Experimental Study Of The Nanoscale Iron Traction’s Release And Biocompatibility Of A Newly Designed Ureteral Stent

Objectives1. To find a safe and dissolvable material which can be used as a dissolvable coated film in a newly designed ureteral stent. 2. To analyze the dissolving characteristic of the coated film made by the material. 3. To evaluate the biocompatibility of the nanoscale iron traction.Methods1. We determined the tentative material according to the comparison of three films made of three different materials. 2. We made some films of same thick made by the tentative material solutions of different concentration, then observed and record the films’ dissolving process and time in 37 ℃human urine,analyzed the relationship between the solution concentration and dissolving time, determined the optimal concentration. Then we made different thick films by the same material solution of the optimal concentration, clipped films of the same area from each one, observed and record their dissolving time in 37℃ human urine, analyzed the relationship between the thickness and dissolving time. 3. Implanted the surgical suture in the muscle tissue on the left side of the spine in the back of SD rats as control group, and implanted the nanoscale iron traction on the right side as experimental group. Specimens were taken at 1, 2, 4, 6, 8 and 12 week after operation, stained with hematoxylin and eosin and investigated by light microscopy. Used a histologic grading scale to evaluate the tissue reaction to the two implants by examining the thickness and quality of the reaction capsule surrounding the implants, and the quality of the interface, then analyzed the data of two groups to evaluate the biocompatibility of the nanoscale iron traction.Results1. The dissolving time of the film made by polyvinyl alcohol comformed to our design requirement. 2. There were no significant differents between the dissolving time of 5 polyvinyl alcohol films made by different solution concentrations(P>0.05), but the film made by 12% solution concentration was more smooth than others. The polyvinyl alcohol film’s dissolving time was related to higher levels of the film’s thickness(P<0.05), we could control the dissolving time of the coated film by the film’s thickness. 3. Biocompatibility: Both groups showed a typical chronic inflammatory reaction caused by foreign body. The two implants were surrounded by mononuclear phagocyte system, and some foreign body giant cells could be seen which had devoured the suture or the nanoscale iron. The histologic grading showed there was statistical different between the two groups’ score on the thickness of the reaction capsule surrounding the implants and the quatily of the interface at 1 week after after operation(P<0.05), there were no significant different between the two groups’ score on the evaluation at the other period(P>0.05).Conclusion1.Polyvinyl alcohol could be used as the dissolvable material in the newly designed ureteral stent. 2. The optimal polyvinyl alcohol solution concentration to make dissolvable films was 12%. 3. The polyvinyl alcohol film’s dissolving time was related to higher levels of the film’s thickness, if the dissolving time of polyvinyl alcohol film should be more than 30 minites, the thickness should be more than 40 μm at least. 4. The nanoscale iron traction possesses good biocompatibility.