In this study, two attempts of new biomaterial development based on the latest results of cell biology and tissue engineering are reported. One is specific cell separation using DNA as linker, and ...another is novel hybrid materials constructed by decellularized tissues complexed with synthetic polymer. Antibody was immobilized via desthiobiotin-avidin interaction. Single strand DNA (20mer) was chemically immobilized on the surface and then antibody (anti-mouse CD45, mCD45) modified with the complementary single strand DNA was immobilized on the surface through DNA duplex formation. Decellularized porcine dermis was prepared and lyophilized. After that, methyl methacrylate (MMA) monomer were immersed in stages, then polymerization was proceeded. The obtained hybrid material was analyzed by tensile strength and SEM observation. Cells were also adhered on the surface at 37 degrees C and detached by 4 degrees C incubation with remaining cells that interacted with the surface via antibody-antigen interaction. The adhered cells were released by DNase treatment. These results suggest that cells can be selectively captured and collected by using the surface that immobilizes an antibody via dissociation molecules. The monomer absorption depends strongly on the tissue structure. Gradient-type decellularized dermis–poly(methyl methacrylate) complex was prepared by controlling the permeation time of the methyl methacrylate monomer. The mechanical strength of this complex gradually increased from the dermis side to the polymer side. Developing new biomaterials combining new knowledge among different science discipline is an indispensable methodology for the next generation of medical development. The materials presented here are example of these biomaterials, and show the direction of future biomaterial development.
The inorganic-organic composite consisting of nano-scaled hydroxyapatite (HAp) and silk fibroin (SF) fibers was prepared through covalent linkage to develop a novel biomaterial for a ...soft-tissue-compatible material. The preparation of the composite was conducted through the three-step procedure consisting of chemical modification using 2-methacryloxyethyl isocyanate (MOI) monomer to introduce vinyl groups on SF, poly(gamma-methacryloxypropyl trimethoxysilane) (MPTS) graft-polymerization on SF, and coupling process between the surface of polyMPTS-grafted SF and HAp nano-particles. The amount of the graft-polymerization of polyMPTS through vinyl groups was well controlled by the reaction time. The nano-crystals were subsequently coated on the grafted fibers by heating at 120 degrees C for 2 h in a vacuum. The crystalline structure of the SF substrate did not change in the procedure. In the SEM observation of the composite surface, it was found that the bonded nano-crystals were separated and partially aggregated with several crystals attached on the SF fiber surface. The HAp particles adhered more strongly on the SF surface with separation or aggregation of several crystals than on the surface of the original SF after ultrasonic treatment.
The detailed seismic responses of pile-soil systems are usually evaluated by a three-dimensional finite-element model which requires a lot of computational resources. In the actual structural design ...for these models, a computationally efficient method with a reasonable accuracy is preferred from the viewpoint of cost and time. As for the seismic response of a pile-soil system, a kinematic effect due to the forced displacement of the surface ground is considered to be important, especially in soft ground, together with the inertial effect due to the inertial forces from superstructures. In this paper, a new response spectrum method in terms of complex modal quantities is developed for the evaluation of the maximum kinematic seismic response of the pile-soil model to the ground motion defined at the engineering bedrock surface as an acceleration response spectrum. The ratio of the pile-head moment due to the kinematic effect to that due to the inertial effect will be discussed in detail.
PDF
