Plasmon-Coupled Silver Nanoparticles for Mobile Phone-Based Attomolar Sensing of Mercury Ions

The ability of plasmonic nanoparticles (NPs) to focus the impinging electromagnetic (EM) radiation to subwavelength regimes assists in the detection of molecules at extremely low concentrations. Numerous nanomaterials have been exploited in the surface plasmon-coupled emission (SPCE) technology, presenting quintessential physicochemical insights. However, seldom attention has been paid toward utilizing the biocompatible nanotechnology for substrate nanoengineering in SPCE. In this context, we present LYCOAT-based silver (Ag) NPs synthesized via a frugal disruptive approach by exposing a simple physical mixture of Ag+ ions and LYCOAT to UV irradiation. Variations in the time of UV exposure resulted in nanofractals and nanocubes of Ag presenting unique architectures for nanophotonic applications, where the biocompatible LYCOAT functions as both reducing and capping agents under ambient conditions. Nanomaterials synthesized in this approach were studied in spacer, cavity, and extended cavity nanointerfaces in the SPCE platform for obtaining tunable plasmonic coupling. The augmented >900-fold SPCE enhancements were utilized for mobile phone-based attomolar sensing of environmentally hazardous Hg2+ ions. The simple, realistic, and eco-friendly methodology adopted here for developing nanomaterials for photonic applications opens the door for exploring such next-generation bio-inspired nanomaterials for point-of-care diagnostic applications.