Search

Wound management following surgery is challenging because of high rates of wound infections due to the rise of antibiotic-resistant bacteria and increased risk of allergic reactions. On the other hand, several factors play significant roles in wound healing such as surgical techniques used, aging, oxygenation and pre-existing medical conditions such as diabetes. The application of wound dressings plays critical roles in wound healing and infectious prevention. The choice of proper wound dressing depends on the type of a wound. This chapter will comprehensively discuss advances in surgical wound dressings for soft and hard tissues with a focus on proper preparations techniques and characterizations. Different post-operative wound healing monitoring procedures will also be covered.

© 2017, Australian Ceramic Society. The marine species are especially suited for the production of bioceramic nano-powders with natural methods for their use in the biomedical field. However, there are only very limited studies regarding the production and synthesis of hydroxyapatite (HAp) and tricalcium phosphate (TCP) nanomaterials from the marine structures. The structure of coral is very unique due to its similarity to bone because their structure consists of calcium carbonate that is the precursor for the synthesis of HAp. In this research, nano-bioceramic powders were produced from the organ pipe red coral (Tubipora musica) by two different simple chemical conversion methods under two different synthesis methods rather than the common hydrothermal method. The main advantages of these two methods are that they are simple and more economical in comparison to other methods used. All samples were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The size and shape of converted particles and structures were controlled by adjusting the calcination temperature and most importantly the agitation-mixing rate. According to XRD and SEM results, it can be concluded that the nano-scale monetite and other calcium phosphate powders were successfully obtained by these simple methods although retained calcium carbonate also observed due to the partial conversion.

© 2016 Coral skeletons can regenerate replacement human bone in nonload-bearing excavated skeletal locations. A combination of multiscale, interconnected pores and channels and highly bioactive surface chemistry has established corals as an important alternative to using healthy host bone replacements. Here, we highlight how coral skeletal systems are being remolded into new calcified structures or synthetic corals by biomimetic processes, as places for the organized permeation of bone tissue cells and blood vessels. Progressive technologies in coral aquaculture and self-organization inorganic chemistry are helping to modify natural corals and create synthetic coral architectures able to accelerate bone regeneration with proper host integration at more skeletal locations, adapted to recent surgical techniques and used to treat intrinsic skeletal deformities and metabolic conditions.

Copyright © 2015 John Wiley & Sons, Ltd. An increase in clinical demand on the controlled release of bisphosphonates (BPs) due to complications associated with systemic administration, has been the current driving force on the development of BP drug-release systems. Bisphosphonates have the ability to bind to divalent metal ions, such as Ca2+, in bone mineral and prevent bone resorption by influencing the apoptosis of osteoclasts. Localized delivery using biodegradable materials, such as polylactic acid (PLA) and hydroxyapatite (HAp), which are ideal in this approach, have been used in this study to investigate the dissolution of clodronate (non-nitrogen-containing bisphosphonate) in a new release system. The effects of coral structure-derived HAp and the release kinetics of the composites were evaluated. The release kinetics of clodronate from PLA–BP and PLA–HAp–BP systems seemed to follow the power law model described by Korsmeyer–Peppas. Drug release was quantified by 31P-NMR with detection and quantification limits of 9.2 and 30.7 mM, respectively. The results suggest that these biocomposite systems could be tuned to release clodronate for both relatively short and prolonged period of time. In addition to drug delivery, the degradation of HAp supplies both Ca2+ and phosphate ions that can help in bone mineralization. Copyright © 2015 John Wiley & Sons, Ltd.

© Springer International Publishing Switzerland 2016. The ability to produce homogeneous high-purity materials is of great interest to industrial and medical applications. In addition, the chemical and physical changes observed at the nanoscale and their influence on properties have been an important academic interest. The gel-structure transition plays a critical role in the formation as well as the current production of various types of sol-gel-derived materials such as nanopowders, nanofibers, nanocoatings, nanocomposites, and solid monoliths. It is the area of thin film coatings produced by sol-gel technology that this chapter covers. In particular, this chapter focuses on the basic synthesis and application methods to produce nanocoatings for biomedical applications. This chapter also attempts to answer some of the pertinent questions related to sol-gel processing and production methods and issues related to the fundamental understanding of the sol-gel process.

