Chemically Induced pH Perturbations for Analyzing Biological Barriers Using Ion-Sensitive Field-Effect Transistors.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Analytical Chemistry

Background:

• Potentiometric pH measurements are vital for bioanalysis but passive sensing faces challenges in signal interpretation and stability.
• Existing methods struggle with the complex spatiotemporal pH dynamics influenced by biological activities.
• Ion-sensitive field-effect transistors (ISFET) offer potential for microenvironmental pH monitoring.

Purpose of the Study:

• To develop an active pH sensing method for analyzing cell barriers in vitro.
• To overcome limitations of passive pH sensing, such as signal drift and interpretation difficulties.
• To enable molecular-level analysis of cell-nanomaterial interactions.

Main Methods:

• Utilized an ion-sensitive field-effect transistor (ISFET) with cells cultured on its gate insulator.
• Employed a superfusion system to introduce temporary pH perturbations using weak acids (NH4+) or bases (CH3COO-).
• Analyzed induced proton dynamics reflecting biomembrane permeability and interactions with exogenous reagents.

Main Results:

• The active pH sensing method demonstrated sensitivity to transmembrane pore formation as small as a proton (H+).
• Successfully analyzed cell barrier properties and interactions at the molecular level.
• Established a novel modality for cell analysis using ISFET technology.

Conclusions:

• The developed active pH sensing method provides a stable and interpretable approach for cell barrier analysis.
• This technique offers high sensitivity for detecting molecular-level changes, including pore formation.
• Potential applications include nanomedicine, drug screening, and tissue engineering.