Functional performance of a bi-layered chitosan-nano-hydroxyapatite osteochondral scaffold: a pre-clinical tribological study.

Osteochondral grafts are used for repair of focal osteochondral lesions. Autologous grafts are the gold standard treatment; however, limited graft availability and donor site morbidity restrict use. Therefore, there is a clinical need for different graft sources/materials which replicate natural cartilage function.

Development and in vitro assessment of a bi-layered chitosan-nano-hydroxyapatite osteochondral scaffold.

An innovative approach was developed to engineer a multi-layered chitosan scaffold for osteochondral defect repair. A combination of freeze drying and porogen-leaching out methods produced a porous, bioresorbable scaffold with a distinct gradient of pore size (mean = 160-275 μm). Incorporation of 70 wt% nano-hydroxyapatite (nHA) provided additional strength to the bone-like layer.

Evaluating the cytotoxicity of Ge-Sb-Se chalcogenide glass optical fibres on 3T3 mouse fibroblasts.

cancer detection based on the mid-infrared molecular fingerprint of tissue is promising for the fast diagnosis and treatment of suspected cancer patients. Few materials are mid-infrared transmissive, even fewer, which can be converted into functional, low-loss optical fibres for non-invasive testing. Chalcogenide-based glass optical fibres are, however, one of the few.

Preclinical biological and physicochemical evaluation of two-photon engineered 3D biomimetic copolymer scaffolds for bone healing.

A major challenge in orthopedics is the repair of large non-union bone fractures. A promising therapy for this indication is the use of biodegradable bioinspired biomaterials that stabilize the fracture site, relieve pain and initiate bone formation and healing. This study uses a multidisciplinary evaluation strategy to assess immunogenicity, allergenicity, bone responses and physicochemical properties of a novel biomaterial scaffold.

In vitro cellular testing of strontium/calcium substituted phosphate glass discs and microspheres shows potential for bone regeneration.

Phosphate-based glasses (PBGs) are ideal materials for regenerative medicine strategies because their composition, degradation rates, and ion release profiles can easily be controlled. Strontium has previously been found to simultaneously affect bone resorption and deposition. Therefore, by combining the inherent properties of resorbable PBG and therapeutic activity of strontium, these glasses could be used as a delivery device of therapeutic factors for the treatment of orthopaedic diseases such as osteoporosis.

Effect of boron addition on the thermal, degradation, and cytocompatibility properties of phosphate-based glasses.

In this study eight different phosphate-based glass compositions were prepared by melt-quenching: four in the (P2O5)45-(CaO)16-(Na2O)15-x -(MgO)24-(B2O3) x system and four in the system (P2O5)50-(CaO)16-(Na2O)10-x -(MgO)24-(B2O3) x , where x = 0,1, 5 and 10 mol%. The effect of B2O3 addition on the thermal properties, density, molar volume, dissolution rates, and cytocompatibility were studied for both glass systems. Addition of B2O3 increased the glass transition (T(g)), crystallisation (T(c)), melting (T(m)), Liquidus (T(L)) and dilatometric softening (T(d)) temperature and molar volume (V(m)).

Development of an elastic cell culture substrate for a novel uniaxial tensile strain bioreactor.

Bioreactors can be used for mechanical conditioning and to investigate the mechanobiology of cells in vitro. In this study a polyurethane (PU), Chronoflex AL, was evaluated for use as a flexible cell culture substrate in a novel bioreactor capable of imparting cyclic uniaxial tensile strain to cells. PU membranes were plasma etched, across a range of operating parameters, in oxygen.

Topographical and chemical effects of electrochemically assisted deposited hydroxyapatite coatings on osteoblast-like cells.

A recently commercialised hydroxyapatite electrochemically assisted chemical deposition technique (BoneMaster) has been shown to induce increased bone apposition; whether this response is caused by the surface topography or chemistry is unknown. An in-vitro examination using human osteoblast-like cells was performed on a series of BoneMaster-coated surfaces. The chemistry was separated from the topography using a thin gold coating; Thermanox coverslips were used as a control.

Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5.

Mechanical properties of epidermal cells of whole living roots of Arabidopsis thaliana: an atomic force microscopy study.

The knowledge of mechanical properties of root cell walls is vital to understand how these properties interact with relevant genetic and physiological processes to bring about growth. Expansion of cell walls is an essential component of growth, and the regulation of cell wall expansion is one of the ways in which the mechanics of growth is controlled, managed and directed. In this study, the inherent surface mechanical properties of living Arabidopsis thaliana whole-root epidermal cells were studied at the nanoscale using the technique of atomic force microscopy (AFM).