© 2015 by the authors. Hydrothermally converted coralline hydroxyapatite (HAp) particles loaded with medically active substances were used to develop polylactic acid (PLA) thin film composites for slow drug delivery systems. The effects of HAp particles within PLA matrix on the gentamicin (GM) release and release kinetics were studied. The gentamicin release kinetics seemed to follow Power law Korsmeyer Peppas model with mainly diffusional process with a number of different drug transport mechanisms. Statistical analysis shows very significant difference on the release of gentamicin between GM containing PLA (PLAGM) and GM containing HAp microspheres within PLA matrix (PLAHApGM) devices, which PLAHApGM displays lower release rates. The use of HAp particles improved drug stabilization and higher drug encapsulation efficiency of the carrier. HAp is also the source of Ca2+ for the regeneration and repair of diseased bone tissue. The release profiles, exhibited a steady state release rate with significant antimicrobial activity against Staphylococcus aureus (S. aureus) (SH1000) even at high concentration of bacteria. The devices also indicated significant ability to control the growth of bacterial even after four weeks of drug release. Clinical release profiles can be easily tuned from drug-HAp physicochemical interactions and degradation kinetics of polymer matrix. The developed systems could be applied to prevent microbial adhesion to medical implant surfaces and to treat infections mainly caused by S. aureus in surgery.

© 2014 Future Medicine Ltd. This article aims to provide a brief background to the current applications of finite-element analysis (FEA) in nanomedicine and dentistry. FEA was introduced in orthopedic biomechanics in the 1970s in order to assess the stresses and deformation in human bones during functional loadings and in the design and analysis of implants. Since then, it has been applied with great frequency in orthopedics and dentistry in order to analyze issues such as implant design, bone remodeling and fracture healing, the mechanical properties of biomedical coatings on implants and the interactions at the bone-implant interface. More recently, FEA has been used in nanomedicine to study the mechanics of a single cell and to gain fundamental insights into how the particulate nature of blood influences nanoparticle delivery.

© 2014 John Wiley & Sons, Ltd. Several studies have shown the effectiveness of zinc-tricalcium phosphate (Zn-TCP) for bone tissue engineering. In this study, marine calcareous foraminifera possessing uniform pore size distribution were hydrothermally converted to Zn-TCP. The ability of a scaffold to combine effectively with mesenchymal stem cells (MSCs) is a key tissue-engineering aim. In order to demonstrate the osteogenic ability of MSCs with Zn-TCP, the scaffolds were cultured in an osteogenic induction medium to elicit an osteoblastic response. The physicochemical properties of Zn-TCP were characterized by XRD, FT-IR and ICP-MS. MSCs were aspirated from rat femurs and cultured for 3 days before indirectly placing four samples into each respective well. After culture for 7, 10 and 14 days, osteoblastic differentiation was evaluated using alizarin red S stain, measurement of alkaline phosphatase (ALP) levels, cell numbers and cell viability. XRD and FT-IR patterns both showed the replacement of CO32- with PO43-. Chemical analysis showed zinc incorporation of 5 mol%. Significant increases in cell numbers were observed at 10 and 14 days in the Zn-TCP group, while maintaining high levels of cell viability (> 90%). ALP activity in the Zn-TCP group was statistically higher at 10 days. Alizarin red S staining also showed significantly higher levels of calcium mineralization in Zn-TCP compared with the control groups. This study showed that MSCs in the presence of biomimetically derived Zn-TCP can accelerate their differentiation to osteoblasts and could potentially be useful as a scaffold for bone tissue engineering.

This study aims to produce apatite structures, such as hydroxyapatite (HA) and fluorapatite (FA), from precursor calcium phosphates of biological origin, namely from sea urchin, with mechano-chemical stirring and hot-plating conversion method. The produced materials were heat treated at 800 °C for 4 hours. X-ray diffraction and scanning electron microscopy (SEM) studies were conducted. Calcium phosphate phases were developed. The SEM images showed the formation of micro to nano-powders. The experimental results suggest that sea urchin, Brissus latecarinatus skeleton could be an alternative source for the production of various mono or biphasic calcium phosphates with simple and economic mechano-chemical (ultrasonic) conversion method.

