Toward a Comprehensive Raman Analysis of Functional Cells With Structured Optical Traps

Area of Science:

• Biophysics
• Spectroscopy
• Cell Biology

Background:

• Optical trapping of red blood cells (RBCs) using Gaussian beams is valuable for studying RBC disorders.
• Conventional methods primarily probe RBC cytoplasm, neglecting the critical cell membrane.
• Advanced techniques like donut and line focus trapping offer improved membrane analysis.

Purpose of the Study:

• To compare the capabilities of point, donut, and line focus trapping for deriving Raman spectroscopy signatures from RBCs.
• To elucidate the distinct information content each trapping method provides, especially regarding the cell membrane.

Main Methods:

• Utilized point, donut, and line focus optical trapping configurations.
• Acquired Raman spectroscopy data from RBCs under different trapping conditions.
• Applied Principal Component Analysis (PCA) for spectral feature reduction and classification.
• Employed Analysis of Variance (ANOVA) to assess spectral component significance.

Main Results:

• PCA effectively differentiated spectral signatures based on trapping methods.
• ANOVA confirmed the significant contribution of the RBC membrane to spectra from donut and line focus trapping.
• Line focus trapping yielded spectra rich in information, particularly in the 1220-1290 cm^-1 range (amide III band).

Conclusions:

• Point, donut, and line focus trapping exhibit distinct capabilities in probing RBCs.
• Donut and line focus trapping are superior for analyzing RBC membrane components via Raman spectroscopy.
• Line focus trapping offers comprehensive spectral information, highlighting the amide III band for RBC analysis.