Study On The Preparation,Stability,Antioxidant,Antibacterial Properties Of Cysteamine Complex

Cysteamine is an amino acid derivative,which has a wide range of applications in feed additives and medicine due to its good biological nutritional effects and good reducibility.However,the stability of cysteamine is poor,and it is easy to deteriorate when exposed to air,which makes its storage conditions strict and the storage period short.Cysteamine is commonly used by researchers to react with hydrochloric acid to be cysteamine hydrochloride which prolongs its storage time,but cysteamine hydrochloride is easy to deliquesce and has poor palatability,which is not conducive to long-term storage.There are few reports on the stability of cysteamine.In this paper,cysteamine zinc complexes were prepared by liquid phase synthesis method.The storage stability and thermal stability of the products were improved by doping metal ions and coating method,respectively.The antioxidant and antibacterial properties of the prepared materials were measured.Using cysteamine hydrochloride and zinc sulfate as the reaction system,cysteamine zinc chelate was synthesized by liquid phase synthesis method.The structure of cysteamine zinc chelate was characterized by X-ray diffraction(XRD)and Fourier infrared spectroscopy(FTIR),and its morphology was analyzed by scanning electron microscopy(SEM).The results clarified that when the molar ratio of cysteamine hydrochloride to zinc ions was 1.4?1.5,the p H of the system was about10,the reaction time was 1 h,and the reaction temperature was 80°C,the zinc chelating efficiency was better.The chemical composition of cysteamine zinc chelate was[Zn₂(SC₂H₆N)₃Cl H₂O]_n,which performed a layered structure and the crystal was monoclinic.The cell parameters were a=7.9581?,b=15.0794?,c=12.2910?,?=90°,?=103.316°,?=90°.Compared with the deliquescence of cysteamine hydrochloride exposed to air in a short time,the daily degradation rate of cysteamine in cysteamine zinc complex in 116 days was about 0.078%.The thermogravimetric test showed that the decomposition temperature was about 225°C,which was increased than the corresponding value of cysteamine hydrochloride 207°C.On the basis of the aforementioned experiments,cysteamine zinc composites were prepared by doping with iron,copper,and manganese ion by liquid phase synthesis method,and the morphology and stability of the cysteamine zinc complexes with doped ions were analyzed.The results showed that when doped with iron,copper,and manganese metal ions of 1%mol,the changes of crystal form and main structure of cysteamine zinc were not obvious,but the size of the particles did.When co-doped with iron,copper and manganese metal ions of 1%mol,the composite morphology changed from layered to irregularly shaped aggregates,and the metal ions were successfully doped and occupied part of the lattice of cysteamine zinc.The cysteamine retention rate of cysteamine zinc was higher than that of cysteamine hydrochloride after being stored at 25°C for 2 weeks.After doping Fe²⁺,Cu²⁺,Mn²⁺,the thermogravimetric decomposition temperature of cysteamine zinc was 228°C.The daily degradation rate of cysteamine in cysteamine zinc was about 0.008%in 116days,which improved about 89.7%compared with pure cysteamine zinc.SiO₂-coated cysteamine zinc[Zn₂(SC₂H₆N)₃Cl H₂O]_n@SiO₂was synthesized by sol-gel method using TEOS(tetraethoxysilane)as a silicon source.When the core material cysteamine zinc mass was 0.5 g,and ethanol solution in the reaction system was 40 cm³,and the volume of TEOS added was 1 cm³,the coating rate of Si O₂was3.85%.Coated cysteamine zinc was not easy to deliquesce,and its fluidity was higher than that of cysteamine zinc.In addition,the daily degradation rate of coated cysteamine zinc in the measured 116 days improved about 62.8%than that of cysteamine zinc.The free radical scavenging abilities of cysteamine hydrochloride,cysteamine zinc,doped cysteamine zinc and coated cysteamine zinc were tested by the pyrogallol autoxidation method.The results clarified that all products could effectively remove·O₂^-,and the clearance rate increased with the increasing of concentration.The scavenging rate of cysteamine hydrochloride was higher than that of cysteamine zinc in the concentration range of 1?5 mg/cm³,and the scavenging ability of cysteamine zinc after doping with iron,copper and manganese ions improved compared with that of unadulterated.The bacteriostatic circle method was used to test and suggested that each composite material had antibacterial properties against Escherichia coli,Staphylococcus aureus,and Bacillus subtilis,and the inhibitory performance of Staphylococcus aureus was more obvious.