NF-kappaB transcription factor is a critical regulator of the expression of genes involved in
tumor formation and progression. Successful RNA interference (
RNAi) therapeutics targeting
NF-kappaB is challenged by
small interfering RNA (
siRNA) delivery systems, which can render targeted in vivo delivery, efficient endolysosomal escape, and dynamic control over activation of RNAi. Here, we report near-IR (NIR) light-inducible
NF-kappaB downregulation through
folate receptor-targeted hollow
gold nanospheres carrying
siRNA recognizing
NF-kappaB p65 subunit. Using micro-positron emission tomography/computed tomography imaging, the targeted nanoconstructs exhibited significantly higher
tumor uptake in nude mice bearing HeLa
cervical cancer xenografts than nontargeted nanoparticles following i.v. administration. Mediated by hollow
gold nanospheres, controllable cytoplasmic delivery of
siRNA was obtained on NIR light irradiation through photothermal effect. Efficient downregulation of
NF-kappaB p65 was achieved only in
tumors irradiated with NIR light but not in nonirradiated
tumors grown in the same mice. Liver, spleen, kidney, and lung were not affected by the treatments, in spite of significant uptake of the
siRNA nanoparticles in these organs. We term this mode of action "photothermal transfection." Combined treatments with p65
siRNA photothermal transfection and
irinotecan caused substantially enhanced
tumor apoptosis and significant
tumor growth delay compared with other treatment regimens. Therefore, photothermal transfection of
NF-kappaB p65
siRNA could effectively sensitize the
tumor to chemotherapeutic agents. Because NIR light can penetrate the skin and be delivered with high spatiotemporal control,
therapeutic RNAi may benefit from this novel transfection strategy while avoiding unwanted side effect.