Excitation-independent yellow-fluorescent nitrogen-doped carbon nanodots for biological imaging and paper-based sensing

We present a facile strategy for fabrication of excitation-independent yellow-fluorescent nitrogen doped carbon nanodots (y-CDs) and illuminate their applications for biological imaging and paper-based sensing. The y-CDs have been synthesized using 4-amino salicylic acid as raw material via one-step hydrothermal treatment without further surface passivation or modification. As-prepared y-CDs exhibit exceptional advantages including unique excitation-independent emission, respectable fluorescence quantum yield (11.0%), superior biocompatibility, low toxicity, and satisfactory optical stability. Depending on these eminent properties, the y-CDs have been utilized for intracellular Al3+ imaging and paper-based Al3+ sensing. They could image Al3+ fluctuations in living cells without interference of auto fluorescence based on their high selectivity and sensitivity detection for Al3+ ions in aqueous solution with a good linearity in the concentration range of 10-200 mu M and 225-400 mu M and a detection limit of 1.69 mu M. Moreover, a paper-based sensor strip containing y-CDs has been prepared for Al3+ sensing, which provides a convenient and user-friendly approach for the visual detection of Al3+. (C) 2017 Elsevier B.V. All rights reserved.