The effect of pH on elastic modulus E and turbidity for mixed gels of gelatin and agar was investigated. For (acylated gelatin)/agar mixed gels, the plot of E against the gelatin concentration C_G shows a minimum for the gels at pH 10.1 and a maximum for the gels at pH 3.5. A theoretical model for the phase-separated mixed gels was shown to be partly applicable to the data of E as a function of C_G. From the pH dependence of turbidity and E for the mixed gels, a correlation between the turbidity and the elastic modulus of the mixed gels was demonstrated.

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The vascular endothelial surface glycocalyx layer consists of fibrous glycoproteins with a thickness of several hundred nanometers to a few microns. The present study focuses on the function of the glycocalyx layer as a modulator of permeability in water transport across the blood vessel wall. A particulate layer model is developed to analyze the fluid permeation through the glycocalyx layer, which has periodic fibrous structures and finite thickness. Theoretical and numerical computations of the permeation resistance across the layer are performed based on the Stokesian dynamics approach. The results show that the resistance near the ends of the layer is affected considerably by the anisotropy of adjacent particle configurations. We describe such an end effect on the permeability in relation to the layer thickness and particle spacing ratio. It is suggested that the variations in thickness or fiber spacing in the glycocalyx layer could significantly alter its fluid permeation properties.

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Various extracorporeal circulation devices require a real time thrombus detection system. This paper presents a study toward the establishment of real-time thrombus detection by measuring the electrical properties of blood. We conducted experiments on static bovine blood samples and determined the change in relative permittivity of the samples by changing the size and red blood cell (RBC) concentration of the thrombus in each sample. Results show that the relative permittivity increases linearly with increases in the number of RBCs that form the thrombus. Similarly, permittivity also increases linearly with increases in the volume of the blood that forms the thrombus. These results are consistent with the numerical simulations. However, we found the linear relationship to be dependent on the AC frequency of the applied voltage. We compare and explain this dependency on the basis of earlier studies.

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This study was performed to develop a new experimental device with a fibrin gel-microgroove structure for study of microvascularization by endothelial cells (ECs). The effects of the width of microgrooves, initial cell seeding density and a supplementation of vascular endothelial growth factor (VEGF) on in vitro microvasculaization of ECs were examined. ECs were cultured in a fibrin gel formed on a polydimethylsiloxane microgroove substrate, with the microgroove width of 50, 100, 150 and 200 μm. ECs were elongated and sprouted within the gel in all the four types of microgrooves. In addition, multicellular network by connected cell branches were frequently observed in 100-μm microgrooves. Both high initial cell density and VEGF demonstrated significant promotional effects on morphology changes. The findings indicate that microgroove structure serves as a geometrical constraint for ECs, with a promotional effect on angiogenic responses of ECs, and thus, it can be used as an experimental model in the study of in vitro vascularization.

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Amyloid fibrils, formed by protein mis-folding, consist of consecutive hydrogen bonds situated between β-strands. To date, experimental data indicate that amyloid fibrils are structured according to the cross-β structure model, wherein β-strands are oriented perpendicular to the fibril axes. Amyloid fibrils are generally 10 nm in width; however, barnase M1 variants are 20 nm in width. In this study, we performed a comparative analysis of the structural stability of amyloid formation by barnase M1 variants. Based on the results of dynamic light scattering, we propose that the presence or absence of C-terminal amino acids in barnase M1 is dependent on resistance to urea.

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We study the shear-induced composite onion phase formation behavior of the nonionic surfactant C₁₀E₃ lamellar phases containing colloidal particles. Composite lamellar phase gives rise to the onion phase similar to the free-particle system. Depending on the particle size and concentration, the nonlinear rheology and shear modulus are significantly influenced, while the critical shear rate and onion formation kinetics remains unchanged from those of the free-particle system. Modification of the nonlinear rheology indicates that the colloidal particles assist the onion structure formation so that undulation instability is easily induced by anchoring of membranes on surface of particles. The shear modulus of the composite lamellar and onion phases is reasonably explained by considering the line tension of defects and the effect of polyhedral edge of the onion, respectively.

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Aim: To develop a prototype device that allows direct observation of the deformation of individual red blood cells (RBCs) in an oscillating shear flow field.
Method: A counter-oscillation mechanism composed of two parallel glass plates was constructed to keep RBCs floating at the centerline of a 30 μm fluid gap. RBCs in the suspension fluid were observed using a high-speed camera with 40-fold magnification.
Results: RBCs remained within the camera’s field of view when exposed to a shear force field that oscillated at 2 Hz. Moreover, glutaraldehyde-treated, hardened RBCs always tumbled and low-density RBCs had a larger elongation than high-density RBCs when exposed to the same shear field.
Conclusion: The feasibility of this counter-oscillating mechanism for evaluating RBC deformability has been demonstrated.

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Cell sorting is an important technology that is widely used for medical diagnosis in hospitals and cell engineering research. Among cell sorting technology, dielectrophoresis (DEP) is one of the most promising approaches for manipulating and separating biological particles because this phenomena requires no labeling procedure with a fluorescent dye or magnetic beads. In this study, we developed a precise cell sorting system by evaluating the DEP force with a liquid flow system. The DEP forces acting on a cell or polystyrene microbead (cell simulant) were characterized using a microfluidic chamber containing an electrode-array and fluid-induced shear forces. On the basis of this characterization, separation of the cells and microbeads was performed using our novel DEP cell sorting system. As a result, the living cells were trapped by the DEP force on the electrode arrays, whereas the beads passed the electrode array. In conclusion, the DEP force combined with fluid-induced shear force could separate the living cells from cell simulants.

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Attaining high hemocompatibility and promoting endothelialization are two major keys to solve the endoleak problems observed in existing stent-grafts. For the satisfactory long-term use of the stent-grafts, blocking the endoleak symptom is highly essential. This paper deals with the fabrication of electrospun nanofibers made of antithrombogenic poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) containing drug that can sustain the endothelial activity of the MPC nanofibers. Moreover, the drug release was controlled by micro-patterned diamond-like carbon (DLC) coated on the MPC nanofibers. It was found that MPC nanofibers retained excellent hemocompatibility and that the micro-patterned DLC efficiently controlled the drug-release rate of MPC fibers.

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