Adhesion force analysis using atomic force microscopy clearly revealed for the first time the mechanism underlying the specific binding between a titanium surface and ferritin possessing the sequence of Ti-binding peptide in its N-terminal domain. Our results proved that the specific binding is due to double electrostatic bonds between charged residue and surface groups of the substrate. Furthermore, it is also demonstrated that the accretion of surfactant reduces nonspecific interactions, dramatically enhancing the selectivity and specificity of Ti-binding peptide.

Ultra thin poly(N-isopropylacrylamide) (PIPAAm) modified glass coverslips (PIAPAm-CS) using electron beam irradiation exhibited a clear relationship between the polymer thickness and thermal cell adhesion/detachment behavior. The polymer thickness dependency and the characteristic of ultra thin PIPAAm layer, has been illustrated in terms of the molecular motion of the modified PIPAAm chains. PIPAAm-CSs surfaces with various area-polymer densities and thicknesses were characterized by AFM and protein adsorption assay. The newly obtained results gave a further insight into the illustration. Finally, the future application of intelligent surfaces was discussed for fabricating tissue and organ.

Temperature-responsive intelligent surfaces, prepared by the modification of an interface mainly with poly(N-isopropylacrylamide) and its derivatives, have been investigated. Such surfaces exhibit temperature-responsive hydrophilic/hydrophobic alterations with external temperature changes, which, in turn, result in thermally modulated attachment and detachment with cells. The advantage of this system is that cells cultured on such temperature-responsive surfaces can be recovered as single cells and/or confluent cell sheets, while keeping the deposited extracellular matrix intact, simply by lowering the temperature without conventional enzymatic treatment. Here, we focus and compare various methods of producing temperature-responsive surfaces for controlling cell attachment/detachment. Spontaneous cell attachment and detachment using several types of temperature-responsive surfaces are mentioned and various effects, such as film thickness and polymer conformation, are discussed. In addition, the development of the next generation of temperature-responsive surfaces using modifications of the polymer coating to allow for rapid cell recovery is summarized.

Thermoresponsive surfaces are prepared via a spin-coating method with a block copolymer consisting of poly(N-isopropylacrylamide) (PIPAAm) and poly(butyl methacrylate) (PBMA) on polystyrene surfaces. The PBMA block suppresses the removal of deposited PIPAAm-based polymers from the surface. The polymer coating affects the temperature-dependent cellular behavior of the surfaces with respect to protein adsorption. By adjusting layer thicknesses, PBMA-b-PIPAAm-coated surfaces are optimized to regulate the adhesion/detachment of cells by temperature changes. Thus, thermoresponsive polymer-coated surfaces are able to harvest contiguous cell sheets with their basal extracellular matrix proteins.