SlipO₂Chip - single-cell respiration under tuneable environments.

Area of Science:

• Biotechnology and Biomedical Engineering
• Cellular Respiration and Toxicology
• Microfluidics and Single-Cell Analysis

Background:

• Oxygen (O2) respiration is a key metric in toxicology and pharmacology, but current methods often overlook cellular heterogeneity by treating populations as uniform.
• Existing approaches segregate cells into control and exposure groups, limiting precise analysis, especially with small sample sizes.
• This lack of single-cell resolution hinders accurate investigation of chemical effects on cellular metabolism.

Purpose of the Study:

• To introduce SlipO2Chip, an innovative microfluidic platform for precise quantification of single-cell O2 respiration.
• To enable coordinated measurement of cellular O2 respiration in the absence and presence of chemical solutes.
• To overcome limitations in analyzing cellular responses in small or heterogeneous sample populations.

Main Methods:

• Development of a microfluidic platform (SlipO2Chip) using fused silica and borosilicate glass with O2-sensing optodes.
• Integration of a 3D-printed holder for controlled horizontal movement ('slipping') to manage fluid flow and cell exposure.
• Sequential measurement of single-cell O2 respiration before and after chemical exposure by coordinated microwell opening and closing.

Main Results:

• Demonstrated proof-of-concept by measuring the impact of 2-heptyl-4-quinolone (HHQ) on diatom (Ditylum brightwellii) O2 dark respiration at single-cell resolution.
• Observed a concentration-dependent decrease in per-cell O2 dark respiration, with a maximum reduction of 40.2% at HHQ concentrations >35.5 μM.
• Determined a half-maximal effective concentration (EC50) of 5.8 μM for HHQ, consistent with bulk respiration methods.

Conclusions:

• SlipO2Chip enables precise, sequential assessment of chemical effects on single-cell O2 metabolism, accounting for cell-to-cell variability.
• The platform is advantageous for research with limited sample volumes, such as clinical biopsies or rare microbial isolates.
• This technology enhances toxicological studies by providing high-resolution data on chemical exposure effects at the single-cell level.