Electrochemistry for Life Detection on Ocean Worlds

Abstract

All forms of terrestrial life include cellular machinery to transform and regulate chemical energy flow through electron‐transfer pathways reliant upon key classes of biological redox molecules; life that evolved elsewhere, presumably, would possess a similar possibly overlapping set of energy‐management molecules. A second set of universal processes in terrestrial biology encompasses enzymatic change to add or remove functional groups, such as phosphate moieties, to biomolecules for a variety of purposes, from managing energy flow to tuning protein function; electrochemical assays can detect such enzymes. Thus, measurement of biological redox activity is a promising means to search for two major classes of life indicators as a component of future exploration missions to the “ocean worlds” of our solar system, those bodies that support substantial liquid oceans. Here, we assay a representative set of life‐critical redox molecules in synthetic seawater (SW) using electrochemical techniques. We also appropriate a well‐developed electrochemical assay that indicates the presence of phosphatase(s) by comparing the redox signatures of a substrate for, and the product of, the enzymatic process. We report measured limits of detection in SW as low as 10 nM for naturally occurring redox molecules and 3.1 aM for alkaline phosphatase over a 60‐minute period, demonstrating the promise and sensitivity of electrochemical sensors as effective life‐detection tools for future ocean worlds missions.

Nutrient Detection Sensors in Seawater Based on ISI Web of Science Database

“…Despite the fact that oceans cover more than 70% of our planet and have a profound impact on global climate, weather patterns, human health, agriculture, and commerce [1,2], human ability to make sustained measurements of ocean processes is limited and much of the oceans remain largely unexplored [3,4]. Meanwhile, marine ecosystem is increasingly deteriorating due to continuous development and utilization of oceans by industrial pressures and growing population [5,6]. These ecosystems of coastal zones, estuaries, and gulfs have been gradually destroyed with different extents, such as dumping of waste, construction of harbours, dredging, and extraction processes [7,8].…”

Fast Degradation of Hydrogen Peroxide by Immobilized Catalase to Enable the Use of Biosensors in Extraterrestrial Bodies

“…To address this limitation, a number of liquid-based analytical techniques have been proposed (Blanco et al, 2017;Ribette et al, 2019). Out of those, immunoassays, electrochemical sensors (Thomson et al, 2020), and microfluidic capillary electrophoresis technologies hold the most promise in terms of power requirement, weight, sensitivity, and ability to detect biomarkers in model systems (Derveni et al, 2012;Sims et al, 2012;Willis et al, 2012;Butterworth et al, 2015;Mathies et al, 2017Mathies et al, , 2019Moreno-Paz et al, 2018;García-Descalzo et al, 2019;Lezcano et al, 2019). Unfortunately, even low concentrations of H 2 O 2 present in the sample could interfere with all of these platforms because it may induce structural changes in the antibodies (required for selectivity in immunoassays) or through oxidizing the dyes used in fluorescence-based systems (Stockton et al, 2013).…”

Electrochemical Sensors in Space Missions

“…2D). 6 In the context of future instrumentation developed for exploration of Europa and Enceladus, the incorporation of electrochemical sensors into a microfluidic block for in-situ measurement would be ideal as sampling of liquid oceans is a future possibility. This analysis capability can be achieved with the use of micromachining as well as the use of 3D printing to achieve unique geometries and accommodate electrodes as shown in a current electrochemical device pictured in Fig.…”