A sequential delivery system based on MoS2 nanoflower doped chitosan/oxidized dextran hydrogels for colon cancer treatment

A sequential delivery system based on MoS 2 nanoflower (MoS 2 NF) doped chitosan (CS)/oxidized dextran (OD) hydrogels is developed for the treatment of colon cancer. 5-Fluorouracil (5-FU) is combined with polyethylenimine (PEI) decorated MoS 2 NF via electrostatic attraction and hydrogen bonding, and the obtained 5-FU/PEI/MoS 2 is encapsulated by 1-tetradecanol (TD), a commonly used phase transition material. The resultant TD/5-FU/PEI/MoS 2 (TFPM) is then co-encapsulated with methotrexate (MTX) in the CS/OD hydrogels generated via Schiff base reaction and electrostatic attraction. Because the electrostatic attraction between CS and OD is pH-sensitive, MTX and TD/5-FU/PEI/MoS 2 can be easily released from the hydrogels at pH 7.4. MoS 2 is an outstanding photothermal agent, and the generated hyperthermia under near infrared (NIR) irradiation can lead to the melting of TD and the consequent release of 5-FU encapsulated. More importantly, the generated hyperthermia under NIR irradiation can realize the chemo-photothermal synergistic tumor therapy. Finally, the practicability of the developed sequential delivery system is demonstrated by cytotoxicity test .