Development of a freezing drier for lyophilization of biomaterials / 生物医学工程学杂志

To observe and assess the performance and effect of our self-made FD-1 freezing drier on biomaterials. R502 compressor and R502 refrigerating agent were adopted. In the experiment, FD-1 lyophilized collagen sponge, strain and defibrinogenase. The evaporating-condenser temperature reached -45 degrees C and the small icebox temperature reached -30 degrees C under the loading or free-loading circumstances in the lyophilizing box. The lyophilized collagen sponge had many pores in the structure, and the strain and the defibrinogenase were lyophilized and maintained satisfactorily. This freezing drier is suitable for lyophilizing some biomaterial samples in small or medium batches.

Preparation of collagen-based materials for wound dressing / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To describe the methods which were used to develop collagen-based materials for wound dressing.</p><p><b>METHODS</b>Fresh frozen bovine tendon was treated with 0.05 mol/L acetic acid at pH 3.2 for 48-72 hours, homogenized, filtered, mixed with 8% chondroitin sulphate, for creating a deaerated 1.5%-2.5% collagen solution. The solution was lyophilized in either a pre-frozen or non-pre-frozen mould. The collagen sponge was then cross-linked with 0.25% glutaraldehyde for 24 hours. Three other types of wound dressings were developed using a similar method: collagen membrane with a polyurethane membrane onlay, polyurethane-coated collagen membrane and collagen membrane on gauze.</p><p><b>RESULTS</b>It was demonstrated that the use of frozen bovine tendon was stable, and that the prepared collagen sponge contained pores of 50-400 microm in diameter.</p><p><b>CONCLUSIONS</b>Collagen could be used as wound dressing.</p>

Study on combined implantation of pig dermis and autologous skin in rats / 生物医学工程学杂志

In this study the treatment effect of combined implantation of autologous skin on pig dermis in injured rats was observed. Twenty-one Wistar rats were used, and the wounds were formed by excising a piece of full thickness skin on the back. After the pig dermis was implanted, the autologous skin was grafted on the dermis at 0.7 and 10 days. In the group with perforated pig dermis, the autograft skin was implanted on the day when the pig dermis was implanted. The healing effect was evaluated by measuring wound area, and by observing the growth of the autograft skin. Two weeks after the autograft skin was implanted, the skin securely adhered to the dermis, and the edge of autograft skin expanded clearly. The wound of the autograft skin implanted in the perforation of the dermis healed completely after 3 weeks, but the other 3 groups had remnant small wound. The autograft skin merged with the dermis and its surrounding tissue, but a clear dividing line still existed between autograft skin and dermis after implantation. The area of the implanted dermis and autograft skin varied from 51.8% to 65.9% compared to its original size. The results suggested that the time and the way of autologous skin grafting on xenogenous dermis may influence wound contraction and healing time.