| It is difficult for the patients with renal failure to remove phosphorus from the body normally,and the long-term phosphorus exceeding standard can lead to hyperphosphatemia,inducing convulsions,fracture,cardiovascular and cerebrovascular,and even death.At present,the treatment of hyperphosphatemia is mainly concentrated in controlling the daily intake of phosphorus,vitro dialysis and oral calcium-based phosphate binders,but the common phosphorus removal effect is not ideal,it is easy to accumulate the toxin,and the tolerance of the patients is higher,therefore the clinical popularization is severely restricted.In order to solve the above problems,the chitosan microspheres encapsulating nano iron oxide were used as the new phosphate binders.Through double emulsion technology,the phosphate adsorption properties of chitosan and Fe2O3 are coupled to enhance the adsorption of phosphate in stomach and intestines,reducing the accumulation of phosphorus in the human body,and avoiding the side effects effectively caused by long-term accumulation of nanometer Fe2O3 in vivo.In this study,the surface hydrophobic modified nano-iron oxide particles(OA-IONPs)were prepared by using pure oleic acid(OA)as modifier to chemically adsorb on the surface of nano-iron oxide particles(IONPs).The degree of hydrophobic modification of nanometer ferric oxide was characterized by FTIR and TEM.The effect of the content of modifier on the contact angle of hydrophobic nano-ferric oxide was investigated.With the increase of the content of modifier,the contact angle increased first and then decreased,and the distribution range was from 16o to 68o.The effects of the hydrophobicity and content of hydrophobic nano-ferric oxide(OA-IONPs)and oil-water volume ratio(kerosene: chitosan)on the stability of Pickering emulsion were investigated.The effects of the concentration of Span-80 on the stability of O/W/O emulsion were investigated.The emulsion stability was characterized by emulsion demulsification index and emulsion morphology.The optimum conditions for the preparation of stable emulsion were as follows: wettability of hydrophobic nano-iron oxide particles was 68o,and the concentration of OA-IONPs was 24 w-v%.The volume ratio of oil to water of Pickering emulsion was 1: 2(kerosene: chitosan solution).Span-80 was 2.5 v-v%(relative to paraffin solution).Under the conditions,the size distribution of the emulsion is uniform,and the emulsion has good stability during 168 h.After adding glutaraldehyde crosslinking for 4h,hollow chitosan microspheres,with a amount of nano-ferric oxide and large specific surface area,the average particle size being about 15 ?m and the dispersity and sphericity being better,were achieved.The vitro adsorption and release behavior of Fe@CH microspheres were obtained under optimal conditions.The kinetic equation of phosphorus adsorption by Fe@CH microspheres in vitro shows that phosphorus adsorption of microspheres is a complex adsorption process involving physical and chemical adsorption,and liquid film diffusion and internal phase diffusion are the main control steps.The composite microspheres have a good phosphorus adsorption capacity,and at pH = 5,the equilibrium adsorption capacity of phosphorus can reach about 65 mg/g within 30 min,and at the same time,the microspheres can effectively prevent the release of iron,only 550 ?g from Fe@CH at pH=1.2.It provides technical support for the research and development of safe and efficient phosphorus binder. |
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