Light-responsive proteins have been
delivered into the cells for controlling intracellular events with
high spatial and temporal resolution. However, the choice of wavelength
is limited to the UV and visible range; activation of proteins inside
the cells using near-infrared (NIR) light, which has better tissue
penetration and biocompatibility, remains elusive. Here, we report
the development of a single-walled carbon nanotube (SWCNT)-based bifunctional
system that enables protein intracellular delivery, followed by NIR
activation of the delivered proteins inside the cells. Proteins of
interest are conjugated onto SWCNTs via a streptavidin-desthiobiotin
(SA-DTB) linkage, where the protein activity is blocked. SWCNTs serve
as both a nanocarrier for carrying proteins into the cells and subsequently
a NIR sensitizer to photothermally cleave the linkage and release
the proteins. The released proteins become active and exert their
functions inside the cells. We demonstrated this strategy by intracellular
delivery and NIR-triggered nuclear translocation of enhanced green
fluorescent protein, and by intracellular delivery and NIR-activation
of a therapeutic protein, saporin, in living cells. Furthermore, we
showed that proteins conjugated onto SWCNTs via the SA-DTB linkage
could be delivered to the tumors, and optically released and activated
by using NIR light in living mice
