Fluorescence turn-off magnetic COF composite as a novel nanocarrier for drug loading and targeted delivery

Covalent organic frameworks (COFs) have unique chemical bonds and special molecular structure and possess great potential for biology applications. However, their utilization in drug delivery has been greatly limited on account of harsh synthesis conditions, poor solubility and single function. Herein, a novel concept of multifunctional COFs-based core-shell nanocomposite with good dispersity in various media was demonstrated and integrated it as a highly efficient targeted drug delivery system with excellent photothermal and magnetic performance. To achieve this, a facile sonication associated method to synthesize the nanocomposite at room temperature without any special equipment was developed, and then was modified by folic acid pre-linked bovine serum albumin, which further allowed long-time stability in media and special targeting toward cancer cells. Interestingly, the nanocomposite well quenched the fluorescence of doxorubicin, and this endowed us for the first time to visually detect drug loading by “turn-off” fluorescence. What's more, the effective combination of photothermal therapy and chemotherapy then achieved much better therapeutic effect than single therapy. Our work integrated magnetic COFs as a novel and effective drug carrier with good surface modification, excellent photothermal performance and high drug loading capacity, and reported the first experimental example of Fe3O4@COF in the application of cancer chemo-photothermal therapy.