Abstract
It has been suggested that plastic adhesives such as Biobond and Aron a, which are clinically used for reinforcement of cerebral aneurysms, have had problems in terms of in vivo degradation and decreased strength. We have previously reported excellent results with Bemsheets, which are composed of 100% cellulose, as a wrapping material. We have prepared various solutions of ethyl cellulose (liquid cellulose) and studied the physical properties, operative manipulability, and histological findings of each solution. The following results were obtained.
1) Cupric sulfate, ethanol, acetone, and diethyl ether solutions of cellulose showed problems in terms of toxicity, flexibility of the film, tissue-adhesive properties, viscosities, and boiling points.
2) Ethyl acetate (concentration of cellulose: 6-25%; polymerization degree: 10-100) solutions showed no histological toxicity and had favorable adhesive properties. The physical property test of the solution revealed that the pH levels of an ethyl acetate solution (cellulose concentration: 10%; polymerization degree: 100) and Biobond were 7.35 and 3.16, respectively, and that the viscosities were 1385 cp and 626 cp, respectively. The test of the physical properties of the film, based on cast coating of 254 ym in thickness, revealed that a) the liquid cellulose and Biobond, after drying, were 17.8±2.8 and 109.8±44.2 in thickness (μm), respectively, b) the formation time of the liquid cellulose and Biobond was 62 sec and 1800 sec, respectively, c) coating strength (gm) (total summation upon rupture of a film of 5cm in length and 5mm in width by tensile force; tension velocity, 100 mm/min) was 432.3±51.4 and 8.0±5.6, d) strength index (Kg/cm2) [strength/(width of coat×thickness of coat)] was 572.8±84.7 and 2.4±1.8, and e) elongation rate (%) was 14.8±3.5 and 705±188.8. Thus, the cellulose coat was markedly stronger than Biobond.
3) When the concentration of cellulose was low, the coat was thin and viscosity and strength were low. On the other hand, when the concentration of cellulose was greater than 15%, the coating flexibility diminished and its strength was also decreased. However, when the degree of polymerization was increased, strength was increased without a reduction in flexibility even at the same concentration of cellulose.
With appropriate arrangement of the degree of polymerization and concentrations of ethyl cellulose, and solvent, liquid cellulose was demonstrated to possess excellent characteristics as a coating material because of its remarkable strength, flexibility, less tendency to elongate and ability to inhibit growth of cerebral aneurysms.
