Yukako Fukuhira

Interfacial tension governs the formation of self-organized honeycomb-patterned polymer films

Hexagonally packed water droplets condensed on a polymer solution are potential templates for the formation of honeycomb-patterned porous polymer films. A small number of surface-active molecules is indispensable for the stabilization of water droplets during solvent evaporation. Biocompatible surfactants; e.g., phospholipids, are required for the fabrication of biodegradable honeycomb-patterned polymer films, which can be used as novel biomedical materials, mainly in vivo. Among various kinds of phospholipids, dioleoylphosphatidylethanolamine (DOPE) has been reported to be the most suitable surfactant for the formation of honeycomb-patterned PLA films. Interfacial tension between a water droplet and the polymer solution is largely dependent on the chemical structure of the phospholipids. DOPE shows high interfacial tension, resulting in the stabilization of water droplets during solvent evaporation. Dierucoylphosphatidylcholine (DEPC) and dierucoylphosphatidylethanolamine (DEPE), both of which display high interfacial tension, were also found to be suitable biocompatible surfactants.

A thin honeycomb-patterned film as an adhesion barrier in an animal model of glaucoma filtration surgery.

PurposeTo evaluate the effectiveness and safety of a thin honeycomb-patterned biodegradable film for glaucoma filtration surgery in rabbits. MethodsA 7 μm-thick film made from poly(L-lactide-co-ϵ-caprolactone) was placed in the subconjunctival space in one eye of rabbits, with or without full thickness filtration surgery. The film had a honeycomb-patterned surface that faced the subconjunctival Tenon tissue and the other side was smooth. Filtration surgery was also performed in the fellow eye, which received either no adjunctive treatment or 0.4 mg/mL mitomycin C (MMC; n=6 each). Intraocular pressure (IOP) measurements and bleb evaluations using ultrasound biomicroscopy were performed periodically for 28 days after surgery followed by histologic observation. ResultsPostoperative IOPs of the film-treated eyes were significantly lower than that of control eyes from day 10 to day 28 (P<0.05), but were not significantly different from those of MMC-treated eyes. The subconjunctival filtration space, detected by ultrasound biomicroscopy, disappeared in 5 control eyes, 1 MMC-treated eye, but none of the film-treated eyes. A bleb leak occurred postoperatively in 2 MMC-treated eyes. Histologically, in eyes without filtration surgery, fibrotic tissue with the film partly attached to it was noted on the honeycomb side, but was minimal on the sclera that faced the smooth side of the film. In eyes with filtration surgery, the honeycomb-patterned film lined the inner bleb wall with minimal inflammatory reaction. ConclusionsThe thin honeycomb-patterned film that attached to the inner bleb wall worked as an adhesion barrier in glaucoma filtration surgery in rabbits, which is worthy of further investigation.

A new nerve coaptation technique using a biodegradable honeycomb‐patterned film

We developed a biodegradable poly‐lactide (PLA) film with a honeycomb‐patterned porous structure (honeycomb film). This study investigated the use of this film in neurorrhaphy. Three types of PLA film were tested following bilateral sciatic nerve transection and neurorrhaphy in 35 rats: 7‐ and 10‐μm thick honeycomb films, and cast film with no porous structures. Initially, following two‐stitch neurorrhaphy, 40 limbs (20 rats) underwent wrapping in 7‐ or 10‐μm honeycomb film, cast film, no wrapping, or extra two‐stitch neurorrhaphy (8 limbs each). Breaking strength was tested 2 days postoperatively. Another 30 limbs (15 rats) then underwent wrapping in 7‐ or 10‐μm honeycomb film, cast film, no wrapping, or sham operation (six limbs each). Histological and functional analyses were performed 6 weeks postoperatively. Breaking strength was significantly higher for the 10‐μm honeycomb film than for no wrapping (P = 0.013), although no significant difference was observed between the 7‐μm honeycomb and no wrapping (P = 0.085). Breaking strength for the cast film was almost equal to that for no wrapping (P = 0.994). Extra two‐stitch (four‐stitch) neurorrhaphy was significantly stronger than all groups, except the 10‐μm honeycomb group. No significant difference was observed between the 10‐μm honeycomb and the four‐stitch (P = 0.497). No negative effects on functional recovery were identified. No adhesions or inflammation were observed between the film and surrounding tissues in the honeycomb groups. Honeycomb film may offer a suitable reinforcing material for adhesion‐free neurorrhaphy.

Artificial perineurium to enhance nerve recovery from damage after neurolysis.

We have developed a novel biodegradable poly‐lactide (PLA) film (honeycomb film) with a micropatterned porous structure on one side. We hypothesized that this film could be used as a substitute for perineurium. We used two types of thin PLA film: honeycomb film and cast film with smooth surfaces on both sides. In a rat extensive internal neurolysis model, the nerve was wrapped with honeycomb film (group H) or cast film (group CA), or left unwrapped (group C). Histological and functional analyses were performed. The honeycomb film closely attached to the nerve surface but did not adhere to surrounding tissues. In contrast, nerves in group C displayed severe adhesion to the neural bed. Mean percent wet muscle weight and motor nerve conduction velocity were significantly higher in group H than in group C. The honeycomb film prevents nerve adhesion and enhances functional recovery after extensive neurolysis. Muscle Nerve, 2010