Synthesis Of Silver Nanoparticles Using Eucommia Ulmoides Extract And Their Potential Biological Functions

It has been determined that silver nanoparticles(AgNPs)have function of antiinflammatory,anti-cancer,antibacterial,and wound-healing promotion.Consequently,owing to the comprehensive bio-applications,AgNPs grasps the attention of recent researches.The orthodox physicochemical techniques change the conditions of reaction to synthesize AgNPs with specific shapes and functions.But the most apparent shortage is the necessary of high energy consumption or toxic chemical reagents during the synthesis process.To avert the aforementioned problems,the biosynthesis method provide a novel route.It employs microorganisms,algae,and plant extracts to synthesize AgNPs,so it is clean,safe,and low bio-toxic.In addition,the bioactive components absorbed onto the AgNPs’ surface play a synergistic role in the biological effects of it.Thus such biosynthesis method also broadens the application of AgNPs in bio-medicinal sphere.Eucommia ulmoides(E.ulmoides)is a vital medicinal material in China,which contains ranges of bioactive components such as flavonoids,phenols,polysaccharides,etc.The bioactive components contribute to anti-inflammatory and antioxidant.In this paper,we synthesized E.ulmoides-AgNPs(Eu-AgNPs)via the aqueous solution of E.ulmoides leaf extract,and scrutinized the physical,chemical and biological properties of them.The main findings of this paper are as follows:(1)The absorbance of the samples at 430 nm was detected by UV-vis to explore the effect of the concentration of E.ulmoides extract and the reaction time between E.ulmoides extract and silver nitrate on the synthesis of Eu-AgNPs.The results showed that the yield of Eu-AgNPs is related to the concentration of E.ulmoides extract and the reaction time of the system,higher extract concentrations and longer reaction times correspond to higher yields of Eu-AgNPs.The synthesized Eu-AgNPs were characterized by high-resolution transmission electron microscopy,Fourier transform infrared spectroscopy,X-ray energy spectroscopy,the results showed that the Eu-AgNPs are irregular spheres with inhomogeneous sizes,those particle sizes rang from 4 to 52 nm,three elements of C,O and Cl existed on the surface of Eu-AgNPs;Thermo gravimetric analysis(TG)results showed that flavonoids and phenolic active substances adsorbed on the surface of Eu-AgNPs.FTIR result showed that OH,C-Cl were involved in the synthesis of Eu-AgNPs as reducing groups and end-capping groups;The result of X-ray diffraction showed that the synthesized Eu-AgNPs are crystals with a face-centeredcubic structure.(2)2,2-Diphenyl-1-picrylhydrazyl(DPPH),2,2’-Azinobis-(3-ethylbenzthiazoline6-sulphonate)(ABTS),and ferric ion reducing antioxidant power(FRAP),all of those antioxidant capacity detection reagents showed the antioxidant ability of Eu-AgNPs.the reducing abilities of Eu-AgNPs to these three reagents were different.Trolox was used as a positive control to evaluate the difference in the reducing ability of Eu-AgNPs to these three reagents,the results indicated that the reduction effect of Eu-AgNPs was FRAP>DPPH>ABTS.Mushroom tyrosinase and L-dopa were used to determine the inhibitory effect of Eu-AgNPs on tyrosinase activity,the result showed the whitening potential of Eu-AgNPs.(3)In order to explore the biological effects of Eu-AgNPs,it is crucial to determine the biological toxicity of Eu-AgNPs.CCK-8 was used to investigate the effect of EuAgNPs on the viability of HaCat cells,and the results showed that the cytotoxicity of Eu-AgNPs was dependent on the concentration of Eu-AgNPs.At low concentrations.Eu-AgNPs had no significant effect on cell viability,Eu-AgNPs not only could reduce the level of ROS in HaCat cells,but also enhance the ability of cells to resist oxidative damage.At the same time,the treatment of melanoma cells and human skin fibroblasts with low concentrations of Eu-AgNPs can inhibit the tyrosinase activity in melanoma cells and promote the expression of collagen.Eu-AgNPs are a new type of nanomaterials that are beneficial to skin due to its’ ability of slowing the aging process and fighting the formation of melanin.(3)CCK-8 was used to evaluate the effect of Eu-AgNPs on the cell viability of HaCat cells(human immortalized epidermal cells).the result showed that the biotoxicity of Eu-AgNPs depends on the concentration of Eu-AgNPs,at low concentrations(5-25μg/L).there is no significant effect on cell viability.The content of ROS in HaCat cells treated with 5,15,25μg/L Eu-AgNPs was determined,and the results showed that Eu-AgNPs could reduce the level of ROS in HaCat cells,meanwhile,H2O2 stimulated HaCat cells pretreated with Eu-AgNPs(5,1 5,25μg/L)and without pretreatment,and found that the increased level of intracellular ROS was lower in Eu-AgNPs pretreated cells,so low concentrations of Eu-AgNPs can enhance the ability of cells to resist oxidative damage without affecting cell viability.(4)Eu-AgNPs(5,15,25μg/L)were used to incubate A375(Human Malignant Melanoma cells)and HFF-1(The Human Foreskin Fibroblasts),and determined the effects of Eu-AgNPs on tyrosinase activity in A375 cells and collagen expression in HFF-1 cells,those results showed that Eu-AgNPs can inhibit the activity of tyrosinase in A375 and promote the expression of collagen in HFF-1.E.ulmoides can be used to synthesis Eu-AgNPs,and many bioactive components absorbed on the surface of Eu-AgNPs.Our experiments showed that Eu-AgNPs can inhibit intracellular tyrosinase activity,promote collagen expression,and enhance the antioxidant capacity of cells without affecting cell viability,which proves that Eu-AgNPs are a new type of nanomaterial which is beneficial to skin health,because it slows the aging process and inhibits the formation of melanin.