Journal of Biomimetics, Biomaterials and Tissue Engineering Vol. 10

Abstract: Biofouling on underwater engineered structures, especially on ship hulls, results in increased operational and maintenance costs. Fouling is not only of an ecological interest, but it is also important from applied and commercial perspectives. With the development of society, widely used Tributyltin compounds (TBT) for biofouling control have been prohibited worldwide at the end of 2008. The need to develop new environment friendly antifouling agents has been highlighted. Herein we report on the synthesis and characterization of a novel cross-linkable copolymer containing a HMBA side chain. The paper is mainly focused on the synthesis of novel resin and its antifouling performance. Apart from use of acrylate monomer, the two other important monomers γ-methacryloxypropyltrimethoxysilane (HD-70) and N-(4-Hydroxy-3-Methoxy-Benzyl) acrylanine (HMBA) were selected to construct low surface energy materials. Finally, the antifouling properties of resins were carried through by the colonization of benthic diatoms (Nitzschia flosterium) and ocean plates of an offshore platform. Experimental results indicated the novel resins containing a HMBA side chain possessing better antifouling properties than a standard polydimethyl siloxane (PDMS) coating in the Qingdao ocean.

Abstract: Clearance of molecules by closed-circuit low-volume dialysis systems is limited by the accumulation of compounds in the dialysate and loss of the diffusion gradient. We sought to maintain dialysance of selected solutes by inducing “sink conditions” through the use of antibody-specific binding in the receiver compartment. Vitamin B12 was used as the test molecule since it is of clinically relevant size (molecular weight 1355 Da) and its clearance has been well-characterized for many dialyzer membranes. Using an in vitro haemodialysis model we perfused high-flux polymethylmethacrylate and low-flux polysulfone dialyzer membranes with known amounts of vitamin B12 through the intracapillary space. Clearances over time were calculated until equilibrium was reached within the fixed dialysate volume after 60 minutes. Anti-B12 monoclonal antibodies were then added to the receiver compartment reservoir. Under these sink conditions B12 clearance was restored, amounting to 77% and 118% of the integrated pre-equilibrium clearance for the high- and low-flux haemofilters, respectively. The magnitude of enhancement was such that the antibodies increased vitamin B12 clearance in low-flux dialyzers to levels observed in the high-flux devices. These studies demonstrate the feasibility of antibody-based sink conditions so as to promote substantial and highly selective solute clearance into small volume recirculating extracorporeal circuits.

Abstract: In this present study a two-phase model for the influence of aspirin on peripheral layer viscosity for physiological characteristics of blood flow through stenosed blood vessels using Casson’s fluid model has been obtained. Flow of blood with axially non-symmetric but radially symmetric stenosis geometry is considered. The non-linear pressure equations have been solved with help of boundary conditions and the results are displayed graphically for different flow characteristics. It was found that the resistance to flow decreases as stenosis shape parameter increases whereas the resistance to flow increases with increasing values of stenosis length, stenosis size and peripheral layer viscosity. The effects of stenosis severity and wall shear stress are discussed in the present computational analysis. Comparisons between the measured and computed peripheral layer viscosity profiles are favourable to the solutions. As a result it can be concluded that a regular dose of Asprin decreases the blood viscosity by diluting the blood of diabetic patients which ultimately decreases the blood pressure. For the validation of the numerical model, the computation results are compared with the experimental data and results from published literature.

Abstract: A dielectrophoretic approach with latest developed three-dimensional (3-D) carbon micro-electro-mechanical system (C-MEMS) has been extended as a potential route with idyllic solution to recommend a low-cost, biocompatible and high throughput manipulation and positioning for bio-particles as compared to 2D-planar microelectrodes. Presented in this paper is a novel platform for modelling and simulation of C-MEMS microfabrication process for dielectrophoresis (DEP) force based on various 3-D offset-microelectrode configurations. Numerical solutions are employed to investigate the upshots of multi-designed microelectrodes, applied voltage, electrode edge-to-edge gap and geometric size of microelectrodes on the electric field intensity gradient, induced by an AC voltage for the deployment of broad categories of bioparticles creation, utilization and their manipulation (separation, concentration, transportation and focusing). Sharp edge electrodes are the principle focus of this paper for DEP manipulation that is more convenient to enhance the electric field intensity distribution. The results show that square column electrodes configuration comparatively create large gradient magnitude in electric field intensity as compared to all other configurations. It is also observed that electric field extends drastically with increases in microelectrode height. These findings are consistent with literature experimental reports and will provide vital strategy for optimal design of DEP devices with 3-D C-MEMS.

Abstract: Modelling of bioelectric phenomena in the human body poses unique problems compared to those encountered in other fields of engineering. Accurate definition of the physical domain and material properties is difficult due to geometrical complexity and uncertainty in tissue characterisation. A workflow is presented for finite element simulation of electric current in the body. This is illustrated through an application on a subject-specific cranial model for simulation of a cochlear implant. Operations required for the full workflow include: data acquisition, image registration and segmentation, material property assignment, numerical analysis, and visualisation. The case study described uses MRI imaging and diffusion tensor MRI for definition of the analysis domain and material properties with analysis conducted in ANSYS. Image registration and segmentation were accomplished using custom designed algorithms. Visualisation was achieved using a 24-bit red-green-blue colour scheme to represent directional vectors.

Abstract: Nano-bacterial cellulose (nBC), secreted by Acetobacter xylinum, is expected to have potential applications in tissue engineering. In this paper, the in-vitro degradation performance and the corresponding mechanism of nBC immersed in phosphate buffer solution (PBS) for different time periods was investigated. The pH value variation of solution, material degradation, and the swelling and structural changes of nBC was analysed successively. The results indicate that water molecules attack the exposed nBC fibrils, weakening the bonding strength of inter- and intra-molecular chains and disconnecting partial C-O-C bonds. The disconnection of C-O-C bonds is considered the primary reason for the degradation of nBC large molecular chains after nBC is immersed in PBS. The present work is instructive for controlling the in-vivo degradation performance of nBC acting as bone tissue engineered scaffold materials.

Abstract: Porous hydroxyapatite (HA) ceramic implants have attracted attention in bone tissue engineering due to their excellent bioactivity and biocompatibility due to their chemical similarity with the mineral component of natural bone. Unfortunately, HA when is formed into porous structures exhibits very low compression strength. In this study, fabrication of porous HA ceramic scaffolds containing HA fibers is presented. The primary aim of the study is to improve mechanical properties of the scaffold by introducing the fiber with uniform component relative to the scaffold. Scanning electron microscopy was used to observe the surface morphology and pore size of the scaffold. X-ray diffraction (XRD) was used to detect the phase composition and crystallinity of the scaffold. The compressive strength was determined using a universal material test machine. The results and the characterizations demonstrate the addition of HA fiber could enhance the uniformity of mechanical properties among samples and also the strength for a given open porosity.

Abstract: Removed at authors request

Abstract: This paper concerns biomimetic exploration of the leaf rib layout problem. Biological venation of organisms is observed to be similar to reinforced plate/shell systems. Similarity analysis makes it clear that dicotyledonous leaves are an ideal research subject. In this paper, global and local regularities are summarized and existing theories on venation morphogenesis are discussed and compared. An energy hypothesis is proposed to cater for interdisciplinary applications. A venation growing model was then used to construct a two-dimensional reinforcement layout model. The biomechanical expressions developed can be an alternative to describe rib-in-plate or fibre-in-composite materials.