Oxygen-replenishing manganese oxide catalytic nanoparticles on removable pipette surfaces for hypoxic tumour photodynamic therapy

Manganese oxide-coated nanopipettes were developed to overcome the limitation of photodynamic therapy (PDT) for cancers. Mn3O4-MnO2 core-shell heterostructure manganese oxide-attached nanopipettes catalysed the decomposition of ubiquitous H2O2 inside a tumour into O-2, which was converted to reactive oxygen species (ROS). Gold nanoparticles (AuNPs) were introduced to increase the surface coverages of the attached manganese oxide species on the nanopipettes. In vitro and in vivo tests indicate that Mn3O4-MnO2-Au-Ce6 [M-A-Ce6]-assembled nanopipettes can reduce hypoxic conditions and tumour sizes by replenishing O-2 during the PDT processes. Our in vivo fluorescence images suggested that the hypoxia levels were reduced by 30% after the 671 nm-treatments for 10 min by using the manganese oxide pipettes. The growth of tumour xenograft was significantly suppressed after the treatment using manganese oxide pipettes for 27 days. The results show that [M-A-Ce6] nanopipettes would be a novel tool for the regional selective PDT treatment which can avoid the accumulation of NPs via removal of the pipettes after finishing treatment.