title: Bio-inspired enhancement of friction and adhesion at the polydimethylsiloxane-intestine interface and biocompatibility characterization.
abstract: An active navigation of self-propelled miniaturized robot along the intestinal tract without injuring the soft tissue remains a challenge as yet. Particularly in this case an effective control of the interfacial friction and adhesion between the material used and the soft tissue is crucial. In the present study, we investigated the frictional and adhesive properties between polydimethylsiloxane (PDMS, microscopically patterned with micro-pillar arrays and non-patterned with a flat surface) and rabbit small intestinal tract using a universal material tester. The friction coefficient-time plot and adhesive force-time plot were recorded during the friction test (sliding speed: 0.25mm/s; normal loading: 0.4N) and adhesion test (preloading: 0.5N; hoisting speed: 2.5×10-3mm/s). In addition, biocompatibility of the PDMS samples was characterized in terms of cell morphology (scanning electron microscope) and cell cytotoxicity (alamarBlue assay) using human vascular endothelial cells (HUVECs). The results demonstrated that the interfacial friction (0.27 vs 0.19) and adhesion (34.9mN vs 26.7mN) were greatly increased using microscopically patterned PDMS, in comparison with non-patterned PDMS. HUVECs adhered to and proliferated on non-patterned/microscopically patterned PDMS very well, with a relative cell viability of about 90% following seeding at 1d, 3d, and 5d. The favorable enhancement of the frictional and adhesive properties, along with the excellent biocompatibility of the microscopically patterned PDMS, makes it a propitious choice for clinical application of self-propelled miniaturized robots.
authors.affiliation: State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China. Electronic address: zhanghyu@tsinghua.edu.cn.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Mathematics and Physical Science, Faculty of Science, University of Technology Sydney, New South Wales 2007, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Vasilescu
authors.affiliation: Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D004129:Dimethylpolysiloxanes; C013830:baysilon
keywords: Adhesion; Biocompatibility; Biotribology; Friction; Surface texture