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Label-Free Detection of Bacillus anthracis Spore Uptake in Macrophage Cells Using Analytical Optical Force
Colin G Hebert1, Sean Hart2, Tomasz A Leski3
1Naval Research Laboratory , Chemistry Division, Bio/Analytical Chemistry Section, Code 6112, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States.
Analytical Chemistry
|September 7, 2017
Summary
Optical chromatography detects Bacillus anthracis spores interacting with macrophage cells. This label-free method rapidly identifies spore exposure, crucial for biodefense and disease prevention.
Area of Science:
- Biophysics
- Cell Biology
- Microbiology
Background:
- Understanding macrophage-Bacillus anthracis interactions is vital for anthrax disease progression and biodefense.
- Current detection methods often rely on labels, limiting rapid, intrinsic property-based analysis.
- Label-free techniques offer an alternative by probing inherent cellular changes.
Purpose of the Study:
- To demonstrate the capability of optical chromatography as a label-free method for detecting macrophage-Bacillus anthracis spore interactions.
- To assess the sensitivity and speed of optical chromatography in identifying spore uptake.
- To investigate the role of phagocytosis in the observed changes in optical force.
Main Methods:
- Utilized optical chromatography, a label-free technique balancing optical and fluidic drag forces in a microfluidic channel.
- Measured the optical force experienced by RAW264.7 macrophage cells upon interaction with microparticles and Bacillus anthracis Sterne 34F2 spores.
- Analyzed macrophage cells treated with cytochalasin D, with and without subsequent spore exposure.
Main Results:
- Observed an increased optical force in macrophage cells after uptake of microparticles and Bacillus anthracis spores.
- Detected Bacillus anthracis spore exposure in as little as 1 hour, without labels.
- Found that a portion of the optical force increase was independent of phagocytosis, as seen with cytochalasin D treatment.
Conclusions:
- Optical chromatography can rapidly and sensitively detect subtle biological differences, such as macrophage-Bacillus anthracis spore interactions.
- This label-free technique holds potential for biodefense applications, including the detection of biological threat agents.
- The method may also be applied to pathogen detection for preventing sepsis and other diseases.
