Temperature-dependent surface CO stretching frequency investigations of functionalized nanodiamond particles

The surface properties of nanodiamonds play a decisive role in many nanodiamond applications, particularly in bio- and medical applications. The surface functional groups largely determine the interactions and conjugations between nanodiamonds and biomolecules. In this work, the spectroscopic properties of surface-carboxylated nanodiamonds with an average diameter of 100 nm are investigated, focusing on the temperature dependence of the surface CO stretching frequency. The CO stretching frequency was found to be sensitive to temperature. Observed water molecules from temperature desorption confirmed that the CO stretching frequency shifts were associated with the formation of hydrogen bonds. Other molecules were also observed during the temperature treatments, associated with desorption of loosely bonded surface atoms. This work provides useful information on the surface group interactions for nanodiamond applications in nanobiotechnology.