University of Illinois Urbana-Champaign

Dynamic imaging of magnetic bioeffects in cells using two-channel two-photon autofluorescence intensity and lifetime microscopy

Tan, Kevin Kaipeng Durfee

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https://hdl.handle.net/2142/129564

Description

Title
Dynamic imaging of magnetic bioeffects in cells using two-channel two-photon autofluorescence intensity and lifetime microscopy
Author(s)
Tan, Kevin Kaipeng Durfee
Issue Date
2025-05-05
Director of Research (if dissertation) or Advisor (if thesis)
Boppart, Stephen A
Department of Study
Bioengineering
Discipline
Bioengineering
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
  • Two-photon microscopy
  • Autofluorescence microscopy
  • Label-free imaging
  • Quantum biology
  • Magnetic bioeffects
  • Radical pair mechanism
  • Reactive oxygen species
  • Fluorescence lifetime imaging microscopy
  • Spin chemistry
  • Metabolic imaging
Abstract
Magnetic fields have long been known to interact with living systems in subtle and often surprising ways. One hypothesis for these effects is the radical pair mechanism which suggests that magnetic fields influence the spin dynamics of redox-active radical pairs, altering the balance of reactive oxygen species (ROS) in cells. These ROS may then initiate signaling and metabolic pathways. In this thesis, a novel two-channel two-photon autofluorescence microscope enabled high-resolution, non-invasive, and simultaneous measurement of autofluorescence intensity and fluorescence lifetime from the metabolic cofactors NAD(P)H and FAD to examine magnetic field effects at the single-cell level. First, A549 lung carcinoma cells were subjected to the redox effects of PEG-SOD and DDC to validate the sensitivity of the microscopy method. While fluorometric assays confirmed altered ROS partitioning, autofluorescence microscopy exhibited limited sensitivity. Next, static magnetic fields ranging from 50 µT to 100 mT were applied for 72 hours. Fluorometric results revealed a significant increase in hydrogen peroxide production in the 0.4–0.8 mT range, consistent with the radical pair mechanism. The autofluorescence microscopy detected subtle changes in fluorescence lifetime features at 0.1 mT, indicating a possible NADPH mediated ROS defense response. Lastly, to probe the dynamics of magnetic bioeffects, a longitudinal imaging protocol including a custom stage-top Helmholtz coil was developed. No statistically significant differences were observed after repeated 2-hour magnetic field exposures, indicating limitations in the sensitivity of the label-free multiphoton imaging. Still, with adjustments, these methods are a promising tool for future investigations of magnetically-induced cellular phenomena.
Graduation Semester
2025-05
Type of Resource
Thesis
Handle URL
https://hdl.handle.net/2142/129564
Copyright and License Information
© 2025 Kevin Kaipeng Durfee Tan

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