We report a new strategy for coupling chromone to Fe3O4 nanoparticles. The chromone-Fe3O4 NP conjugate shows a dramatic increase in chromone solubility in cell culture medium from less than 2.5 to 633 mu g/ml, leading to the enhanced chromone uptake by HeLa cells. Chromone can be released at low pH and as a result, the chromone-Fe3O4 conjugate is much more efficient in inhibiting the HeLa cell proliferation. Such chromone-Fe3O4 NPs are promising as a powerful multifunctional delivery system for both chromone-based diagnostic and therapeutic applications.