Preparation of bioactive composite material for bone tissue repair

master's thesis

• Title (croatian): Priprava bioaktivnog kompozitnog materijala za popravak koštanog tkiva
• Author: Nikolina Šandrk
• Mentor: Marica Ivanković (mentor)
• Committee member: Marica Ivanković (predsjednik povjerenstva)
• Committee member: Anamarija Rogina (član povjerenstva)
• Committee member: Hrvoje Ivanković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2016-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Tissue engineering and regenerative medicine has been providing exciting technologies for the development of functional macroporous biomaterials (scaffolds) aimed to repair and regenerate damaged bone. Biodegradability, high mechanical strength, osteointegration and formation of bony tissue are properties required for such materials. Bioactive synthetic hydrogels have emerged as promising materials because they can provide molecularly tailored biofunctions and adjustable mechanical properties, as well as an extracellular matrix-like microenvironment for cell growth and tissue formation. In this study, injectable composite hydrogels were designed to be used in bone tissue regeneration. To mimic the mineralogical and organic components of the natural extracellular matrix of bone, hydroxyapatite and a tyramine conjugate of gelatin were combined to manufacture the composites. Gelatin conjugate is able to crosslink through the oxidative coupling of tyramine molecules, catalyzed by hydrogen peroxide and horseradish peroxidase, via non-cytotoxic conditions. The effect of various amounts of in situ synthesized hydroxyapatite in gelatin-tyramine solutions was investigated by analysing the morphology and physical properties of the resulting hydrogels. Characterization of hydroxyapatite within the hydrogels was performed by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The morphology of prepared hydrogel was characterized using scanning electron microscope. Shear storage and loss moduli were measured as a function of gelation time, while the rheological properties of the completely crosslinked hydrogels were tested by changing the shear strain and frequency. Results have confirmed adequate formation of apatite within the gelatin-tyramine matrix. Microscopy reveals better dispersion of hydroxyapatite crystals by in situ synthesis than in control samples prepared by classical blending. The rheological testing has shown no significant effect of hydroxyapatite content on the gelation time with respect to pure gelatin-tyramine matrix, while shear strength of the different hydogels seems to needs to be further investigated.

Abstract (croatian)

Inženjerstvo tkiva i regenerativna medicina pružaju mnoge razvijene tehnologije za razvoj funkcionalnih nadomjestaka, kojima je cilj popravak ili regeneracija koštanog tkiva ili organa. Karakteristike koje takvi materijali trebaju ispunjavati su biorazgradivost, visoka mehanička čvrstoća, osteointegracija i stvaranje koštanog tkiva. Kao obečavajući materijali javili su se bioaktivni, sintetski hidrogelovi zbog mogućeg pružanja molekularno prilagođenih biofunkcija, podesivih mehaničkih svojstava te pogodni mikrookoliš za razvoj stanica i stvaranje tkiva. U ovom radu, pripravljeni su kompozitni hidrogelovi za popravak koštanog tkiva. Za imitaciju kemijskog sastava prirodne kosti, kao komponente su se koristili hidroksiapatit i želatina modificirana tiraminom. Stvaranje injekcijskih hidrogelova postignuto je djelovanjem enzima peroksidase uz pomoć vodikova peroksida. Istraživan je utjecaj različite koncentracije in situ sintetiziranog hidroksiapatita istraživan je na morfologiji i fizikalnim svojstvima hidrogela. Prisutnost hidroksiapatita u hidrogelovima potvrđena je karakterizacijskim tehnikama uključujući rendgensku difrakcijsku analizu i infracrvenu spektorskopiju s Fourijerovim transformacijama. Morfologija pripravljenih hidrogelova istražena je pretražnim elektronskim mikroskopom. Smični modul pohrane i gubitka mjereni su u ovisnosti o vremenu geliranja, dok su reološka svojstva potpuno umreženog gela ispitana promjenom smične deformacije i frekvencije. Rezultati karakterizacije potvrdili su stvaranje apatitne faze unutar matrice modificirane želatine. Mikroskopska analiza ukazuje na bolju disperziju hidroksiapatita sintetiziranog in situ u odnosu na kontrolne uzorke dobivene klasičnim umiješavanjem. Reološka ispitivanja pokazala su da ne postoji utjecaj različitog udjela hidroksiapatita na vrijeme geliranja u odnosu na tiraminom modificiranu želatinu, dok se utjecaj reoloških parametara na smičnu čvrstoću različitih hidrogelova treba detaljnije istražiti.

• Keywords: injectable hydrogels; in situ hydroxyapatite; gelatin-tyramine; gelation time; rheology
• Keywords (croatian): injekcijski hidrogelovi; in situ hidroksiapatit; tiraminom modificirana želatina; vrijeme geliranja; reologija
• Language: english
• URN:NBN: urn:nbn:hr:149:587254
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Repository: Repository of Faculty of Chemical Engineering and Technology University of Zagreb
• Created on: 2017-11-25 10:40:53