Surface enhanced Raman scattering traceable and glutathione responsive nanocarrier for the intracellular drug delivery.

A surface enhanced Raman scattering (SERS) traceable nanocarrier is presented through a simple strategy for the intracellular redox environment triggered drug delivery. Basically, the nanocarrier has a core-shell structure, with the Raman molecule tagged Au@Ag nanorods as the SERS active core and mesoporous silica (MS) as the drug containing shell. In the presented system, the locations of nanocarriers can be tracked by SERS signals while those of drugs can be monitored through their fluorescence, allowing the simultaneous investigation of the intracellular distribution of both the nanocarriers and the drugs. To endow the nanocarrier with the glutathione (GSH) responsive behavior, disulfide, which can be cleaved by GSH, is used to directly attach drug molecules to the MS. Compared with other disulfide based drug delivery strategies, this is a quite simple and efficient method. The experimental results confirmed that the drug release can be triggered by the stimuli. Moreover, after the cellular uptake of the nanocarriers, a gradual drug release from the nanocarriers was observed by monitoring both the fluorescence of the drug molecules and the SERS signals of the nanocarriers. Considering its stimuli-responsive properties, this kind of nanocarrier would have great potential in improving the efficacy of cancer chemotherapy by avoiding premature drug leakage. More importantly, this SERS based tracking method of the nanocarrier would be more powerful than that based only on the fluorescence of the drug in the studies of drug release dynamic processes.