BPS2026 – Probing cytoskeletal dynamics on tunable heparin/collagen bio-interfaces using QCM-D

Cytoskeletal motors, filaments, and crosslinkers exhibit emergent responses to mechanical changes within and around the ensemble. However, how their activity adapts to such environments remains poorly understood. Most in vitro studies use unmodified glass coverslips that are very stiff, so we engineered nanoscale surfaces with tunable mechanical properties via layer-by-layer (LbL) assembly of heparin and collagen (HEP/COL). Using the quartz crystal microbalance with dissipation (QCM-D), we characterized these surfaces, enabling a novel application of mechanically tunable substrates to study emergent cytoskeletal mechanics. We built up to six HEP/COL bilayers on glass coverslips, verified by Azure A dye adsorption. Fluorescence microscopy confirmed actin attachment to modified glass slides through adding a PEI coating on top of the final heparin layer. QCM-D frequency and dissipation shift measurements revealed that increasing the number of bilayers systematically alters surface thickness and viscoelasticity, as well as mechanical feedback from cytoskeletal activities on top of the bilayers. On one- versus three-bilayer surfaces, actin binding at the same concentration differed, as well as actomyosin activity within bundles of actin filaments. This platform provides a tunable system to probe how substrate mechanics regulate motor protein activity and cytoskeletal crosstalk.