Green synthesis of pregabalin-stabilized gold nanoclusters and their applications in sensing and drug release.

This is the first report on the simple preparation of gold nanoclusters stabilized with pregabalin (PREG) as a capping and reducing agent. PREG is an active pharmaceutical ingredient of the commercially available drug "Lyrica" used to treat different diseases like epilepsy and anxiety. PREG has never been used before in the synthesis of any nanoparticles or nanoclusters. The prepared gold nanoclusters (PREG-stabilized gold nanoclusters [PREG-AuNCs]) have blue fluorescence with excitation/emission at 365/425 nm, respectively. The reaction conditions were optimized for the synthesis of the as-prepared AuNCs. Different tools were used for the characterization of the synthesized nanoclusters in terms of size and surface properties. The PREG-AuNCs were exploited as a sensitive and selective fluorescent nanosensor for Cu 2+ detection. The quenching of AuNC fluorescence intensity in the presence of Cu 2+ is due to the aggregation-induced fluorescence quenching mechanism. The detection limit of Cu 2+ ions was found to be 1.11 × 10 -7  M. The selectivity of the PREG-AuNCs was studied and proved to be excellent. The drug entrapment efficacy and in vitro drug diffusion studies along with drug release kinetics helped to understand more about the pharmaceutical approaches of PREG-AuNCs. Moreover, we think that PREG-AuNCs open new opportunities as a promising candidate material for drug delivery systems and medical applications.