Preparation Of Gold-coated Magnetic Nanoparticles And Study On Peroxidase Activity

Objectives:Establish a method for the preparation of gold nanoparticles and gold-coated magnetic nanoparticles and the determination of peroxidase activity.Explore the most suitable conditions for the two to exert peroxidase activity,and finally compare and analyze the difference in peroxidase activity between the two.Methods:(1)Firstly,the reaction temperature,reaction time,and p H,etc.reaction conditions were screened,and the gold nanoparticles with different particle sizes were prepared using the reducing agent of sodium tartrate(St).In addition,the eight reducing agents,including St,sodium malate(Sm),sodium citrate(Sc),vitamin c(Vc),gallic acid(Ga),catechol(Cc),resorcinol(Rs),hydroquinone(Hq)were used to prepare gold nanoparticles with similar particle size based on screening the optimum reaction conditions.Then the peroxidase activity of the gold nanoparticles were determined.(2)The Fe₃O₄MNPs were prepared using citric acid reduction at different time(4h,7h,10h)and oleic acid,respectively.Then the prepared Fe₃O₄MNPs were used as the core,and the gold-coated magnetic nanoparticles were prepared using hydroxylamine hydrochloride reduction method based on screening the optimum reaction conditions.Finally,peroxidase activity of the gold-coated magnetic nanoparticles were determined by optimizing the reaction temperature,p H and H₂O₂ concentration.(3)The peroxidase activity of gold nanoparticles with similar particle size was compared with that of gold-coated magnetic nanoparticles.Results:(1)The prepared gold nanoparticles and gold-magnetic nanocomposite particles were subjected to a series of characterization,and the results showed good.Firstly,the peroxidase activity is measured to determine the temperature and p H at which it can exert the most suitable enzyme activity.Secondly,the OD value of gold nanoparticles with different diameters was measured,and it was found that with the increase of the particle diameter,the OD values were 2.87,2.26,1.98,respectively.Finally,using formulas,the specific activities of gold nanoparticles prepared with eight different reducing agents were calculated to be 1.415(Cc),0.464(Hq),0.378(Rs),0.242(Vc),0.219(Ga),0.084(Sc),0.047.(Sm),0.044(St).(2)The Fe₃O₄MNPs were prepared using citric acid reduction at different time(4h,7h,10h)and oleic acid,respectively.Then the prepared Fe₃O₄MNPs were used as the core,and the gold-coated magnetic nanoparticles were prepared and determine the peroxidase activity,and determine that the temperature at which the optimal enzyme activity is exerted is 38^oC,and the optimal p H is 3.8.Using formulas to calculate the specific activity is 0.894(4h),0.865(7h),0.462(10h),1.354.(3)The peroxidase activity of gold nanoparticles and gold-magnetic nanocomposite particles with similar diameters were measured,and their specific activities were 0.084 and 0.894,respectively.Conclusions:(1)The the particle size of the gold nanoparticles prepared using eight reducing agents was negatively correlated with it's peroxidase activity.The peroxidase activity of gold nanoparticles prepared by the reducing agent with benzene ring structure was highest,and the peroxidase activity of gold nanoparticles prepared by the reducing agent with straight chain structure was lowest.(2)The peroxidase activity of gold-coated magnetic nanoparticles prepared using the Fe₃O₄MNPs prepared by oleic acid and citric acid as reducing agents were decreased with the increase of particle size.The peroxidase activity of gold-coated magnetic nanoparticles prepared using the Fe₃O₄MNPs prepared by oleic acid as reducing agent was highest.(3)The peroxidase activity of gold-coated magnetic nanoparticles was higher than gold nanoparticles.