| Nanozymes are functional nanomaterials with enzymatic properties such as catalytic efficiency and dynamic properties of enzymatic reactions,which are similar to those of natural enzymes.However,nanozymes have advantages over natural enzymes due to its wide source,low cost,easy preparation and adjustable activity.Since the concept of nanozyme was proposed in 2004,especially since Fe3O4 nanoparticle was found to have the intrinsic peroxidase-like activity in 2007,its design,preparation and application have attracted wide attention of the researchers in the field of material chemistry,environment and biology.Starting from the design and regulation of the catalytic activity of nanozyme,this paper studies a wide range of manganese-based nanomaterials and realizes the improvement of manganese-based nanozymes'enzyme-like activity with structure doping modification and functional substrate composite.Furthermore,combined with the colorimetric technology,which has the advantage of naked eye recognition in the field of detection,its application in colorimetric sensing is explored and some beneficial results are obtained.The specific research contents are as follows:1.In this chapter,a series of ABO3 type La Mn O3 perovskite materials with oxidase-like activity were prepared by the coprecipitation method and they were modified by A-site Ce substitution and acid treatment.The study of oxidase-like activity showed that when the stoichiometric ratio of Ce was 0.3 and the acid treatment duration was 4 h,the activity of the material was the strongest,which was recorded as ox La0.7Ce0.3MnO3-4h.X-ray photoelectron spectroscopy experiments before and after catalytic reaction revealed that the enhanced oxidation ability was attributed to the synergistic effect of Mn4+,Ce4+ and lattice oxygen in the modified material.ox La0.7Ce0.3MnO3-4h was further used as the nanozyme to construct a COD colorimetric sensor detection platform.Under the optimized conditions,the detection range was 5-150 mg/L,which was better than the national standard method of potassium dichromate.It is worth noting that the measurement results of the actual samples are consistent with the national standard method.2.In this chapter,oxygen-doped carbon nitride?OCN?with ultra-thin structure was successfully prepared with the mixed acid?H2SO4 and HNO3?and ultrasonic co-treatment method to modify g-C3N4 prepared by the raw material melamine.The study of enzyme-like activity showed that under the same conditions,OCN obtained by acid treatment for 0.5 h had the highest activity of peroxidase-like activity,which was 3.3 times higher than g-C3N4.Moreover,ESR,timing amperometric method and spectroscopic experiments confirmed that the introduction of oxygen atoms and ultrathin structure helped to improve the electron transfer capacity of g-C3N4 materials,thus enhancing their enzymatic activities.Based on the excellent peroxidase-like activity of OCN,a fast and sensitive colorimetric sensing system for the detection of H2O2 was successfully constructed.Under the optimized conditions,the linear range was 1×10-7?5×10-5 mol/L.It can be concluded that the sensor system can be used for the determination of H2O2 in commercial milk samples.Furthermore,the colorimetric sensing system of dual-enzyme glucose detection was constructed by using OCN as peroxidase and glucose oxidase.Under the optimized conditions,the linear range of glucose detection was 1×10-7?1×10-4 mol/L.It is worth mentioning that the OCN prepared in this experiment,which has two-dimensional plane ultrathin structure and are rich in oxygen-containing functional groups also provides a good carrier for the subsequent composite with manganese-based nanozyme.3.In this chapter,MnO2-OCN functional nanocomposite was successfully prepared through simple chemical precipitation method with the OCN prepared in the previous chapter as the carrier material.Due to the introduction of the OCN with excellent peroxidase activity,the Mn O2-OCN obtained overcomes the defect of weak Mn O2 peroxidase-like activity and shows good cascade catalytic performance.Based on Mn O2 catalyzing the formation of H2O2 from glucose,OCN selectively catalyzes the oxidation of TMB by H2O2.A non-enzyme glucose colorimetric sensing system was then successfully constructed.The linear range was 5×10-5?2×10-3 mol/L and the detection limit was 2.3×10-5 mol/L?S/N=3?.This colorimetric sensing system can be used for the accurate determination of glucose in serum with the recovery rate from 91.94% to 94.30%. |
PDF Full Text Request