Marine species, such as corals, sea shells and nacres, attract special interest in bioceramics field for bone graft, bone cements and drug delivery applications. Most of the marine structures are made up of pure calcium carbonate (calcite or aragonite) with a very small amount of an organic matrix. In the past the most common way to transform these structures to hydroxyapatite was hydrothermal transformation method. This current work introduces a new approach for producing fine powders of calcium phosphates from Mediterranean mussel (Mytilus galloprovincialis) shells. A comparative study was carried out to investigate the differences of these powders under only hot plate heating and hot plate heating together with ultrasonic agitation while H3PO4 was added. The temperature of the hotplate was kept constant at 80 degrees C and then, H3PO4 was added drop wise into the solution for 2 hrs. The mixture was then placed into an oven at 100 degrees C for 24 hrs. They were further calcined at 800 degrees C for 3 hrs. XRD, FTIR. and ICP-MS were used to identify the structure and composition. It was found that the final powders were predominantly monetite, with some tricalcium phosphate as a secondary phase. This relatively simple and efficient method can be easily applied to produce calcium phosphate precursor powders for a range of biomedical applications.

Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin.

Coral sand grains were analyzed using simultaneous differential thermogravimetric analysis (DTA/TGA), Fourier-Transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and environmental scanning electron microscopy (ESEM). These techniques were performed to confirm the characteristics and properties as well as the composition of the coral sand grains. Imaging of the full surface topography were conducted in the ESEM. After characterization coral sand grains were treated for impurities and organic materials were subsequently removed. The materials were than converted to calcium phosphates utilizing hydrothermal treatment. The results have shown that the coral sand grains were composed of calcium carbonate with a network of uniform inner porous structure. The ESEM has provided valuable information through the imaging of the samples which in turn allowed a comparison of the pore sizes before and after the hydrothermal treatment. The current study shows that the coral sand to be a promising source of converted calcium carbonate to calcium phosphates for biomedical applications.

White cast irons are used extensively throughout the mining industry for their wear resistant properties. Since their original development in the early 1900's researchers have continued to develop a range of white cast iron compositions with varying degrees of hardness, toughness or corrosion resistance. This study focuses on the development of a low melting point white cast iron which has applications in the composite alloy manufacturing industry. The compositional range for the study was developed through analysis of the iron-chromium-carbon phase diagram. Experimental work has included the casting and thermal analysis of a range of alloy compositions. The microstructures of the alloys have been studied to determine the relationship with the phase diagram, and a comparison of the experimental data with computer generated phase diagrams is presented. The results of this study permitted an alloy white cast iron to be produced with a melting point of approximately 1200°C. The experimentally derived thermal data for the liquidus and solidus temperatures are generally lower compared to the predicted data based on CALPHAD simulations. © Institute of Materials Engineering Australasia.

New methods for manufacturing alloy composites have been used to produce a number of wear parts for the mining industry. The use of composites incorporating white cast iron and steel permit brittle and wear resistant materials to be used in applications where moderate impact conditions are encountered. Analysis of the alloy composite interfaces has provided an enhanced understanding of the bonding mechanisms between the white cast iron and the steel and has also permitted further improvements in the manufacturing techniques. Analysis methods used to examine the interfacial features include quantitative x-ray mapping (QXRM) and electron beam backscattered diffraction (EBSD) mapping. Examples of successful field trials include mineral sands dredging and wear parts for heavy earthmoving equipment. © Institute of Materials Engineering Australasia Ltd.

In the biomedical field, the surface modification of titanium aims to inhibit wear, reduce corrosion and ion release, and promote biocompatibility. Sol-gel-derived ceramic nanoscale coatings show promise due to their relative ease of production, ability to form a physically and chemically uniform coating over complex geometric shapes, and their potential to deliver exceptional mechanical properties due to their nanocrystalline structure. In this study hydroxyapatite coatings on titanium were investigated for their fracture toughness.

This paper reports neutron diffraction data and its analysis of bone derived hydroxyapatite and synthetic hydroxyapatite (HAp). FTIR spectroscopy showed a number of changes in the bone derived hydroxyapatite as a function of temperature, and that firing at 600°C provides an increased crystallinity without decomposition of the HAp. The neutron diffraction data has elucidated the crystal structure of both materials, and enabled the positions of the hydrogen atoms to be accurately determined, and the lattice parameters to be compared. The only noticeable difference was a slight reduction in the lattice parameter a, and an increase in c in the bone derived HAp material. This can be attributed to the residual carbonate phase. The data also shows the improvement of crystallinity of the bovine bone during the heat treatment process.

