Because of the advances in the scaffolds fabrication techniques, bone tissue engineering is increasingly becoming a method of choice for the development of viable substitutes for skeletal reconstruction. The scaffolds designed for bone tissue-engineering applications should be three-dimensional (3D), highly porous and interconnected to support cell attachment as well as proliferation. They should have sufficient structural integrity matching the mechanical properties of native tissue. They should provide suitable pore size distribution for transportation of nutrients and wastes. The scaffolds should offer ideal and critical micro-environment so that they can function as an artificial extra-cellular matrix (ECM) onto which cells attach, grow, and form new tissues. Most available scaffold fabrication methods, such as solvent casting, sol-gel, freeze drying are either limited to producing scaffolds with simple geometry, or depend on indirect casting method for scaffold fabrication. These traditional scaffold fabrication methods result in structures of random internal architecture. Recently, it is proven that cells are inherently sensitive to their surroundings. The more the culturing environment of cell is similar to natural tissue the more the cell attachment and proliferation. For this, more biomimetic environments must be created. Various solid freeform fabrication (SFF) techniques including 3D printing, selective laser sintering, multi-phase jet solidification, and fused deposition modeling (FDM) have been used successfully to manufacture advanced tissue scaffolds with specific designed properties. The scaffolds manufactured using SFF methods have 100% interconnectivity and the highly oriented porosity of these scaffolds can easily be controlled by optimizing the processing. Electrophoretic deposition (EPD) is known to be one of the most effective and efficient techniques to assemble fine particles. This technique has received huge attention due to its simplicity in setup, low equipment cost and the capability to form complex shapes and patterns in room temperature. Recently, its application in biomedical area have also been widely explored. However, the feasibility of using EPD for fabricating scaffolds that can mimic the architecture of bone tissue and can be comparable with expensive SFF methods has not been investigated yet. In this study, an attempt has done to survey on possibility of using (EPD) technique as a method to design and fabricate chitosan/Bioglass composite scaffolds mimicking the Haversian system of compact bone. Materials that were used in this study was chitosan and Bioglass 45S5®. Bioglass 45S5® is a well-known commercial composition of bioactive glasses with high bioactivity is proven to enhance formation of hydroxyapatite in physiological fluids and can be readily attached to the bone in relatively short time. However, it suffers from low mechanical properties. It is suggested to be composited by a high biocompatible hydrogel as a matrix or supporter. Derived from chitin, chitosan is a unique biopolymer that exhibits outstanding properties, beside biocompatibility and biodegradability. Most of these peculiar properties arise from the presence of primary amines along the chitosan backbone. As a consequence, this polysaccharide is a relevant candidate in the field of biomaterials, especially for tissue engineering. In this regards, firstly parameters such as voltage, pH, Bioglass to chitosan ratio on quality of deposited composite has been explicitly investigated. Secondly, after optimizing the parameters, by exploiting oriented patterned porous aluminum substrates with pore size similar to that of Haversian system, composite scaffolds with highly oriented microchannels has fabricated. Scanning electron microscope (SEM) images shows very good distribution of Bioglass particle embedded in chitosan matrix. In-vitro analysis shows dissolution of Bioglass particles in Phosphate Bovine Saline (PBS) solution. in Simulated Body Fluid (SBF), weight gain measurements and X-ray diffraction (XRD) analysis reveals the crystallization of a calcium phosphate dihydrate with formula CaHPO4.2H2O which increases in amount and size by soaking time and also accompanying a small decrease in pH of SBF solution.
Gli scaffold progettati per la rigenerazione del tessuto osseo dovrebbero essere tridimensionali (3D), altamente porosi e interconnessi per sostenere l'adesione cellulare e la proliferazione. Essi dovrebbero avere sufficiente integrità strutturale corrispondente alle proprietà meccaniche del tessuto nativo. Essi dovrebbero avere adeguata distribuzione delle dimensioni dei pori per il trasporto di sostanze nutritive e di scarto. Gli scaffold dovrebbero offrire un micro-ambiente ideale e critico in modo che possano funzionare come matrice extracellulare artificiale (ECM) su cui le cellule possano aderire, crescere e formare nuovi tessuti. La maggior parte dei metodi di fabbricazione disponibili, come l’evaporazione da solvente, sol-gel, freeze drying sono o limitate a produrre scaffold con geometria semplice, o dipendono dallo stampo utilizzato. Queste metodi di fabbricazione tradizionali si traducono in strutture con architettura interna casuale. Varie solide tecniche di fabbricazione prive di stampo (SFF), tra cui la stampa 3D, sinterizzazione laser selettiva, multi-fase di solidificazione del getto, e la modellazione a deposizione fusa (FDM) sono stati utilizzati con successo per la produzione di scaffold avanzati per l’ingegneria del tessuti proprietà specifiche. I scaffold realizzati con metodi SFF mostrano 100% di interconnettività e hanno una porosità altamente orientata che può essere facilmente controllata ottimizzando l'elaborazione. La deposizione elettroforetica (EPD) è nota per essere una delle tecniche più efficaci ed efficienti per assemblare particelle fini. Questa tecnica ha ricevuto grande attenzione grazie alla sua semplicità, il bassa costo delle apparecchiature e la capacità di creare forme complesse e modelli a temperatura ambiente. Recentemente, la sua applicazione in campo biomedico è stata ampiamente esplorato. Tuttavia, la possibilità di utilizzare EPD per la realizzazione di scaffold che possano mimare l'architettura del tessuto osseo, con risultati e paragonabili con costosi metodi SFF non è stato ancora studiata. In questo studio, si è cercato di rilevare la possibilità di utilizzare la tecnica (EPD) come metodo per progettare e fabbricare scaffold compositi chitosano / Bioglass