Fabrication and characterization of three-dimensional poly(ether- ether- ketone)/-hydroxyapatite biocomposite scaffolds using laser sintering.

The ability to have precise control over porosity, scaffold shape, and internal pore architecture is critical in tissue engineering. For anchorage-dependent cells, the presence of three-dimensional scaffolds with interconnected pore networks is crucial to aid in the proliferation and reorganization of cells. This research explored the potential of rapid prototyping techniques such as selective laser sintering to fabricate solvent-free porous composite polymeric scaffolds comprising of different blends of poly(ether-ether-ketone) (PEEK) and hydroxyapatite (HA). The architecture of the scaffolds was created with a scaffold library of cellular units and a corresponding algorithm to generate the structure. Test specimens were produced and characterized by varying the weight percentage, starting with 10 wt% HA to 40 wt% HA, of physically mixed PEEK-HA powder blends. Characterization analyses including porosity, microstructure, composition of the scaffolds, bioactivity, and in vitro cell viability of the scaffolds were conducted. The results obtained showed a promising approach in fabricating scaffolds which can produce controlled microarchitecture and higher consistency.

Selective laser sintering of biocompatible polymers for applications in tissue engineering.

The ability to use biological substitutes to repair or replace damaged tissues lead to the development of Tissue Engineering (TE), a field that is growing in scope and importance within biomedical engineering. Anchorage dependent cell types often rely on the use of temporary three-dimensional scaffolds to guide cell proliferation. Computer-controlled fabrication techniques such as Rapid Prototyping (RP) processes have been recognised to have an edge over conventional manual-based scaffold fabrication techniques due to their ability to create structures with complex macro- and micro-architectures. Despite the immense capabilities of RP fabrication for scaffold production, commercial available RP modelling materials are not biocompatible and are not suitable for direct use in the fabrication of scaffolds. Work is carried out with several biocompatible polymers such as Polyetheretherketone (PEEK), Poly(vinyl alcohol) (PVA), Polycaprolactone (PCL) and Poly(L-lactic acid) (PLLA) and a bioceramic namely, Hydroxyapatite (HA). The parameters of the selective laser sintering (SLS) process are optimised to cater to the processing of these materials. SLS-fabricated scaffold specimens are examined using a Scanning Electron Microscope (SEM). Results observed from the micrographs indicate the viability of them being used for building TE scaffolds and ascertain the capabilities of the SLS process for creating highly porous scaffolds for Tissue Engineering applications.

Development of tissue scaffolds using selective laser sintering of polyvinyl alcohol/hydroxyapatite biocomposite for craniofacial and joint defects.

The growing interest in scaffold-guided tissue engineering (TE) to guide and support cell proliferation in the repair and replacement of craniofacial and joint defects gave rise to the quest for a precise technique to create such scaffolds. Conventional manual-based fabrication techniques have several limitations such as the lack of reproducibility and precision. Rapid prototyping (RP) has been identified as a promising technique capable of building complex objects with pre-defined macro- and microstructures. The research focussed on the viability of using the selective laser sintering (SLS) RP technique for creating TE scaffolds. A biocomposite blend comprising of polyvinyl alcohol (PVA) and hydroxyapatite (HA) was used in SLS to study the feasibility of the blend to develop scaffolds. The biocomposite blends obtained via spray-drying technique and physical blending were subjected to laser-sintering to produce test specimens. The SLS-fabricated test specimens were characterized using scanning electron microscopy and X-ray diffraction. The test specimens were also tested for bioactivity by immersing the samples in simulated body fluid environment. The results obtained ascertained that SLS-fabricated scaffolds have good potential for TE applications.

Scaffold development using selective laser sintering of polyetheretherketone-hydroxyapatite biocomposite blends.

In tissue engineering (TE), temporary three-dimensional scaffolds are essential to guide cell proliferation and to maintain native phenotypes in regenerating biologic tissues or organs. To create the scaffolds, rapid prototyping (RP) techniques are emerging as fabrication techniques of choice as they are capable of overcoming many of the limitations encountered with conventional manual-based fabrication processes. In this research, RP fabrication of solvent free porous polymeric and composite scaffolds was investigated. Biomaterials such as polyetheretherketone (PEEK) and hydroxyapatite (HA) were experimentally processed on a commercial selective laser sintering (SLS) RP system. The SLS technique is highly advantageous as it provides good user control over the microstructures of created scaffolds by adjusting the SLS process parameters. Different weight percentage (wt%) compositions of physically mixed PEEK/HA powder blends were sintered to assess their suitability for SLS processing. Microstructural assessments of the scaffolds were conducted using electron microscopy. The results ascertained the potential of SLS-fabricated TE scaffolds.

Solid freeform fabrication of three-dimensional scaffolds for engineering replacement tissues and organs.

Most tissue engineering (TE) strategies for creating functional replacement tissues or organs rely on the application of temporary three-dimensional scaffolds to guide the proliferation and spread of seeded cells in vitro and in vivo. The characteristics of TE scaffolds are major concerns in the quest to fabricate ideal scaffolds. This paper identifies essential structural characteristics and the pre-requisites for fabrication techniques that can yield scaffolds that are capable of directing healthy and homogeneous tissue development. Emphasis is given to solid freeform (SFF), also known as rapid prototyping, technologies which are fast becoming the techniques of choice for scaffold fabrication with the potential to overcome the limitations of conventional manual-based fabrication techniques. SFF-fabricated scaffolds have been found to be able to address most, if not all the macro- and micro-architectural requirements for TE applications. This paper reviews the application/potential application of state-of-the-art SFF fabrication techniques in creating TE scaffolds. The advantages and limitations of the SFF techniques are compared. Related research carried out worldwide by different institutions, including the authors' research are discussed.

Characterization of microfeatures in selective laser sintered drug delivery devices.

From initial applications in the fields of prosthesis, implants, surgery planning, anthropology, paleontology and forensics, the scope of rapid prototyping (RP) biomedical applications has expanded to include areas in tissue engineering (TE) and controlled drug delivery. In the current investigation, the feasibility of utilizing selective laser sintering (SLS) to fabricate polymeric drug delivery devices (DDDs) that are difficult to make using conventional production methods was studied. Two features, namely porous microstructure and dense wall formation, inherent in SLS fabricated parts were investigated for their potential roles in drug storage and controlling the release of drugs through the diffusion process. A study to determine the influence of key SLS process parameters on dense wall formation and porous microstructure of SLS fabricated parts was carried out. Composite-type DDDs incorporating dense wall and porous matrix features were designed and fabricated using SLS. The characteristics of the fabricated devices were investigated through microstructural examination and in vitro release tests carried out using a drug model or dye in a simulated body environment.