A group of ferrous alloy composites have been produced using a novel vacuum casting process. The bonding and the interfacial analysis of these composites has been studied using various techniques including: optical microscopy, energy dispersive spectroscopy (EDS) microanalysis, X-ray mapping (XRM) and electron back scattered diffraction (EBSD). A number of phase changes and unique microstructural features have been observed. Some of these microstructural features are the result of the solidification process, whilst other changes have resulted from diffusion of elements across the composite interface. This study demonstrates the uniqueness of the vacuum casting process as an efficient bonding process and the importance of comparing data from a variety of analytical techniques to enable a thorough model of the solidification and diffusion processes to be properly developed. © Institute of Materials Engineering Australasia Ltd.

Multinuclear NMR spectroscopy has been used to monitor synthesis of hydroxyapatite (HAp) from diethyl hydrogen phosphonate and calcium diethoxide in solution at two different temperatures. Acetyl 2-hydroxyethyl phosphonate, bis(2-hydroxyethyl) phosphonate, and acetyl ethyl phosphonate have been identified for the first time in this reaction solution as intermediates. The formation of these compounds is shown to be crucial in controlling the phase purity of the final hydroxyapatite product. A possible mechanism for the formation of acetyl 2-hydroxyethyl phosphonate is discussed.

Current bone graft materials are mainly produced from coralline hydroxyapatite (HAp). Due to the nature of the conversion process, commercial coralline HAp has retained coral or CaCO3, and the structure possesses nanopores within the inter-pore trabeculae, resulting in high dissolution rates. Under certain conditions these features reduce durability and strength and are not utilised where high structural strength is required. To overcome these limitations, a new coral double-conversion technique has been developed. The technique involves a two-stage application route where, in the first stage, complete conversion of coral to pure HAp is achieved. In the second, a new sol-gel-derived HAp nano-coating is directly applied to cover the micro- and nano-pores within the intra-pore material, whilst maintaining the large pores. Biaxial strength was improved two-fold due to this unique double treatment. This application is expected to result in enhanced durability and longevity due to the monophasic hydroxyapatite structure and strength in the physiological environment. It is anticipated that this new material can be applied to load-bearing bone graft applications where high strength requirements are pertinent. © 2004 Elsevier Ltd. All rights reserved.

Three-dimensional finite element analysis (FEA) was used to evaluate the influence of the design of dental implants on distortion and stresses (the maximum and minimum principal, and Von Mises) acting in the dental implant and the surrounding osseous structures during clenching. The model geometry was derived from physical measurements taken of an average size human mandible. Implants of various lengths and root configurations were embedded into the first molar region of the right mandible. Four dental implant materials have been selected for this analysis: Titanium-aluminum-vanadium (Ti-6Al-4V), cobalt-chromium-molybdenum (Co-Cr-Mo), alumina, and zirconia. All of the materials used in this analysis were idealized as homogeneous, isotropic and linear elastic. The complete model 3D-model was completed using STRAND7 and consists of 700 solid elements and 3738 nodes. The results indicated that the stresses acting in the implants are determined by several factors such as implant length, root configurations, and the implant material.

Overall, the benefits of advanced ceramic materials in biomedical applications have been universally appreciated, specifically, in terms of their strength, biocompatibility and wear resistance. However, the amount of supporting data is not large and the continuous development of new methods is pertinent for better understanding of the microstructure-properties relationship and, in general, for obtaining new directives for their further improvement. This paper gives an overview of some of the more innovative applications of bioceramics in medicine. © Institute of Materials Engineering Australasia Ltd - Materials Forum Volume 27 - Published 2004.

The hydrothermal synthesis of hydroxyapatite (HAp) from Australian corals was investigated. The characterization of the corals and the converted HAp was reported. X-ray diffraction was used to analyze the phase composition of the coral and converted samples. Fourier transform infrared spectra (FTIR) and nuclear magnetic resonance spectra (NMR) of the converted HAp were studied.

