Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 61

Abstract: Nature always has the ability to offer various solutions in day-to-day life of humans in various fields of engineering and science. The term biomimicry refers to the process of adopting solutions from nature to solve complicated problems that refers to analysing the environment for sustainable solutions. This concept is used in various fields of engineering and science. This concept is emerging now in the field of construction also. Biomimics concept is used in analysing the behaviour of structural elements which forms a symbiosis between the environment and construction. In the field of construction, thin shell structures are lightweight structures that are preferred as roof elements for covering high spans and also gives an aesthetic appearance. In this study, three different shapes like spherical with different rise to span ratios, circular and elliptical are considered. The concept of reflecting the human skull shape into thin shell structures was considered, because the reflection from the environment helps in solving the complicated problems of both engineering and sciences. This study focused on the mesh convergence study for numerical analysis using Ansys 18.1 software. The parameters of the thin shells such as thickness, span and rise were taken from the geometrical characteristics of scanned human skull models in comparison with the standard skull models. From the results, mesh sizes were optimized for the three different shapes considered and also predicted the most efficient model. These results were obtained based on the equivalent stress in comparison with the theoretical stresses of the respective models. This study inspires the naturally available forms in the environment to incorporate it in the field of construction and technology for a sustainable solution.

Abstract: Magnesium (Mg) alloys are promising biodegradable implant materials. If successful, they do not require second surgical operation for their removal. However, the focus of this study is to address the limitation of fast degradation rate (DR) which hinders the clinical application of Mg alloys. The bio-corrosion rate of any intermetallic alloy is related to its beta (β) phase volume fraction. Thus, homogenization heat treatment (HHT) was carried out to reduce the β phase. The influence of β phase and the hydroxyapatite powders (HAp) was employed to slow down the initial DR of Mg AZ91 alloy. Samples were cut from Mg grade AZ91 alloy ingot in 10mm x 10mm x 3mm dimension. The samples were prepared and divided into two; the first part was classified as as-received sample (sample a) while the second one was processed for HHT. HHT was carried out at 410°C/10h, cooled inside the furnace and named as homogenized sample (sample b). The HAp was synthesized using a simple wet chemical precipitation technique (SWCPT) and deposited on sample b via electrophoretic deposition (EPD) at different voltages with different deposition times. The HAp, uncoated and coated samples were characterized. Potentiodynamic polarization (PP) and immersion tests were carried out in stimulated body fluid (SBF) to estimate the DR and in vitro bioactivity of Mg AZ91 respectively. The results revealed a significant drop in DR from sample a (1.421 mm per year) to coated sample h (3.73 x 10^-4 mm per year). Keywords: Magnesium alloy, biodegradable implants, beta phase, homogenization heat treatment, hydroxyapatite, electrophoretic deposition.

Abstract: Objectives. This study aimed to evaluate antibacterial activity of elastomeric ligatures coated with Zinc oxide particles against Streptococcus mutans. Methods. ZnO particles grafted with (3-Aminopropyl) trimethoxysilane (APTMS) were prepared in situ. The ATR-FTIR spectrum was used to analyze the APTMS grafted on ZnO surfaces. Two concentrations of ZnO-APTMS, i.e., 5 and 10 wt%, were coated on orthodontic elastomeric ligatures by the dip coating method. Antibacterial property of the ZnO-APTMS coated elastomeric ligatures against S. mutans ATCC25175 were investigated by the agar diffusion test. The effect of ligature aging on antibacterial property was evaluated by the direct contact test, in which the growth of bacteria was determined by the turbidity after exposed to the samples that had been immersed in distilled water for 0, 3, 7, 14, 28 days. The drop plate test was also performed to determine the inhibitory and the bactericidal effects. Results. The analysis of ATR-FTIR spectrum confirmed that APTMS was successfully grafted on ZnO surfaces. The agar diffusion test could not demonstrate the antimicrobial effects of the ZnO-coated elastomeric ligatures. However, results from the direct contact and the drop plate tests showed the inhibitory effects on bacterial growth compared to the positive controls (p < 0.05). The inhibitory effect of the ZnO-coated elastomeric ligatures was observed even after they had been immersed in distilled water for 28 days. Conclusions. The surface coating elastomeric ligatures with 5 and 10 wt% ZnO-APTMS exhibited antibacterial activity against cariogenic bacteria, S. mutans. The bacterial inhibitory effect was prolonged until 28-day.

