Mohd Izzat Hassan

Bioactivity assessment of poly( ε -caprolactone)/hydroxyapatite electrospun fibers for bone tissue engineering application

Electrospinning is useful for fabricating nanofibrous structure with different composition and morphologies. It offers great advantages through its geometrical structure and biomimetic property, which can provide a suitable environmental site for cell growth. The fiber diameter is entangled by the concentration of PCL with some adjustment of parameters during electrospinning process. PCL with lower concentration had bead structure while higher concentration had smooth fiber. The incorporation of nanoparticle hydroxyapatite (nHA) into poly(e-caprolactone) fiber was studied. The fiber diameter of PCL was increased with the addition of nHA. Composition of fiber at lower concentrations of PCL and nHA into the polymer produced fiber with a homogenous distribution of nHA in PCL fiber with less agglomeration. The immersion of PCL/nHA fiber in simulated body fluid (SBF) had bonelike apatite layer on its surface while PCL showed no results. PCL/nHA showed high water uptake and had improved wettability compared to PCL alone, suggesting that PCL/nHA fibers were more hydrophilic than PCL fiber.

Fabrication of nanohydroxyapatite/poly(caprolactone) composite microfibers using electrospinning technique for tissue engineering applications

Tissue engineering fibrous scaffolds serve as three-dimensional (3D) environmental framework by mimicking the extracellular matrix (ECM) for cells to grow. Biodegradable polycaprolactone (PCL) microfibers were fabricated to mimic the ECM as a scaffold with 7.5% (w/v) and 12.5% (w/v) concentrations. Lower PCL concentration of 7.5% (w/v) resulted in microfibers with bead defects. The average diameter of fibers increased at higher voltage and the distance of tip to collector. Further investigation was performed by the incorporation of nanosized hydroxyapatite (nHA) into microfibers. The incorporation of 10% (w/w) nHA with 7.5% (w/v) PCL solution produced submicron sized beadless fibers. The microfibrous scaffolds were evaluated using various techniques. Biodegradable PCL and nHA/PCL could be promising for tissue engineering scaffold application.

Chitosan-Based Nanocomposite Scaffolds for Tissue Engineering Applications

This article reports the fabrication of three-dimensional porous chitosan and hydroxyapatite (HA)/chitosan composite scaffolds by the thermally induced phase separation (TIPS) technique, for bone tissue engineering. Different amounts of HA nanoparticles (10%, 20%, and 30% g/g) were added to the chitosan solution to produce HA/chitosan composite scaffolds of varying compositions. The morphology and pore structure of the scaffolds vis-à-vis composition were characterized using scanning electron microscopy (SEM) and an energy dispersive X-ray (EDX). Both pure chitosan and HA/chitosan composite scaffolds were highly porous and had interconnected pores. The pore sizes ranged from several micrometers to a few hundred micrometers. The HA nanoparticles were well dispersed and physically coexisted with chitosan in the composite scaffolds. However, some agglomeration of HA nanoparticles was observed on the surface of pore walls when a relatively large amount of HA was used. The composite 3D scaffolds are very promising for use in bone tissue engineering application.

Composite Synthetic Scaffolds for Tissue Engineering and Regenerative Medicine

The aim of tissue engineering is to develop cell, construct, and living system technologies to restore the structures and functions of damaged or degenerated tissues. Scaffolds are supporting materials used in tissue engineering applications to repair or restore damaged tissues. Biomaterials are used to fabricate scaffolds. There are different types of biomaterials including biopolymers, bioceramics and biodegradable metals. Biomaterials have to be biocompatible and nontoxic. To fabricate scaffold, appropriate biomaterial has to be chosen according to the desired characteristics and application of the scaffold. This chapter reviews different types of biomaterials for different tissue engineering applications.

Production of hydroxyapatite(HA) nanoparticle and HA/PCL tissue engineering scaffolds for bone tissue engineering

Hydroxyapatite (HA) is biological apatite has close similarity of composition with human bone and teeth. Thus, it has been used in biomedical application in orthopedic and dentistry. The wet slurry of HA was successfully produced by mixing an acetone solution of calcium nitrate 4-hydrate with an aqueous solution of ammonium phosphate and ammonium carbonate with control pH of 11. The nano-emulsion was kept in freezer about one day and after that was kept in freeze drying machine about three days to obtain dry HA powder with low degree of agglomeration. The nanoparticles were studied under scanning electron microscopy (SEM). Energy Dispersive Xray (EDX) showed the spectrum of elements in HA with Ca/P ratio close to biological bone. The polycaprolactone (PCL) and hydroxyapatite/polycaprolactone (HA/PCL) composite scaffolds were produced using thermally induced phase separation (TIPS) technique. The scaffolds were studied under SEM and it was observed that both types of scaffolds had porous structures. The pore sizes of HA/PCL scaffold was slightly decreased compared to PCL scaffold. The HA nanoparticles were successfully produced and the PCL and HA/PCL scaffolds showed promises for bone tissue engineering application.

