Fluorescent carbon dots with real-time nucleolus-monitoring capability for gene delivery and biosensing of NO2– and pH

Abstract

To achieve gene therapy, DNA, one of the most commonly used therapeutic nucleic acids, is typically employed to transfer into the nucleous. However, it remains extremely challenging to seek vectors with high transfection efficiency and low toxicity to introduce DNA into the nucleolus. Herein, we have designed and developed green fluorescent carbon dots (G-CDs) for nucleolus targeting, gene delivery, and biosensing of NO2– and pH. G-CDs were synthesized by a simple hydrothermal mean using 3,5-diaminobenzoic acid and citric acid as precursors. As-prepared G-CDs not only possess bright green fluorescence with respectable fluorescence quantum yield of 41%, but also exhibit low cytotoxicity and superior biocompatibility. Interestingly, G-CDs display accurate nucleolus targeting characteristic due to the response of G-CDs to DNA in the nucleolus. More unexpectedly, G-CDs could effectively deliver exogenous ROX-labelled DNA into the nucleolus of HeLa cells, which is the first time that fluorescent CDs are used as nanocarriers to transfer DNA to nucleolus. What’s more, G-CDs have been expanded to visually monitor NO2– and pH fluctuations in living cells.