Logic Gate Design Using Multicolor Fluorescent Carbon Nanodots for Smartphone-Based Information Extraction

Carbon nanodot (CD)-based logic gates, depending on the fluorescence response of CDs toward various chemicals and biological inputs, have attracted increasing research attention recently. However, it is still challenging to transform multicolor CD-based logic operations into convenient, reprogrammable, and independent readout sensing systems for practical applications. In this study, blue (CD-1), green (CD-2), and red (CD-3) emissive CDs were synthesized and conditioned to implement a series of logic operations, including NOT, PASS 1, NOR, NAND, and IMP. CDs served as logic gates, while Hg2+, Fe3+, H+, and OH– served as chemical inputs. In addition, logic operation information was encoded into Quick Response (QR) codes, which could be easily decoded by a smartphone, highlighting the convenience of information storage and extraction. This study demonstrates an avenue in molecular computing that enables multilevel logic operations, and a convenient and user-friendly readout system for molecular computing. The method reported here holds a great promise to simplify complicated chemo/biosensing for practical applications in the future.