In Situ Synthesis of Gold@3,4-Dihydroxy-l-Phenylalanine Core−Shell Nanospheres Used for Cell Imaging

A facile and effective approach to synthesize Au nanoparticle encapsulated 3,4-dihydroxy-l-phenylalanine monodisperse hybrid nanospheres (Au@DOPA) has been developed. TEM measurements show that all Au nanoparticles are located inside the hybrid nanospheres and every nanosphere is loaded with gold nanoparticles. The obtained Au@DOPA core−shell nanospheres have not only uniform size, similar surface properties, and good biocompatibility, but also unique optical properties provided by the embedded Au nanoparticles. It has been demonstrated that Au@DOPA core−shell nanospheres can be internalized by human vascular smooth muscles cells (HVSMC) and breast cancer cells and hence act as a novel optical contrast reagent in tumor cell imaging by confocal laser scanning microscopy (CLSM) and optical microscopy. In addition, the hybrid nanospheres can be used as precursors to synthesize the DOPA capsules by using KI/I2 solution to dissolve the gold cores. The obtained materials could find potential applications in other biomedical-related areas such as photothermal therapy and drug delivery.