Two-Dimensional Micropatterns of Self-Assembled Poly(N-isopropylacrylamide) Microgels for Patterned Adhesion and Temperature-Responsive Detachment of Fibroblasts

摘要

Thermoresponsive poly(N-isopropyl acrylamide) (PNIPAM) microgels were patterned on polystyrene substrates via dip coating, creating cytocompatible substrates that provided spatial control over cell adhesion. This simple dip coating method, which exploits variable substrate withdrawal speeds form particle suspension formed stripes of densely-packed PNIPAM microgels, while spacings between the stripes contained sparsely-distributed PNIPAM microgels. The assembly of three different PNIPAM microgel patterns, namely patterns composed of 50 μm stripes/50 μm spacings, 50 μm stripes/100 μm spacings, and 100 μm stripes/100 μm spacings was verified using high-resolution optical micrographs and ImageJ analysis. PNIPAM microgels existed as monolayers within stripes and spacings, as revealed by atomic force microscopy (AFM). Upon cell seeding on PNIPAM micropatterned substrates, NIH3T3 fibroblast cells preferentially adhered within spacings to form cell patterns. Three days after cell seeding, cells proliferated to form confluent cell layers. The thermoresponsiveness of the underlying PNIPAM microgels was then utilized to recover fibroblast cell sheets from substrates simply by lowering the temperature, without disrupting the underlying PNIPAM microgel patterns. Harvested cell sheets similar to these have been used for multiple tissue engineering applications. Also, this simple, low cost, template-free dip coating technique can be utilized to micropattern multifunctional PNIPAM microgels, generating complex stimuli-responsive substrates to study cell-material interactions and allow drug delivery to cells in a spatially and temporally-controlled manners.