Abstract: Composite scaffolds are promising regenerative medicines. Chitosan-TiO₂ nanotubes (CTNTs) scaffold as a composite scaffold is, however, associated with low biocompatibility. This research aims to increase in vitro efficacy of CTNTs scaffolds by using fibronectin (FN) and investigate the adsorption affinity of such scaffolds towards FN. CTNTs scaffolds were prepared via direct blending of TiO₂ nanotubes (TNTs) and chitosan solution. The mixture was then subjected to 24-h freezing and 24-h freeze drying. The scaffolds were further functionalized with FN solution (20, 40, 60, 80 and 100 μg/mL) via adsorption. The amount of adsorbed FN by the scaffolds was determined via colorimetric method. MG63 was used to evaluate the in vitro efficacy of CTNTs scaffolds with FN. The adsorption affinity of CTNTs scaffolds towards FN was high, as no saturation was achieved. The adsorption isotherm of FN onto CTNTs scaffolds fitted well with Temkin isotherm suggesting there was electrostatic interaction between the scaffolds and FN. Enhanced proliferation and early differentiation were observed in MG63 cultured on CTNTs scaffolds with FN. Particularly, CTNTs scaffolds functionalized with 60 μg/mL FN promoted the highest proliferation and early differentiation. CTNTs scaffolds with FN showed potential as scaffolding material for bone regeneration.

Abstract: This study constructed poly (vinyl alcohol)/ biphasic-calcium phosphate (PVA/ BCP) composite scaffolds. The biphasic-calcium phosphate (BCP) was incorporated in 0, 5, 10, and 25 wt%; BP0, BP1, BP2, and BP3, respectively. The surface morphology was done with a scanning electron microscope (SEM) to observe the porosity and the pore size and distribution of fabricated samples. The Fourier Transform Infrared spectroscopy (FTIR), and some physical properties such as porosity, density, swelling ratio, flexural strength, impact strength, and compression strength were also investigated. The biodegradation and bioactivity were also tested. The SEM results showed that the pores increased and became more regular and interconnected to each other with the increasing addition of BCP. The density decreased with the addition of BCP, while the porosity and mechanical properties increased with additives. The sample of BP3 has a high porosity (67%) and high impact strength (11.9 MPa). The high porosity is favorable for bone implants, and the mechanical strength must also be considered. The bio tests show that the biodegradation became regular by adding the BCP powder, which leads to ease of controlling the gradual degradation and the samples are bioactive for bone tissue. Keywords: Bone Tissue Engineering, PVA, Biphasic-Calcium Phosphate, Porosity, Mechanical properties

Abstract: The integration of phosphotungstic acid and niobium oxide forms a bifunctional catalyst that demonstrates an interplay between Brønsted-Lowry and Lewis acid which is able to provide a synergistic effect for the conversion of biomass to LA. This bifunctional acid catalyst shows a higher yield of levulinic acid (LA) (16.4%) as compared to that of sole phosphotungstic acid (10.5%) or niobium oxide (13.2%), presumably caused by a higher selectivity at the tandem steps of the conversion reaction. The bifunctional catalyst was then doped to a lignin-derived carbon cryogel to mitigate the deactivation and leaching of the catalysts. The durability and thermal stability of the carbon cryogel allow the catalyst to recycle up to 3 times while retaining similar performance.

