Selenium Nanoparticle Loaded-Thermosensitive Hydrogel As A Submucosal Injection Material:Preparation And Characterization

Endoscopic submucosal dissection(ESD)has become a useful worldwide technique for the treatment of early gastric neoplasms cancer.As a minimal invasive treatment,ESD has the advantages of small trauma,fast recovery and high cure rate.However,iatrogenic artificial ulcers caused by ESD can easily lead to delayed bleeding and perforation,which increase the risk of,and complexity of the surgery.In clinic,ESD requires the use of submucosal injection to separate the mucosal and muscle layers.The development of submucosal injections that can inhibit the formation of ulcers and promote wound healing is still an important topic of clinical research.Chitosan(CS)is a natural biological material with good biocompatibility,biodegradability,antiinflammatory,antibacterial,and bioadhesive properties.It is widely used as a hydrogel material.The topic of this thesis is based on the injectable/temperature-sensitive CS/GP hydrogel,adding biologically active Selenium nanoparticles(SeNPs)to develop new gel-type submucosal injections by taking advantage of the selenium properties in scavenging free radicals,promoting cell growth,and anti-inflammatory.In this study,a gel-type submucosal injection was prepared using CS,β-GP and SeNPs as raw materials,and the hydrogel system was characterized by microstructure,gel time,swelling performance,degradation performance and rheological properties.The antioxidizing activities and biocompatibility of the CS/GP/SeNPs hydrogel containing different concentrations of SeNPs were also evaluated.The research contents and results of this article are as follows:(1)SeNPs were successfully prepared with different molecular weights of CS as stabilizer,and carried out some material science characterization.The results of scanning electron microscope(SEM)and transmission electron microscopy(TEM)show that both types of CS can successfully prepare spherical SeNPs.The SeNPs prepared by high molecular weight CS have poor dispersion and easy to aggrege.However,the SeNPs prepared by low molecular weight CS are uniform in size and shape,and have a smooth spherical structure,with a particle size distribution between75-100 nm.The results of dynamic light scattering(DLS)show that the size distribution of SeNPs prepared by high molecular weight CS is larger,while the size distribution of SeNPs prepared by low molecular weight CS is concentrated and monodispersed.Therefore,SeNPs prepared by low molecular weight CS were selected to the subsequent preparation of hydrogels.In addition,through energy dispersive X-ray spectroscopy(EDS),it is observed large numbers of Seelements in the SeNPs prepared by low molecular weight CS.(2)CS/GP and CS/GP/ SENPS hydrogels were synthesized and characterized.SEM results show that both hydrogels have a porous network structure,and the distribution of spherical SeNPs can be seen on the enlarged SEM image of the surface of the CS/GP/SeNPs hydrogel.The results of fourier transform infrared spectroscopy(FT-IR)showed that the hydrogel was successfully cross-linked,and SeNPs had no effect on the chemical composition of the hydrogel.(3)CS/GP/SeNPs hydrogels with different SeNPs concentrations(0-20 μg/m L)were synthesized and their properties were tested.Compared with the control CS/GP hydrogel,as the concentration of SeNPs increases,the gel time of the hydrogel decreases,and the pH value increases.The swelling test results show that the addition of SeNPs improves the swelling performance of the hydrogel,thereby increasing the absorption of wound exudate.The degradation test results show that CS/GP/SeNPs hydrogel has good biodegradability,and can basically achieve complete degradation within eight weeks.The rheological test results show that as the concentration of SeNPs increases,the gel temperature of the hydrogel decreases and is closer to the human body temperature,while the mechanical properties of the hydrogel improve.Finally,the antioxidation test results show that the addition of SeNPs improves the efficiency of scavenging free radicals of the hydrogel,which confirms that the hydrogel has good antioxidation properties and is helpful for the healing of ulcer wounds.(4)The human gastric mucosal cell(GES-1)model was used to evaluate the biocompatibility of the CS/GP/SeNPs composite hydrogel at the cellular level.CCK-8results show that CS/GP/SeNPs(1.25 ～ 10 μg/m L)composite hydrogel has no obvious toxicity to GES-1 cells and has good biocompatibility.The result of a live/dead assay showed that the cells can adhere and grow well on the CS/GP/SeNPs composite hydrogel.In addition,A CCK-8 assay was also used to evaluate the proliferation of GES-1 cells within the extracted liquid of all groups,it is find that the lowconcentration CS/GP/SeNPs hydrogel extract can promote the proliferation of GES-1cells.In summary,the CS/GP/SeNPs composite hydrogel was successfully prepared in this thesis.The hydrogel gel transition can occur at body temperature.This study has proved that the prepared hydrogel has good biodegradability,antioxidant properties and biocompatibility,and has the potential to be used as a submucosal injection.