Dual-stimuli responsive near-infrared emissive carbon dots/hollow mesoporous silica-based integrated theranostics platform for real-time visualized drug delivery

Due to better penetrating abilities of near-infrared (NIR) light and lower autofluorescence of biological tissue at NIR region, the combination of NIR fluorescent imaging with therapeutic abilities has gradually emerged as a promising strategy for cancer therapy. Herein, tumor microenvironment (TME) sensitive nanocarriers based on doxorubicin hydrochloride (DOX), NIR emitting carbon dots (C-dots), hollow mesoporous silica nanoparticles (HMSN) and anionic polymer citraconic anhydride-modified polylysine (PLL(cit)) are fabricated for imaging guided drug delivery. The NIR emitting C-dots were conjugated onto the surface of HMSN via disulfide bonds which can be reduced by intracellular glutathione (GSH) and result in the release of DOX into cells. And then the PLL(cit) was grafted on the surface of the nanocarriers to endow the nanocarriers with charge convertible property in mildly acidic TME (pH = 6.50) which results in prolonged blood circulation time and enhanced cellular internalization. The in vitro and in vivo experiments confirmed that the dual pH/GSH responsive features of nanocarriers can eliminate the tumor tissues effectively and elicit much slighter side effects. Moreover, since the fluorescence of C-dots can be recovered after the reduction of disulfide bonds and selectively accumulation of nanocarriers around tumor tissue, the DOX@HMSN-SS-C-dots-PLL(cit) can be served as a promising NIR fluorescence probe for targeted imaging of tumor tissue. As a kind of multifunctional nanocarrier with NIR fluorescent imaging and therapeutic functions, the theranostic nanocarriers hold great potential for tumor therapy and in vivo imaging of tumor tissue.