Biosynthesis Of CuNPs With Peroxidase Activity And Its Decolorization Effect On Dyes

Copper is an important raw material in industrial production.Compared with precious metals such as gold and silver,copper has higher natural reserves and lower price.It has more advantages in practical application.Copper nanoparticles(CuNPs)with large specific surface area and excellent catalytic performance are widely used in the production of acetylene.The results showed that the tensile properties of nano-copper materials with grain size of 10-110 nm were good.The flexural and elongation strength of nano-copper materials with grain size of 10-110 nm was 900%higher than that of 20 micron copper materials prepared by conventional annealing process and 8%higher than that of common copper materials.Copper nanoparticles can be attached to the surface of the alloy to improve the charge transfer rate and electrical conductivity of the alloy.In view of the special properties and great potential application value of nano-copper in mechanics,electronics and chemistry,the research on nano-copper materials has attracted wide attention.In this study,CuNPs were synthesized by Bacillus licheniformis HLS,and the synthetic sites and conditions of CuNPs were explored.The particles were characterized by transmission electron microscopy(TEM)and X-ray diffraction(XRD).CuNPs synthesized by the strain had peroxidase activity,and the optimal conditions for the activity of CuNPs peroxidase could be explored to detect the concentration of glucose.Meanwhile,the factors influencing the decolorization effect of remazol brilliant blue R,congo red,indigo carmine and crystal violet of CuNPs and the decolorization principle can be explored.The main research results were as follows:(1)Conditions optimization of CuNPs synthesis by strain HLSThe conditions of CuNPs synthesis by strain HLS were optimized.The co-culture supernatant,cell-breaking supernatant and cell-breaking bacteria precipitation were observed by transmission electron microscopy.CuNPs were observed in cell-breaking bacteria precipitation.When the types of copper salts were CuSO4,CuCl2 and Cu(NO3)2,only the two groups of Cu(NO3)2 have better synthesizing effect on CuNPs.The introduction of Na2WO4,a specific inhibitor of nitrate reductase,suggested that the main enzyme for CuNPs synthesis by HLS might be nitrate reductase.(2)Characterization and identification of CuNPs by TEM and XRDTEM microscopic examination revealed that particles with particle size of 10-20 nm were observed,and the distance between the two lattice fringes was 0.208 nm and that between the two lattice fringes was the same as that of(1 1 1)lattice fringes of Cu.XRD detection showed that there were diffraction peaks at 43.5 degrees,50.6 degrees,74.3 degrees and 89.9 degrees,which were(1 1 1),(2 0 0),(2 2 0)and(3 1 1)crystal faces of Cu.It is concluded that the synthetic particles may be CuNPs.(3)Properties of CuNPs peroxidase and application of glucose detectionWhen the strain HLS synthesized CuNPs at 40?,pH 4.2,the final concentration of CuNPs suspension was 300 ?g/mL,and the concentration of hydrogen peroxide was 1.5 moL/L,the optimal peroxidase activity was 228.9 U/g dry weight.The linear range of the detection of the concentration of hydrogen peroxide is 0.13-5.3 mmoL/L.The linear range of the detection of the concentration of hydrogen peroxide is taken as the concentration range of the detection of glucose,and the linear range of the detection of the concentration of glucose is determined to be 1-5.3 mmoL/L.High concentration of a-lactose,D-fructose,maltose and sucrose was weaker than that of CuNPs for low concentration of glucose.The detection error of glucose solution by CuNPs is small.(4)Study on decolorization of dyes by CuNPsAt pH 7,the decolorization rate of indigo carmine and crystal violet by CuNPs was significantly increased by 2,2,6,6,-tetramethylpiperidine oxide(TEMPO),and that of remazol brilliant blue R by Syringaldehyde(SA).At pH 3,CuNPs had better decolorization effect on remazol brilliant blue R and indigo carmine;at pH 7,CuNPs had better decolorization effect on congo red and crystal violet.The decolorization rate of indigo carmine could still reach 29.56%after 5 times reuse of CuNPs and 42.88%for crystal violet after 7 times reuse.The depigmentation of four different dyes by CuNPs was investigated by full-wavelength ultraviolet-visible scanning.CuNPs had no new peak in decolorization of remazol brilliant blue R for 24 hours,and the decolorization of remazol brilliant blue R might be adsorption.After 24 hours of decolorization of congo red,indigo carmine and crystal violet by CuNPs,new peaks appeared at 258,256 and 258 nm,respectively.It is speculated that CuNPs may degrade the three dyes.