Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 65

Abstract: The focal concern of this study is to examine the behaviour of bio-convective flow featuring micropolar nanofluids over an inclined permeable stretching surface while considering the influence of radiative activation energy. This investigation addresses the complex interplay of factors such as biological activity, convective heat and mass transfer, unique attributes of micropolar fluids, the dynamics of nanofluids, and radiative effects. This analysis employed Buongiorno’s model, considering thermal radiation and activation energy on the bioconvective flow of micropolar nanofluids over an inclined stretching surface. Some suitable similarity variables were used to obtain a set of non-linear differential equations from the initial partial differential equations which were then solved numerically using the Runge-Kutta Fehberg method along with shooting technique. The effects of some physical parameters were examined on the velocity, temperature, concentration, and microorganism density profiles of the flow. The result revealed that each increase in the heat source/sink, thermal radiation, thermophoresis, and Brownian motion lead to a corresponding increase in the thermal boundary layer; activation energy increased the concentration while Peclet number and bioconvective Lewis number declined the microorganism density profile. Insights gleaned from this study can find applications in biomedical fields. Understanding the behavior of bio-convective nanofluids has implications for controlled heat transfer in medical applications like hyperthermia treatments or targeted drug delivery, thereby impacting patient care.

Abstract: Background: Patients with chronic ankle instability (CAI) demonstrated altered movement patterns during unanticipated landing compared to coper patients. Understanding the effects of kinematics, dynamics and energetics on individual movement patterns during landing could enhance motor control strategies for patients with ankle sprains while avoiding the transition of coper patients to CAI patients. Therefore, the purpose of this study was to investigate the differences in movement patterns of coper patients compared to CAI patients during the unanticipated landings; Methods: Fifteen individuals with CAI (age: 22.8±1.4 years; height: 180.1±4.2 cm; weight: 81.5±5.8 kg) and fifteen copers (age: 23.1±1.2 years; height: 179.8±4.4 cm, weight: 80.4±6.2 kg) participated in an unanticipated landing task, during which three-dimensional motion capture, ground reaction force (GRF), and muscle activation data were collected. A musculoskeletal model was used to estimate muscle force and joint power among these two groups. Joint power was calculated as the product of angular velocity in the sagittal plane and joint moment data, reflecting the energy transfer at the ankle, knee, and hip joints. Furthermore, energy dissipation and generation within these joints were determined by integrating specific regions of the joint power curve; Results: Individuals with CAI demonstrated a greater muscle force in the vastus lateralis compared copers during the unanticipated landing task, while copers exhibited higher peak muscle forces in the medial gastrocnemius (p=0.007), lateral gastrocnemius (p=0.002), soleus (p=0.004). The muscle activation patterns of CAI patients also differ from those of coper patients. Compared to copers, CAI patients exhibit earlier activation of the rectus femoris (p<0.001) and lateral gastrocnemius muscles (p=0.042). Conversely, copers demonstrate earlier activation of the soleus (p=0.004) and medial gastrocnemius (p=0.003) muscles. In addition, joint power in CAI individuals during unanticipated landing shifted from the ankle to the knee and hip (p<0.001); Conclusions: These findings suggest that individuals with CAI exhibit a change in motion control strategy during unanticipated landing tasks. The variations in peak forces and the ability of proximal muscles to generate force might enable them to offset the deficits noted in distal muscles. Energy redistribution issues observed in CAI patients may help to prevent the transition of coper patients towards developing CAI patients.

