Cu-CuFe₂O₄ Was Used As A Nano-enzyme To Detect H₂O₂,Glutathione And Dopamine

In recent years,due to the advantages of artificial enzymes compared to natural enzymes,it has aroused great research interest in the scientific community.The general formula for replacing ferrite by nano-spinel is MFe2O4,where M represents a transition metal,which has attracted wide attention from researchers due to its excellent catalytic performance,biomedical application ability and environmental remediation ability.They often mimic the catalytic activity of natural enzymes such as peroxidase,oxidase,and catalase.It is well known that synergistic effects play an important role in improving the catalytic activity of enzyme-like reactions.Multi-component nano-enzymes usually exhibit enhanced enzymatic catalytic activity compared to single-component enzymes.This article mainly synthesized Cu-CuFe2O4 composite material,and further modified and compounded it,using easy-to-operate colorimetric method to study it as a peroxidase to detect H2O2,GSH,DA and other substances.The main research contents of this paper are as follows:(1)Most artificial nano-enzymes have a low substrate affinity,which means that a high concentration of the substrate is required to convert colorless 3,3’,5,5’-tetramethylbenzidine(TMB)to blue oxTMB.In order to improve the affinity between the material and substrate,Cu-CuFe2O4 nanosheets were synthesized by one-step solvothermal method in this paper.Cuo improved the oxide reduction capacity of Cu-CuFe2O4 and promoted electron transfer between CuFe2O4 and H2O2.Cu-CuFe2O4 have a good activity as Peroxidase and a high affinity to H2O2,and its Km is lower than that of ferrite and Horseradish enzyme(HRP).Determination of hydrogen peroxide(H2O2)and glutathione(GSH)by Cu-CuFe2O4 colorimetry takes only five minutes.In compared to CuFe2O4,the detection limit(LOD)of Cu-CuFe2O4 for H2O2 is approximately 90-times lower.Finally,the action mechanism of Cu-CuFe2O4 has been proposed.(2)Cu-CuFe2O4 showed a better affinity for H2O2 and excellent activity as an enzyme peroxide.But the affinity for TMB(another substrate)was weaker than the enzyme horseradish spicy(HRP).Therefore,the anionic surfactant sodium dodecylbenzene sulfonate(SDBS)was used to modify Cu-CuFe2O4 and was named SDBS/Cu-CuFe2O4.More negative Zeta were found through SDBS adsorption on the SDBS/Cu-CuFe2O4 surface,the affinity with the positive charge increases.The peroxidase-like activity and the peroxidase-like activity of per unit concentration were also improved.The catalytic efficiency was increased for TMB as the substrate.The effects of different factors on the activity of SDBS/Cu-CuFe2O4 peroxidase,including Zeta potential,oxidation and reduction capacity,electron transfer and the sequence of H2O2 and TMB incorporation into the system.Mechanisms similar to those for peroxides are proposed.SDBS/Cu-CuFe2O4 allows rapid identification of H2O2 and dopamine(DA)and the lower limit of detection is lower than that reported in the literature.(3)CNTs/Cu-CuFe2O4 composites with different proportions were synthesized by one-step solvothermal method,which were used as artificial nano-enzymes to detect the content of GSH in human serum.The results showed that the content of CNTs increased and the catalytic activity was enhanced.With the introduction of CNTs,electron transfer between H2O2 and CNTs/Cu-CuFe2O4 was further accelerated.Through electrostatic interaction and the formation of Fe-O-C chemical bond,CNTs and Cu-CuFe2O4 were closely linked to form heterojunctions.The synergistic effect between the two also showed the enhancement of nano enzyme activity.Compared with most materials of the same type,when the detection temperature is 35 degrees,the serum GSH content can be detected in a short time,and the detection limit is as low as 0.34 μM.The material system is not affected by amino acids in serum and has potential application in practice.