Green synthesis of nitrogen and sulfur co-doped carbon dots from Allium fistulosum for cell imaging

Nature provides an almost limitless supply of natural sources, which inspires scientists to develop new materials with novel applications and lower environmental impact. Here, we prepared nitrogen and sulfur co-doped carbon dots (CDs) by hydrothermal treatment of Allium fistulosum (Af-CDs). These materials exhibited strong fluorescence with an absolute quantum yield of 10.48%. The photoluminescence of the CDs is very stable across different pH values, high NaCl concentrations, and in the presence of different metal ions, suggesting that the CDs have a wide range of applications even under rugged conditions. The CDs offer a selective optical stain for multicolor imaging in MCF-7 and K562 cell cytoplasm. The as-prepared CDs were explored for cell imaging and offer great biocompatibility. The remarkable properties of the CDs indicated their potential toward sensing and bioapplications.