Enhancing Sensitivity of Novel Hg2+ Fluorescent Sensor via Plasmonic Enhancement of Silver Nanoparticles

Contamination of Hg2+ in an aqueous environment is dangerous for all living species including human. In this work, a new rhodamine B derivative fluorescent sensor (sensor RBS) for Hg2+ detection was successfully synthesized. In addition, the synthesized yellow silver nanoparticles (Y-AgNPs) were incorporated into sensor RBS to obtain sensor RBS + Y-AgNPs. The sensitivity studies for Hg2+ detection of the sensors showed that the Hg2+ detection limit of sensor RBS and sensor RBS + Y-AgNPs were 12.9 ppb and 0.7 ppb, respectively. The result indicated that incorporation of Y-AgNPs into sensor RBS led to significantly lower Hg2+ detection limit of sensor RBS + Y-AgNPs, which could be attributed to plasmonic enhancement of Y-AgNPs. Furthermore, the selectivity studies of the sensors showed that sensor RBS and sensor RBS + Y-AgNPs were highly selective toward Hg2+ against interference ions. We also showed that sensor RBS + Y-AgNPs could be used to detect Hg2+ in real samples. Importantly, we have demonstrated that utilization of plasmonic enhancement could improve the sensitivity of the Hg2+ fluorescent sensor, which could pave the way for development of portable fluorescent sensor for the on-site Hg2+ detection.