Cuprous oxide nanospheres as probes for light scattering imaging analysis of live cells and for conformation identification of proteins.

ABSTRACT

A facile solution-phase synthesis route of highly uniform Cu(2)O nanospheres (Cu(2)O NPs) with the size of 57.7+/-4.7nm was developed, and then the nanoparticles were applied to live cell imaging under a common dark-field microscope. Starting from copper(II) salts, the synthesis of Cu(2)O NPs was made in the presence of cetyltrimethylammonium bromide (CTAB) by reducing the copper(II) with sodium borohydride (NaBH(4)) in aqueous medium and by aging process in the air. Monitoring of morphology evolution process of Cu(2)O NPs with scanning electron microscopy (SEM) and measuring of the UV-visible spectra showed that the synthesis of Cu(2)O NPs follows the reduction-oxidation coupled process of Cu(2+) into Cu(0) species at first and then the resulted Cu(0) species into Cu(2)O NPs in the air. Light scattering (LS) features have been measured with a common spectrofluorometer and a common dark-field microscope, and it was found that the as-prepared Cu(2)O NPs display strong blue scattering light and can be applied for cell imaging. If incubated with human bone marrow neuroblastoma, transferrin-conjugated Cu(2)O NPs can get into the cells and show strong pure blue light in cytoplasm. Further investigations showed that the Cu(2)O NPs could be applied for probes for conformation of proteins.