Electronic Supplementary Material (ESI) for Nanoscale. This is © The Royal Society of Chemistry 2016 Supporting Information A highly fluorescent nitrogen-doped carbon dots with excellent thermal and photo stability and applied as an invisible ink for loading important information and anti-counterfeiting Lingbo Liu, a Liang Zhou, a Yanan Li, a Ruping Deng a and Hongjie Zhang a a. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022, People’s Republic of China, Tel: +8643185262127; fax: +8643185685653. Email: zhoul@ciac.ac.cn (L. Zhou), hongjie@ciac.ac.cn (H. Zhang) Electronic Supplementary Material (ESI) for Nanoscale. This journal is © The Royal Society of Chemistry 2016