One-step ultrasonic synthesis of water-soluble carbon nanoparticles with excellent photoluminescent properties

Monodispersed water-soluble fluorescent carbon nanoparticles (CNPs) were synthesized directly from glucose by a one-step alkali or acid assisted ultrasonic treatment. The CNPs were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectrophotometry, fourier transform infrared spectrophotometry and ultraviolet-visible spectrophotometry. The results showed that the particle surfaces were rich in hydroxyl groups, giving them high hydrophilicity. The CNPs could emit bright and colorful photoluminescence covering the entire visible-to-near infrared (NIR) spectral range. Notably, the NIR emission of the CNPs could be obtained by NIR excitation. Furthermore, these CNPs also had excellent up-conversion fluorescent properties.