Hydroxyapatite nanoscale particles (nHA) were prepared by wet chemical precipitation using four different synthesis methods. Differences in physico-chemical properties including morphology, particle-size, and crystallinity were investigated following alteration of critical processing parameters. The nanoparticles were also studied using X-ray diffraction (XRD), Fourier Transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), and transmission electron microscopy (TEM) with energy dispersive X-ray (EDS) spectrometry. The results showed that the particles obtained were composed of nHA, with different morphologies and aspect ratios (1.5 to 4) and degrees of crystallinity (40% to 70% following calcination) depending on the different process parameters of the synthesis method used, such as temperature, ripening time and pH. This study demonstrated that relatively small adjustments to processing conditions of different wet chemical preparation methods significantly affect the morphological and chemical characteristics of nHA. For the predicable preparation of biomimetic nHA for specific applications, the selection of both production method and careful control of processing conditions are paramount.

Autologous cancellous-bone grafts are the current gold standard for therapeutic interventions in which bone-regeneration is desired. The main limitations of these implants are the need for a secondary surgical site, creating a wound on the patient, the limited availability of harvest-safe bone, and the lack of structural integrity of the grafts. Synthetic, resorbable, bone-regeneration materials could pose a viable treatment alternative, that could be implemented through 3D-printing. We present here the development of a polylactic acid-hydroxyapatite (PLA-HAp) composite that can be processed through a commercial-grade 3D-printer. We have shown that this material could be a viable option for the development of therapeutic implants for bone regeneration. Biocompatibility in vitro was demonstrated through cell viability studies using the osteoblastic MG63 cell-line, and we have also provided evidence that the presence of HAp in the polymer matrix enhances cell attachment and osteogenicity of the material. We have also provided guidelines for the optimal PLA-HAp ratio for this application, as well as further characterisation of the mechanical and thermal properties of the composite. This study encompasses the base for further research on the possibilities and safety of 3D-printable, polymer-based, resorbable composites for bone regeneration.

Abstract:Laser-Induced Breakdown Spectroscopy (LIBS) was applied to the analysis of bioceramic samples. The relationship between sample hardness and LIBS plasma properties was investigated, with comparison to conventional Vickers hardness measurements. The plasma excitation temperature T e was determined using the lineto-continuum ratio for the Si (I) 288.16 nm emission line; we have demonstrated a linear relationship between sample surface hardness and plasma temperature. Results indicate that hardness determination based on measurements of T e offers greater reproducibility than Vickers hardness measurements, under the conditions considered here. The validity of spectroscopic diagnostics based on LTE was confirmed.

Statement of problem. The current chemical solubility method in the International Standards Organization (ISO) 6872 (2015) specifies only the total surface area of specimens for testing (≥30 cm 2) but does not describe the morphology or geometry. This could impact the reproducibility of the test outcomes. Purpose. The purpose of this in vitro study was to investigate the factors influencing the reliability of the ISO 6872:2015 'Dentistry-Ceramic materials' test for chemical solubility. Material and methods. Chemical solubility analysis of a range of materials and specimen geometries was performed in accordance with ISO 6872:2015. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), Vitablocs Mark II, IPS e.max Press, and IPS e.max ZirPress materials were formed into a range of cubic and spherical geometries to comply with the 30 cm 2 minimum surface area requirement. The surface microstructure of the specimens was analyzed by scanning electron microscope, inductively coupled plasma optical emission spectrometry (ICP-OES) was used to analyze the solutes, and surface hardness of the specimens was measured using a Vickers hardness tester before and after testing. An optimized solubility test was devised which eliminated specimen handling once the specimens had been ground and polished. This modified test was performed on Vitablocs Mark II and Y-TZP. Results. The results of the original chemical solubility method of ISO 6872:2015 showed significantly variable findings for each tested material, with a predictable relationship between

Highlights TopoStats is a Python toolkit for automated AFM data processing. TopoStats takes raw data as input, and outputs processed data and statistical information without user input. TopoStats can accurately trace linear and circular biomolecules and provide conformational analysis. We applied TopoStats to analyse DNA minicircles, origami and pore-forming proteins. TopoStats can be used on both ideal and contaminated samples.