Zirconia sol-gel-derived ceramic coatings have a variety of uses, due to their ease of production and ability to coat complex shapes. The sol-gel's nanocrystalline grain structure results in improved mechanical properties of the zirconia coating, which further aids their use in a variety of applications from thermal barrier coating to improved tribological properties on titanium substrates. Stabilised zirconia thin films were spin coated on anodised titanium substrates. The titanium was anodised in a dilute H3PO 4ZH2SO4 solution before spin coating with the zirconia sol gel. These films were then studied using secondary ion mass spectrometry (SIMS), to depth profile the elemental species through to the titanium substrate. In conjunction, scanning electron microscopy (SEM) and X-ray microanalysis were used to examine the craters formed by SIMS to gain an understanding of the diffusion gradient existing with the anodised titanium substrate and zirconia thin film. © Institute of Materials Engineering Australasia.

© 2014, Australasian Ceramic Society. All rights reserved. Biogenic materials like corals, which are readily available, could be used to produce bioceramic materials and address significant advantages due to their unique structures and chemical compositions that contain Mg and Sr. Many conversion processes has been in the past proposed. In this work, a comparison study between the conversion of coral with orthophosphoric acid and ammonium dihydrogen phosphate was conducted. The resultant structures and compositions were studied using XRD, ICP-MS, SEM and FTIR. The results show that with phosphoric acid the coral was converted into mainly monetite (92%). The ammonium dihydrogen phosphate converted approximately 76% of the coral to hydroxyapatite through solid state reactions. The two routes proved to be effective in producing bioceramic materials from corals under moderate conditions of temperature with a basic condition favouring the yield of hydroxyapatite.

The production of porous ceramics for biomedical applications is widely available in the Ceramics industry. In bioceramic applications, interconnected pores are pertinent to increase osteoconductivity and cell proliferation. However, an increase in pore size and the pore amount decrease the mechanical properties. For this reason, pore properties must be precisely controlled. In this study, the effect of a natural pore-forming agent, corn starch addition, and sintering conditions on mechanical properties and biocompatibility was investigated. During mixing, four different starch amounts (1, 3, 5, and 10 wt%) were added to pure beta-tricalcium phosphate (β-TCP) ceramic powders and pressed. Pressed pellets were sintered at 1000, 1100, 1200, and 1300 °C. A scanning electron microscope (SEM) is used to investigate microstructure, texture, pore size, and cell adhesion. The mechanical properties of the β-TCP ceramic parts were further characterized by measuring the density and compressive strength. Cytotoxicity tests were carried out with MTT assays. The optimum mechanical properties were obtained at 1100 °C sintered biocomposites. Although starch starts to burn around 410 °C and analytical results show no presence of starch after the sintering process, biocomposites initially containing 10% starch showed improved cell proliferation. However, a reduction of 59% in compressive strength and a 16% reduction in the density were also recorded. It was observed that 10 wt% starch addition increases cell proliferation by 10% in sintered β-TCP samples. Starch powder additions can be used to increase the cell viability of the material by facilitating the creation of pores, as a low-cost pore-forming agent for porous bone graft and non-load-bearing material in both orthopaedics and maxillofacial applications. Graphical abstract: [Figure not available: see fulltext.]

Extensive research has been conducted on hydroxyapatite as a bone tissue engineering scaffold due to its low toxicity, biocompatibility, bioactivity and chemical similarity to bone. Hard coral species as well as red and green calcified marine algae have naturally porous skeletons that resemble cancellous bone. Under controlled hydrothermal conditions, these materials can be converted to hydroxyapatite with their porosity and interconnectivity preserved. The availability of hard coral species is limited due to the damage caused by harvesting procedures and decline in coral reefs. As an alternative, hydroxyapatite can be produced from red and green algae species. Currently, red algae derived Algipore® grafts are commercially available for maxillary sinus bone augmentation. Long term clinical studies have confirmed the bone regenerating capabilities of Algipore® when mixed with autologous bone debris and blood, but research on the use of Algipore® tissue scaffolds seeded with mesenchymal stem cells is still ongoing. This chapter reviews the synthesis of hydroxyapatite derived from marine algae and gives background to clinical studies as well as the characterisation techniques used to analyse these materials.