Morphology Controlled Synthesis Of Metal Based Nano-structures For Biological And Catalytic Applications

The bacterial infection is a global problem,and the available antibacterial drugs have serious side effects as well as majority of pathogenic organisms shown resistance toward most of these drugs.Hence easy and simple approaches are required to prepare more efficient and safe material that can control the microbial resistance and spread of pathogenic organisms such as bacteria,fungi,and other parasites.The development of biologically glorious synthetic processes for the synthesis of metal nano-materials is an emerging and important area of nanotechno lo gy which can overcome all the aforementioned problems.Biosynthesis process is considered safe,economically benign and nontoxic for the synthesis of metal nanoparticles.The fudamental goal and importance of the present study were to synthesize eco-friendly as well as financially favorable antibacterial,antioxidant and photocatalytic nanometerials.The current thesis is consists of four parts regarding the biosynthesis of silver nanoparticles(AgNPs),hybrid nanocomposite(Ag/Fe2O3),and Se nanorods(SeNr)using medicinal plants.Medicinal plants have bioactive materials which act as reducing agents for metal ions and capping them for long term stability.The prepared biogenic nanomaterial was successfully characterized by various available technique i.e.UV-visible spectroscopy,Transmission Electron Microscopy(TEM),Scanning Electron Microscopy(SEM),Energy Dispersive X-ray Spectroscopy(EDX),Fourier Transform transmission electron Microscopy(FT-IR)and X-ray Diffraction(XRD).These nanoparticles show a promising antibacterial,antioxidant activities and Photocatalytic activity for the degradation of methylene blue.Project(1).In this work,silver(Ag)nanoparticles were prepared from three fractions methanol,ethyl acetate,and water extract ofArisaema flavum tuber(medicinal plant).Different experimental conditions(salt concentration,pH and temperature)were optimized in order to prepare the desired nanoparticles.The antibacterial properties of AgNPs prepared with various extracts were tested against multi-drug resistant bacteria,which showed significant antibacterial activity against all the muitidrug-resistant bacterial strains and especially an engineered E.coli QH4.In detail,the AgNPs synthesized with methanolic extract of Areseama Flavum exhibited excellent activity against all the bacterial strains as it showed 16 mm zone of inhibition against S.Auruos,23 mm against P.Putida,20 mm against E.Coli,19 mm against B.Subtilus,21 mm against S.Auruos(Ampicillin resistant),13 mm against engineered E.Coli QH4(multidrug-resistant)and 13 mm against wild type E.Coli.AgNPs synthesized by methano lic,Ethyl Acetate,and aqueous Extracts of Areseama Flavum exhibited significant Photocatalytic activity to degrade methylene blue.Small size,spherical shape,and high dispersion are the key properties due to which the AgNPs have substantial biological and photocatalytic activity.To the best of our knowledge,it is the first report of biogenic AgNPs regarding antibacterial activity against nultidrug-resistant Engineered E.coli QH4.Project(2).In this work,an economical and environmentally friendly biogenic method to synthesize silver nanowires was developed by using the Sonchus Oleraceus L.leaves extract as a reducing and surface coating agent.The synthesized silver nanowires were characterized by the aforementioned techniques.The synthesized silver nanowires were tested against some common human pathogenic bacteria and showed excellent antibacterial activity against the bacterial pathogens being tested.In detail,the zone of inhibition against S.aureus and P.Putida was recorded as 19(±0.5)mm and 12(±0.4)mm,respectively.The prominent antibacterial activity was further confirmed by Propidium Iodide assay.From propidium iodide assay,we noticed that the number of injured cells increased at higher doses of Ag nano wires,indicating its concentration-dependent cellular injury.All these observations conclude that Ag nanowires upon interaction with bacterial cells cause membrane damage with subsequent release of cytoplasmic materials and cellular death.The silver nano wires have excellent photocatalytic activity in efficiently degrading a toxic pollutant methylene blue(MB).The results of this report show the vast remedial and photocatalytic potential of bio-inspired silver nanowires,which can be a potent candidate for the effective remediation of microbes and harmful organic pollutants.Project(3).This work investigates the green synthesis of multifunctional Ag/Fe2O3 nanocomposite by aqueous extract of Algaia Monozyga.The silver-iron oxide bimetallic nanocomposite was prepared using AgNO3,FeCl3 anhydrous,and plant leaves extract as a natural source for reduction of these nanoparticles.This article investigates a facile one-pot method for the synthesis of Ag/Fe2O3 nanocomposite by aqueous extract reduction/capping under ambient conditions.We prepared separate solutions of Silver and Iron salts,and upon addition of these solution to the plant extract,a brown color mixture was formed within 10 minutes confirming the formation of the desired product.To confirm the synthesis of the nanocomposite,UV-Visible spectroscopy,Scanning electron microscopy(SEM),EDX,and X-ray diffraction spectroscopy were used.The formation of nanocomposite from the surface plasmon resonance(SPR)peak at the UV-vis region 410 nm suggests the presence of metal particles.Tlie nanocomposite was used for photocatalytic activity and Degradation of Methylene Blue(MB)in the presence of light,which showed efficient photocatalytic activity.The antimicrobial activities were determined for nanocomposite which was found to be increased with increasing the amount of nanocompos ite The silver-iron oxide nanocomposite showed good antibacterial activities against different pathogens.In detail,the zone of inhibition against S.aureus and P.Putida and E.Coli QH4 was recorded as 23(±0.5)mm and 19(±0.4)mm and 21(±0.4)mm respectively.The prominent antibacterial activity was further confirmed by Propidium Iodide assay.From propidium iodide assay we noticed that the number of injured cells increased at higher doses of Ag nanowires,indicating a concentration-dependent cellular injury.Project(4).Herein,we report the preparation of Se nanorods(SeNr),their surface decoration with gold(Au)nanoparticles using fatty acid(stearic acid)as a shape directing agent.The selenium nanorods were prepared under the specified experimental conditions(pH and temperature 100?).Our findings indicate that stearic acid plays an essential role in regulating the size of Se-Nanorods in solution.The Se nanorods and SeNr-Au composite obtained by this method were efectiv'e against Escherichia coli and Staphylococcus aureus.SeNr-Au composite induced cell component release from bacterial cells,indicating its excellent ability to damage the cytoplasmic membrane as compared to bare SeNr.In addition,the antioxidant study of the prepared nanomaterial shows that the designed material is a competent agent in scavenging the stable DPPH free radicals.The promising antibacterial and impressive antioxidant potentials of the newly designed material made sure that it could be used as a potential agent in antimicrobial therapy with a protective effect against the overproduced radicals.In detail,the zone of inhibition against S.aureus and E.Coli JCL-16 were recorded as 25(±0.5)mm and 18(±0.4)mm respectively.The prominent antibacterial activity was further confirmed by Propidium Iodide assay.From propidium iodide assay we noticed that the number of injured cells increased at higher doses of Ag nanowires,indicating a concentration-dependent cellular injury.