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In order to prepare the absorbable medical textile material with different degradation rates, two biopolymers of poly L-lactic acid (PLLA) and polycaprolactone (PCL) with different degradation rates, were mixed in different proportions, and made into PLLA/PCL masterbatch. The experiment of degradation in vitro was conducted to reveal the degradation behaviour of PLLA/PCL masterbatch, and the characteristics of masterbatch in degradation, such as surface morphol- ogy, chemical structure, crystallization, mass loss and strength, were analyzed. The results indicated that the surface of PLLA/PCL masterbatch was etched in degradation, and the larger proportion of PCL, the less etching and slower degra- dation. The ester bonds were hydrolyzed firstly, and the crystallization region in PLLA/PCL masterbatch was destroyed gradually to form a non-crystalline region in degradation. The degradation rate of PLLA in composite masterbatch was faster than that of PCL. With increasing of PCL involved in masterbatch, the mass loss rate of masterbatch in degrada- tion decreased. In addition, the more PCL involved in composite masterbatch, the lower breaking strength.

Drug loaded PLA suture has been one most potential surgery material to help wounds healing. The loaded drug amounts and sustained drug release effect were a vital part for PLA suture. In th...

The drug-release time of suture should meet with the healing time of wound, so it is needed to control the drugrelease performance of polylactic acid (PLA) suture. In this paper, two biodegradable polymers with different degradation rates, such as polycaprolactone (PCL) and polyglycolide (PGA), were applied to carry the drug of tea polyphenol (TP). The drug-loading finishing solution which is made of PCL/PGA carriers and TP, was coated on the PLA suture. The drug-release rate and time of PLA suture could be regulated by adjusting the proportion of PCL/PGA carriers. The results indicate that the surface of drug-loaded PLA suture becomes rough. There is no obvious chemical reaction among the drug, carriers and PLA suture, just physical adhesion. With the increasing of PCL in drug-carriers, the strength of suture gradually increases. At 70/30 of PCL/PGA, the fracture elongation of suture reaches the highest point. In process of degradation, the surface of drugloaded PLA suture appears some holes after 25 weeks. The strength of sutures decreases gradually during degradation, and the effective strength time of sutures with various proportions of PCL/PGA is different. The drug-release rate of the suture is fast at early stage and slow at later stage and the higher the PGA proportion is, the faster the drug-release rate of the suture is.

Polylactic acid (PLA) surgical sutures are a new type of absorbable sutures that can be degraded and absorbed in the body. However, there is high hydrophobicity for the surface of PLA sutures, which leads to poor biocompatibility and cellular affinity. In order to increase the hydrophilicity, the PLA sutures were etched by lipase firstly, and then grafted with chitosan. The results indicate that the optimal conditions of treating PLA sutures by lipase were as follows: 45℃ reaction temperature, 4.5 g/L concentration of lipase and 8 h reaction time. The sutures were etched by lipase and then formed some grooves and a number of hydroxyl (-OH) bonds, which led to increased surface area and hydrophilicity, but a drop in mass and strength. The optimal conditions of grafting chitosan onto PLA sutures were as follows: 4 h reaction time and 3 g/L concentration of chitosan. The chitosan grafted and loaded on the surface of PLA sutures, and in some areas of the sutures the chitosan reunited, which led to a rough surface and large friction coefficient. Finally, the hydrophilicity of the PLA sutures, treated by lipase and then grafted with chitosan, was greatly improved.

Polylactic acid (PLA) surgical suture can be absorbed by human body. In order to avoid surgical site infections (SSIs), the drug is usually loaded on the PLA suture, and then the drug can release directly to the wound. Because the different types of wounds heal at different times, it is needed to control the drug release rate of PLA suture to consistent to the wound healing time. Two biopolymers, polyglycolide (PGA) and polycaprolactone (PCL), were selected as the carrier of ciprofloxacin (CPFX) drug, and then the CPFX-PCL/PGA was coated on the PLA suture. The degradation rate of drug-carrier can be controlled by adjusting the proportion of PCL/PGA, which can regulate the rate of CPFX drug release from PLA suture. The results show that the surface of PLA suture, coating with PCL/PGA, was very rough, which led to increased stitching resistance when we were suturing the wound. These materials, such as the PLA suture, the PCL/PGA carriers and the CPFX drug, were just physically mixed rather than chemically reacted, which was very useful for ensuring the original efficacy of CPFX drug. With the increasing of PCL in the carriers, both the breaking strength and elongation of these un-degraded sutures increased. During degradation, the breaking strength of all sutures gradually decreased, and the more PCL in the coating materials, the longer effective strength-time for the suture. With the increasing of PCL in the drug-carrier, the rate of drug releasing became lower. The drug release mechanism of CPFX-PCL/PGA was a synergistic effect of drug diffusion and PCL/PGA carrier dissolution.

Poly(lactic acid) (PLA) suture can be absorbed by the human body, and so have wide applications in modern surgery operations. The degradation period of PLA suture is expected to meet with the healing time of different types of wounds. In order to control the degradation period of the PLA suture, the carbon nanotubes (CNTs) were composited with PLA suture, and the degradation experiment in vitro was performed on sutures. The structure and properties of sutures during degradation, such as surface morphology, breaking strength, elongation, mass and chemical structure, were tracked and analyzed. The results indicated that the degradation brought about surface defects and resulted in 13.5 weeks for the strength valid time of the original PLA suture. By contrast, the strength valid time of the CNTs/PLA suture was increased to 26.6 weeks. Whilst the toughness of both the pure PLA and CNTs/PLA sutures decreased rapidly and almost disappeared after 3 to 4 weeks of degradation. The mass loss demonstrated that the time required for complete degradation of the two sutures was obviously different, the pure PLA suture 49 weeks, while CNTs/PLA sutures 63 to 73 weeks. The research proved that CNTs delayed PLA degradation and prolonged its strength valid time in degradation.