Abstract: Tissue engineering by self-assembly hypothesises that optimal repair and regeneration can be achieved best by using the cells’ inherent ability to create organs with proficiency still unmatched by currently available scaffold fabrication technologies. However, the prolonged culture time required to develop an implantable device jeopardises clinical translation and commercialisation of such techniques. Herein, we report that macromolecular crowding, a biophysical in vitro microenvironment modulator, dramatically accelerates extracellular matrix deposition in cultured human corneal, lung and dermal fibroblasts and human bone marrow mesenchymal stem cells. In fact, an almost 5 to 30 fold increase in collagen type I deposition was recorded as early as 48 hours in culture, without any negative effect in cell phenotype and function.
Abstract: A series of glass compositions with varying equimolar amounts of Na2O:Al2O3 were designed using Appen factors. High purity batch reagents were ball milled for 30 min and transferred to Pt/Rh crucible and melted in an electric furnace (EHF1700, Lenton, UK) at high temperatures then held for 90 min. The molten glass was poured into a graphite mould, annealed at 50°C below the glass transition temperature for 1h and the remaining glass was quenched into water. Glass frits were crushed and ball milled into powders with different particle sizes. Glass powders (PS<125μm) were heat-treated via two-step heat treatment cycles and air quenched. Experimental glasses and glass-ceramics were characterised using X-Ray Diffraction (XRD), Dilatometry, Scanning Electron Microscopy (SEM) and solid state Nuclear Magnetic Resonance (NMR).
Abstract: Silica aerogels have attracted increasingly more attention due to their extraordinary properties and their existing and potential applications in a wide variety of technological areas. Materials that promote bone-tissue formation at their surface and bond to osseous tissues when implanted are called bioactive, such as pseudowollastonite particles. In this work, the synthesis of aerogels with pseudowollastonite particles was performed. The synthesis involved the preparation of an alcogel by a two step sol-gel route followed by ambient pressure drying. To promote a higher bioactivity the obtained aerogels were then biomimetically treated using simulated body fluids, SBF and 1.5 SBF. A high bioactivity was demonstrated by FT-IR, SEM, EDS, and XRD. The in vitro biocompatibility was assessed by testing cytotoxicity using rat osteoblasts cultures. The results obtained indicate that these materials are highly potential aerogels for bone tissue regeneration.
Abstract: Hydroxyapatite [Ca5(PO4)3(OH)] is a form of calcium phosphate inorganic compound of great importance in the health area because of its presence in bone as in teeth where it provides structural rigidity to the matrix. Hydroxyapatite is often used in the biomaterial area as a primary material for implants that help regenerate tissues. The addition of doping agents may improve the degree of crystallization providing new characteristics to the material without losing its biocompatibility. The present study shows characterization results for a hydroxyapatite biomaterial doped with silver and/or fluorine prepared through combustion method. The mineralogy was determined using X-Ray diffraction identifying the following phases: Ca5(PO4)3OH, Ca2P2O7, Ag3PO4, Ca5(PO4)3F and CaF2; the oxidation state of elements was determined by X-ray photoelectron spectroscopy; the morphological structure was studied by scanning electron microscopy and atomic force microscopy. Biocompatibility tests through intramuscular and subcutaneous implantation were performed in rodents to evaluate inflammatory response at 7, 14 and 30 days.
Abstract: Poly (lactic acid) (PLA) blended with poly (butylene succinate) (PBS) were prepared by using twin screw extruder and injection molding machine at various contents of PBS from 0-15 wt%. The surface of titanium dioxide (TiO2) nanoparticles was treated using aminopropyl trimethoxy silane (ATS) order to disperse them into the biopolymer blends. The mechanical and thermal properties of PLA/PBS/TiO2 nanocomposites were investigated over a range of filler content 0-5 wt%. All samples with a wide range of TiO2 addition exhibit the translucency. The surface morphology showed that the addition of PBS at 10 wt% was miscible with PLA while the other contents of PBS exhibited phase separation in the blends. Additionally, a uniform dispersion of filler in the matrix existed when the nanoparticles content was less than 3 wt%. The surface treated nanoparticles played an important role in mechanical and thermal properties of the nanocomposites because of its well dispersion and strong interfacial interaction between the nanoparticles and PLA/PBS matrix.
Abstract: In recent decades, Heat and Moisture Exchange (HME) devices have been employed increasingly for short-term use in anaesthesia and long-term use in intensive care units. These devices work as heat exchangers, accumulating the patient’s expired heat and moisture and returning them to the patient during the inhalation phase. Porous matrices obtained from freeze-drying of blends of natural polymers exhibit high open and interconnected porosity and water vapour intake characteristics which make them possible candidates for HME devices. Preliminary tests were conducted on specimens made of gelatine blended with chitosan and treated with a non-toxic cross-linking agent. The tests were carried out in cyclic flow conditions with saturated and dried air. Results show water vapour retention comparable with accepted standards for HME devices.
Abstract: Graphene oxide was electrodeposited on titanium (Ti-GO) and anodized titanium (ATi-GO) as label-free sensors for the detection of challenging living organisms, specifically Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The graphene modification contributed to two sets of oxidation-reduction peaks in cyclic voltammograms (CVs) of bacteria growth on the electrode surfaces (ATi-GO) that resulted in increasing direct electron transfer and stimulating excretion of mediating molecules for higher electron transfer between electrodes and bacteria. Additionally, similar wave patterns of CVs were found when E. coli or S. aureus were grown and electrocatalyzed on ATi-GO. The results suggest that bacteria on titanium implant surfaces could be easily detected by using mediatorless ATi-GO sensors electrochemically. These finding open another interesting method in using ATi-GO as in situ electrochemical sensors for label-free, close to real-time detection of bacteria infection in orthopedic implants.
Abstract: Novel silica-based bioactive glasses were successfully prepared by the sol-gel method. The optimized glass composition for fabrication of the scaffolds was (in mol.%) 60% SiO2 – 30% CaO - 5% Na2O - 5% P2O5 (60S30C5N5P). This composition was confirmed to develop a thick hydroxycarbonate apatite (HCA) layer in Simulated Body Fluid (SBF) after 7 days, as revealed by Fourier Transform Infrared Spectroscopy (FTIR), indicating the bioactive character of the scaffolds. The mesoporous nature of the glass structure allows the load of tetracycline and a sustained release of the drug in PBS during 7 days was measured.