Alternate release of different target species based on the same gold nanorods and monitored by cell imaging

In this study, a strategy for load and release of different kinds of molecules on the same gold nanorods (GNRs) was developed. An anticancer drug, doxorubicin hydrochloride (DOX), was firstly chemically conjugated on the GNRs. To efficiently load another type of target molecules DNA on the same GNRs, a polyelectrolyte Poly (ethylene imine) (PEI) was adsorbed on the GNR@DOX to form GNR@DOX@PEI. Then, the positive charge GNR@DOX@PEI allows the GNR conjugates to interact with negative charged DNA by an electrostatic interaction, enabling their full conjugation. A platform to load two kinds of target molecules conjugated on the same GNRs was fabricated. On the other hand, selective and sequential release of the different target species may be triggered by chemical reaction and near infrared (NIR) laser. The release of DOX was achieved by Na2S2O3 reacting with GNRs and the discharge of DNA conjugated on the GNR@DOX@PEI was accomplished by local-heating using NIR laser triggered release. Furthermore, the selective and alternate release of different target species from the GNRs inside MCF-7 cells was monitored by fluorescent imaging, providing a potential synergistic cancer treatment.