Background-Free Mid-Infrared Photothermal Microscopy via Single-Shot Measurement of Thermal Decay

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Spectroscopy

Background:

• Mid-infrared photothermal (MIP) microscopy offers high sensitivity and resolution for biological imaging.
• Water absorption in the mid-infrared spectrum creates significant background noise, masking low-concentration analyte signals.
• Existing MIP techniques struggle to differentiate between water background and desired molecular signals.

Purpose of the Study:

• To develop a novel MIP measurement technique for effective background suppression in biological samples.
• To differentiate between water background signals and intracellular analyte signals based on their unique photothermal dynamics.
• To enhance the detection sensitivity of low-concentration molecules in biological systems using MIP microscopy.

Main Methods:

• Implementation of a single-shot, time-resolved MIP measurement.
• Analysis of distinct photothermal decay dynamics between water background and intracellular signals.
• Application of two-component exponential fitting to separate and remove background absorption.

Main Results:

• Demonstrated significant differences in thermal decay times between water background and intracellular signals.
• Successfully differentiated and suppressed water background absorption in both fingerprint and cell-silent windows.
• Preserved and enhanced the detection of desired intracellular signals despite high water content.

Conclusions:

• The developed time-resolved MIP method effectively suppresses water background noise.
• This technique significantly improves the detection of low-concentration molecules in biological imaging.
• Single-shot time-resolved MIP microscopy provides a robust approach for sensitive biological analysis.