Abstract: Polymethyl methacrylate (PMMA) is a polymer that is a suitable biomaterial for applications such as bone cement and replacement hip joints because it is inert, non-toxic, and has good mechanical properties. Hydroxyapatite (HA) is among the most thoroughly investigated bioceramics because its composition is similar to that of human bone and it has excellent biocompatibility and osteoconductive properties. Moreover, HA can be modified to regulate its physiochemical properties. In this study, boron and strontium were co-substituted into HA (SrBHA) to improve its biological characteristics. Previous studies have shown that strontium can increase bone density, although it negatively affects bone production. Moreover, boron helps to regulate the calcium balance to prevent bone loss. PMMA/SrBHA composites were prepared with different concentrations of SrBHA powder and the effects on the mechanical properties of the composites were investigated. The composites were fabricated using twin-screw extruders and compressed into test specimens using compression molding machinery. When the SrBHA powder concentration was <10 phr, the SrBHA particles were uniformly dispersed throughout the composite via a continuous polymer matrix reaction. Moreover, this concentration produced the greatest increase in compressive strength compared to the sample with no SrBHA (127.4 MPa). The composites were analyzed using energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction to determine the dispersion of the reinforced nanoparticles. Scanning electron microscopy (SEM) was used to analyze the dispersion of the SrBHA powder inside the matrix and to determine the causes of the fractures. The SrBHA powder improved the mechanical properties of PMMA, which is critical for applications in biomedical components. The mechanical tests and SEM analysis indicated that PMMA/SrBHA composites could be used for replacement joints and orthopedic implants.

Abstract: This study presents a comprehensive investigation into the preparation and characterization of PCL/EA cellulose composites. The Fourier-transform infrared (FTIR) spectroscopy results confirm the successful composite fabrication, indicating the absence of chemical reactions during melt-compounding. Scanning electron microscopy (SEM) revealed distinct morphologies, with PCL forming a continuous phase and EA cellulose exhibiting a fibrous network. Despite successful embedding of EA cellulose fibers in the composite, fractured surfaces indicated poor interfacial interaction, potentially leading to fiber pull out. Thermogravimetric analysis (TGA) revealed enhanced thermal stability in the composites, while differential scanning calorimetry (DSC) indicated minimal impact on PCL melting behavior. X-ray diffraction analysis (XRD) further demonstrated enhanced crystallinity in the composites, highlighting increased order in PCL crystals. Mechanical testing revealed a modest increase in stiffness attributed to the rigid cellulose fibers. However, a decrease in yield strength, tensile strength, and elongation at break suggested reduced ductility and inferior mechanical properties, consistent with poor interfacial adhesion observed in SEM. Overall, this study contributes valuable insights into the structural, thermal, and mechanical characteristics of PCL/EA cellulose composites, offering a foundation for potential applications in various fields.

Abstract: The 45S Bioactive glass-ceramic (BG) and Chromium (Cr)-doped BG materials were successfully produced in this study. XRD, FTIR, and ICP-MS techniques were used to characterize the prepared materials. The XRD testing showed that all samples contained pure BG. Increased Cr ion inclusion shifted the BG diffraction peaks to a lower value of 2 Theta and increased crystallinity. FTIR was used to detect Si-O, P-O, and Ca-O functional groups. Cr ions steadily decreased the Ca-vibration mode area. The ultraviolet-visible spectrophotometry was used to measure the optical characteristics of pure and Cr BG-doped materials. The Cr-doped BG was green in colour, whereas the lab-synthesized BG was white. Two additional bands formed at 433 and 615 nm when Cr ions were doped into the BG structure. These bands may be caused by ⁴A₂ → ⁴T₁ and ⁴A₂ → ⁴T₂ electronic d-d transitions. The findings show that biomedical applications may exist for fluorescent probes manufactured from Cr-BG materials.

Abstract: In view of the growing concern over the threat of antibiotic resistance and bacterial infections, this study evaluated the antimicrobial performance and characteristics of chitosan/polyvinyl alcohol (PVA) nanofibers incorporated with Methylene Blue (MB). Following the fabrication of chitosan/PVA nanofibers loaded with different MB concentrations via electrospinning, the samples were characterised through Field-emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared (FTIR) spectroscopy, and leaching tests. Finally, the antimicrobial inhibition level of the samples was assessed via the disc diffusion method. Based on the results, the MB-integrated chitosan/PVA nanofibers exhibited a nanoscale morphology, and the FTIR confirmed the presence of MB. The findings also established a positive correlation between the MB concentration and leaching intensity. Furthermore, the optimal antimicrobial efficacy against Escherichia coli was achieved by the chitosan/PVA/MB (5 wt.%) sample with a 2-min laser exposure, which recorded a significant inhibition zone of 8.65 mm. In conclusion, MB demonstrated potent antimicrobial properties against E. coli, suggesting its potential integration in electrospun nanofibers for combating bacterial infections via photodynamic therapy.