Fabrication of hydrophilic medical catheter with hydrogel grafting and the in vivo evaluation of its histo-compatibility / 生物医学工程学杂志

The biocompatible hydrogel was fabricated under suitable conditions with natural dextran and polyethylene glycol (PEG) as the reaction materials. The oligomer (Dex-AI) was firstly synthesized with dextran and allylisocyanate (AI). This Dex-AI was then reacted with poly (ethyleneglycoldiacrylate) (PEGDA) under the mass ratio of 4∶6 to get hydrogel (DP) with the maximum water absorption of 810%. This hydrogel was grafted onto the surface of medical catheter via diphenyl ketone treatment under ultraviolet (UV) initiator. The surface contact angle became lower from (97 ± 6.1)° to (25 ± 4.2)° after the catheter surface was grafted with hydrogel DP, which suggests that the catheter possesses super hydrophilicity with hydrogel grafting. The evaluation after they were implanted into ICR rats subcutaneously verified that this catheter had less serious inflammation and possessed better histocompatibility comparing with the untreated medical catheter. Therefore, it could be concluded that hydrogel grafting is a good technology for patients to reduce inflammation due to catheter implantation, esp. for the case of retention in body for a relative long time.

Hyaluronic acid production by Streptococcus iniae and its application in rabbit skin's regeneration / 生物工程学报

Hyaluronic acid (HA) is an important biomaterial as the extracellular matrix in human body. We produced HA by fermentation of Streptococcus iniae (Strep.). Production of HA by Strep. was evaluated and further improved by strain mutation by ultraviolet. One strain with higher HA yield and lower content of protein was obtained. Its HA yield increased from (82.3±3.3) mg/L to (120±10.6) mg/L, and protein decreased from (0.178±0.011) mg/L to (0.032±0.017) mg/L. The molecular weight (MW) of HA yield from Strep. is about 3.0×10⁵ Da. Using the method of freezing and thawing, HA aqueous solution was transferred into hydrogel. This HA hydrogel, casted on sterilized non-woven fabric, was applied to repair rabbit skin with full-thickness defect. The preliminary results of the animal tests displayed that HA hydrogel obviously reduced the inflammation around the wound and promoted the skin regeneration comparing with the control tests.