Effects of surface functionalization and physical constraints of poly (dimethylsiloxane) on cellular behaviors
Date of Issue2017-09-05
School of Mechanical and Aerospace Engineering
Mammalian cell behaviors are highly regulated by the complex cell microenvironments. In vitro models with precise manipulation of cell-substrate interactions can provide realistic insights into the chemical and topographical signals which critically affect cell functions. Poly(dimethylsiloxane) (PDMS) based systems are increasingly used in in vitro cell studies due to several advantages such as low cost, mechanical viability and convenience of rapid prototyping of cellular/subcellular environments. However, the high surface hydrophobicity and low surface reactivity of PDMS surfaces impose serious practical limitations in long-term studies of complex yet therapeutically significant behaviors such as the mesenchymal stem cell (hMSCs) and neuronal cell systems. To address these critical problems, a silanization based chemical modification of PDMS surfaces was employed against the traditional approaches, for covalent immobilization of extracellular matrix (ECM) proteins. The resulting modification promoted stable adhesion, highly spread morphology and viability of hMSCs with stronger cell sheet formation which positively affected cell differentiation. The strategy could be successfully applied to facilitate long-term culture and osteogenic differentiation within PDMS micro-chip. Moreover, the inclusion of hybrid physical micro-features further enhanced hMSC adhesion and differentiation. Eventually, the ECM proteins relevant in nascent neuron development were immobilized by silanization route, which resulted in a healthy neurite density and morphology. Additionally, diverse physical signals in neuronal cell vicinity was studied on micro-fabricated geometrical arrays of varying angularity/curvature which critically affected neurite growth, branching and directional commitment. Taken together, a tunable model was developed to study the independent and synergistic influences of both chemical and physical cues on both cell types. The simple, reproducible and adaptable system devised in this work, could be readily employed in strategic design of cell instructive bio-materials and interfaces to promote tissue regeneration as well as to understand the intricacies and abnormalities associated with cell development.