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Abstract: The aim of this study was to determine how the activities of human osteoblastic cells and osteoclasts respond to substrates of thermal-sprayed mechanical blends of hydroxyapatite and fluorapatite with a view of determining an optimal blend ratio for osseointegration. Human osteoblastic cells and osteoclasts were grown on titanium alloy discs coated with blends of hydroxyapatite and fluorapatite, with concentrations ranging from 0 to 100% fluorapatite. Human osteoblastic cells attached in greater numbers and proliferated at a greater rate on blends containing 40% fluorapatite. Human osteoblastic cells grown on blends containing 40% fluorapatite for 7days also expressed the highest levels of mRNA for several proteins involved with regulating bone metabolism (osteoprotegerin and receptor activator nuclear factor kappa B ligand), and bone formation (osteopontin, osteonectin and bone sialoprotein 1). Osteoclasts resorbed the dentine but poorly resorbed the hydroxyapatite–fluorapatite blends, particularly at high levels of fluorapatite. This in vitro study demonstrates that thermal-sprayed hydroxyapatitecoatings containing 40% fluorapatite may promote optimal bone growth and improve osseointegration of implants. [Copyright &y& Elsevier]

Abstract: The interactions of biomolecules and cells with solid interfaces play a pivotal role in a range of biomedical applications and have therefore been studied in great detail. An improved understanding of these interactions results in the ability to manipulate DNA, proteins and other biomolecules, as well as cells, spatially and temporally at surfaces with high precision. This in turn engenders the development of advanced devices, such as biosensors, bioelectronic components, smart biomaterials and microarrays. Spatial control can be achieved by the production of patterned surface chemistries using modern high-resolution patterning technologies based on lithography, microprinting or microfluidics, whilst temporal control is accessible through the application of switchable surface architectures. The combination of these two surface properties offers unprecedented control over the behaviour of biomolecules and cells at the solid–liquid interface. This review discusses the behaviour of biomolecules and cells at solid interfaces and highlights fundamental and applied research exploring patterned and switchable surfaces. [Copyright &y& Elsevier]

• Prebiotic chemistry inspired polymer (AMNT30) was applied to develop antimicrobial media. • AMNT30 coating took place at room temperature via spontaneous polymerization. • AMNT30 coated zeolite enabled enhanced loading of silver and copper on the surface. • Excellent disinfection by silver coated materials lasted up to 100 pore volumes at high flow rates. • Metal leaching from the media was stabilized with AMNT30 at different water qualities. Greywater and stormwater have received significant attention due to increasing water scarcity. Passive filtration such as biofiltration has been a popular treatment method with its low energy input and environmental friendliness. However, pathogen removal capacity needs improvement to achieve safe water quality. In this study, a prebiotic chemistry inspired copolymer based on aminomalononitrile and 3,4,5-trihydroxybenzaldehyde (AMNT30) was introduced to develop antimicrobial media for passive filtration. The AMNT30 polymer provided an adhesive coating on zeolite substrates following a spontaneous polymerisation process at room temperature. AMNT30 coated media were investigated for metal loading capacity, surface morphology, E. coli removal and metal leaching after filtration of different water sources (i.e. stormwater, greywater, and deionised water) at low/high conductivity. The coating enhanced metal ion loading on the surface and demonstrated that >8 log reduction of E. coli can be achieved for silver loaded materials compared to a 1 log reduction for copper loaded materials. The coating also increased the stability of the metals on the media irrespective of inflow characteristics. This study provided the first example using AMNT30 to create antimicrobial water purification media. It is expected that this technology will find applications in the water treatment industry. [ABSTRACT FROM AUTHOR]

In order to overcome the continuing infection rate associated with biomaterials, the use of covalently bound furanones as an antibiofilm coating for biomaterials has been investigated. Furanones have previously been shown to inhibit growth of Gram-positive and Gram-negative bacteria. The aim of these studies were to covalently bind furanones to polymers and to test their efficacy for inhibiting biofilm formation of Staphylococcus epidermidis and in vivo infection rate.Two methods of covalent attachment of furanones were used. The first, a co-polymerisation with a styrene polymer, and second, a plasma-1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) reaction to produce furanone-coated catheters. Biofilm formation by S. epidermidis in vitro was inhibited by 89% for polystryene–furanone disks and by 78% by furanone-coated catheters (p<0.01). In an in vivo sheep model we found furanones were effective at controlling infection for up to 65 days. Furanones have potential to be used as a coating for biomaterials to control infection caused by S. epidermidis. [Copyright &y& Elsevier]

