ساخت و مشخصه يابي سيمان نانو كامپوزيتي متخلخل كلسيم فسفات

چكيده انگليسي :

118AbstractAn increase in the number of bone injuries consisted of bone defects and development ofminimally invasive surgeries have led to development of injectable biomaterials withenhanced bone regeneration ability The aim of present study was to fabricate porousnanocomposite of laponite LAP dexamethasone DEX calcium phosphate bone cement In the first step DEX was encapsulated with concentration of 2 mg ml into LAP nanodisksat different pHs 3 7 and 13 and the effects of pH changes were assessed on the DEXloading efficiency Moreover DEX release mechanism in both acidic and physiologicalenvironments was evaluated As prepared nanohybrids were evaluated using X raydiffraction scanning electron microscope transmission electron microscopy Fouriertransform infrared spectroscopy zeta potential and UV spectroscopy Moreover effects ofLAP DEX nanohybrids on the MG63 cell line behavior were studied In the second step calcium phosphate cement based on three calcium phosphate TCP 98 wt andhydroxyapatite HA 2 wt nanopowders as powder phase and a 2 5 wt Na2HPO4aqueous solution as liquid phase was fabricated and characterized In order to improve themechanical properties of calcium phosphate cement LAP DEX nanohybrids at differentconcentrations 0 5 1 2 and 3 wt was added into powder phase of cement and afteroptimization of LAP concentration based on mechanical and biological properties thenanocomposites were employed as drug delivery system for controlled release of DEX Inthe last step porous nanocomposite calcium phosphate cement was made using NaHCO3as foaming agent and the effects of its concentration on the mechanical and biologicalproperties of cement were evaluated Zeta potential and UV vis results revealed that inacidic condition DEX was loaded on the surface and interlayer space of LAP nanoplatesthrough hydrogen bonds and electrostatic forces Moreover release of DEX from LAPnanoplates at both environments occurred in a sustained manner Differently in acidiccondition due to the protonation of LAP surfaces the amount of released DEX wasincreased On the other hand the incorporation of LAP DEX nanohybrids upon 2 wt ledto significantly enhance in compression strength 1 4 times and elastic modulus 2 5times compared to pure bone cement Nevertheless more increasing of LAP DEX contentled to reduce in mechanical properties of the nanocomposite cement Moreover incorporation of foaming agent to powder phase of cement containing 2 LAP DEXnanohybrid resulted in the development of porous nanocomposite cement consisting of62 50 4 95 macropores Although macroporosity resulted a reduction in compressionstrength 10 times and elastic modulus 4 times of porous nanocomposite cementcompared to those of bulk nanocomposite cement they were still more than those of pureporous calcium phosphate cement Cell culture was performed on the both bulk and porousnanocomposite cements Results demonstrated that incorporation of LAP DEXnanohybrids led to improvement of MG63 cell proliferation adhesion and growthcompared to free LAP DEX samples Moreover results of drug release fromnanocomposite cements and porous nanocomposite cements displayed sustained release ofDEX from these carriers Finally porous nanocomposite of LAP DEX calcium phosphatebone cement might be used as filler for bone defects and facilitate the regeneration of boneformation Key words Calcium phosphate cement Laponite nanoplates Dexamethasone and mechanicalproperties

روزبهاني، مهران

ساخت و مشخصه يابي سيمان نانو كامپوزيتي متخلخل كلسيم فسفات - لاپونيت براي پر كردن عيوب استخواني

دگزامتازون و خواص مكانيكي , نمونه هاي سيماني