Cellular micromotion monitored by long-range surface plasmon resonance with optical fluctuation analysis

Area of Science:

• Biosensing
• Cellular Biophysics
• Nanotechnology

Background:

• Conventional surface plasmon resonance (cSPR) has limitations in probing depth and sensitivity.
• Cellular micromotion, or dynamic fluctuation of adherent cells, provides insights into cell health and activity.
• LRSPR offers enhanced probing depth and sensitivity over cSPR.

Purpose of the Study:

• To demonstrate LRSPR as a sensitive method for noninvasive measurement of cellular micromotion.
• To compare the performance of LRSPR and cSPR in monitoring cell micromotion.
• To investigate the role of membrane fluctuations in LRSPR measurements of cellular activity.

Main Methods:

• Utilized LRSPR and cSPR techniques to measure optical fluctuations in confluent cell layers (3T3 fibroblasts, MDA-MB-231 cancer cells).
• Calculated the micromotion index from the power spectral density (PSD) of optical fluctuations.
• Performed simulations to determine the relative sensitivities of LRSPR and cSPR to membrane fluctuations.

Main Results:

• LRSPR successfully measured dynamic fluctuations in live and fixed cell layers, showing significant differences.
• LRSPR sensors recorded a higher micromotion index compared to cSPR, indicating superior sensitivity.
• Simulations predicted increased signal intensity for LRSPR, supporting the significant role of membrane fluctuations.

Conclusions:

• LRSPR is a highly sensitive technique for noninvasive monitoring of cellular micromotion.
• LRSPR exhibits greater sensitivity to cell membrane fluctuations than cSPR.
• LRSPR-based cellular micromotion measurement holds potential for assessing cell metabolic activity and viability.