Carbon-based dot-capped gold nanoparticles hybridized with manganese dioxide for enhanced photodynamic cancer therapy

Carbon-based dot-capped gold nanoparticles (AuNPs/CDs) were synthesized and found to exhibit high singlet oxygen (O-1(2)) generation capability owing to the synergistic effect of the strong localized surface plasmon resonance (LSPR) absorption of AuNPs and high O-1(2) yield of CDs. The obtained AuNPs/CDs were further hybridized with folic acid (FA)-modified and CD-capped manganese dioxide nanosheets (FA/MnO2/CDs). The hybridization-induced aggregation produced a new and strong LSPR absorption peak of AuNPs at around 680 nm. Furthermore, MnO2 nanosheets in the obtained FA/MnO2/CDs-AuNPs/CDs nanohybrids could react with intracellular H2O2 to release O-2, which could relieve the tumor hypoxia microenvironment. The O-1(2) quantum yield of the nanohybrids under 660 nm laser irradiation was about 1.05% in the absence of H2O2 and increased to 2.60% in the presence of 1 x 10(-5) mol L-1 H2O2. In vitro cell viability studies demonstrate that >95% of HeLa cells were killed by treatment with FA/MnO2/CDs-AuNPs/CDs under irradiation (660 nm, 2.5 W cm(-2)) for 20 min. The as-developed nanohybrids are thus proved to be promising photosensitizers for photodynamic therapy applications.