pH-controllable drug carrier with SERS activity for targeting cancer cells.

A type of pH-controllable drug carrier is demonstrated based on mesoporous silica nanoparticles and chitosan/poly (methacrylic acid), which can simultaneously serve as the surface enhanced Raman scattering (SERS) traceable drug carriers for targeting cancer cells. The pH-sensitive releasing characteristics can be achieved by coating the nanoparticles with a layer of chitosan/poly (methacrylic acid) (CS-PMAA), while strong SERS signals can be obtained from the SERS reporter tagged Ag nanoparticles in the core. Our experimental results show that doxorubicin (DOX) was effectively encapsulated into the nanocarriers and can be released in response to the ambient pH value. Specifically, an increased amount of DOX release was observed at lower pH value. In addition, the composite nanoparticles were conjugated with transferrin (Tf) to target transferrin receptor (TfR)-overexpressed cancer cells. The targeting ability as well as the intracellular location of the drug carrier was investigated through SERS mapping while the distribution of DOX was monitored by fluorescence images. The results show that the demonstrated drug carrier can simultaneously fulfill the functionalities of pH-responsive drug release, SERS-traceable characteristics and cancer cells targeting, which has a unique potential for the pH-controllable drug delivery nanosystems.