mimando il sistema Haversian dell'osso compatto. I materiali che sono stati utilizzati in questo studio sono chitosano e Bioglass 45S5®. Bioglass 45S5® è un noto prodotto commerciale composito da vetri bioattivi ad elevata bioattività capaci aumentare la formazione di idrossiapatite in fluidi fisiologici e di attaccarsi all'osso in tempi relativamente brevi. Tuttavia, possiede basse proprietà meccaniche. Si suggerisce di mescolarlo ad un altro idrogel biocompatibile come matrice o sostenitore. Derivato da chitina, il chitosano è un biopolimero unico che presenta proprietà eccellenti, tra cue accanto biocompatibilità e biodegradabilità. La maggior parte di queste proprietà peculiari derivano dalla presenza di ammine primarie lungo la catena del chitosano. Di conseguenza, questo polisaccaride è un ottimo candidato nel campo dei biomateriali, in particolare per l'ingegneria tissutale. A questo proposito, in primo luogo parametri quali la tensione, il pH, il rapporta Bioglass/chitosano sulla qualità depositato è stato esplicitamente studiato. In secondo luogo, dopo l'ottimizzazione dei parametri, sfruttando substrati di alluminio con prosita orientate e con dimensioni dei pori simili a quella del sistema Haversian, sono stati fabbricati scaffold compositi con microcanali altamente orientati ha fabbricato. Le immagini ottenute con microscopio elettronico a scansione (SEM) mostrano una molta buona distribuzione di particelle Bioglass incorporate nella matrice di chitosano. Analisi in vitro mostrano la dissoluzione delle particelle di Bioglass in soluzione salina (PBS). In soluzione fisiologica (SBF), le misurazioni del guadagno di peso e la diffrazione a raggi X (XRD) rivelano la cristallizzazione di fosfato di calcio diidrato con formula CaHPO4.2H2O che aumenta in quantità e dimensioni in base al tempo di immersione che determina una piccola diminuzione della pH delle soluzione SBF.
Electrophoretic deposition of bioglass chitosan composites for bone tissue engineering applications
SOLEIMANZADE, MEHDI
2015/2016
Abstract
Because of the advances in the scaffolds fabrication techniques, bone tissue engineering is increasingly becoming a method of choice for the development of viable substitutes for skeletal reconstruction. The scaffolds designed for bone tissue-engineering applications should be three-dimensional (3D), highly porous and interconnected to support cell attachment as well as proliferation. They should have sufficient structural integrity matching the mechanical properties of native tissue. They should provide suitable pore size distribution for transportation of nutrients and wastes. The scaffolds should offer ideal and critical micro-environment so that they can function as an artificial extra-cellular matrix (ECM) onto which cells attach, grow, and form new tissues. Most available scaffold fabrication methods, such as solvent casting, sol-gel, freeze drying are either limited to producing scaffolds with simple geometry, or depend on indirect casting method for scaffold fabrication. These traditional scaffold fabrication methods result in structures of random internal architecture. Recently, it is proven that cells are inherently sensitive to their surroundings. The more the culturing environment of cell is similar to natural tissue the more the cell attachment and proliferation. For this, more biomimetic environments must be created. Various solid freeform fabrication (SFF) techniques including 3D printing, selective laser sintering, multi-phase jet solidification, and fused deposition modeling (FDM) have been used successfully to manufacture advanced tissue scaffolds with specific designed properties. The scaffolds manufactured using SFF methods have 100% interconnectivity and the highly oriented porosity of these scaffolds can easily be controlled by optimizing the processing. Electrophoretic deposition (EPD) is known to be one of the most effective and efficient techniques to assemble fine particles. This technique has received huge attention due to its simplicity in setup, low equipment cost and the capability to form complex shapes and patterns in room temperature. Recently, its application in biomedical area have also been widely explored. However, the feasibility of using EPD for fabricating scaffolds that can mimic the architecture of bone tissue and can be comparable with expensive SFF methods has not been investigated yet. In this study, an attempt has done to survey on possibility of using (EPD) technique as a method to design and fabricate chitosan/Bioglass composite scaffolds mimicking the Haversian system of compact bone. Materials that were used in this study was chitosan and Bioglass 45S5®. Bioglass 45S5® is a well-known commercial composition of bioactive glasses with high bioactivity is proven to enhance formation of hydroxyapatite in physiological fluids and can be readily attached to the bone in relatively short time. However, it suffers from low mechanical properties. It is suggested to be composited by a high biocompatible hydrogel as a matrix or supporter. Derived from chitin, chitosan is a unique biopolymer that exhibits outstanding properties, beside biocompatibility and biodegradability. Most of these peculiar properties arise from the presence of primary amines along the chitosan backbone. As a consequence, this polysaccharide is a relevant candidate in the field of biomaterials, especially for tissue engineering. In this regards, firstly parameters such as voltage, pH, Bioglass to chitosan ratio on quality of deposited composite has been explicitly investigated. Secondly, after optimizing the parameters, by exploiting oriented patterned porous aluminum substrates with pore size similar to that of Haversian system, composite scaffolds with highly oriented microchannels has fabricated. Scanning electron microscope (SEM) images shows very good distribution of Bioglass particle embedded in chitosan matrix. In-vitro analysis shows dissolution of Bioglass particles in Phosphate Bovine Saline (PBS) solution. in Simulated Body Fluid (SBF), weight gain measurements and X-ray diffraction (XRD) analysis reveals the crystallization of a calcium phosphate dihydrate with formula CaHPO4.2H2O which increases in amount and size by soaking time and also accompanying a small decrease in pH of SBF solution.| File | Dimensione | Formato | |
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thesis final.pdf
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https://hdl.handle.net/10589/121341