Self-Assembly of Autofluorescent Polyphenol-Based Core@Shell Nanostructures and Their Selective Antibacterial Applications

We demonstrate that large-scale autofluorescent tea polyphenol (TP)-based core@shell nanostructures can be assembled by one-pot preparation under microwave irradiation within 1 min. The formation mechanism of the heterogeneous well-defined core@shell nanocomposites involves microwave-assisted oxidation inducing self assembly and directed aggregation. The strategy is general to construct Ag@TP and Au@TP nanocomposites. Moreover, a simple galvanic replacement reaction was introduced to synthesize hollow Au/Ag@TP bioconjugates with near-infrared (NIR) absorption, which could be exploited for NIR cancer diagnosis and treatment. It could be expected that more complex alloy@TP nanostructures can be obtained under proper reaction conditions. Furthermore, as a first application, it is shown that the heterogeneous Ag@TP nanostructures can strongly inhibit Escherichia cob growth, while they exhibit no obvious normal cell toxicity. The sharp contrast of the two effects promises that the nanocomposites are excellent low toxicity biomaterials for selective antibacterial treatment.