Tailoring Photothermally Triggered Phase Transition of Multimodal Cascade Theranostics Platform by Spherical Nucleic Acids

Accurate targeting and low side effects are crucial for tumor theranostics. Herein, an in situ targeted therapy strategy which relies on a photothermally triggered theranostics nanoplatform is proposed. Taking advantage of spherical nucleic acids, black phosphorus nanosheets and zinc porphyrin metal‐organic framework (PPF‐1) nanosheets are programmed by DNA hybridization to result in a “sandwich” like structure. Its phase‐transition temperature is finely tuned by altering the strand length and the proportion of (A + T) and (C + G) of the oligonucleotides. The superstructure can disassemble during photothermal therapy (PTT) process once the temperature reaches the melting point (Tm) of oligonucleotides duplex. Since the relief of fluorescence resonance energy transfer, the photothermally triggered photodynamic therapy can be realized under the irradiation of near‐infrared laser. In turn, the enhanced singlet oxygen generation downregulates the heat shock proteins and thus improves the effect of PTT. Furthermore, the behaviors of superstructures in living cells and animals are elaborated by fluorescence and magnetic resonance imaging, and the in vivo therapy efficiency is also evaluated. This superstructure may establish a multiple synergistic platform for advanced cancer theranostics. A photothermally triggered theranostics nanoplatform is established by spherical nucleic acids. The phase‐transition temperature is finely tuned, and the superstructure can disassemble during photothermal therapy process once the temperature reaches the melting point of oligonucleotides duplex. Thus, the photothermally triggered photodynamic therapy can be realized under the irradiation of near‐infrared laser.