Supplementary Methods Synthesis of pyropheophorbide-lipidIn a standard reaction, 100 nmol of 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (Avanti Polar Lipids), 50 nmol pyropheophorbide (prepared from Spirulina Pacifica algae as described previously;Zheng et al., Bioconj. Chem., 2002, 13-392), 50 nmol of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (Sigma), 25 nmol of 4-(dimethylamino) pyridine (Sigma) and 50 µL of N,Ndiisopropylethylamine (Sigma) were combined in 10 mL of anhydrous dichloromethane. The reaction mixture was stirred at room temperature under argon in the dark for 48 hours. The solvent was evaporated and the residue was subjected to thin layer chromatography purification (20 x 20 cm pre-coated silica gel plate with fluorescent indicator, 1.5 mm in thickness). Chloroform-methanol-glacial acetic acid-water 65:25:8:2 (volume ratio) was used as the solvent. The major band with R f =0.4 was isolated from the plate and eluted giving a final yield of 45%. Recently, we found that improved purification could be achieved by using diol modified silica (Sorbtech) and eluting the product with 8% methanol in DCM after washing out impurities with 2% and 5% methanol in DCM. The pyropheophrobide-lipid was then dried under

Tumor hypoxia is increasingly being recognized as a characteristic feature of solid tumors and significantly complicates many treatments based on radio-, chemo-, and phototherapies. While photodynamic therapy (PDT) is based on photosensitizer interactions with diffused oxygen, photothermal therapy (PTT) has emerged as a new phototherapy that is predicted to be independent of oxygen levels within tumors. It has been challenging to meaningfully compare these two modalities due to differences in contrast agents and irradiation parameters, and no comparative in vivo studies have been performed until now. Here, by making use of recently developed nanostructured self-quenched porphysome nanoparticles, we were able to directly compare PDT and PTT using matched light doses and matched porphyrin photosensitizer doses (with the photosensitizer being effective for either PTT or PDT based on the existence of nanostructure or not). Therefore, we demonstrated the nanostructure-driven conversion from the PDT singlet oxygen generating mechanism of porphyrin to a completely thermal mechanism, ideal for PTT enhancement. Using a novel hypoxia tumor model, we determined that nanostructured porphyrin PTT enhancers are advantageous to overcome hypoxic conditions to achieve effective ablation of solid tumors.