CISM

1
Describing and Measuring Chemical Signatures of
Life
Research Team

• Principal Investigators
• Prof. Ron Crawford, Team Leader (microbiology)
• Dr. Mohammed M. Mojarradi, Team Leader (Jet
  Propulsion Laboratory)
• Prof. Rick Wells (microelectronics)
• Prof. Frank Cheng (chemistry)
• Prof. Chien Wai (chemistry)
• Prof. Tony Anderson (mechanical engineering)
• Senior Scientists
• Dr. Andrzej Paszczynski (staff biochemist)
• Dr. Qingyong Lang (postdoctoral chemist)
• Students and Staff
• Mr. Bruce Barnes (microelectronics Ph.D.
  candidate)
• Ms. Lisa Allenbach (technical assistant)
• Mr. Dan Erwin (undergraduate researcher)

2

• The Goal
• To develop a suite of prototype devices that
  together will indicate the presence or absence of
  life beyond Earth.
• Assumptions
• Life requires continual energy input, tapped in
  a controlled manner. - Metabolism
• Form of energy Chemical energy
• The life forms we are seeking are living
  entities, not fossils.

El
3

• H2, NH3/NH4, CH4, H2S
• Metal ions (Fe2), Metals
• Hydrocarbons

Electron Donors - Reducing Agents
e-
Energy

• O2, NO3-, SO2/SO3
• Metal Ions (Fe3 and higher)

Electron Acceptors - Oxidizing Agents
4
Respiratory Chain
(CH2O)n ? - 0.70 volts
NAD H 2e- ? NADH -0.32
volts
FMN 2H 2e- ? FMNH2 -0.30 V
FAD 2H 2e- ? FADH2 -0.22 V
CoQ 2H 2e- ? CoQH2 0.04 V
Cytochrome b (3) e- ? Cytochrome b (2)
0.07 V
Cytochrome c1 (3) e- ? Cytochrome c1 (2)
0.023 V
Cytochrome c (3) e- ? Cytochrome c (2)
0.025 V
Cytochrome a (3) e- ? Cytochrome a (2)
0.029 V
Cytochrome a3 (3) e- ? Cytochrome a3 (2)
0.055 V
O2 4H 4e- ? 2H2O 0.77 volts
5
Water flow
waterfall
Vs. series of dams
6

• Waterfall vs. Dams
• Regulation of water flow ? metabolism
• Control of energy utilization
• More efficient utilization of energy
• Storage of energy

7

• Electron transport agents range from 1.0 to
  1.0 volt
• In order to transport electrical current, agents
  must be able to undergo several
  reduction-oxidation (redox) cycles.

Ox ne- Red

• Electrochemical properties - reversible,
  quasi-reversible
• Detectable by voltammetric methods

8
Sample Extraction Module

• Sample will be obtained and life signature
  compounds (redox agents) extracted by either a
  chemical solvent or supercritical CO2
• Extracted compounds will be separated, probably
  by capillary electrophoresis (CE).
•  
• Components separated in the previous module will
  be detected here using voltammetric, spectral
  absorbance detectors, and MS/MS.
• Data will be transmitted to Earth for processing.

Compound Separation Module
Detection Module
Data Processing Module
9
Methodology

• Biological samples for validating methods
• Pure cultures of representative soil bacteria
• Pseudomonas stutzeri (gram negative,
  facultative)
• Arthrobacter (gram positive, aerobic)
• Bacillus (gram positive, facultative,
  endospores)
• Sand containing various numbers of these bacteria
  
• Real soils known to contain few active bacteria
  e.g., hot or cold desert soils

10
Structures of Model Compounds
A Flavin Riboflavin
Protoporphyrin IX of Heme
A Diphosphopyridine Nucleotide NAD
11
CE-ECD analysis of bacterial redox components
Control
Pseudomonas putida
10
Arthrobactor
10 ?M standards
10
10
10
12
Future Directions

• Square-wave or Cyclic voltammetric CE detection
• Redox potential concentration information.

current
potential
Energy

• Series of reversible redox agents over the range
  of -1 to 1 volts may indicate life

retention time
13
Possible Lab on a Chip Design
The extraction module can be designed to handle
either traditional solvents (e.g., DMF/ Borate /
SDS or 1.0 M formic acid) or pressurized
supercritical carbon dioxide.
14
Prototype CE-Square Wave Voltammetry System
Acknowledgement Agilent Technologies
15
Continuing Work

• Extraction / Analysis Methods Additional Redox
  Molecules
• Rigorously Test Miniaturized CE /SW-Voltammetry
  System with Standards and Soil Extracts
• Additional Testing with Earth-based Soils
  (Craters of the Moon and others)
• Develop Collaborations Miniaturized ES-MS/MS
• Completion of Primary Objective (4-6 Months
  Finalize Conceptual Design of Life Detection
  System)