Sequential Visual Sensing of H<sub>2</sub>O<sub>2</sub> and GSH Based on Fluorescent Copper Nanoclusters Incorporated Eggshell Membrane
Mengna Liang, Lili Yuan, Congying Shao, Xingqun Zheng, Qingchun Song, Zhengrong Gu, Shun Lu
Abstract
Digital imaging technology provides a unique advantage for the portable on-site detection of targeted analytes. In this work, copper nanoclusters (CuNCs) based on the eggshell membrane (ESM) were combined with the photograph-taking and color recognition functions of a smartphone to build an “ON-OFF-ON” detection platform, which realized the dual visual detection of hydrogen peroxide ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}_{{2}}$ </tex-math></inline-formula> ) and glutathione (GSH). First, a red fluorescent nanocomposite membrane (GSH-CuNCs@ESM) was prepared by in situ synthesis with GSH as the protective and reducing agent. The physical characterization results confirmed its long fluorescence (FL) lifetime ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$23.77 \mu \text{s}$ </tex-math></inline-formula> ), high quantum yield (QY, 23.79%), large Stokes shift, and good stability. In addition, it is found that <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}_{{2}}$ </tex-math></inline-formula> has a specific response to the GSH-CuNCs@ESM, which can quench its FL. However, the FL of the quenched membrane was restored after it was put into the GSH solution. So, visual detection of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}_{{2}}$ </tex-math></inline-formula> and GSH was developed based on this phenomenon integrating with a smartphone and color recognition functions. Consequently, the limit of detection (LOD) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}_{{2}}$ </tex-math></inline-formula> is as low as 63 nM when the concentration of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}_{{2}}$ </tex-math></inline-formula> is between 0 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100 \mu \text{M}$ </tex-math></inline-formula> . The LOD of GSH is as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.0 \mu \text{M}$ </tex-math></inline-formula> when the concentration of GSH was between 0 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$800 \mu \text{M}$ </tex-math></inline-formula> .