title: Probing poly(N-isopropylacrylamide-co-butylacrylate)/cell interactions by atomic force microscopy.
abstract: Poly(N-isopropylacrylamide) based hydrogels have been proposed as cell culture supports in cell sheet engineering. Toward this goal, we characterized the poly(N-isopropylacrylamide-co-butylacrylate) copolymer thermo-sensitivity and the cell/copolymer interactions above and below the copolymer lower critical solution temperature. We did that by direct force measurements at different temperatures using an atomic force microscope with either a polystyrene or a glass microbead as probes. We used a copolymer-coated microbead to measure adhesion after a short contact time with a single fibroblast in culture. Statistical analysis of the maximum adhesion force and the mechanical work necessary to separate the probe from the cell surface confirmed the hydrophilic/hydrophobic behavior of poly(N-isopropylacrylamide-co-butylacrylate) as a function of temperature in the range 20-37°C and, consequently, a reversible increase/decrease in cell adhesion with the copolymer. As control experiments we measured interactions between uncoated microbeads with the copolymer hydrogel or cells as well as interaction of the Poly(N-isopropylacrylamide) homopolymer with cells. These results show the potential of an assay based on atomic force microscopy for an in situ and quantitative assessment of cell/substrate interactions and support the use of poly(N-isopropylacrylamide-co-butylacrylate) copolymer as an efficient culture substrate in cell sheet engineering.
authors.affiliation: Department of Informatics Bioengineering, Robotics and System Engineering (DIBRIS), University of Genova, Via Opera Pia, 13, Genova, Italy; Grupo Ciencia de Materiales. Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín, Colombia; Grupo Ingeniería de Tejidos y Terapia celular Facultad de Medicina Laboratorio Terapia celular y Biobanco, IPS Universitaria, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín, Colombia.
authors.forename: Becerra
authors.initials: B
authors.lastname: Natalia
authors.forename: Andrade
authors.initials: A
authors.lastname: Henry
authors.forename: López
authors.initials: L
authors.lastname: Betty
authors.forename: Restrepo Luz
authors.initials: RL
authors.lastname: Marina
authors.forename: Raiteri
authors.initials: R
authors.lastname: Roberto
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000818:Animals; D051379:Mice; D018625:Microscopy, Atomic Force / Q000379:methods*; D015335:Molecular Probes; D041681:NIH 3T3 Cells
chemical_list: D000180:Acrylic Resins; D015335:Molecular Probes; C583911:poly(N-isopropylacrylamide-co-butylacrylate)
keywords: atomic force microscopy; cell adhesion; cell sheet engineering; cell/substrate interaction; thermo-sensitive polymer hydrogel