Poly(glycerol sebacate) is an attractive biomaterial for tissue engineering due to its biocompatibility, elasticity and rapid degradation rate. However, poly(glycerol sebacate) requires harsh processing conditions, involving high temperatures and vacuum for extended periods, to produce an insoluble polymer matrix. These conditions make generating accurate and intricate geometries from poly(glycerol sebacate), such as those required for tissue engineering scaffolds, difficult. Functionalising poly(glycerol sebacate) with methacrylate groups produces a photocurable polymer, poly(glycerol sebacate)-methacrylate, which can be rapidly crosslinked into an insoluble matrix. Capitalising on these improved processing capabilities, here, we present a variety of approaches for fabricating porous tissue engineering scaffolds from poly(glycerol sebacate)-methacrylate using sucrose porogen leaching combined with other manufacturing methods. Mould-based techniques were used to produce porous disk-shaped and tubular scaffolds. Porogen size was shown to influence scaffold porosity and mechanical performance, and the porous poly(glycerol sebacate)-methacrylate scaffolds supported the proliferation of primary fibroblasts in vitro. Additionally, scaffolds with spatially variable mechanical properties were generated by combining variants of poly(glycerol sebacate)-methacrylate with different stiffness. Finally, subtractive and additive manufacturing methods were developed with the capabilities to generate porous poly(glycerol sebacate)-methacrylate scaffolds from digital designs. These hybrid manufacturing strategies offer the ability to produce accurate macroscale poly(glycerol sebacate)-methacrylate scaffolds with tailored microscale porosity and spatially resolved mechanical properties suitable for a broad range of applications across tissue engineering.

1Three novel borosilicate bioactive glasses (BBGs) of general formula of 0.05Na2O0.35x 2 0.20B2O30.40SiO2 (molar ratio, where x = MgO or CaO or SrO) were prepared and used to 3 investigate the effect of crystallisation on their properties including cytotoxicity. The three post-4 melt compositions were determined using X-ray fluorescence spectroscopy and crystallisation 5 events were studied using differential thermal analysis and x-ray diffraction. This information was 6 used to determine heat treatments to prepare glass-ceramics by controlled crystallisation. X-ray 7 diffraction analysis and Fourier transform infrared spectroscopy showed that, after higher heat 8 treatment temperatures (800-900 ºC), borosilicate bioactive glass-ceramics (BBGCs) contained 9 mainly borate and silicate crystalline phases. Specifically, BBG-Mg, BBG-Ca and BBG-Sr glass-10 ceramics detected the presence of magnesium silicate-Mg2(SiO3)2 and magnesium borate-Mg2B2O5; 11 wollastonite-2M-CaSiO3 and calcium borate-Ca(BO2)2; and strontium silicate-SrSiO3 and strontium 12 borate-Sr2B2O5, respectively. In vitro cytotoxicity tests were performed using the mouse fibroblast 13 cell line (L929). Glass and glass ceramic at concentrations lower than 50 mg/ml did not exhibit any 14 level of cytotoxicity when compared with the control. However, quantitative evaluation indicated 15 that greater cell growth occurred in the presence of materials with crystalline phases. Control of 16BBGs crystallisation may therefore be used to influence the biocompatibility of these glass-ceramic 17 systems. 18

Restoring subgingival class-V cavities successfully, demand special biological properties from a restorative material. This study aimed to assess the effects of incorporating bioactive materials to glass ionomer cement (GIC) on its mechanical and biological properties. Hydroxyapatite, chitosan, chondroitin sulphate, bioglass, gelatine and processed bovine dentin were incorporated into a GIC restorative material. Compressive strength, biaxial flexural strength (BFS), hardness, setting and working time measurements were investigated. Biocompatibility of the new materials was assessed using both monolayer cell cultures of normal oral fibroblasts (NOF) and TR146 keratinocytes, and a 3D-tissue engineered human oral mucosa model (3D-OMM) using presto-blue tissue viability assay and histological examination. Significant reduction in the compressive strength and BFS of gelatine-modified discs was observed, while chondroitin sulphate-modified discs had reduced BFS only (p value > 0.05). For hardness, working and setting times, only bioglass caused significant increase in the working time. NOF viability was significantly increased when exposed to GIC-modified with bovine dentine, bioglass and chitosan. Histological examination showed curling and growth of the epithelial layer toward the disc space, except for the GIC modified with gelatine. This study has highlighted the potential for clinical application of the modified GICs with hydroxyapatite, chitosan, bioglass and bovine dentine in subgingival class-V restorations.