Upper critical solution temperature thermo-responsive polymer brushes and a mechanism for controlled cell attachment

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Surface Science

Background:

• Controlling cell attachment is crucial for applications like cell manufacture and regenerative medicine.
• Thermo-responsive polymers are widely used to modify surface properties.
• Existing systems often rely on Lower Critical Solution Temperature (LCST) polymers.

Purpose of the Study:

• To synthesize thermo-responsive polymer brushes with Upper Critical Solution Temperature (UCST) behavior on glass surfaces.
• To investigate the tunable phase transition temperatures (T_p) of these polymer brushes.
• To demonstrate the control of cell attachment and detachment using these novel surfaces.

Main Methods:

• Synthesis of poly(N-acryloyl glycinamide)-stat-poly(N-phenylacrylamide) (PNAGAm-PNPhAm) brushes with varying monomer ratios.
• Contact angle measurements to determine surface energies at different temperatures.
• Atomic Force Microscopy (AFM) to analyze polymer brush conformation.
• Cell culture studies using NIH-3T3 cells to assess attachment and detachment dynamics.

Main Results:

• Tunable phase transition temperatures (T_p) were achieved by adjusting monomer ratios.
• Polymer brushes were highly extended near T_p in physiological conditions.
• NIH-3T3 cells attached to collapsed brushes at 30 °C and detached from extended brushes at 37 °C.
• Cell attachment changes correlated with surface energy variations.

Conclusions:

• Novel UCST-type thermo-responsive polymer brushes enable temperature-controlled cell detachment, contrasting with established LCST paradigms.
• These materials offer a new strategy for manipulating cell attachment on surfaces.
• Potential applications include advanced cell manufacturing and regenerative medicine.