Polydiacetylene liposome-encapsulated alginate hydrogel beads for Pb2+ detection with enhanced sensitivityElectronic supplementary information (ESI) available: Characterization and general methods, synthesis of PCDA-DA, NMR spectra of PCDA, optimization of PDA liposomes for Pb2+ detection, study on the size distribution of PDA-DA liposomes by DLS, and study on the selectivity of PDA liposomes prepared from pure PCDA. See DOI: 10.1039/c5ta04480d

The development of a novel and simple method to trace lead ions (Pb 2+ ) has received great attention due to its high toxicity to human health and the environment. In this paper, we describe a new polydiacetylene (PDA)-based liposome sensor for the colorimetric and fluorometric detection of Pb 2+ in aqueous solution and in alginate hydrogel microbeads. In the sensor system, a dopamine group was rationally introduced into a diacetylene monomer to work as a strong binding site for Pb 2+ . The dopamine-functionalized monomer and 10,12-pentacosadiynoic acid (PCDA) were then incorporated into PDA liposomes in aqueous solution. After UV light-induced polymerization, deep blue colored liposome solutions were obtained. Upon the addition of various metal ions into the liposome solution, only Pb 2+ could cause a distinct color change from blue to red and a dramatic fluorescence enhancement. To further improve its sensitivity and address its intrinsic aggregation, we then developed a liposome-immobilized detection system by encapsulating PDA-DA liposomes into alginate hydrogel beads through a microfluidic droplet-based method. The results showed that the PDA-DA liposome-containing hybrid hydrogel beads possessed excellent stability and high sensitivity. These interesting findings demonstrated that the PDA liposome system developed in the current study may offer a new method for Pb 2+ recognition in a more efficient manner. A new polydiacetylene liposome-based sensor was successfully constructed for the colorimetric and fluorometric detection of Pb 2+ .