Biopolymer/plasmid DNA microspheres as tracers for multiplexed hydrological investigation

Pollutants being discharged into water body from unknown sources are one of the major threats to environmental sustainability and human health. Herein a plasmid DNA (pDNA)-based tracing system for multiplexed detection of potential hydrological processes of pollutants is developed. pDNA is incorporated with magnetic nanoparticles (MNPs) and then the pDNA-MNPs nanocomposites are encapsulated inside polylactic acid (PLA) microspheres as pDNA tracers. pDNA, produced in large quantities by engineering bacteria (E. coli), served as the "marker" which can be arbitrarily designed and specifically identified through well-established molecular biology tools including enzyme. MNPs are employed to facilitate the collection and separation of tracers in diluted water body. PLA microspheres provide effective protections for pDNA against unpredictable influences in environment such as high temperature, UV radiation, and deoxyribonuclease degradation. In addition, pDNA tracers containing MNPs are buoyant and concentrated at the surface of the water, facilitating tracer collection with an external magnetic device. pDNA extracted from tracers is specifically detected via quantitative Polymerase Chain Reaction (qPCR) with extreme sensitivity. Multiplexed detection is also achieved both in a laboratory test and in a simulated-stream test. Moreover, the preliminary application strategies of pDNA tracer system in different scales of a real-world river have been envisioned. The advantages of pDNA-based tracing system include: massive and cost-effective production of pDNA, high stability in harsh environment, environmental friendly, ultrasensitive, and allowing for multiplexed detection.