Tissue engineering scaffolds with oxygen generating elements have shown to be able to increase the level of oxygen and cell survivability in specific conditions. In this study, biphasic calcium phosphate (BCP) scaffolds with the composition of 60% hydroxyapatite (HA) and 40% beta-tricalcium phosphate (β-TCP), which have shown a great potential for bone tissue engineering applications, were fabricated by a direct-write assembly (robocasting) technique. Then, the three-dimensional (3D)-printed scaffolds were coated with different ratios of an oxygen releasing agent, calcium peroxide (CPO), which encapsulated within a polycaprolactone (PCL) matrix through dip-coating, and used for in situ production of oxygen in the implanted sites. The structure, composition and morphology of the prepared scaffolds were characterized by different techniques. The oxygen release kinetics and biological investigations of the scaffolds were also studied in vitro. The results showed that oxygen release behaviour was sustained and dependant on the concentration of CPO encapsulated in the PCL coating matrix. It was also demonstrated that the coated scaffolds, having 3% CPO in the coating system, could provide a great potential for promoting bone ingrowth with improving osteoblast cells viability and proliferation under hypoxic conditions. The findings indicated that the prepared scaffolds could play a significant role in engineering of large bone tissue implants with limitations in oxygen diffusion.
With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.
In recent assassinations reported in London and Malaysia, nerve agents were used to cause death, by skin poisoning. Skin decontamination is the ultimate and most important defense against nerve agent poisoning, because no effective antidote currently exists. However, almost no existing material can achieve effective and rapid decontamination without irritating the skin. This study links proteins that exhibit no decontamination ability with polymers to form a nanocomposite. This creates a nanospace on the surface of the protein that attracts and traps organic molecules, effectively adsorbing the nerve agent Soman within several seconds, without irritating the skin. Analysis of the different components of proteins and polymers reveals that the decontamination efficiency is considerably affected by the thickness of the coated polymer. Moreover, the thickness of the layer is predominantly determined by the size and species of the core and the crosslinking method. Further in vivo experiments on rats poisoned with Soman verify the efficiency and safety of the nanocomposite. These results could be used to design and synthesize more multi-functional and effective decontamination materials.
The combination of metallic bio-inert material, stainless-steel 316L (SS316L) and a bio-active material, hydroxyapatite (HA) can produce a composite which has superior properties for orthopaedic applications. The main objective of this study is to investigate the effects of sintering temperature and holding time on the physical and mechanical properties of the sintered part. 50wt.% SS316L and 50wt.% HA were mixed with a binder system of palm stearin (PS) and polyethylene (PE) at 61 vol.% powder loading. Rheological properties show a pseudo-plastic behaviour of the feedstock, where viscosity decreases with increasing shear rate. The feedstock was injection moulded into a tensile bar shape while thermal debinding was carried out at 320°C and 500°C. The brown parts were sintered at 1000, 1100, 1200 and 1300°C, with three different sintering times of 1, 3 and 5 hours in the furnace. It was found that the highest sintered density measured was 95.61% of the theoretical density. In addition, the highest hardness and Young's modulus measured were 150.45 HV and 52.61 GPa respectively, which are higher than those of human bone. The lowest percentage of carbon content was 0.022wt.% given by the sample sintered at 1300°C for 1 hour. Therefore, SS316L/HA composite with good mechanical and physical properties was successfully produced through the PIM process.
Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.
Latex, a milky substance found in a variety of plants which is a natural source of biologically active compounds. In this study, Latex was collected from raw Carica papaya and was characterized using UV-Vis, FTIR and GC-MS analyses. Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) were synthesized, coated with C. papaya latex (PL-Sp) and characterized using UV-Vis, FT-IR, SEM-EDX, XRD, VSM and Zeta potential analyses. SPIONs and latex coated SPIONs (PL-Sp) were used in batch adsorption study for effective removal of Methylene blue (MB) dye, where (PL-Sp) removed MB dye effectively. Further the PL-Sp was used to produce a nanoconjugate loaded with curcumin and it was characterized using UV-Vis spectrophotometer, FT-IR, SEM-EDX, XRD, VSM and Zeta potential. It showed a sustained drug release pattern and also found to have good antibacterial and anticancer activity.
A novel hydrothermal process has been developed various hydroxyapatite(HA) powder. The HA powder was investigated in different calcination temperatures over the range of 200 degrees C-800 degrees C. TG/DTA and XRD analysis revealed that at temperatures of 700-800 degrees C the decomposition processes and phase changes took place. It is due to the appearance of TCP phase substituting the HA phase. FESEM observation showed that the produced hydroxyapatite powder was extraordinarily fine with nanosize primary particles and almost evenly spherical in shaped. Its high purity proved that the powder fulfills medical requirement.
The effect of Manganese (Mn) addition on the Vickers hardness and relative density of nanocrystalline hydroxyapatite (HA) dense bodies were studied. The starting Mn doped HA powders was synthesized via sol-gel method with Mn concentration varies from 2 mol% up to 15 mol% Mn. The Mn doped HA disc samples were prepared by uniaxial pressing at 200MPa and subsequently sintered at 1300 degrees C. Characterization was carried out where appropriate to determine the phases present, bulk density, Vickers hardness of the various content of Mn doped HA dense bodies. The addition of Mn was observed to influence the color appearance of the powders and dense bodies as well. Higher Mn concentration resulted in dark grey powders. It was also found that the hardness and relative density of the material increased as the Mn content increased and influenced by the crystallinity of the prepared Mn doped HA powders.
The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3 photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concrete surface under illumination of UV-visible or sunlight and showed that LiNbO3 achieved high conversion of CO2 into products despite the low levels of band-gap light available. The high reaction efficiency of LiNbO3 is explained by its strong remnant polarization (70 µC/cm(2)), allowing a longer lifetime of photoinduced carriers as well as an alternative reaction pathway. Due to the ease of usage and good photocatalytic efficiency, the research work done showed its potential application in pollution prevention.
Stem cell differentiation is guided by contact with the physical microenvironment, influence by both topography and mechanical properties of the matrix. In this study, the combined effect of substratum nano-topography and mechanical stiffness in directing mesenchymal stem cell (MSC) chondrogenesis was investigated. Three polyesters of varying stiffness were thermally imprinted to create nano-grating or pillar patterns of the same dimension. The surface of the nano-patterned substrate was coated with chondroitin sulfate (CS) to provide an even surface chemistry, with cell-adhesive and chondro-inductive properties, across all polymeric substrates. The surface characteristic, mechanical modulus, and degradation of the CS-coated patterned polymeric substrates were analyzed. The cell morphology adopted on the nano-topographic surfaces were accounted by F-actin distribution, and correlated to the cell proliferation and chondrogenic differentiation outcomes. Results show that substratum stiffness and topographical cues affected MSC morphology and aggregation, and influenced the phenotypic development at the earlier stage of chondrogenic differentiation. Hyaline-like cartilage with middle/deep zone cartilage characteristics was generated on softer pillar surface, while on stiffer nano-pillar material MSCs showed potential to generate constituents of hyaline/fibro/hypertrophic cartilage. Fibro/superficial zone-like cartilage could be derived from nano-grating of softer stiffness, while stiffer nano-grating resulted in insignificant chondrogenesis. This study demonstrates the possibility of refining the phenotype of cartilage generated from MSCs by manipulating surface topography and material stiffness.