Browsing by Subject "Calcium phosphate"

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Open Access
Bioinspired organic-inorganic composite materials
(2016-05) Eren, Egemen Deniz
Nature has been an inspiration and information source for scientists over centuries, for developing new materials. A great e ort has been spent in order to understand biological materials. The biomineralization process is observed in the nature and it creates perfectly hierarchical structures, which give the living organisms extraordinary properties. It is also a fact that along with the nature; living creatures such as nacre and bacteria employ biomineralization in order to produce minerals for protection and navigation purposes. In addition, bone is a composite material which protects the internal organs and provides mechanical support and is a result of biomineralization process. In this thesis, the biomineralization processes of living organisms and bone is mimicked by employing peptide amphiphile nano bers as templates for inorganic materials production. Glutamic acid residue is used in order the mimic the negatively charged domains for proteins, which play crucial roles in biomineralization process in some organisms and bone. In order to mimic the structure of sea shell, which is composed of calcium carbonate, and bone, which consists of calcium phosphate, relevant mineral solutions were used. In conclusion, when organic and inorganic components are used together, they demonstrate superior mechanical properties, when compared to organic molecules alone.
Open Access
Chemical and topographical modification of PHBV surface to promote osteoblast alignment and confinement
(John Wiley & Sons, Inc., 2008) Kenar, H.; Kocabas, A.; Aydınlı, Atilla; Hasirci, V.
Proper cell attachment and distribution, and thus stronger association in vivo between a bone implant and native tissue will improve the success of the implant. In this study, the aim was to achieve promotion of attachment and uniform distribution of rat mesenchymal stem cell-derived osteoblasts by introducing chemical and topographical cues on poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV) film surfaces. As the chemical cues, either alkaline phosphatase was covalently immobilized on the film surface to induce deposition of calcium phosphate minerals or fibrinogen was adsorbed to improve cell adhesion. Microgrooves and micropits were introduced on the film surface by negative replication of micropatterned Si wafers. Both chemical cues improved cell attachment and even distribution on the PHBV films, but Fb was more effective especially when combined with the micropatterns. Cell alignment (<10° deviation angle) parallel to chemically modified microgrooves (1, 3, or 8 μm groove width) and on 10 μm-thick Fb lines printed on the unpatterned films was achieved. The cells on unpatterned and 5 μm-deep micropitted films were distributed and oriented randomly. Results of this study proved that microtopographies on PHBV can improve osseointegration when combined with chemical cues, and that microgrooves and cell adhesive protein lines on PHBV can guide selective osteoblast adhesion and alignment.