Fluorescent silver nanoclusters embedded in hydrogel matrix and its potential use in environmental monitoring

The optical absorption and fluorescence of silver nanoclusters (AgNCs) are widely exploited in many different application fields such as sensors, bio-imaging, drug delivery, etc. In the sensor field, optical devices are highly versatile thanks to their ease of fabrication and low costs and, therefore, are optimal candidates to replace expensive apparatuses commonly used. In this study, we synthesized AgNCs in aqueous phase by photochemical synthesis using poly methacrylic acid (PMAA) as a stabilizer. Colloidal water solutions of these NCs showed a very good sensitivity to Pb(II) ions, and in order to fabricate a solid-state sensor, we introduced them in a hydrogel material formed by poly(ethylene glycol) diacrylate with a molecular weight of 700 g/mol (PEGDA(700)). The systems were characterized using absorption and fluorescence spectroscopy and transmission electron microscopy (TEM). Finally, the sensitivity to Pb(II) ions has been tested with the aim to use these systems as solid-state optical sensors for water quality.