The mechanical properties of guidewires
Stiffness is always one of two factors that determine frictional resistance. The other factor, the coefficient of friction, depends on the surface characteristics. Teflon coating reduces the sliding friction to one-half, and a hydrophilic plastic coat to about one-sixth compared with steel.
Plastic-coated guide wire for hepatic arteriography.
A guide wire made of a superelastic alloy coated with hydrophilic polymer has been developed for superselective catheterization in hepatic arteriography. In this study, the new wire was tested in 15 patients and a conventional spring wire was used in 25. Catheterization of the proper or more peripheral hepatic arteries was successful in 93.3% of cases in which the new wire was used versus 76.0% in which the conventional spring wire was used. Moreover, the frequency of complications, such as spasm and subintimal injury, was reduced from 28.0% to 6.7%.
Engineering bio-inks for 3D bioprinting cell mechanical microenvironment
Three-dimensional (3D) bioprinting has become a promising approach to construct­ing functional biomimetic tissues for tissue engineering and regenerative medicine. In 3D bioprinting, bio-inks are essential for the construction of cell microenviron­ment, thus affecting the biomimetic design and regenerative efficiency. Mechanical properties are one of the essential aspects of microenvironment, which can be char­acterized by matrix stiffness, viscoelasticity, topography, and dynamic mechanical stimulation. With the recent advances in functional biomaterials, various engineered bio-inks have realized the possibility of engineering cell mechanical microenviron­ment in vivo. In this review, we summarize the critical mechanical cues of cell micro­environments, review the engineered bio-inks while focusing on the selection princi­ples for constructing cell mechanical microenvironments, and discuss the challenges facing this field and the possible solutions for them.