Preparation Possibilities and Examination of Calcium alginate UHMWPE blends
Abstract
Previous researches were made on UHMWPE (Ultra-High-Molecular-Weight-Polyethylene) based implant material and its fusion with Ca-alginate. New methods were made for preparing UHMWPE-Ca-alginate blends. If the coating Ca-alginate salt can be achieved on the surface of UHMWPE, it might lead to an implant material which could promote the bone formation. Earlier results show that we can make the coating layer on the polymer powder surface. Our new approach is to modify the method we made earlier, and this way the alginate layer can withstand washing and sterilization as it’s shown in the paper. We also realized that the layer slowly can give off Ca2+ ions which can be absorbed with specific cells. Since we modified the surface structure of the UHMWPE samples we carried out wear testing of the new prepared samples. All of these measurements and experiments have been done as preparative ones to make one time real prosthetic material.
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Introduction
Previous research was carried out based on the work of Jian-Ping Wang, Xing-Xiang-Zhang, Xue-Chen Wang (1). As we had earlier experienced with UHMWPE implant materials, by modifying the surface properties of it using acrylate type monomersits wear resistance was enhanced, it was interesting to evaluate if further surface modifying would improve the biocompatibility of the prosthetic material (2).
We had a previous surface modification method experience with methyl-methacrylate monomer (MMA) (3,4) which didn’t work with the hydrophillic alginate material. So after that we worked powder type of UHMWPE raw material. We made basic experiments with GUR 4210 UHMWE powder to form an alginate layer which could trap calcium from calcium solutions; we also have determined the optimal sequence of the treatments, and the necessity of etching the UHMWPE powder (5).
We used GUR 1020 UHMWPE powder for all of our experiments and we made two methods for making insoluble alginate layers. After preparation of the samples, morphological examinations, Ca2- ion extraction tests and wear tests were carried out (6,7,8)
Conclusion
The completed treatments proved they are suitable for fixating Calcium(II) ions on UHMWPE polymer surfaces. The polymer powder is capable to bind with the surface of the sodium alginate and is able to hold the created calcium alginate during processing and after the 35 kGy irradiation process. The radiation did not affect the behavior and properties of the alginate salts. The presence of calcium alginate on the surface was proved with great confidence using FTIR measurements. The wear tests and the extraction experiments are still in progress.
It was also proved, that the created Ca-alginate layers can release the bonded Ca(II) ions in time which under specific conditions can promote bone growth or at least make the implants more tissue and bone friendly, thus more acceptable by their surroundings. It is also important to do further experimental work on the kinetics of the Ca(II) ion release process, and to work on the promotion of calcium uptake into the neighboring tissues.
All of these measurements and experiments were done as preparative ones to make one time real prosthetic material. We worked with GUR 1020 UHMWPE powder and we also would like to carry out these experiments on a production UHMWPE hip joint cup to check whether the alginate layer is able to add to the surface.