Pyrene Associates As a New Highly Sensitive Sensor for Monitoring the Content of Silver Nanoparticles in Aqueous Media

A study is performed of the luminescence of pyrene molecules solubilized in a supramolecular ordered structure formed as a result of the self-organization of molecules of cationic surfactant cetyltrimethylammonium bromide (CTAB) in the presence of trace amounts of aggregated silver nanoparticles (NPs). The study is performed using dilute aqueous solutions of CTAB and at CTAB concentrations that exceed the critical micelle concentration. The formation of a number of pyrene associates (high-energy excimers) that glow in the short-wavelength region of the optical spectrum is observed, relative to the glow of a low-energy dimer (470 nm), and the intensity of the glow of the resulting associates depends on the concentration of silver aquasol introduced into the considered solution. The phenomenon is explained by the location of pyrene molecules near the surfaces of aggregated silver nanoparticles, which have high-density electromagnetic fields caused by surface plasmon resonance. It is found that pyrene associates can be used as sensors for determining trace amounts of silver NPs in aqueous media.