Preparation of orthogonally functionalized surface using micromolding in capillaries technique for the control of cellular adhesion

This study presents a simple method for the fabrication of an orthogonal surface that can be applied for cell patterning without the need to immobilize specific adhesive peptides, proteins, or extracellular matrix (ECM) for cell attachment. Micromolding in capillaries (MIMIC) produced two distinctive regions. One region contained poly(ethylene glycol)–poly(d,l-lactide) diblock copolymer (PEG–PLA) designed to provide a biological barrier to the nonspecific binding of proteins and fibroblast cells. The other region was coated with polyelectrolyte (PEL) to promote the adhesion of biomolecules including proteins and cells. Resistance to the adsorption of proteins increased with the length of PEG and PLA chains because the longer PEG chain increased the PEG layer thickness and the longer PLA chain induced stronger interaction with the PEL surface. The PEG5k–PLA2.5k (20 mg/ml) was the most efficient candidate for the prevention of protein adhesion among the PEG–PLA copolymers examined. The orthogonal functionality of prepared surfaces having PEL regions and background PEG–PLA regions resulted in rapid patterning of biomolecules. Fluorescein isothiocyanate-tagged bovine serum albumin (FITC-BSA) and fibroblast cells successfully adhered to the exposed PEL surfaces. Although methods for cell patterning generally require an adhesive protein layer on the desired area, these fabricated surfaces without adhesive proteins provide a gentle microenvironment for cells. In addition, our proposed approach could easily control patterns, sizes, and shapes at micron scale.