Fig. 3: Hypoxia responsiveness of molecules and nanoparticles.

a Absorption and (b, c) PL spectra of BN-O after hypoxic stimuli for varying time. d HRMS results of BN-O before and after hypoxia treatment, indicating the successful transformation into BN. e PA profiles of BN-O under normoxic and hypoxic conditions. f Relative turn-on NIR-II PL (at 950 nm) and PA intensity (at 720 nm) of BN-O (2 μM) after 2 h of incubation with various metal ions (2 mM for Na⁺, Ca²⁺, Mg²⁺, and K⁺; 50 μM for other metal ions) or reactive oxygen, nitrogen, and sulfur species (100 μM), indicating its selective response to hypoxia (n = 3 independent samples). g PDT and PTT properties of BN-O under 730 nm light (1.0 W cm⁻²) irradiation before and after hypoxia treatment (n = 3 independent samples). h Representative TEM image and DLS result of BC@Z-M. Scale bar: 100 nm. i The average sizes and Zeta potentials of BC@Z and BC@Z-M (n = 3 independent samples). j Western blots of BC@Z, M1-like macrophage membrane, and BC@Z-M. k XRD patterns of various nanoformulations. l Excitation-emission mappings of BC@Z-M before and after hypoxia treatment. m Representative TEM image and DLS result of BC@Z-M in acidic environment (pH = 6.5). Scale bars: 200 nm. n The release profiles of CA4P from BC@Z-M at different pH conditions (n = 3 independent samples). All data are presented as mean ± SD. For (a‒e, h, j‒m), experiment was repeated three times independently with similar results. Source data are provided as a Source Data file.