Dual-emissive gold nanocluster / polylysine complex for ratio and visual luminescent detection

Heavy metals pollution shows a serious threat to global human and animal populations. Especially, mercury ions (Hg 2+ ) are non-biodegradable and could accumulated through the food chain, causing severe damage to central nervous system and immune system. The sensitive and rapid detection of Hg 2+ is important for human safety. In this study, based on the host–guest interaction between D-penicillamine (DPA) modified AuNCs and polylysine (PLL), a AuNCs@PLL complex system is constructed. The network of PLL enhances the luminescence properties of AuNCs through electrostatic interaction and hydrogen bonding. In combination with the blue emission of PLL, the AuNCs@PLL complex exhibits dual-emitting luminescence, which could be employed as a promising luminescent probe for Hg 2+ detection. The high-affinity metallophilic Hg 2+ -Au + interactions leads to the decomposition of AuNCs and consequently quenches the red emission, but the blue emission originating from PLL is unaffected. Based on this characteristic, a ratio luminescent probe targeted for quick accurate detection of Hg 2+ is developed. Furthermore, paper test strips were fabricated employing the AuNCs@PLL luminescent probe for visual semi-quantitative Hg 2+ detection. In addition to the benefits for sustainable development of the environment, health of the human, this study also has theoretical values for understanding the mechanism of NCs self-assembly.