Thin polymer brush decouples biomaterial's micro-/nanotopology and stem cell adhesion

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Stem Cell Biology

Background:

• The surface characteristics of biomaterials, particularly polymers, critically influence human mesenchymal stem cell adhesion and behavior.
• Poly(ε-caprolactone) (PCL) scaffolds exhibit varied surface morphologies and roughness due to differing spherulitic superstructures, impacting cell interactions.
• Understanding these structure-property-cell behavior relationships is crucial for designing effective tissue engineering scaffolds.

Purpose of the Study:

• To investigate how varying surface morphologies of semicrystalline poly(ε-caprolactone) (PCL) scaffolds affect human mesenchymal stem cell adhesion and morphology.
• To determine if bioadhesive polymer brush coatings can decouple the influence of substrate topology from cell response.
• To establish a method for controlling stem cell behavior on biomaterial surfaces irrespective of underlying micro-/nanoscale topography.

Main Methods:

• Semicrystalline poly(ε-caprolactone) (PCL) substrates were fabricated with controlled crystallization conditions to yield diverse surface morphologies and roughness.
• Human mesenchymal stem cells were cultured on PCL substrates with varying spherulitic structures.
• Sub-100 nm bioadhesive polymer brush coatings of oligo(ethylene glycol) methacrylates were grafted onto PCL and functionalized with fibronectin.
• Cell adhesion and morphology were analyzed on both bare PCL substrates and those coated with polymer brushes.

Main Results:

• Stem cell morphology varied significantly in response to the different spherulite densities and sizes on the PCL substrates.
• Dense, sub-100 nm thick polymer brush coatings effectively determined stem cell response.
• The influence of the underlying substrate's micro-/nanoscale surface texture on cell behavior was decoupled by the polymer brush coatings.

Conclusions:

• Bioadhesive polymer brushes can effectively mask or override the effects of substrate surface topology on stem cell adhesion and behavior.
• This approach offers a powerful strategy to independently control cell responses on biomaterial scaffolds for tissue engineering applications.
• Polymer brushes provide a versatile platform for tuning cell-material interactions, independent of the inherent properties of the base scaffold material.