Green Synthesis and Characterization of Gold and Silver Nanoparticles and their Application for Development of a Third Generation Lactose Biosensor

Abstract

[a] 1Introduction Nanotechnology is one of the most active areas of modernr esearch. New applications of nanoparticles (NPs) and nanomaterials are emerging rapidly.I nt he last decade metal nanoparticles (MNPs) have played an importantr ole in the development of biofuel cells,i on batteries and (bio)sensing devices [1][2][3][4] especially in the medical diagnostics field. MNPsa re commonly described as nanosized metals with dimensions within1 -100 nm with manyo pto-electronic properties such as larger surface area-volumer atio compared to their corresponding bulk material, large surface energies,p lasmonic excitation and quantum confinement [5].H istorically,g old, silver and copper MNPs were the most largely synthesized,b ecause of the particular properties of the noble metals, followed by iron oxide MNPsf or their magnetic properties [6][7][8].Thei ntegration of green chemistry principles to nanotechnology is one of the key issues of nanoscience research.G reen synthesis has become the way for asustainable and safe production of NPs and it has been proven to be an advantegeous methodd ue to its slower kinetics, easy manipulation and control over crystal growth for stabilization of NPs [9,10].Theuse of environmentally friendly materials,inparticular plant extracts,f ungi, bacteriaa nd enzymes,f or the synthesis of MNPs showed numerous benefits in pharmaceuticala nd other biomedical applications [11][12][13].G reen synthesis resulted also in being very cost effective and therefore can be used as ac heep suitable alternative for large-scale production of MNPs.Several approaches have been reported in the literature usinge xtracts from av ariety of differentp lant species in combination with av ariety of acids and metals alts.F or example aqueous extractso fFerocactuse chidne have been used to reduce silver nitrate (AgNO 3 )t of orm silver nanoparticles (AgNPs) within 6h.I th as been reported that both polyphenols and ascorbic acid present in aqueous Ferocactus echidne extractsc an easily reduce silver ions and can also act as capping agents to prevent the agglomeration of AgNPs [12].R ecently,g old nanoparticles (AuNPs) have been synthesized within 30 min by reducing sodium tetrachloroaurate (NaAuCl 4 )w ith extracts of Abstract:I nt his paper we report on af acile,c ost effective and environmental friendly green synthesis method of gold and silvern anoparticles (NPs) by using quercetin as reducing agent. Theo btained NPs were characterized by transmission electronm icroscopy (TEM), energyd ispersive spectroscopy (EDS), dynamicl ight scattering (DLS) and UV-Vis spectroscopy and parameters such as pH, ionic strength and temperature,e ffectively affecting shape and size of NPs,h ave been carefully studieda nd optimized.T he obtained results showed that the synthesized NPs were circular in shape with an average diameter of 5a nd 8nmf or the AuNPs and the AgNPs,r espectively.T he "green" NPs,s howing increased electroactive areas (A EA )a nd electronic transfer rate constants (k 0 ), were successively used to fabr...

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