Preparation And Properties Of Polylactic Acid Surgical Sutures With Controlled Drug Release

In recent years,the polylactic acid(PLA)surgical suture has been widely applied in the medical and health industry,due to its many advantages,such as plant origin,excellent biocompatibility and biodegradability,antibacterial property,mildew resistance and weak acid for skin.But the wound is often infected.When the wound is infected,the usual practice is to take a large number of related drugs orally.The whole body will be treated by oral drugs,which will also have great side-effects on the tissues and organs besides wounds.The best way is to target the drug directly at the wound.In order to directly act on the wound site and improve the added value of PLA suture,we can carry the drug on the suture line.The prepared drug loaded suture line not only needs to maintain the original mechanical properties and flexible properties,but also the drugs can be loaded.The amount of drugs on suture line is suitable,the release rate is appropriate,and the release period is suitable for different types ofwounds.The drug loading,drug release rate,and drug release cycle of the sutures can be controlled.In order to achieve the above purpose,two biodegradable polyester materials with different degradation rates were used as drug carriers.Firstly,PGA with a faster degradation rate,and PCL with a slow degradation rate,are dissolved in ethyl acetate.The water solution of drugs(two kinds of drugs as tea polyphenols and ciprofloxacin as the representative)and the oil solution of polyester are blended by emulsification method.The prepared PCL/PGA drug-loaded coating solution has good stability and uniform drug dispersion.In order to explore the performance of the drug-loaded coating,the PCL/PGA drug-loaded coating solution was solidified into a drug-loaded coating.The structure,mechanical properties,degradation and release properties of PCL/PGA drug-loaded coatings were analyzed.It is found that the drug loaded coating has good drug controlled release effect.Then PCL/PGA emulsion was applied to coating the PLA surgical suture line through the dip rolling process,and the PCL/PGA drug-loaded coating PLA surgical suture line was obtained.The effects of carrier ratio,drug content and coating times on mechanical properties,degradation and release properties of surgical sutures were studied.The conclusions are summarized as follows:(1)According to the orthogonal experiment,the order of the factors affecting the preparation of the coating liquid is as follows: carrier concentration> amount of glycerol>volume ratio of water and oil phase>amount of Tween-80.The optimum ratio is as follows: 0.075 g/mL the carrier solution concentration,0.35% mass fraction of glycerol in aqueous solution(mass ratio:water phase / glycerin=42.16 g/0.15 g),and 0.024% mass fraction of Tween-80(mass ratio:water phase/Tween-80=42.16 g/0.01 g),water phase:oil phase =4 mL:40 mL.The coating time of the suture is about 5-8 minutes.The coating solution with different carrier ratios and different drug loading levels can basically remain unchanged in 20 minutes,which can meet the coating requirements.The fracture strength and elongation at break of pure PGA coating are much lower than that of pure PCL.In addition to the coating of PGA/PCL at50/50 proportion,the fracture strength of the other coatings increased with the increase of PCL,and the fracture strength and elongation of the drug-loaded coating decreased with the increase of the drug content.After 144 hours,the release rate of the coating with carrier ratio of PCL/PGA=100/0,PCL/PGA=50/50 and PCL/PGA=0/100 was 37.8%,53.68% and 46.69%,respectively,when the drug dosage was 1.5 g.In 24 h,the cumulative release rate of all drug-loaded coatings reached over 15%.144 hours later,the release rate of the coating with carrier ratio of PCL/PGA=70/30 reached 46.54% when the drug dosage was 2.5 g,and the drug release rate reached 24.2% when the drug dosage was 0.5 g.(2)Suture of the tea polyphenols coating: The coating will damage the original mechanical properties of the suture,and the fracture strength and breaking elongation of the suture lines with two layers of coating are better.Thestrength of the coating with carrier ratio of PCL/PGA=100/0 can be maintained for 22.3 weeks,when the drug dosage is 1.5 g and the coating is 1 time.The strength of the coating with carrier ratio of PCL/PGA=70/30 can be maintained for 22 weeks,after coating for 1 times and the drug dosage is 1.0 g.The strength of the coating with carrier ratio of PCL/PGA=70/30 can be maintained for 19.9weeks,after coating for 2 times and the dosage of drugs is 1.5 g.The drug release of different carrier ratio suture line: The release rate of the coating with carrier ratio of PCL/PGA=100/0 is 37%,when the drug dosage is1.5 g and the coating is 1 time,after 14 days of degradation.The release rate of the coating with carrier ratio of PCL/PGA=50/50 is 59% and the release rate of the coating with carrier ratio of PCL/PGA=0/100 is 52.93%,in the case of the same other conditions.Except for the coating of PGA/PCL at 50/50 proportion,the amount of cumulative release drugs of the other coating proportion suture lines basically increased with the increase of PGA content in the carrier.Drug release with different dosage of suture: The release rate of the coating with carrier ratio of PCL/PGA=70/30 is 55.23%,when the drug dosage is 2.5 g and the coating is 1 time,after 14 days of degradation.And the release rate of the suture line was 30.02% when the dosage of the drug was 1.0 g,on the premise of the same coating time and the same coating carrier ratio.The whole drug release process can be roughly divided into 3 stages:(1)The phase of drug diffusion;(2)Drug diffusion and release of drugs caused by PGA degradation;(3)The phase of drug diffusion and the release of drugs resulting from thedegradation of PGA and PCL.(3)Suture of ciprofloxacin drug coating: Compared with the suture of the tea polyphenols,the fracture strength of ciprofloxacin is relatively strong and the rate of degradation is relatively slow.The strength of the coating with carrier ratio of PCL/PGA=100/0 can be maintained for more than 25 weeks,when the drug dosage is 1.5 g and the coating is 1 time.The strength of the coating with carrier ratio of PCL/PGA=70/30 can be maintained for 22.01 weeks,after coating for 1 times and the drug dosage is 0.5 g.The strength of the coating with carrier ratio of PCL/PGA=70/30 can be maintained for 20.56 weeks,after coating for 2 times and the dosage of drugs is 1.5 g.The drug release of different carrier ratio suture line: The release rate of the coating with carrier ratio of PCL/PGA=100/0 is 30.36%,when the drug dosage is 1.5 g and the coating is 1 time,after 14 days of degradation.The release rate of the coating with carrier ratio of PCL/PGA=50/50 is 57.06% and the release rate of the coating with carrier ratio of PCL/PGA=0/100 is 50.99%,in the case of the same other conditions.Drug release with different dosage of suture: The release rate of the coating with carrier ratio of PCL/PGA=70/30 is 52.47%,when the drug dosage is 2.5 g and the coating is 1 time,after 14 days of degradation.And the release rate of the suture line was 26.93% when the dosage of the drug was 0.5 g,on the premise of the same coating time and the same coating carrier ratio.