Green synthesis of fluorescent copper nanoclusters for reversible pH-sensors

A simple, green and one-step synthesis approach in aqueous solution was reported for the preparation of the inexpensive chicken egg white (CEW) protected copper nanoclusters (CEW@CuNCs). It was developed without using any reducing agents and the product exhibited extremely stable properties. The fluorescent CEW@CuNCs for reversible pH sensors has been designed based on the distinctly fluorescence enhancing of CuNCs. Meanwhile, the fluorescence intensity of the CuNCs showed a linear relation over the pH ranges of 6.14-12.08 and increased by around 5-fold approximately at high pH values compare with a low pH of 6.14. As expected, the pH sensor was also sensitive to the different buffer solutions and the ionic strength had only a slight influence on the pH-responsive behavior. All above features indicated that functionalized copper nanoclusters-based fluorescent pH sensors as sensing platform with nanoscaled physical dimensions would be a great potential for applications in biological, medical and analytical detection fields. (C) 2015 Elsevier B.V. All rights reserved.