Synthesis of fluorescent polydopamine nanoparticles by Michael addition reaction as an analysis platform to detect iron ions and pyrophosphate efficiently and construction of an IMPLICATION logic gate

Unique water-soluble endogenous fluorescent polydopamine-glutathione nanoparticles (PDA-GNPs) with high fluorescence quantum yield were firstly prepared through Michael addition reaction of glutathione and polydopamine. The PDA-GNPs were prepared under mild conditions, and the preparation process was facile (one-pot reaction) and environmentally friendly. With the introduction of Fe 3+ , the fluorescence intensity of PDA-GNPs decreased sharply. Interestingly, the fluorescence can restore by adding PPi to the system of PDA-GNPs/Fe 3+ . Based on these phenomena, a probe for quantification of Fe 3+ and PPi was set up. With a wide linear range of 0.1–300   μM, the probe can be used to determine Fe 3+ in practical water samples because of its nanomolar magnitude detection limit and negligible influences of other interferences. As to the detection of PPi, the linear range was 2–12   μM and the detection limit was 0.6   μM. In addition, an IMPLICATION logic gate was built by utilizing Fe 3+ and PPi as inputs and the fluorescence signal of PDA-GNPs as output.