Abstract: Healthcare-associated infections (HAIs) are a major safety concern globally that contribute to mortality rates amongst patients especially associated with indwelling or implanted medical devices. The advanced metal-oxide nanocomposites (MNPs) embedded in polymer matrix present an outstanding antibacterial profile, especially for MDR strains owing to reactive oxygen species (ROS) and free radicals’ mode of action. To date, there is still a lack of knowledge on the implication of external reactive species from MNPs-based polymers to humans. This study investigates the bio-interaction of TiO2-ZnO nanocomposite films embedded in linear low-density polyethylene (LLDPE/ TiO2-ZnO) on human fibroblast and blood cell lines model at molecular genes and protein level. The initial analysis of the in vitro bio-interaction responses on fibroblast and blood cell line models showed signs of cell membrane integrity disturbance, which might be due to free radicals’ activities, such as the release of intracellular ROS and Zn ions (Zn²⁺) during the initial cellular adaptation process on the TiO2–ZnO polymer nanocomposite film. Further findings found that cell–polymer nanocomposite film interaction could possibly trigger transitory oxidative stress response and cellular redox regulation via NF-kβ interactions. However, further comprehensive studies are needed to support this study, especially involving animal models.

Abstract: The Catharanthus roseus plant was extracted and converted to nanoparticles in this work. The Soxhlet method was used to extract alkaloid compounds from the Catharanthus roseus plant and converted them to the nanoscale. Chitosan polymer was used as a linking material and converted to Chitosan nanoparticles (CSNPs). The extracted alkaloids were linked with Chitosan nanoparticles by maleic anhydride to get the final product (CSNPs-Linker-alkaloids). The pure Chitosan, Chitosan nanoparticles, and CSNPs-Linker-alkaloids were characterized by X-ray diffractometer, and Fourier Transform Infrared spectroscopy. X-ray results show that all samples have an orthorhombic structure with crystallite size in nanodimensions. FTIR spectra prove that the P=O is the cross-linkage between chitosan and phosphate groups by ionic bond, which indicate that the Chitosan nanoparticle has been formed in the solution. FTIR spectrum for CSNPs - Linker - alkaloids appear a new distinct band at 1708.93 cm^-1 which demonstrates the presence of C = O esterification. Atomic Force Microscope images of the Chitosan nanoparticles and CSNPs-Linker-alkaloids show that they have almost spherical shapes with average sizes of 90 and 92.6 nm respectively. The electroactive surface area of glassy carbon electrodes (GCE), extract plant, and Linker-alkaloids were calculated in KCl solution containing K₃[Fe (CN)₆]. The presence of CSNPs-Linker-alkaloids in modified glassy carbon electrodes about 3 times. The successful synthesis of organic nanoparticles from the Catharanthus roseus plant can be used safely in biosensors, environmental monitoring, and biomedical applications.

Abstract: Osseointegration prosthesis is a directly implanted fixation in the bone for limb amputees. It has been used as an excellent alternative for amputees experiencing difficulties from the use of a traditional socket type prosthesis. A novel implant used for implanted prosthetics is designed and it depended on polymer as a primary material to increase bone osseointegration. As an alternative to the metallic material on the interface with the bone. The design consists of several parts and relies on thread to increase installation. This research aims to overcome the problems of loss implantation by using new designs for fixations. Evaluated this design by FEA (Finite element analysis) in different load cases to obtain the distribution of stress and force reaction when the implant displacement was applied. The polymeric part was designed in two shapes, each shape relies on a different size of threaded to verify the change of fixation with the threaded. As for the metal part, two cases were used, the first case, stainless steel 316L, and the second case titanium metal to reach the best stress distribution in this design.

Abstract: The systematic study of human locomotion known as gait analysis can be applied in various contexts, including athletics, rehabilitation, and clinical diagnoses. However, the present gait analysis methods have several limitations that make them inappropriate for individual use, such as the fact that they are expensive, non-portable, need a significant amount of time to set up, and require additional time for post-processing. This study aims to investigate and develop a gait analysis system to measure the vertical ground reaction forces. The measurement instrument qualities of being flexible, portable, and comfortable are essential to the design of wearable sensors. The device was calibrated using a universal testing machine (Force plate device). In addition, this study used flexible force sensors for detecting vGRF. The result shows the device works with high efficiency and accuracy in measurement when calculating the values of ground reaction force compared with the values ​​ of reaction force measured by the university testing machines. Keywords: Gait cycle, Ground reaction force, Arduino, Force plate, Smart sole