Study On Preparation And Properties Of Biodegradable Intestinal Anastomosis Stents

Poly(propylene sebacate)was synthesized by means of tin(â…¡)2-ethylhexanoate (SnOct₂)catalyzed condensation polymerizaion of 1,2-propanediol,1,3-propanediol and 1,10-sebacic acid with different compositions and reaction time.The structure of the polyesters were characterized by Fourier Transform Infrared(FTIR),Nuclear Magnetic Resonance(1H-NMR)and Gel Permeation Chromatography(GPC).The physical properties of copolyesters were investigated by Differential Scanning Calorimetry(DSC),Dynamic Mechanical Analysis(DMA)and tensile stress-strain measurements.It was found that most polymers have the glass-transition temperature(Tg) below -50℃and present rubber state at both room and body temperatures(37℃). The tensile strength and elastic modulus of the polymers were more than 9.47 MPa and 9.52 MPa,respectively.The hydrophilicity was adjusted by changing the content of 1,2-propanediol and 1,3-propanediol.The copolyesters had strong hydrophobicity with the static contact angle from 79.1°to 108.4°to prevent anastomotic leakage.The biodegradation of copolyesters were investigated in a simulate intestinal fluid in vitro.The change was observed weekly.The mass loss and the degradation of molecular weight(Mw)were measured by analytical balance and GPC respectively each week.The mechanism of hydrolytic degradation and enzymatic degradation was discussed.The anastomosis stents were manufactured in the designed mold in a plate vulcanization machine for animal test.The efficacy was compared between the anastomosis stents and conventional hand-suture by determination of intraperitoneal adhesion,bursting pressure,hydroxyproline and HE staining. The operative time in stents group was shorter than that of hand-sutured group. No anastomotic leakage and anastomotic stenosis happened in the two groups.The anastomotic stoma healed well.The difference of bursting pressure in the 7th day was significant statistically.The level of hydroxyproline had no significant differences between two groups in the 7th and 14th day.Therefore,these materials are expected to be useful for bowel reconstruction and other biomedical applications.The anastomosis was proved to be a safe and highly reliable technique in surgery.