Electrospun Polycaprolactone (PCL) and PCL/ nano-hydroxyapatite (PCL/nHA)-based nanofibers for bone tissue engineering application

Ceramic/polymer composite scaffolds have been widely investigated for repairing and regeneration of damaged bone tissues. In this report, the electrospinning technique was chosen to fabricate two different kinds of fibrous scaffolds which were Polycaprolactone (PCL) and PCL/nano-hydroxyapatite (PCL/nHA). Several characterizations such as morphologies of fibers, average diameter and water uptake property were done. Based on the results obtained, PCL/nHA fibers with the average diameters of 521.10nm exhibited good water uptake properties and were more hydrophilic than pure PCL fibers. PCL/nHA-based nanofibers could be potential in bone tissue regeneration.

Scaffold Fabrication Protocols

Development of scaffolds in tissue engineering applications is growing in a fast pace. Scaffolds play a pivotal role in scaffold-based tissue engineering. The scaffolds must possess some important characteristics. Scaffolds should be biocompatible, should have appropriate porosity and porous microstructure and proper surface chemistry to allow cell attachment, proliferation and differentiation. Scaffolds should possess adequate mechanical properties and controlled biodegradability. There are many techniques available to fabricate scaffolds including freeze drying, electrospinning and rapid prototyping. Some of these techniques have gained much attention due to their versatility. This chapter points up the protocols for the fabrication and characterization of appropriate scaffolds for tissue engineering using biopolymers and composite biomaterials.

Fabrication and Characterization of Polymer and Composite Scaffolds Using Freeze-Drying Technique

This chapter reports the emulsion freezing/freeze-drying technique for the formation of three dimensional scaffolds. Composite scaffolds based on biodegradable natural polymer and osteoconductive hydroxyapatite (HA) nanoparticles can be promising for a variety of tissue engineering (TE) applications. This study addressed the fabrication of three dimensional (3D) porous composite scaffolds composed of HA and chitosan fabricated via thermally induced phase separation and freeze-drying technique. The scaffolds produced were subsequently characterized in terms of microstructure, porosity, mechanical property. In vitro degradation and in vitro biological evaluation were also investigated. The scaffolds were highly porous and had interconnected pore structures. The pore sizes ranged from several microns to a few hundred microns. The incorporated HA nanoparticles were well mixed and physically co-existed with chitosan in composite scaffold structures. The addition of 10 % (w/w) HA nanoparticles into chitosan enhanced the compressive mechanical properties of composite scaffold compared to pure chitosan scaffold. In vitro degradation results in phosphate buffered saline (PBS) showed slower uptake properties of composite scaffolds. Moreover, the scaffolds showed positive response to mouse fibroblast L929 cells attachment. Overall, the findings suggest that HA/chitosan composite scaffolds could be suitable for TE applications.

Fabrication of Polymer and Composite Scaffolds Using Electrospinning Techniques

This chapter reports the electrospinning technique for the formation of nano and microfibers. Due to the ability to fabricate fibrous scaffolds with micro and nano-scale properties, electrospinning technique has received much interest. Poly(caprolactone) (PCL) fibrous scaffolds with micro and nano-scale fibers and surface-porous fibers have not been explicitly investigated. In this study, the results of modulating the factors on processing route on nanofibrous scaffold morphology were investigated. 10 and 13 % w/v of PCL/dichloromethane (DCM) or chloroform was used at different flow rate and applied voltage. The result shows that 13 % w/v of PCL/chloroform produced better fibers. The fibrous scaffolds had two different ranges of fiber diameters. Average fiber diameter in the higher range was 4.52 μm while average fiber diameter in the lower range was 440 nm. In vitro degradation study suggested slow degradability of PCL electrospun fibers. This chapter also reports the fabrication of hydroxyapatite/PCL microfibers and their characteristics.