Melt-extruded polyethylene oxide (PEO) rods as drug delivery vehicles: Formulation, performance as controlled release devices and the influence of co-extruded excipients on drug release profiles

The utility of controlled release medication formulations lies in their ability to keep drugs at steady levels in the blood plasma of recipients and within the termini of the maximum and minimum effective therapeutic levels. This avoids the “ups” and “downs” of medication levels within the body which would have been the result had conventional immediate release tablets been administered instead. In the veterinary field, controlled release medications are essential¹ because of the logistical difficulties of administering drugs on a regular (e.g., daily) basis to animals. The chief advantages of controlled release veterinary medications lie in the ease with which they can be administered; decrease in stress for animals, owing to less need for rounding up and frequent dosing; and, most importantly for farmers, the reduced cost of treatment relative to that for a multiple dosage regime

A cursory study of the bulk and glaze composition plus metal leaching properties of a selection of antique, vintage and present day food and drink ceramic wares using XRF, FTIR, ²⁷Al, ²⁹Si, ³¹P MAS NMR and ICP-MS for providing a characterisation of the types of domestic ceramic ware used in New Zealand currently

The ceramic utensils used for eating and drinking such as plates, cups, bowls and other items have been a fundamental part of many societies since ancient times. The word “ceramics” is itself derived from the Greek word κεραμικός (“Keramikos”)¹ meaning “of or for pottery”. The art of making ceramics dates back thousands of years with evidence of pottery from 20,000 years ago² being reported recently from Xianrendong Cave in China. Ceramics manufacture depends on a source of various materials, namely clay, e.g. kaolinite, silica and feldspar.³ When these clay and mineral materials are mixed and soaked in water with removal of the excess water, a wet clay is produced which can then be fashioned into the desired shapes using moulds. Water is then removed via drying and the articles fired at temperatures up to 1170 °C during which complex chemical transformations occur in the clay with physical changes in the added silica and feldspar. Kaolinite (Al₂Si₂O₅(OH)₄ ) is converted via a series of precursor compounds to mullite (Al₆Si₂O₁₃) and cristobalite (SiO₂). The feldspar acts as a flux with the alkali metal ion content (Na₂O, K₂O and CaO) causing a lowering of the melting point of the silica early on in the firing process. This melt effectively forms a glass which then draws the individual particles of the fired mixture together and additionally reacts with them so giving the ceramic body strength (when it cools) and reducing porosity

Biomedicals from Bone

The realm of biomaterials, under which biomedical materials can be categorised, has a broad definition base and recognises materials that are synthesized or naturally sourced. Biomaterials are normally those that come into contact with live tissue and physiological fluids. They have applications as prostheses to replace lost function of joints or to replace bone tissue, for diagnosing medical conditions, as a form of therapy, or as a storage unit. The diversity and scope of biomaterials science research, and especially its application to the improvement of trauma, disease, and congenital defects in the human condition, are making this branch of science increasingly dominant and topical in many countries. An exciting aspect is that such research is interdisciplinary. The varied problems of the human condition that biomaterials research addresses occupy the efforts not only of medical doctors who act as the end users of such technology, but also those of chemists, physicists, engineers, and biologists in creating the technological advances. Chemistry, in particular, plays a major role in such research, after all it is the foundation stone on which biomaterials polymer science and biomedical scaffold materials are built

In Situ IR Study of the Anodic Polarization of Gold Electrodes in Polar Aprotic Solvents: DMSO and DMF Solutions of Cyanate, Thiocyanate and Selenocyanate Ions

