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Polyhedral oligomeric silsesquioxane (POSS)–poly(ethylene glycol) (PEG) hybrids as injectable biomaterials
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Materials in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Materials in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Materials in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Materials in Medicine)
2012 (English)In: Biomedical Materials, ISSN 1748-6041, E-ISSN 1748-605X, Vol. 7, no 3, 035013- p.Article in journal (Refereed) Published
Abstract [en]

One of the major issues with the currently available injectable biomaterials for hard tissue replacement is the mismatch between their mechanical properties and those of the surrounding bone. Hybrid bone cements that combine the benefits of tough polymeric and bioactive ceramic materials could become a good alternative. In this work, polyhedral oligomeric silsesquioxane (POSS) was copolymerized with poly(ethylene glycol) (PEG) to form injectable in situ cross-linkable hybrid cements. The hybrids were characterized in terms of their mechanical, rheological, handling and in vitro bioactive properties. The results indicated that hybridization improves the mechanical and bioactive properties of POSS and PEG. The Young moduli of the hybrids were lower than those of commercial cements and more similar to those of cancellous bone. Furthermore, the strength of the hybrids was similar to that of commercial cements. Calcium deficient hydroxyapatite grew on the surface of the hybrids after 28 days in PBS, indicating bioactivity. The study showed that PEG–POSS-based hybrid materials are a promising alternative to commercial bone cements.

Place, publisher, year, edition, pages
2012. Vol. 7, no 3, 035013- p.
National Category
Bio Materials Engineering and Technology
Research subject
Engineering Science with specialization in Materials Science
Identifiers
URN: urn:nbn:se:uu:diva-172865DOI: 10.1088/1748-6041/7/3/035013ISI: 000303667600013OAI: oai:DiVA.org:uu-172865DiVA: diva2:515916
Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Injectable Biomaterials for Spinal Applications
Open this publication in new window or tab >>Injectable Biomaterials for Spinal Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of injectable biomaterials is growing as the demands for minimally invasive procedures, and more easily applicable implants become higher, but their availability is still limited due to the difficulties associated to their design.

Each year, more than 700,000 vertebral compression fractures (VCF’s) are reported in the US and 500,000 VCF’s in Europe due to primary osteoporosis only. VCF’s can compromise the delicacy of the spinal canal and also cause back pain, which affects the patient’s quality of life. Vertebroplasty was developed in the 80’s, and has proven to be a safe minimally invasive procedure that can, quickly and sustainably, relieve the pain in patients experiencing VCF’s. However, biomaterials for vertebroplasty still have limitations. For instance, ceramic bone cements are difficult to distinguish from the bone using X-ray techniques. On the other hand, acrylic bone cements may cause adjacent vertebral fractures (AVF’s). Large clinical studies have indicated that 12 to 20% vertebroplasty recipients developed subsequent vertebral fractures, and that 41 to 67% of these, were AVF’s. This may be attributed to the load shifting and increased pressure on the adjacent endplates reached after vertebroplasty with stiff cements.

The primary aim of this thesis was to develop better injectable biomaterials for spinal applications, particularly, bone cements for vertebroplasty. Water-soluble radiopacifiers were first investigated to enhance the radiopacity of resorbable ceramic cements. Additionally, different strategies to produce materials that mechanically comply with the surrounding tissues (low-modulus bone cements) were investigated. When a suitable low-modulus cement was produced, its performance was evaluated in both bovine bone, and human vertebra ex vivo models.

In summary, strontium halides showed potential as water-soluble radiocontrast agents and could be used in resorbable calcium phosphates and other types of resorbable biomaterials. Conversely, linoleic acid-modified (low-modulus) cements appeared to be a promising alternative to currently available high-modulus cements. It was also shown that the influence of the cement properties on the strength and stiffness of a single vertebra depend upon the initial bone volume fraction, and that at low bone volume fractions, the initial mechanical properties of the vertebroplasty cement become more relevant. Finally, it was shown that vertebroplasty with low-modulus cements is biomechanically safe, and could become a recommended minimally invasive therapy in selected cases, especially for patients suffering from vertebral compression fractures due to osteoporosis.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 66 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1114
Keyword
injectable, biomaterials, bone cement, vertebral compression fractures, spine, radiopacity, minimally invasive treatment, low-modulus cement, oligomer, PMMA, calcium phosphate, vertebroplasty, bone
National Category
Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-215606 (URN)978-91-554-8854-3 (ISBN)
Public defence
2014-02-28, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2014-02-05 Created: 2014-01-15 Last updated: 2014-02-10

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Publisher's full texthttp://iopscience.iop.org/1748-605X/7/3/035013

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Engstrand, JohannaLópez, AlejandroEngqvist, HåkanPersson, Cecilia

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