Quasi-Spherical Cell Clusters Induced by a Polyelectrolyte Multilayer.

Area of Science:

• Biomaterials Science
• Cell Biology
• Surface Chemistry

Background:

• Polyelectrolyte multilayers (PEMUs) are versatile materials with tunable surface properties.
• Fibroblast behavior on biomaterials is crucial for tissue engineering and medical device applications.
• Understanding cell-substrate interactions is key to designing biocompatible surfaces.

Purpose of the Study:

• To investigate fibroblast attachment and behavior on PEMUs with varying surface charges.
• To identify the mechanisms underlying unusual cell adhesion patterns on specific PEMU surfaces.
• To explore potential applications of these PEMUs in controlling cell-surface interactions.

Main Methods:

• Fabrication of PEMUs using poly(diallyldimethylammonium) (PDADMA) and poly(styrene sulfonate) (PSS) under different salt concentrations.
• Culturing human fibroblasts on PEMUs with varied terminal layers (PDADMA or PSS) and salt conditions.
• Assessing cell attachment modes, morphology, viability, and surface properties (roughness, wetting, surface charge).

Main Results:

• PEMUs terminated with PDADMA were cytotoxic in high salt (1.0 M NaCl) but cytophilic in low salt (0.15 M NaCl).
• PSS-capped PEMUs generally showed poor cell adhesion, except for those fabricated under specific conditions (0.15 M NaCl build, 1.0 M NaCl PSS cap).
• These specific PSS-capped PEMUs induced fibroblast clustering with high subsequent cell viability upon replating, independent of substrate stiffness, roughness, or wetting.

Conclusions:

• Fibroblast behavior on PEMUs is highly dependent on surface charge and fabrication conditions.
• A novel cell-clustering behavior was observed on specific PSS-capped PEMUs, linked to a strong negative surface charge.
• This behavior suggests a mechanism involving prevention of protein adsorption, impacting cell adhesion and mechanotransduction, offering new avenues for biomaterial design.