Subtractively normalised Fourier transform infrared spectroscopic (SNIFTIRS) studies combined with volammetric and supporting model solution studies have conclusively shown that Au electrodes anodically polarized in DMSO and DMF solutions containing the pseudohalide ions: cyanate, thiocyanate and selenocyanate with tetrabutylammonium perchlorate as supporting electrolyte dissolve to form Au(I) pseudohalide complex ions (i.e. [Au(NCO)₂]⁻, [Au(SCN)₂]⁻ and [Au(SeCN)₂]⁻. This work has demonstrated the significance of the Au(I) oxidation state which occurs after applied voltages of +500 mV(AgCl/Ag) in the little characterized electrochemistry of this metal in polar aprotic solvents, DMSO and DMF The Au(I) species observed electrochemically by SNIFTIRS were confirmed by independent preparation in DMSO/DMF containing mixtures of KAuBr₄ and the pseudohalide salt (KOCN/NaSCN/KSeCN) and exploiting fortuitous redox chemistry where Au(I) formed spontaneously. The model solutions examined by transmission FTIR and ESI-MS confirmed the existence of the Au(I) species posited in the SNIFTIRS experiments but additionally revealed other interesting side reactions occurring in the model solutions

A combined SNIFTIRS and XANES study of electrically polarised copper electrodes in DMSO and DMF solutions of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) ions

A SNIFTIRS (subtractively normalized interfacial Fourier transform infrared spectroscopy) and X-ray absorption spectroscopy (XAS) study of electrically polarized copper electrodes in six polar aprotic solvent-based systems is presented. In the systems investigated, i.e. dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) solutions containing pseudohalide species of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) codissolved with tetrabutylammonium perchlorate (TBAP), Cu was found to dissolve over a wide range of potentials to produce the corresponding Cu(I) pseudohalide and/or Cu(II) pseudohalide complex ion species. Insoluble deposited films were also observed at higher anodic applied potentials, thought to be CuSCN in the Cu/NCS⁻/DMSO or DMF systems, and solid K(SeCN)₃ in the Cu/NCSe⁻/DMSO or DMF systems respectively. The presence of the Cu(II) and/or Cu(I) oxidation states in complexes formed by polarization in Cu/pseudohalide ion systems in DMSO was clearly proven using XAS of cell solutions sampled after SNIFTIRS/electrical polarization experiments. In addition, Fourier transform infrared (FTIR) and X-ray absorption near edge spectroscopy (XANES) data obtained from model solutions prepared from mixing Cu(I) and/or Cu(II) salts with the respective pseudohalide ions in DMF and DMSO confirmed the speciation observed in the electrochemical experiments

Anodically polarized nickel electrodes in DMSO or DMF solutions of pseudohalide ions: IR spectroelectrochemical studies

A novel subtractively normalized interfacial Fourier transform infrared spectroscopic (SNIFTIRS) investigation of anodically polarized nickel electrodes in pseudohalide-containing DMF or DMSO solutions (i.e. OCN⁻, SCN⁻, SeCN⁻), in supporting electrolyte, tetrabutylammonium perchlorate (TBAP), is presented. In general, the data showed that nickel demonstrated irreversible anodic dissolution in all solutions studied at very high values of the applied potential, > +500 mV (AgCl/Ag). The predominant speciation of nickel in these systems was as complex ions consisting of Ni²⁺ ion complexed to pseudohalide ions and solvent molecules. Insoluble films and dissolved CO₂ were also detected, though mostly in the Ni/OCN⁻ systems studied. Ni(II)/pseudohalide complex ion species detected were modeled using solutions containing Ni²⁺ ion mixed with pseudohalide ion in different mole ratios. In general, the Ni/OCN⁻ electrochemical system behaved differently relative to those of Ni/SCN⁻ and Ni/SeCN⁻ due to the difference in colors observed in cell solutions after SNIFTIRS experiments which was mirrored in the model solutions. Ni(II)-cyanate species had a different, coordination geometry and gave a characteristic bright blue color due possibly to Ni(NCO)₄²⁻ ion while Ni(II) thiocyanate and selenocyanate complex ion species had octahedral coordination geometries containing solvent and one coordinated pseudohalide ion and formed greeny yellow solutions

Special Issue: Novel Advances and Approaches in Biomedical Materials Based on Calcium Phosphates [Editorial]

