Use of nanodiamonds (NDs) as nontoxic nanoparticles for biological imaging, sensing, and drug delivery is expanding rapidly. The interest in NDs is triggered by their unique combination of optical properties. ND can accommodate nitrogen-vacancy color centers which provide stable fluorescence without photobleaching or photoblinking and their electronic structure is very sensitive to magnetic and electric fields. The limited options to control ND properties during synthesis or by direct surface functionalization leave room to be improved upon by employing surface coatings engineered precisely for a particular application. The major disadvantages of unmodified NDs are their limited colloidal stability and tendency to non-specifically adsorb biomolecules. This review aims to summarize recent advances in coating NDs (namely with silica and polymer shells), which addresses these disadvantages and enables the use of NDs in biological applications such as targeting of specific cells, drug delivery, and biological imaging.

纳米金刚石（NDs）作为用于生物成像，传感和药物递送的无毒纳米颗粒的使用正在迅速扩大。对ND的兴趣是由它们的光学性质的独特组合引起的。ND可以容纳氮空位色心，提供稳定的荧光而不会发生光漂白或光闪烁，并且其电子结构对磁场和电场非常敏感。在合成过程中或通过直接表面官能化来控制ND特性的有限选择留下了通过采用为特定应用专门设计的表面涂层来改进的空间。未修饰的ND的主要缺点是其有限的胶体稳定性和非特异性吸附生物分子的趋势。