Fine Adjustment of Interfacial Potential between pH-Responsive Hydrogels and Cell-Sized Particles

Area of Science:

• Biomaterials Science
• Soft Matter Physics
• Surface Chemistry

Background:

• Stimulus-responsive hydrogels are crucial for dynamic cell-material interactions.
• Understanding interfacial potentials is key to controlling cell behavior on substrates.
• ABA triblock copolymer micelles offer tunable properties for biomaterial applications.

Purpose of the Study:

• To quantitatively determine interfacial potentials between cell-sized particles and pH-responsive hydrogels.
• To investigate the influence of pH on these interfacial potentials.
• To assess the potential of these hydrogels as biocompatible substrates for dynamic cell interactions.

Main Methods:

• Utilized microinterferometry and Reflection Interference Contrast Microscopy (RICM) to measure particle-substrate interactions.
• Employed ABA triblock copolymer micelles (PMPC-PDPA-PMPC) as the hydrogel material.
• Analyzed experimental data using a modified Ross and Pincus model, incorporating gravitational, lubrication, and van der Waals forces.

Main Results:

• Quantitatively determined interfacial potentials, showing a systematic reduction in potential minima height (⟨Δh⟩) with increasing pH (7.0-7.8).
• Observed a concomitant increase in potential curvature (V″(Δh)) with increasing pH.
• Elastic moduli derived from potential curvature agreed well with Atomic Force Microscopy measurements.

Conclusions:

• The study successfully quantified interfacial potentials between particles and pH-responsive hydrogels.
• Demonstrated the ability to fine-tune gel elasticity and interfacial potential around physiological pH.
• Highlighted the potential of these triblock copolymer hydrogels as promising biocompatible substrates for dynamic cell-material interactions.