A noncovalent backbone planarization strategy increases the NIR-II extinction coefficients for gas/phototheranostic applications.

We propose a noncovalent backbone planarization strategy to fabricate a gas/phototheranostic nanocomposite (B-E-NO NPs) in the near-infrared-II (NIR-II, 1000-1700 nm) window by incorporating noncovalent conformational locks. B-E-NO NPs display a giant NIR-II extinction coefficient, realizing multimodal imaging-guided high-efficiency NIR-II photothermal therapy ( = 45.4%) and thermal-initiated nitric oxide combination therapy.