Employing gold nanoclusters for analysis of pectinase activity

A method for sensing pectinase activity was proposed based on the formation of polyelectrolyte complexes of negatively charged, glutathione-coated, fluorescent gold nanoclusters Au<sub>22</sub>(SG)<sub>18</sub> with the polycation 3,3-ionene and the anionic polysaccharide pectin. The formation of polyelectrolyte complexes of the nanoclusters with ionene leads to an increase in fluorescence due to the aggregation-induced emission enhancement effect, while after the addition of the natural polyanion pectin, the emission decreases. Enzymatic hydrolysis of pectin by pectinase resulted in the recovery of the fluorescence of nanoclusters, which allows sensing the activity of pectinase.