Study On The Degradation Mechanism Of Oxidized Regenerated Cellulose Sodium Salt Absorbable Hemostatic Gauze

With the development of medical technology, hemostatic materials have been theessential surgical item. In many species, oxidized regenerated cellulose （ORC） hemostaticagent is the focus of study. The sodium salt of oxidized regenerated cellulose （ORC-Na） isobtained by the sodium hydroxide controllable neutralization, and it is a new water solublehemostatic material. Compared to ORC, ORC-Na has a lot of advantages, such as fasterhemostasis speed, wider application scope. However, it also has its limits. Because of thechange of molecular structure, the degradation of ORC-Na is easier under the condition ofstorage. The degradation leads to the decrease of molecular weight, and the drop ofstrength. Meanwhile the by-products contribute to the yellow of ORC-Na. According to thechanges of ORC-Na, we study the degradation mechanism, degradation law andhemostatic performance after degradation.When study the degradation law of ORC-Na, the different degradation time,temperatures and environments, irradiating-sterilization doses, way of packing werediscussed. The result showed that the longer degradation time and the higher degradationtemperature indced the more obvious degradation; Air and water accelerated degradation.After irradiating sterilization, the degradation happened, but the level of degradation didnot rise as the dose increased. The nitrogen-filled packing was the least degradation amongthe different packing ways. The study of in vitro degradation indicated that the completedegradation required14days, and the products were glucose and glucuronic acid, whichwere detected by high performance liquid chromatography （h.p.i.c.） coupling with pulsedamperometric detection （p.a.d.）.In order to study the degradation mechanism, the ORC-Na was analysed and tested.Firstly, the ORC-Na before and after degradation were characterized by scanning electronmicroscope （SEM） and X-ray photoelectron spectroscopy （XPS）. The results showed thatsurface of fiber had cracks and breaks. The oxygen and sodium content showed decrease inthe surface, which was due to the decarboxylic reaction. Secondly, the ORC-Na wasanalyzed by FTIR, UV spectroscopy,¹³C NMR and1H NMR. The results indicated that themajor structure of ORC-Na had no change after degradation, but the conjugated groupsappeared after degradation. The acyl group, aromatic heterocyclic and diketone weredetected, and all of these groups were produced in the production stage. From the NaBH4reduction reaction, it is noticed that the yellow of ORC-Na aqueous solution recede.Hydrogen peroxide was used to oxidize the chromophore in ORC-Na, and refresh thewhite before degradation. The change of structure was characterized by FTIR, ultravioletspectroscopy,¹³C NMR. The results showed that H2O2oxidized acyl to carboxyl. Furthermore, model compounds ware used to prove the specific groups that lead to theyellow color.1,2-cyclohexanedione was chosen as the model compound. The conclusionwas that the factors resulted in degradation were the existence of diketone and theβ-eliminate degradation reaction. Enol and ketone composed the conjugated system whichwas the chromophore of ORC-Na. H2O2destroyed the conjugate structure by oxidizing theenol to ketone, companying with the yellow dispear. Hemostasis trial was performed thedegradation sample and H2O2oxidation sample. The ear artery model and liver model wasused to study the hemostatic time and blood loss. The result showed that the hemostaticperformance had not been affected by H2O2oxidation.