Polyetheretherketone (PEEK) is a biocompatible material widely used in spinal and craniofacial implants, with potential use in percutaneous implants. However, its inertness prevents it from forming a tight seal with the surrounding soft tissue, which can lead to infections and implant failure. Conversely, the surface chemistry of percutaneous organs (i.e., teeth) helps establish a strong interaction with the epithelial cells of the contacting soft tissues, and hence a tight seal, preventing infection. The seal is created by adsorption of basement membrane (BM) proteins, secreted by epithelial cells, onto the percutaneous organ surfaces. Here, we aim to create a tight seal between PEEK and epithelial tissues by mimicking the surface chemistry of teeth. Our hypothesis is that collagen I, the most abundant tooth protein, enables integration between the epithelial tissue and teeth by promoting adsorption of BM proteins. To test this, we immobilized collagen I via EDC/NHS coupling on a carboxylated PEEK surface modified using diazonium chemistry. We used titanium alloy (Ti-6Al-4V) for comparison, as titanium is the most widely used percutaneous biomaterial. Both collagen-modified PEEK and titanium showed a larger adsorption of key BM proteins (laminin, nidogen, and fibronectin) compared to controls. Keratinocyte epithelial cell viability on collagen-modified PEEK was twice that of control PEEK and ∼1.5 times that of control titanium after 3 days of cell seeding. Both keratinocytes and fibroblasts spread more on collagen-modified PEEK and titanium compared to controls. This work introduces a versatile and biomimetic surface modification technique that may enhance PEEK−epithelial tissue sealing with the potential of extending PEEK applications to percutaneous implants, making it competitive with titanium.
According to the directive of the European Union on the incorporation of biodiesel in fuels by 2020, the aim of this study is to contribute to understanding the feasibility of using ester methyl of waste cooking oil (EMWC Oil) in diesel engine. However, biodiesel is a renewable environmental friendly fuel consisting of esters methyl of vegetable oil, generally produced by transesterification reaction of oils seeds and animal fats. In this study, biodiesel synthesis by transesterification of waste cooking oil has been realized. The biodiesel is produced via transesterification reaction using methanol (6:1 molar ration), 0.5% of sodium hydroxide at 55°C for 60 min of duration and Stirring speed of 200 rpm. The application of design experiment methodology for response surface has allowed us to determine the optimum factors influencing on the transesterification reaction efficiency. The synthesized biodiesel has been subject to several characterizations in order to evaluate its quality by comparing its different physicochemical properties with those described in international norms. Keywords Biodiesel • Transesterification • Response surface methodology 24.1 Introduction Depletion of the fossil fuels and environment degradation mainly caused by vehicles emissions, lead to search an alternative fuel that is available, renewable, technically feasible, biodegradable, economically profitable and environmentally friendly [1, 2]. Biodiesel is one of one potential candidate to replace conventional diesel fuel.
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