Direct functionalization of nanodiamond particles using dopamine derivatives.

The article reports on the strong linking of dopamine derivatives as a simple and a versatile strategy for the surface functionalization of hydroxyl-terminated nanodiamond (ND-OH) particles. Azide- (ND-N(3)) or poly-N-isopropylacrylamide-terminated (ND-PNIPAM) particles were obtained from ND-OH particles through the reaction with the corresponding dopamine derivatives. The azide-terminated ND particles were further derivatized with a fluorescent probe, alkynyl-pyrene, via copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition. The modified ND particles were characterized using transmission Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, electrochemical measurements, thermogravimetric analysis (TGA), and particle size measurements. The surface loading of ND particles with dopamine was estimated from TGA and UV-vis spectroscopy and was found to be around 0.27 mmol g(-1). Because of its simple, gentle nature and versatility, the chemistry developed in this work can be used as an avenue for the preparation of functional nanodiamond particles for various applications.