The development of sophisticated
theranostic systems for simultaneous near infrared (NIR) fluorescence imaging and
phototherapy is of particular interest. Herein, anisotropic plasmonic
metal heterostructures, Pt end-deposited Au nanorods (PEA NRs), are developed to efficiently produce hot electrons under 808 nm
laser irradiation, exhibiting the strong electric density. These hot electrons can release the heat through electron-phonon relaxation and form
reactive oxygen species through chemical transformation, as a result of potent photothermal and photodynamic performance. Simultaneously, the confined electromagnetic field of PEA NRs can transfer energy to adjacent
polyethylene glycol (PEG)-linked NIR fluorophores (CF) based on their energy overlap mechanism, leading to remarkable NIR fluorescence amplification in CF-PEA NRs. Various PEG linkers (1, 3.4, 5.0, and 10 kD) are employed to regulate the distance between CF and PEA NRs of CF-PEA NRs, and the maximum fluorescence intensity is achieved in CF5k-PEA NRs. After further attachment with i-motif DNA/Nrf2
siRNA chimera to simultaneously suppress both cellular
antioxidant defense and
hyperthermia resistance effects, the final biocompatible CF5k-bPEA@
siRNA NRs present promising NIR fluorescence imaging ability and 808 nm
laser-activated photothermal and photodynamic
therapeutic effect in MCF7 cells and
tumor-bearing mice, holding great potential for
cancer therapy.