Browsing by Author "DiPaolo, Brian"

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New-generation spacecraft water monitoring with flight-ready solid state nanopore
(51st International Conference on Environmental Systems, 7/10/2022) Xia, Zehui; DiPaolo, Brian
To provide a fast, simple and reliable way of identifying inorganics and organics present in the water systems aboard the international space station (ISS) and potentially other spacecraft (e.g., NASA's Artemis Gateway Outpost), we aim to develop a robust, portable and easy-to-use sensor system based on solid-state nanopore technology. The current water monitoring capability in the ISS is only limited to electrical conductivity, total organic carbon and selected ions of iodine and silver. Any other analyte must be brought back to Earth. The maintenance of safe living conditions in ISS is important in order to support the scientific activities of the crew, and to ensure their unharmed return to Earth upon mission completion. The solid-state nanopore system presents an inherently single-molecule sensor system that works on the principle of pore occlusion by the molecule which then can be registered as a change of the electrical current. Each analyte establishes its unique electrical signal upon passing through the nanopore of tailored characteristics. We use a low-noise and low-capacitance glass chip with an ultrathin (20 nm-thick) silicon nitride (SiN) membrane material which has flight heritage, together with a compact (centimeter-scale) nanopore reader to sense and identify analytes of interest to NASA. Enabled by special short DNA molecules ("aptamers") as probes, we demonstrate the detection of mercury and lead using 2-5 nm- diameter nanopores at concentrations down to 0.5 nM and 5 nM, respectively, which are below EPA and SWEGs levels. We observed distinct electrical translocation characteristics between these two metal ions, paving a path towards selective nanopore sensors by identifying their "electrical fingerprints." Our single-molecule nanopore instrument allows the detection of low-concentration analytes in water and is thus a promising tool for a miniaturized analytical laboratory for future NASA missions, together with other analytical tools available.
Spacecraft Water Analysis with Nanopore (SWAN)
(2023 International Conference on Environmental Systems, 2023-07-16) Xia, Zehui; Niedzwicki, David; DiPaolo, Brian
To provide a fast, simple and reliable way of identifying unwanted constituents present in the water systems aboard ISS and potentially other spacecraft (e.g., Artemis Gateway Outpost), we aim to develop a robust, portable and easy-to-use sensor system based on solid-state nanopore technology, a.k.a. SWAN. The current water monitoring capability in the ISS is only limited to electrical conductivity, total organic carbon and selected ions of iodine and silver. Any other analyte must be brought back to Earth. The maintenance of safe living conditions in ISS is important in order to support the scientific activities of the crew, and to ensure their unharmed return to Earth upon mission completion. The solid-state nanopore system presents an inherently single-molecule sensor system that works on the principle of pore occlusion by the molecule which then can be registered as a change of the electrical current. Each analyte establishes its unique electrical signal upon passing through the nanopore of tailored characteristics. Previously we reported the detection of mercury and lead using 2-5 nm- diameter and 20-nm thick nanopores at concentrations down to 5 nM and 0.5 nM, respectively, both of which are below both EPA requirements and SWEGs. We continued to mature the sensor platform and successfully used it to detect diethyl phthalate (DEP), a desirable small organic analyte (~1 nm) to NASA for water monitoring purpose, without tedious sample prep and heavy use of organic solvents which are required in the typical mass spectroscopic methods on earth. This direct detection of the naked molecule is enabled by innovative ultrathin (< 5 nm) and ultrasmall (~ 1.5 nm) nanopores. SWAN will allow the detection of low-concentration analytes in water and is thus a promising tool for a miniaturized analytical laboratory for future NASA missions, together with other analytical tools available.