Folic acid protected silver nanocarriers for targeted drug delivery.

A one-step approach towards the synthesis of folic acid (FA) coated silver nanoparticles (AgNPs) and doxorubicin (DOX) for drug delivery is proposed. The FA-AgNPs were 23 +/- 2 nm in diameter and showed good monodispersity with a characteristic surface plasmon peak at 409 nm. Taking advantage of the enhanced Raman signal of FA on AgNPs and targeting specificity of FA to folate-receptor expressing cancer cells, the as-prepared FA-AgNPs showed excellent receptor-mediated cellular uptake, as demonstrated both by surface enhanced raman scattering (SERS) imaging and fluorescent lifetime imaging (FLIM). Next, a chemotherapeutic drug, DOX was attached to the FA-AgNPs surface through electrostatic bonding and the release of DOX from FA-AgNPs was monitored by FLIM. The release of DOX into the cytoplasm after 4 hours of incubation was clearly seen by FLIM. After 8 hours, the cells underwent cell death due to the release of DOX from nanoparticles. However, in control cell lines with low-expression levels of the FA receptor, no scattering signal from AgNPs could be observed from within the cells even after an incubation period of 24 hours. Our study shows that nanocarriers can be designed with various chemistries to study targeting and release of disease-specific drugs.