Photodynamic Cancer Therapy by an Oxygen Gas Carrier Consisting of PEGylated Carbon Nanohorn-Based Nanomaterials

Photodynamic therapy (PDT) is a promising approach for cancer treatment. However, PDT has been limited by oxygen (O2) availability in tumor tissues, particularly within hypoxic regions. A PEGylated nitrogen-doped carbon nanohorn (NCNH) has unique structural properties that encapsulate O2 and deliver it efficiently to tumor sites, overcoming the limitation of O2 availability. The O2 uptake on O2-loaded PEGylated NCNH nanocarriers was approximately 1.24 times higher than O2-loaded pristine NCNH and 0.80 times that of O2-loaded nanocarriers with additional O2 adsorbers of dendrimers (DEN) and fluorocarbons (F) named NCNH/DEN-F/F-PEG. Then, singlet oxygen was generated nearly proportionately to the O2 loading. However, on cellular uptake, PEGylated NCNH and NCNH/DEN-F/F-PEG had higher uptake (81.7% and 90.4%, respectively) than pristine NCNH (51.2%), implying the superior uptake ability of PEGylated carriers. From high singlet oxygen generation and the preferable cellular uptake, the decrease in cell viability of MCF-7 breast cancer cells, which were incubated with O2-loaded nanocarriers under light irradiation, occurred at the lowest concentration (IC50 = 9.6 µg/mL) for NCNH/DEN-F/F-PEG. This innovative strategy not only advances much production of singlet oxygen by accumulating O2 adsorber units but also facilitates the uptake of carriers into biological membranes by PEGylating, enhancing the therapeutic outcome and contributing to personalized and effective cancer therapies.