The typical 13 C CPMAS spectrum (Figure ) of nanodiamonds exhibits a prominent peak centered at 34.7 ppm, which is attributed to the sp 3 hybridized core/bulk carbons in the nanoparticles and confirmed by the DPMAS measurements. Notably, the DPMAS experimental scheme shows a relatively sharp peak independent of the strengths of heteronuclear decoupling. In contrast, the CPMAS measurements exhibit relatively broad peaks, indicating the heterogeneous chemical characteristics of carbon species associated with the surface layers of nanoparticles. The sp 2 carbon layers (110-160 ppm) are not quite prominent in these samples. However, a modest peak at ~75 ppm indicates the presence of oxygenated carbons (CHO) in the nanodiamond samples. We also observed two broad resonances at 1.3 and 4.5 ppm in the solid-state 1 H MAS spectra (Figure )-these peaks can be assigned to >CH-, -CH2-, and -CHO groups (alkyl C and O-alkyl C) , which can be subject to chemical and biological functionalization. Notably, the relatively wide 13 C chemical shift range (up to 200 ppm) helps to more precisely designate the main types of carbon moieties that constitute the nanoscale materials . The relative abundance of cross-polarizable carbon functional groups is significantly less in comparison with the core sp 3 carbons observed by the DPMAS measurements, underscoring the presence of alkyl C and O-alkyl C in the shell/surface regions of the nanoparticles.