金针菇无细胞滤液合成纳米银颗粒

为探索金针菇菌丝体无细胞滤液(cell-free filtrate of Flammulina velutipes,FV-CFF)还原银离子合成纳米银颗粒(AgNPs)的效果,采用两阶段发酵培养获得无细胞滤液,用以合成银纳米颗粒。结果显示,FV-CFF作用于AgNO 3可以生成稳定的棕褐色AgNPs溶液,在pH<5时FV-CFF还原力受到明显抑制,在pH 5~11,生成的AgNPs基本呈线性增长趋势。通过测定FV-CFF在pH 7.22及pH 11条件下冻融前后反应生成AgNPs的动力学曲线及阿累尼乌斯方程,获得其表观活化能分别为98.96 kJ/mol(pH 7.22,冻融前)、106.725 kJ/mol(pH 7.22,冻融后)、119.82 kJ/mol(pH 11,冻融前)、80.21 kJ/mol(pH 11,冻融后),结果表明pH和冻融后除去的絮状不溶物均对AgNPs的合成具有一定影响。成分分析和还原力测定结果显示,冻融虽然会除去FV-CFF中大量的蛋白和碳水化合物,但对还原力的影响较小,而pH的提高则可显著提升其还原力,而且pH 11时产物AgNPs的最大吸收波长和溶液粒径也显著降低。实验结果有助于进一步分析金针菇合成纳米颗粒的反应机制。

Synthesis of silver nanoparticles using cell-free filtrate of Flammulina velutipes

The cell free filtrate of Flammulina velutipes(FV-CFF)obtained by two-stage fermentation was used for the synthesis of silver nanoparticles(AgNPs)and their effects were studied.The results showed that FV-CFF acted on AgNO 3 to produce stable brown AgNPs solution,and AgNPs production was increased with pH elevation.The reducing power of FV-CFF on AgNO 3 was significantly inhibited at pH<5,but exhibited a linear growth trend within the pH range of 5-11.The kinetic curve of AgNPs synthesis was acquired by determining AgNPs generation using FV-CFF at normal pH(7.22)and pH 11,respectively.The effect of freezing and thawing was also compared by calculating the formation kinetic curve.The apparent activation energy(E a)obtained was 98.96 kJ/mol(pH 7.22,initial),106.725 kJ/mol(pH 7.22,thawed),119.82 kJ/mol(pH 11,initial),80.21 kJ/mol(pH 11,thawed),respectively.The results of composition and reducing power determination showed that although freeze-thaw could remove a mass of proteins and carbohydrates in FV-CFF,it had a relatively low effect on reducing power.However,the increasing pH could significantly improve the reducing power of FV-CFF,and the maximum absorption wavelength and particle size of synthesized AgNPs were also significantly reduced at pH 11.The present results will be contributed to further analysis of AgNPs synthesis mechanism by F.velutipes.