Influence of screw holes and gamma sterilization on properties of phosphate glass fiber-reinforced composite bone plates.

Polymers prepared from polylactic acid (PLA) have found a multitude of uses as medical devices. For a material that degrades, the main advantage is that an implant would not necessitate a second surgical event for removal. In this study, fibers produced from a quaternary phosphate-based glass (PBG) in the system 50P2O5-40CaO-5Na2O-5Fe2O3 were used to reinforce PLA polymer.

Mono-functional aminosilanes as primers for peptide functionalization.

When covalently attaching biomolecules to surfaces such as titanium, trifunctional silanes are commonly used as primers to produce surface amine groups. However, these primed surfaces are rarely uniform in structure due to networking of the silane. Mono-functional aminosilanes may result in more uniform structures, although their long-term stability and effect on osteoblast cell responses are possible issues for orthopedic applications.

In vitro study of hydroxyapatite-based photocurable polymer composites prepared by laser stereolithography and supercritical fluid extraction.

The fabrication of three-dimensional (3-D) structures using computer-controlled ultraviolet (UV) photopolymerization of acrylates (laser stereolithography) often results in the trapping of residual unreacted monomer and initiator. These residuals can leach from the finished structure and affect the biological response of cells and tissues. Thus the potential applications of these structures for tissue engineering have not been fully realized.

The effect of different surface morphology and roughness on osteoblast-like cells.

Increased magnitude of biomaterial surface roughness and micromachined-grooved surfaces has both been shown to stimulate osteoblast activity, but have not been compared in the same study quantitatively. A series of titanium alloy (Ti6Al4V) samples were prepared using simple machining techniques to undertake such a comparison. Samples were either grit blasted (Gb) or shot peened (Sp) to give random discontinuities, or silicon carbide ground (SiC) to produce ordered grooves.

Human osteoblast cell spreading and vinculin expression upon biomaterial surfaces.

Any biomaterial implanted within the human body is influenced by the interactions that take place between its surface and the surrounding biological milieu. These interactions are known to influence the tissue interface dynamic, and thus act to emphasize the need to study cell-surface interactions as part of any biomaterial design process. The work described here investigates the relationship between human osteoblast attachment, spreading and focal contact formation on selected surfaces using immunostaining and digital image processing for vinculin, a key focal adhesion component.

In vitro assessment of cell penetration into porous hydroxyapatite scaffolds with a central aligned channel.

There is a clinical need for synthetic scaffolds that promote bone regeneration. A common problem encountered when using scaffolds in tissue engineering is the rapid formation of tissue on the outer edge of the scaffold whilst the tissue in the centre becomes necrotic. To address this, the scaffold design should improve nutrient and cell transfer to the scaffold centre.

Comparison of environmental scanning electron microscopy with high vacuum scanning electron microscopy as applied to the assessment of cell morphology.

The efficacy of conventional high vacuum scanning electron microscopy (SEM), environmental SEM (ESEM), and confocal laser scanning microscopy techniques in the assessment of cell-material interactions is compared. Specific attention is given to the application of these techniques in the assessment of the early morphological response of human osteoblast-like cells cultured on titanium dioxide. The processing of cells cultured for conventional high vacuum SEM leads to the loss of morphological features that are retained when using ESEM.

Use of a novel carbon fibre composite material for the femoral stem component of a THR system: in vitro biological assessment.

A novel, low elastic modulus femoral component for THR has been developed using a composite of polyetheretherketone and carbon fibre. The objectives of this study were to investigate human osteoblast-like cell and macrophage responses to this material in vitro. Cells were grown on composite discs and controls.

Cytotoxicity of glutaraldehyde crosslinked collagen/poly(vinyl alcohol) films is by the mechanism of apoptosis.

Collagen has been investigated as a potential natural biomaterial, because of its occurrence in the extracellular matrix. Collagen requires crosslinking in this context, by reagents that are often cytotoxic. Glutaraldehyde is one such agent that is potentially cytotoxic.

Protein adsorption and human osteoblast-like cell attachment and growth on alkylthiol on gold self-assembled monolayers.

Protein adsorption and growth of primary human osteoblasts on self-assembled monolayers of alkylthiols on gold (SAMs) with carboxylic acid and hydroxyl and methyl termini were investigated. Single-component SAMs and SAMs patterned by photolithographic techniques were used. Cell growth on patterned SAMs demonstrated preferences for one pattern region in all combinations of alkylthiols, with the hierarchical preference COOH > OH > CH(3).