Study On Flammulina Velutipes Induced Synthesis Of Gold Nanomaterials

Gold nanoparticles（AuNPs）are widely used in catalysis,optics,electronics and many other fields due to their unique physical and chemical properties.The current common physical and chemical synthesis methods have disadvantages such as high energy consumption,strong pollution,and slow speed.Therefore,we are looking for a green environmentally-friendly and sustainable synthesis methods are the current research hotspot.As a result,the use of organisms to synthesize AuNPs has entered the public eye,and fungi have attracted much attention because of their strong tolerance and strong enzyme production.Flammulina velutipes is the third largest edible mushroom in the world.In this paper,with the help of fungi’s super-enrichment capacity of heavy metals,AuNPs were synthesized by biomineralization.Therefore,Flammulina velutipes was selected as the research carrier to explore the effects of HAuCl₄ solution on the growth and development of fruit bodies and mycelium under different conditions.At the same time,the particle size and morphology of the synthesized AuNPs were characterized.In addition,AuNPs were synthesized by extracting from Flammulina velutipes.This is the first time to use Flammulina velutipes to synthesize AuNPs to obtain real"golden"mushrooms.Choose different temperatures and pH to culture the mycelium,and explore the influence of heavy metal Au³⁺on the growth and development of mycelium and some physiological and biochemical indicators under its optimal growth environment,in order to clarify the nature of the green synthetic carrier Flammulina velutipes,and through flame atomic absorption（AAS）measures the gold content.Comprehensive selection of 20℃pH 7,25℃natural pH,25℃pH 6,30℃pH 7 conditions are the best growth environment for mycelium.The results show that the effect of Au³⁺on the growth and development of mycelium is a complicated process,and it is impossible to analyze the trend from the change of a single physiological index.The concentration of HAuCl₄ solution is directly proportional to the gold content in organisms.Utilize UV-vis spectroscopy（UV-vis）,scanning electron microscope（TEM）,X-ray energy spectrum analysis（EDS）,electrokinetic potential（Zata）,fourier infrared spectroscopy（FTIR）for AuNPs research.The results showed that the mycelium successfully synthesized the near spherical,spherical,triangular,quadrilateral,pentagonal,hexagonal,octagonal,irregular AuNPs and aggregates of 19.543-35.435 nm.Functional groups such as-C=C-,-C≡C-,-O=C-H,-C-H,-OH,-C-N-participated in the reduction of AuNPs.And the higher the concentration of HAuCl₄ and the higher the temperature,the richer the morphology and the larger the particle size of AuNPs.In addition,30.015 nm-74.113 nm spherical and irregular AuNPs and aggregates were successfully synthesized in vitro through mycelial secretion culture fluid,extract culture fluid and cell-free filtrate.The mycelium was subjected to a single stress treatment by HAuCl₄ solution and Pb²⁺induced HAuCl₄ solution to grow into fruiting bodies in HAuCl₄ solution culture to obtain live Flammulina velutipes enriched in AuNPs and to characterize AuNPs.At the same time,the physiological and biochemical conditions of the fruit body were determined.The results show that under the condition of Au³⁺,it promotes the scavenging ability of peroxidase（POD）,malondialdehyde（MDA）,soluble sugar,total sugar,DPPH·and·OH,and inhibits superoxide dismutase（SOD）and soluble protein The content of catalase（CAT）was firstly promoted and then suppressed.Under the induction of Pb²⁺,it promotes soluble protein,soluble sugar,total sugar concentration,DPPH·and·OH scavenging ability,inhibits SOD content,and firstly promotes and then suppresses CAT,POD,and MDA.At the same time,the fruit body successfully synthesized 0.444 nm-536.122 nm hexagonal,quadrilateral,near spherical,irregular AuNPs and polymers,and functional groups such as-C=C-,-C-H,and-OH participated in the reduction of AuNPs.In addition,the gold in the stalk and cap is more present in the organelles and cell walls.