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Thin‐layer photodegradable polyrotaxane (PRX) gel‐immobilized surfaces were fabricated to investigate the photoregulation of surface properties. Photodegradable PRXs comprising α‐cyclodextrin as a cyclic molecule, poly(ethylene glycol) as a polymer axel, and bulky trithiocarbonate as a photolabile stopper molecule (PRX‐MTP) were utilized for the fabrication of thin‐layer gels. PRX‐MTP gels were prepared on the surface of the glasses, where the surfaces were treated with an isocyanate group‐containing silane coupling agent to allow the covalent immobilization of the PRX‐MTP gels. This PRX‐MTP gel layer was disappeared upon irradiation with ultraviolet (UV; 365 nm) or visible light (465 nm) for 2 h due to the photodegradation of PRX‐MTPs. The surface wettability and roughness were changed owing to the photodegradation of the PRX‐MTP gel layer. When cells were seeded on the PRX‐MTP gel surfaces, adhesion was not observed. However, visible light irradiation of the PRX‐MTP gel layer resulted in cell adhesion on the irradiated surfaces. Consequently, it was determined that the surface properties and cell adhesiveness of the PRX‐MTP gel surfaces could be regulated by visible light irradiation. The photodegradable PRX‐MTP gel surfaces could be utilized for research on cell patterning, cell function control, and advanced cell culture system. [ABSTRACT FROM AUTHOR]

The temperature‐dependent phase transition behavior of acetylated polyrotaxanes (PRXs) consisting of acylated α‐cyclodextrins threaded onto a poly(ethylene glycol) chain in an aqueous solution is investigated. Acetyl (Ac), propionyl (Pr), and butyryl (Bu) group‐modified PRXs with different degrees of substitution are synthesized to elucidate the effect of the alkyl chain length of the acyl groups on temperature responsivity. Ac‐PRXs, Pr‐PRXs, and Bu‐PRXs are dissolved in water and exhibit temperature‐dependent transmittance changes accompanied by coacervate formation. However, the temperature responsivity of acylated PRXs is seen in limited degree of substitution range (≈10%). The maximum degree of substitution to show temperature responsivity of acylated PRXs decreases with increasing alkyl chain length of the acyl groups. Transmittance measurements of acylated PRXs in the presence of urea reveal that the alkyl chain length of the acyl groups determines the predominant force involved in the temperature‐induced phase transition. During the temperature‐induced phase transition of Pr‐PRXs and Bu‐PRXs, hydrophobic interactions are predominant; however, hydrogen bond formation may occur in Ac‐PRXs. These fundamental findings related to acylated PRXs will facilitate the application of PRXs as thermoresponsive supramolecular materials. [ABSTRACT FROM AUTHOR]

In this paper, a cartilage acellular-matrix (CAM) is chosen as a biomaterial for an effective antiadhesive barrier to apply between injured tissue and healthy tissues or organs. CAM is cross-linked using glutaraldehyde to create a cross-linked CAM (Cx-CAM) film. Cx-CAM has higher elastic modulus and toughness and more hydrophobic surface properties than CAM before cross-linking. Small intestinal submucosa (SIS), cross-linked SIS (Cx-SIS) as a negative control, and Seprafilm as a positive control are used in an experiment as adhesion barriers. Human umbilical vein endothelial cells (HUVECs) on SIS, Cx-SIS, or in a culture plate get attached and effectively proliferate for 7 days, but Cx-CAM and Seprafilm allow for little or no attachment and proliferation of HUVECs, thus manifesting antiadhesive and antiproliferative effects. In animals with surgical damage to the peritoneal wall and cecum, Cx-CAM and Seprafilm afford little adhesion and negligible inflammation after seven days, as confirmed by hematoxylin and eosin staining and macrophage staining, in contrast to an untreated-injury model, SIS, or Cx-SIS film. Cx-CAM significantly suppresses the formation of blood vessels between the peritoneal wall and cecum, as confirmed by CD31 staining. Overall, the newly designed Cx-CAM film works well as an antiadhesion barrier and has better anti-tissue adhesion efficiency. [ABSTRACT FROM AUTHOR]