Yoshikazu Teranishi

Production of Stable Ion Beam of Os3(CO)12 with Compact Metal-Cluster-Complex Ion Source

Metal-cluster-complex ion beams were produced stably using a cluster ion source, which is compact enough to be installed in commonly used secondary ion mass spectrometry (SIMS) systems. As a metal cluster complex, triosmium dodecacarbonyl, Os3(CO)12, was utilized, which has a molecular weight of 906.7. Since precise temperature control is necessary to sublimate the metal cluster complex stably without thermal decomposition, the ion source was equipped with compact heat-removal devices in addition to an external heater. Experimental results showed that the crucible temperature of the metal cluster complex can be maintained at about 130 °C in continuous operation, which is an appropriate temperature for sublimation without the problem of decomposition. The ion source produced steady-state beams of Os3(CO)n+ (n=7 or 8) ions with a beam current exceeding 10 nA at 10 keV. Beam current increased with gas pressure, depending on the temperature of the crucible holding the metal cluster complex. The rate of the change in beam current was within a few percent per hour; hence, in view of stability, the ion source was confirmed as usable in SIMS. Furthermore, beam profile was investigated using a Faraday cup with a knife-edge as well as a GaAs/AlAs multilayer substrate as a beam target.

Observation of Sputtered Si Surface Irradiated with Metal Cluster Complex Ions

In this paper, we report the result of surface sputtering of Si using a proto-type compact cluster ion source which has been developed using Os3(CO)12 as a low damage-sputtering source. The surface roughening of Si under the acceleration energy 10 key at incidence angles about 0/spl deg/ and 60/spl deg/ has been studied. The sputtered Si surface was observed by using AFM (atomic force microscope) and SEM (scanning electron microscope).

Fabrication of high-density collagen fibril matrix gels by renaturation of triple-helix collagen from gelatin.

Collagen-based 3-D hydrogels often lack sufficient mechanical strength for tissue engineering. We developed a method for fabrication of high-density collagen fibril matrix (CFM) gels from concentrated solutions of uncleaved gelatin (UCG). Denatured random-coil UCG exhibited more rapid and efficient renaturation into collagen triple-helix than cleaved gelatin (CG) over a broad range of setting temperatures. The UCG solution formed opaque gels with high-density reconstituted collagen fibrils at 28-32 °C and transparent gels similar to CG at <25 °C. The unique gelation properties of UCG enabled the encapsulation of cultured cells in CFM of high solid volume (>5%) and elasticity (1.28 ± 0.15 kPa at 5% and 4.82 ± 0.38 kPa at 8%) with minimal cell loss. The elastic modulus of these gels was higher than that of conventional CFM containing 0.5% collagen. High-strength CFM may provide more durable hydrogels for tissue engineering and regenerative medicine.