Preparation And Properties Of Macromolecule-crosslinked Pectin Nanofibers

Electrospun pectin nanofibers are promising biomaterials with good biocompatibility,biodegradability,high specific surface area and nano size.Previously,our research group developed a method of using small molecule dihydrazine as crosslinking agents to crosslink the oxidized pectin nanofibers,which solved the water solubility problem of pectin nanofibers and laid a foundation for their biomedical applications.However,the role of small molecule crosslinking agents in crosslinking oxidized pectin nanofibers is relatively single,and the obtained fibers lack biological functions.The purpose of this work is to introduce the biological functions to pectin nanofibers and promote their biomedical applications by using polymers with biological functions as crosslinking agents to crosslink the oxidized pectin nanofibers.Specific research contents and results include two parts:In the first part,gelatin was used as the crosslinking agent to crosslink the electrospun oxidized pectin nanofibers,which introduced cell adhesion and infiltration capability to pectin nanofiber mats.Firstly,sodium periodate was used to oxidize pectin,and the oxidized pectin was electrospun,then gelatin was used as crosslinking agent to crosslink the oxidized pectin nanofibers.The properties of pectin nanofiber mats as tissue engineering scaffolds were studied.The results showed that the gelatin-crosslinked pectin nanofiber mats had a medium mechanical strength,with a maximum tensile strength of 2.3 MPa and an ultimate tensile strain of 15%.They had high fluid absorption capacity,and were able to absorb their weight of 30 to 43 times the simulated fluid.Moreover,they had excellent water resistance,and could degrade gradually in simulated body fluids for 4 weeks or longer time.More importantly,cell culture experiment results demonstrated that cells were able to grow into the gelatin-crosslinked pectin nanofiber mats rather than only spread on mat surface.The gelatin crosslinked pectin nanofiber mats can provide a three-dimensional growth space for cells and are expected to be used in the regeneration of soft tissues such as skin and cartilage.This work solves the problem that pectin nanofiber mats cannot support cell growth and is of significance to promote their applications in tissue engineering.In the second part,polyethylenimine was used as a crosslinking agent to crosslink the electrospun oxidized pectin nanofibers and introduce antibacterial properties to pectin nanofibers.The performance of the crosslinked nanofiber mats as wound dressing were characterized.The results showed that the polyethylenimine-crosslinked pectin nanofiber mats had medium mechanical strength and their ultimate tensile strength was up to 4.5 MPa.They had good absorbency and could absorb wound exudates equal to 32 times of their own weight.They were suitably permeable and could transmit 0.32 grams of water vapor per square centimeter every 24 hours.They were well wettable and could absorb excess fluid in 1s.The crosslinked nanofibers had excellent water resistance and could retain more than 50% of their original mass after soaking in simulated body fluids for 21 days.In addition,polyethylenimine-crosslinked pectin nanofibers also showed good cell compatibility and antibacterial properties.The polyethylenimine-crosslinked oxidized pectin nanofiber mats are expected to be used as dressings for the treatment of exuding and infectious wounds.This work introduces antibacterial function to pectin nanofibers,which is beneficial to their applications as wound dressing.Overall,this work using gelatin and polyethylene imine to crosslinking pectin nanofibers,respectively,while water resistance is constructed for pectin nanofiber mats,cell ingrowth and antibacterial capacity are also introduced,which promotes the applications of pectin nanofibers in the fields of tissue engineering and wound healing.