Microwave-assisted synthesis of luminescent and biocompatible lysine-based carbon quantum dots

Water-soluble carbon quantum dots presenting strong blue photoluminescence with the quantum yield up to 23.3% are simply prepared by microwave treatment of lysine as a building block within 5 min in household microwave oven. The formation of lysine-based carbon quantum dots is estimated to proceed through the microwave induced thermal polyamidation and the subsequent carbonization reaction. More importantly, the control experiments using the other amino acids having linear structures reveals that the branched molecular structure of lysine (AB(2) type polyamidation monomer) is one of prerequisite points to obtain strongly luminescent carbon quantum dots with high mass yield. Lysine-based carbon quantum dots are highly nontoxic and biocompatible, enabling bioimaging of cellular media with high degree of pysiological safety. (C) 2016 The Korean Society of Industrial and Engineering Chemistry.