Water-Mediated On-Demand Detachable Solid-State Adhesive of Porous Hydroxyapatite for Internal Organ Retractions.

Novel adhesives for biological tissues offer an advanced surgical approach. Here, the authors report the development and application of solid-state adhesives consisting of porous hydroxyapatite (HAp) biocompatible ceramics as novel internal organ retractors. The operational principles of the porous solid-state adhesives are experimentally established in terms of water migration from biological soft tissues into the pores of the adhesives, and their performance is evaluated on several soft tissues with different hydration states. As an example of practical medical utility, HAp adhesive devices demonstrate the holding ability of porcine livers and on-demand detachability in vivo, showing great potential as internal organ retractors in laparoscopic surgery.

Immediate soft-tissue adhesion and the mechanical properties of the Ti-6Al-4V alloy after long-term acid treatment.

Close attachment of soft tissues onto implantable devices inside the body is regarded as an optimal condition for preventing complications (e.g., infections and abscess formation around implants, and the migration of small injectable devices). We have recently reported that an α-type commercially pure Ti (CpTi) film after a long-term acid treatment and air drying showed a remarkable soft tissue adhesiveness immediately (i.e., within a few seconds) after the attachment onto soft tissues. Herein, we conducted acid treatment for (α + ß)-type Ti-6Al-4V alloys and compared their mechanical properties and the immediate soft-tissue adhesiveness with α-type CpTi. The acid treatment for Ti-6Al-4V also promoted immediate soft-tissue adhesion, although the treatment was less effective than for CpTi. The tensile strength of acid-treated Ti-6Al-4V was much higher than that of acid-treated CpTi or human skin tissues, although the degree of hydrogen embrittlement was more severe than that for CpTi. These results suggest that the small amount of Al in the major α phase and/or the minor ß phase of Ti-6Al-4V has a significant influence not only on the mechanical properties but also on the immediate soft-tissue adhesiveness of Ti-based solid-state adhesives after the acid treatment.

Micro-Architectural Investigation of Teleost Fish Rib Inducing Pliant Mechanical Property.

Despite the fact that various reports have been discussing bone tissue regeneration, precise bone tissue manipulation, such as controlling the physical properties of the regenerated bone tissue, still remains a big challenge. Here, we focused on the teleost fish ribs showing flexible and tough mechanical properties to obtain a deeper insight into the structural and functional features of bone tissue from different species, which would be valuable for the superior design of bone-mimicking materials. Herein, we examined their compositions, microstructure, histology, and mechanical properties. The first rib of Carassius langsdorfii showed a higher Young's modulus with a small region of chondrocyte clusters compared with other smaller ribs. In addition, highly oriented collagen fibers and osteocytes were observed in the first rib, indicating that the longest first rib would be more mature. Moreover, the layer-by-layer structure of the oriented bone collagen was observed in each rib. These microarchitectural and compositional findings of fish rib bone would give one the useful idea to reproduce such a highly flexible rib bone-like material.