Hyperbranched polyglycerol modified fluorescent nanodiamond for biomedical research

Abstract : The aim of the present work was to functionalize fluorescent nanodiamond by covalentgrafting with hyperbranched polyglycerol. Fluorescent nanodiamond, derived from highpressure high temperature diamond microdiamond, was oxidized then thermally reacted withpure glycidol in the absence of catalyst. Thermal polymerization of glycidol was notablyfaster on the nanodiamond surface as a result of a surface initiation of the isothermal ringopening polymerization. Interestingly, the aqueous dispersion of the resulting nanoparticlesappeared stable at high ionic strength. Furthermore, the fluorescent nanodiamond grafted withhyperbranched polyglycerol displayed several hydroxyl end–groups which could be furtherderivatized by carboxylation or carbamatization and subsequently conjugated with proteinlinked via an amide bound. Notably, nanodiamonds retain their unique fluorescentcharacteristics. This work suggests that fluorescent nanodiamond coated with hyperbranchedglycidol could be promising in biomedical research where aqueous dispersion of fluorescentnanoparticles stable in physiological medium are in high demand to label, track and quantifybiomolecules.