A cellulosic gold nanocluster multi-emission fluorescence probe for assessing types and levels of hROS

The distinction of high reactive oxygen species (hROS) types has positive significance for disease diagnosis. Here, to visibly assess hROS types and levels, a cellulosic multi-emission fluorescence probe was designed by incorporating proline-protected gold nanoclusters (Em: 450 nm), glutathione-protected gold nanoclusters (Em: 680 nm) and o-phenylenediamine (Em: 565 nm) onto cellulose nanocrystal. Ingeniously, the probe displayed the stabilized, quenched and activated fluorescence signals corresponding to hROS at 450 nm, 680 nm, and 565 nm, respectively. The response time of the probe for hROS was greatly reduced from 29 min to 7 min through gold nanoclusters releasing Au(Ⅲ) during the fluorescence quenching process to accelerate the fluorescence opening of o-phenylenediamine. Therefore, the probe with long-term stability (12 months) possessed excellent sensitivity and selectivity to distinguish hROS types, and exhibited visually yellow, white, and green fluorescence for •OH, ClO−, and ONOO−, respectively, and the corresponding detection limits were 0.56 μM, 0.73 μM and 0.81 μM within 5 min, 6 min and 7 min, respectively. The design strategy provides the ideas for constructing multi-emission probe to distinguish multiple analytes at similar levels.