The use of graft polymers for the functionalisation of biomaterial surfaces is already widespread. We investigated the adsorptive and covalent binding of a variety of proteins and peptides to poly(d,l-lactide) grafted with polyacrylic acid. Covalent attachment was achieved through coupling of amino groups of the protein/peptide to the carboxyl groups of the graft polymer by using a water-soluble carbodiimide and N-hydroxysuccinimide. Binding densities were determined by automated amino acid analysis after acid hydrolysis of both the poly(d,l-lactide) and the adsorbed and covalently bound proteins. Experiments in the absence and presence of the coupling reagents allow to discriminate between adsorptive and covalent binding. Although the adsorptive binding is quite substantial in absolute terms, the amount of adsorbed protein is relatively low as compared to the total amount of bound protein.Total binding densities of 20–30 μg/cm2 can easily be achieved. Depending on the concentration and on the properties of the proteins and peptides, between 5% and 80% of the totally bound protein may be physically adsorbed.Densities expressed in molecules/10 nm2 vary from 0.5 molecule fibronectin to 2000 laminin-peptide molecules: their binding densities clearly correlate with their respective molecular masses. Obviously, the binding densities are governed by their individual three-dimensional space requirements rather than the density of the available carboxyl groups.From the number of carboxyl groups/10 nm2 (18,000–30,000 COOH/10 nm2) the average length of the acrylic acid graft polymer molecules was estimated. Based on the assumption that about 10 copolymer chains can be accommodated on 10 nm2, the average length of the polymer chains, which corresponds to the thickness of the graft phase, is estimated to be 0.5–1 μm.The organisation of the proteins and peptides within the polyacrylic acid phase was further investigated by experiments in which a protein (BSA) and a peptide (Val-Lys) were allowed to react in either a singular, a consecutive or a simultaneous way. Together with XPS and IR-ATR surface characterisation experiments a three-dimensional picture of the arrangement of the immobilised proteins and peptides within the graft polymer phase emerges. [Copyright &y& Elsevier]

Purpose Driveline infections remain a major complication of ventricular assist device (VAD) implantation. This study aimed to characterize in vivo microbial biofilms causing driveline infections and the degree of tissue integration into the velour of explanted drivelines. Methods Drivelines were obtained from ten VAD patients undergoing heart transplantation at the Alfred Hospital, Melbourne and St Vincent Hospital, Sydney between June 2017 to October 2018. Four uninfected drivelines and six infected drivelines were aseptically sectioned into 10 pieces of 1.5 cm in length, from the smooth tube section at the exit site to the velour section adjacent to the VAD. Organisms on each section were isolated and identified. Microbial biofilms on the infected driveline sections were assessed using scanning electron microscopy (SEM) and viable counts. Computed tomography (micro-CT) and SEM were used to assess tissue integration into each section. All sections were analysed histologically to confirm human matrix protein deposition. Results No organisms were isolated from non-infected drivelines using microbiological culture. Staphylococcus aureus, Pseudomonas aeruginosa , and Staphylococcus epidermidis were found on the velour sections of infected drivelines and correlated with the microbiological culture results from patient swabs of the infected exit site. Although histological analysis found considerable collagen fiber and fibroblast deposition on both the smooth tube and the velour, SEM and micro-CT suggested insufficient tissue integration throughout the driveline velour. Microgaps were observed between the velour fibres, with evidence of microbial biofilms within these gaps. Such biofilms were morphologically distinct from in vitro biofilms grown on biomaterials and might be responsible for the antimicrobial treatment failure. Conclusion This study demonstrated inadequate tissue integration of clinical drivelines in the subcutaneous tissue tunnel, with associated microbial biofilms formed within the microgaps between velour fibres. These data provide important insights into a potentially novel therapeutic strategy against driveline infections that is focused on enhancing tissue integration into the velour, thereby preventing microbial adherence, biofilm formation and migration. [ABSTRACT FROM AUTHOR]