Dual-functional alginic acid hybrid nanospheres for cell imaging and drug delivery

An effective and facile approach to prepare gold-nanoparticle-encapsulated alginic acid-poly[2-(diethylamino)ethyl methacrylate] monodisperse hybrid nanospheres (ALG-PDEA-Au) is developed by using monodisperse ALG-PDEA nanospheres as a precursor nanoparticulate reaction system. This approach utilizes particle-interior chemistry, which avoids additional reductant or laborious separation process and, moreover, elegantly ensures that all the gold nanoparticles are located inside the hybrid nanospheres and every nanosphere is loaded with gold nanoparticles. These obtained ALG-PDEA-Au hybrid nanospheres have not only uniform size, similar surface properties, and good biocompatibility but also unique optical properties provided by the embedded gold nanoparticles. It is demonstrated that negatively charged ALG-PDEA-Au hybrid nanospheres can be internalized by human colorectal LoVo cancer cells and hence act as novel optical-contrast reagents in tumor-cell imaging by optical microscopy. Moreover, these hybrid nanospheres can also serve as biocompatible carriers for the loading and delivery of an anti-cancer drug doxorubicin. In vitro cell viability tests reveal that drug-loaded ALG-PDEA-Au hybrid nanospheres exhibit similar tumor cell inhibition to the free drug doxorubicin. Therefore, the obtained hybrid nanospheres successfully combine two functions, that is, cell imaging and drug delivery, into one single system, and may be of great application potential in other biomedical-related areas.