A polyelectrolyte-functionalized siloxane biointerface for BV2 microglial culture

Microglia are mechanosensitive cells whose in vitro responses are influenced by the mechanical and chemical properties of the culture interface. We developed BEASTS (Bio-Engineered Adhesive Siloxane-based Tunable Stiffness), a compliant Sylgard 527-based biointerface functionalised by plasma-assisted layer-by-layer deposition of PDAC/SPS polyelectrolyte bilayers. Representative AFM force-indentation traces demonstrate a strong qualitative mechanical contrast between BEASTS and tissue-culture polystyrene (TCPS), while contact-angle, roughness, XPS, film-thickness, zeta-potential and 11-day stability measurements support formation of the PDAC/SPS multilayer. BV2 cells were evaluated over 11 days using direct cell counting and an MTT assay of cellular metabolic activity. Analysis at the independent-culture-preparation level identified significant substrate × GM-CSF × day interactions for both MTT signal and cell accumulation, indicating that BEASTS-versus-TCPS differences depended on cytokine supplementation and culture time rather than representing a uniform substrate effect. Day-11 qRT-PCR showed treatment-combination-associated differences in ITGAM, CX3CR1, NOS2, PTGS2, PPARG and TGM2 expression. Because BEASTS and TCPS differ in multiple interface properties and the qRT-PCR design lacked TCPS without GM-CSF, these findings are interpreted as associations with the complete BEASTS culture interface rather than evidence of a stiffness-specific mechanism or definitive microglial phenotype transition.