| Uncontrolled traumatic and surgical bleeding is a major cause of death and injury in war,accidents,disasters and crime.Not only does the wound need to stop bleeding in time,but also subsequent healing.Therefore,it is necessary to develop a powerful multi-functional wound dressing.Fibrous wound dressings show great potential for wound healing due to their advantages such as similarity to ECM,adequate air permeability,significant absorptive capacity,large surface area and high porosity.In recent years,researchers have successively developed hemostatic,antibacterial and anti-inflammatory,exudate self-pumping fiber dressings.However,electrostatic textile Janus fiber membrane with hemostatic,antibacterial and anti-adhesion properties has not been reported.In addition,Janus structures have not been reported for directional transport of liquid drugs.So,we prepared a Janus composite membrane PVA/CS/Ag@TPU with hemostasis and prevention of blood extravasation,antibacterial and bacterial anti-adhesion,and directional transportation of liquid drugs for the first time.The main research contents of this paper are as follows:(1)Preparation and characterization of Janus composite membrane: firstly,We synthesized Ag nano triangular sheet by light induction method;Janus composite membrane PVA/CS /Ag@TPU prepared by 3% CS solution,9% PVA solution,15% TPU solution and silver nano triangular sheet solution was selected as experimental objects.The results of FTIR,SEM,EDS,XRD and XPS show that Janus composite membrane PVA/CS/Ag is successfully prepared.(2)Study on coagulation performance and mechanism of Janus composite membrane:The water contact angle results shows that the hydrophilic layer of Janus composite membrane PVA/CS/Ag@TPU has superhydrophilic properties(WCA=0°),and the WCA of hydrophobic layer was 128°;In the whole blood clotting test,61.3% of the blood was clotted.The clotting time of 2m L blood was 403±10s.The blood absorption ratio was10.21±0.54 of its own weight.In the vascular injury model,blood loss was 0.Clotting occurs when hydrophilic side absorb water from the blood,hydrophobic side provide negative force for wound and positive charged amino group of CS binds to negative charged platelets.(3)Study on directional transport performance and mechanism of Janus composite membrane: Transportation results of water on Janus composite membrane surface showed that water could be transported from hydrophobic surface to hydrophilic surface,but not from hydrophilic surface to hydrophobic surface;Janus composite membrane could efficiently carry out directional transportation of liquid drugs;The directional transport mechanism of Janus composite film is that when water is on the hydrophobic side of Janus film,hydrophobic pressure HP and pore size difference between hydrophobic layer and hydrophilic layer will jointly push water to overcome hydrophobicity and enter the hydrophilic layer,and the high capillary force generated by superhydrophilic layer will make water quickly diffuse once it contacts the hydrophilic layer.When water is on the hydrophilic side of Janus membrane,the high capillary force CF generated by the superhydrophilicity causes water to diffuse rapidly in the hydrophilic layer,and at the same time leads to the decrease of hydrostatic pressure per unit area HP.So when water reaches the hydrophobic layer,it is immediately blocked by reverse hydrophobicity.So water cannot be transported from the hydrophilic side to the hydrophobic side.(4)Study on antibacterial and bacterial anti-adhesion performance of Janus composite membrane: The results of antibacterial,bacterial anti-adhesion and fluorescence test showed that Janus composite membrane could effectively kill bacteria and bacterial anti-adhesion,and the killing rate of E.coli and S.aureus were all 99.99%,respectively.Through the underwater oil adhesion force and underwater oil contact angle test and the construction of the corresponding model diagram revealed the mechanism of anti-bacterial adhesion,the hydrophilic layer contact water formed a strong hydration layer and excellent antibacterial property.(5)Animal experiment and tissue section analysis: Animal experiment results showed that the wound healing of mice treated with Janus composite membrane and liquid drug was the best(day 10).The percentage of wound area was 2.19 after 10 days,and the percentage of body weight gain was 1.68.HE staining and Masson staining showed that the mice treated with Janus composite membrane and liquid drug have the best effect.On day 10,granulation tissue was more mature than the other groups,the epidermis and dermis were regenerated,the collagen area was the largest and neatly arranged,the subcutaneous tissue was intact without inflammatory cell infiltration.The results of immunohistochemical fluorescent tissue sections in the middle and late period of wound healing(day 7)showed that the mice treated with Janus composite membrane and liquid drug showed better therapeutic effect,abundant subcutaneous neovascularization,and the healing degree was better than other treatment groups. |
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