Cellulose film regenerated from Styela clava tunics have biodegradability, toxicity and biocompatibility in the skin of SD rats.

Cellulose is one of the most widespread biomolecules in nature and has been exploited in various applications including scaffolding, tissue engineering, and tissue formation. To evaluate the biocompatibility of cellulose film manufactured from Styela clava tunics (SCT-CF), these films were implanted in Sprague-Dawley (SD) rats for various lengths of time, after which they were subjected to mechanical and biological analyses. The cellulose powders (12-268 m) obtained from SCT was converted into films via casting methods without adding any additives. SCT-CF contained about 98 % α-cellulose and very low concentrations of ßß-cellulose. Additionally, the crystallinity index (CrI) of SCT-CF was lower (10.71 %) than that of wood pulp-cellulose films (WP-CF) (33.78 %). After implantation for 90 days, the weight loss and formation of surface corrugations were greater in SCT-CF than that of WP-CF, while the surface roughness was significantly higher in WP-CF than SCT-CF. However, there were no differences in the number of white blood cells between SCT-CF implanted rats and vehicle implanted rats. The level of metabolic enzymes representing liver and kidney toxicity in the serum of SCT-CF implanted rats was maintained at levels consistent with vehicle implanted rats. Moreover, no significant alteration of the epidermal hyperplasia, inflammatory cell infiltration, redness, and edema were observed in SD rats implanted with SCT-CF. Taken together, these results indicate that SCT-CF showed good degradability and non-toxicity without inducing an immune response in SD rats. Further, the data presented here constitute strong evidence that SCT-CF has the potential for use as a powerful biomaterial for medical applications including stitching fiber, wound dressing, scaffolding, absorbable hemostats and hemodialysis membrane.

Optimization of photonic crystal cavity for chemical sensing.

We optimize photonic crystal cavities for enhancing the sensitivity to environmental changes by finite-difference time-domain method. For the heterostructure cavity created by local modulation of the air hole radius, the resonance shifts due to refractive index change of the background material are investigated. The shifts can be enhanced by reducing the photonic crystal slab thickness or introducing air holes in the cavity. The sensitivity of the thinner slab with central air holes is 310 nm/RIU (refractive index unit). The heterostructure created in the slotted waveguide of thin PhC slab shows better sensitivity of 512 nm/RIU owing to strong confinement of electric field in the low-index region.