Spectral characterization of yeast cells with an epitaxy-based UV-Vis optical sensor

Area of Science:

• Biophotonics
• Spectroscopy
• Biosensing

Background:

• Yeast cell concentration monitoring is crucial for food safety and industrial processes.
• Existing methods for yeast quantification can be time-consuming or lack sensitivity.
• Optical methods offer potential for rapid and non-invasive analysis.

Purpose of the Study:

• To investigate the optical absorption spectra of yeast cells in phosphate-buffered saline (PBS) using a novel UV-vis sensor.
• To correlate spectral features, specifically absorption peaks, with varying yeast cell concentrations.
• To assess the feasibility of using optical spectral analysis for quantitative yeast cell measurements.

Main Methods:

• Utilized a UV-vis sensor based on a p(+)n junction silicon device for optical analysis.
• Measured absorption spectra of yeast cells in PBS across the 250-500 nm wavelength range.
• Varied yeast cell concentrations from 6 x 10^6 to 2 x 10^8 cells/ml.

Main Results:

• Identified key absorption peaks at 310, 350, 400, and 427 nm.
• Observed a significant, non-linear red shift in the 427 nm absorption band with increasing yeast concentration.
• Noted saturation in the red shift behavior at concentrations above 5 x 10^7 cells/ml.
• Found non-linear variations in the half-peak bandwidth of the 427 nm peak.

Conclusions:

• Monitoring the 427 nm absorption band parameters provides a reliable method for quantifying yeast cell concentrations.
• The developed optical sensor demonstrates high sensitivity due to the n/n(+) interface.
• This approach could be integrated into spectrometric microsystems for fast, quantitative analysis in bio-samples, particularly for the food industry.