Lubricant-infused surfaces (LIS) are created by modifying chemical and physical properties of surfaces with aim of lowering surfaces energy where designed surface will possess liquid-repelling behaviors under low tilting angles. LIS has great potential to be applied on implantable devices due to it is stable anti-biofouling properties under fluidic environment. However, a few studies have reported that the existing research on implant surface uses complicated methods and high cost fabrication to create LIS on titanium implants. Furthermore, current limitation of LIS coatings for titanium implants lies in the lack of tissue integration and cell interaction. As a result, LIS prevents both bacteria and bone cells from adhering to the interface between implant and natural bone. This unselective blocking is problematic for titanium implants used in orthopaedic surgery when devices are required to possess tissue integration properties to facilitate long term fixation in the human body. The overall objective of this thesis is to apply LIS on titanium surfaces via a chemical modification technique and simultaneously integrate bio-functional features onto LIS to promote osteoblasts adhesion. In this project, chitosan and collagen were used to facilitate cell adhesion. To start with, three methods were used to immobilize chitosan on titanium to obtain the desired bio-functional LIS coatings: (1) LIS on top of (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) crosslinked chitosan; (2) LIS on dip-coated chitosan; (3) LIS generated from GPTMS and Trichloro(1H,1H,2H,2H-perfluorooctyl) silane (TPFS) mixed silanes modified titanium surface followed by chitosan functionalization. Among these modification techniques, method (3) showed optimal anti-biofouling and osseointegration properties. Since collagen is well known for increase of cell interactions, it was used via mixed silanes functionalization method. Finally, the properties were compared with chitosan coated surfaces. During tests, surface wettability was measured, anti-biofouling properties and osseointegration was examined with staphylococcus aureus and SAOS-2 cells, respectively. We found that chitosan modified surfaces using method (3) not only significantly increased cell adhesion in comparison with the other two modification methods, but also dramatically decreased bacterial adhesion compared to collagen coated LIS on titanium. Although collagen has better cell adhesion properties than chitosan, collagen coated surface significantly decreased antibiofouling properties. In conclusion, bio-functional lubricant-infused titanium surfaces created by chemical vapor deposition (CVD) method with mixed silanes is a feasible and straightforward method to immobilize biomaterials and stabilize the lubricant layer on titanium substrates. Chitosan coated LIS on titanium prevents bacterial adhesion and simultaneously promotes targeted cell binding. / Thesis / Master of Applied Science (MASc) / Biofouling is a major issue in implantable titanium devices such as coronary stents, plates and nails, and formation of biofilm on implants can lead to infection and failure of the device. Biofilms formed by bacterial adhesion could be resistant to antibiotics and can provoke a series of inflammatory response. Recent advances in anti-biofouling surface treatment has resulted in designing supper slippery lubricant-infused omniphobic surfaces which are inspired from the Nepenthes pitcher plant. Liquid which is tethered on the surface offers a stable liquid interface, repelling both aqueous and organic liquids meanwhile showing excellent bacteria repellency. Lubricant-infused surfaces (LIS) are resistant towards biofilm formation and produce a stable surface that prevent non-specific adhesion. As a result of this repellent properties, LIS also repels the adhesion of desired biomolecules and cells such as osteoblasts, bone cells and growth factors which are essential factors for bone recovery at the implant-bone interface. Our motivation in this thesis is to create a lubricant-infused coating on titanium surfaces that possesses both bio-functional and blocking features. We designed surfaces that decrease implant infection caused by non-specific adhesion and simultaneously promote targeted binding of biomolecules and cells that will increase osseointegration of the implant to enable long-term fixation.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25530 |
| Date | January 2020 |
| Creators | Zhang, Yuxi |
| Contributors | Didar, Tohid, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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