Hypoxia-alleviating hemoglobin nanoclusters for sensitizing chemo-photodynamic therapy of cervical cancer

Hypoxia-alleviating hemoglobin (Hb) nanoclusters (NCs) have been developed for sensitizing combined chemo-photodynamic therapy (chemo-PDT) of cervical cancer. Hb was conjugated with chlorin e6 and biotinylated polyethylene glycol and adsorbed with doxorubicin (DOX), resulting in the self-assembly of 220 nm diameter protein NCs. These oxygen-carrying NCs, namely [email protected], exhibited improved colloidal stability in the serum compared to that of native Hb and pH-responsive drug release favorable for cancer treatment. [email protected] alleviated hypoxia by 64.8% in HeLa cells cultured under hypoxia and normalized the levels of related biomarkers, HIF-1α and MDR1, with enhanced cellular uptake via biotin–receptor interactions. Moreover, antitumor efficacy tests performed in HeLa monolayer and spheroid cultures revealed that [email protected] possessed 3.8-fold improved therapeutic efficacy compared to DOX and chlorin e6 physical mixture, showing synergism between chemotherapy and PDT. [email protected] chemo-PDT significantly suppressed tumor growth in heterotopic (96.6% reduction in tumor volume compared to no-intervention) and orthotopic (comparable uterus weight to the normal group) HeLa-xenografted mice with no significant toxicity. These results showed the hypoxia amelioration effect, which lowered HIF-1α and MDR1 levels in tumor tissues, and efficient DOX distribution to hypoxic regions of the tumor, suggesting that [email protected] could be a promising chemo-PDT strategy for cervical cancer treatment.