Research on calcium phosphate use in the development and clinical application of biomedical materials is a diverse activity and is genuinely interdisciplinary, with much work leading to innovative solutions for improvement of health outcomes. This Special Issue aimed to summarize current advances in this area. The nine papers published cover a wide spectrum of topical areas, such as (1) remineralisation pastes for decalcified teeth, (2) use of statins to enhance bone formation, (3) how dolomitic marble and seashells can be processed into bioceramic materials, (4) relationships between the roughness of calcium phosphate surfaces and surface charge with the effect on human MRC osteogenic differentiation and maturation being investigated, (5) rheological and mechanical properties of a novel injectable bone substitute, (6) improving strength of bone cements by incorporating reinforcing chemically modified fibres, (7) using adipose stem cells to stimulate osteogenesis, osteoinduction, and angiogenesis on calcium phosphates, (8) using glow discharge treatments to remove surface contaminants from biomedical materials to enhance cell attachment and improve bone generation, and (9) a review on how classically brittle hydroxyapatite based scaffolds can be improved by making fibre-hydroxyapatite composites, with detailed analysis of ceramic crack propagation mechanisms and its prevention via fibre incorporation in the hydroxyapatite

A Method for Avoiding the Xanthoproteic-associated Discolouration in Reprecipitated (Nitric-acid-digested) Hydroxyapatite Prepared from Mammalian Bone Tissue

A procedure for producing kilogram quantities of a biomedically suitable reprecipitated hydroxyapatite (HAp) powder, which is free of the xanthoproteic-associated discolouration caused by nitric acid interaction with the protein content in bones during digestion, has been developed. Essentially bones were defatted by boiling and then pyrolysed at 1000 °C to burn off the collagenous proteins and produce flakey bleached bones. This bone was then crushed and ground and digested in nitric acid solution to produce digest solutions free of the highly staining orange colouration normally associated with nitric acid digestions of bone material.. Finely divided, white solids could then be reprecipitated as usual from the digests by addition of NaOH solution under a nitrogen atmosphere with heating and stirring at 70 °C of the precipitate to enable its maturation into an HAp phase. The products derived from this procedure were characterised using spectroscopic, microscopic and particle sizing techniques. These analyses showed the resultant powders to be low crystallinity hydroxyapatite of consistent morphology and which possessed either acceptably low or below detection limit levels of heavy metals so rendering it as a potentially valuable source of powder for biomedical applications such as plasma spraying or for implant or prosthesis manufacture

An X-ray absorption spectroscopy investigation of the coordination environment of electrogenerated Ni(ii)-pseudohalide complexes arising from the anodic polarization of Ni electrodes in DMSO solutions of NCO⁻ , NCS⁻ and NCSe⁻ ions

X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) were used to provide direct information in solution on the coordination state of electrogenerated products from anodically polarized nickel electrodes in pseudohalide-ion-containing dimethyl sulfoxide (DMSO) solvent (i.e. NCX⁻, X = O, S, Se) in the presence of a supporting electrolyte of tetrabutylammonium perchlorate (TBAP). Electrogenerated solutions and model solutions representative of the chemical speciation in electrolyzed systems (prepared by mixing Ni(II) and pseudohalide ion solutions in DMSO), were also examined. In general for Ni(II) interacting with NCS⁻ and NCSe⁻, the complex ion generated appears to be 6-coordinate [Ni(NCX)(DMSO)5]⁺, while EXAFS/XANES data of the Ni/cyanate system suggest an average coordination number of 5, which in reality is due to the electrogenerated solution containing a mixture of 4 coordinate (tetrahedral) [Ni(NCO)4]²⁻ and octahedral [Ni(DMSO)6]²⁺ species. These observations of the octahedral geometry for the Ni(II)/thiocyanate and Ni(II)/selenocyanate systems and 5-coordinate geometry in the Ni(II)/cyanate systems (being electrogenerated products of anodic polarisation of Ni in the DMSO-supported pseudohalide ion electrolytes) agree with the differences in colour observed between samples. EXAFS/XANES measurements combined with IR spectroelectrochemical analyses of solutions provide a versatile way of analyzing these electrochemical systems without the need for isolating compounds from the electrolyte