Immobilization of bovine serum albumin-protected gold nanoclusters by using polyelectrolytes of opposite charges for the development of the reusable fluorescent Cu2+-sensor

In this paper, we reported a facile method of fabricating a reusable fluorescent Cu2+-sensor. To fabricate the reusable sensor, the bovine serum albumin-protected gold nanoclusters (BSAGNCs) were complexed with polyelectrolytes, i.e., positively charged polydiallyldimethylammonium (PDDA) and negatively charged polystyrenesulfonate (PSS), and were coated on a glass slide. The prepared film-modified glass slides exhibited the recyclability of fluorescent signal “off–on” behaviors: the fluorescence could be switched “off” by immersing the film sensors in Cu2+ solution and “on” by washing with ethylene diamine tetraacetic acid (EDTA) solution. The prepared film-modified glass slides exhibited high selectivity towards Cu2+ the fluorescence quenching behavior in the form of the Stern–Volmer equation. In addition, the spiked tap water samples were analyzed with satisfactory results. These demonstrations provide a new convenient approach to develop the BSAGNCs-based, reusable fluorescence sensors.

► The BSA-protected GNCs were modified with polyelectrolytes of opposite charges.
► Bare glass slides were modified with the prepared complexes of protein–polyelectrolytes.
► A reusable fluorescence sensor for copper ion was proposed.