Study On The Catalytic Mechanism Of Hollow Prussian Blue Nanozyme

Due to the capacity of catalyzing special chemical reactions,natural enzymes have been employed in the area of in vitro diagnosis,biosensor,sewage disposal and food safety.However,their catalytic activities tend to be influenced by temperature,pH and other external factors.Especially in some extreme conditions such as strong acid,strong alkali or high temperature,natural enzymes will be inactive,which greatly limit their application.In addition,the production of natural enzymes is not able to satisfy the currently huge industrial demands,owing to their high cost and low yield.In 2007,Gao firstly found that iron oxide nanoparticles?IONPs?possessed a similar catalytic function like natural peroxidase,and definited them as nanozymes.As a member of them,Prussian blue nanoparticles?PBNPs?have attracted a lot of attention,because they respectively have similar catalytic performance with peroxidase?POD?,catalase?CAT?and superoxide dismutase?SOD?at different pH.In our study,Co-doped Prussian blue nanoparticles?Co-PBNPs?and hollow Prussian blue nanoparticles?HMPBNPs?were fabricated by doping Co element and being acid corroded,while the adjusting function to catalytic activities brought by doping element as well as porous structure was investigated.Besides,HMPBNPs'application on ultrasonic imaging was explored as well.The specific research objectives in this paper are as followings:1.Co-PBNPs were manufactured by doping different dose of cobalt chlorine?CoCl₂?into PBNPs by the coprecipitation method.It was found that with the increase on the percentage of doping Co element,the catalytic activities of Co-PBNPs were greatly improved.Their morphologies would be evolved from cube into polyhedron and the valence state of Co was changed via observation under transmission electron microscope?TEM?,scanning electron microscope?SEM?,and X-ray photoelectron spectroscopy?XPS?,also their affinities to reactants were apparently enhanced using Michaelis-Menten equation to analyze enzymatic reaction kinetics.2.PBNPs were prepared in 80?through putting potassium ferricyanide as the single source reactant in hydrochloric acid solution.HMPBNPs were successfully prepared by placing PBNPs synthesized with single source method in 80?and being processed with acid etch in 140?.Results indicated that after being corroded,HMPBNPs had stronger catalytic activities with hollow structures,having a great deal of holes with a size of 1.7 nm as well as larger specific area.Compared with those without being corroded,their catalytic efficiency towards reactants had been improved by 3 times.3.HMPBNPs exhibit peroxidase-like activity under acidic conditions and catalase-like?CAT?activity under neutral and alkaline conditions.HMPBNPs could be good substitutes of natural catalases to catalyze H₂O₂ and generate O₂.It can be overserved under dark-field microscope that HMPNPs possessed a very strong capacity of loading O₂ with a decent stability.The grey values presented very obvious changes under small animal ultrasound imaging system?US?,demonstrating they held larger potential of being applied in ultrasound imaging.