Functionalization of gold nanoparticles by ß-cyclodextrin as a probe for the detection of heavy metals in water and photocatalytic degradation of textile dye.

Gold nanoparticles (AuNPs) and AuNPs functionalized by ß-cyclodextrin (ß-CD/AuNPs) were prepared successfully through chemical reduction method. The structural, morphological, optical, compositional and vibrational studies for the AuNPs and ß-CD/AuNPs were carried out. Functionalization of AuNPs by ß-CD was confirmed with FT-IR results. The UV-visible absorption spectra exhibit a red-shift with decreasing average particle size. This sustains the enhancement in surface area (SA) to volume (V) ratio that is one of the peculiar characteristics of nanoparticles. TEM results show that ß-CD/AuNPs formed were monodispersed and self assembled. Also it shows a decrease in average particle size and improved distribution. The use of ß-CD in the synthesis of AuNPs are revealed not only create uniform small sized nanoparticles but these water soluble nanoparticles have very good antibacterial action by inhibiting the growth of bacteria commonly found in water and sensing activity for sensing the concentration of toxic metals in water. The sensitivity of the system towards copper (Cu) concentration was found as 1.788/mM for ß-CD/AuNPs and 1.333/mM for AuNPs. The photocatalytic action of the obtained nanoparticles increases with decreasing average particle size. The kapp value of this photocatalytic degradation of textile dyeing waste water in presence of AuNPs was 0.002/min and ß-CD/AuNPs was 0.005/min. This is a non-toxic and eco-friendly approach.

Visible light assisted photocatalytic degradation of commercial dyes and waste water by Sn-F co-doped titanium dioxide nanoparticles with potential antimicrobial application.

The disintegration of natural water sources signals out the scarcity of adam's ale and will be hurdle for the human physical state. So it is necessary to decrease waste loads and hence pressure on the ecology for the sustainability of fishery and dye industry. Herein, TiO2 nanoparticles doped with Sn and F are synthesized and the influence of simultaneous doping on the optical, surface morphological, structural, photocatalytic and antibacterial activities are investigated. Doping of TiO2 with Sn and F suppress the growth of both anatase and rutile phase because of the dissimilar boundaries. All the prepared doped and undoped samples are found to possess tetragonal structure. The influence of F and Sn in TiO2 lattice is recognized with the XRD and FT-IR spectra of the prepared particles The size of the obtained nanoparticles decreases as increasing concentration of F and Sn. TiO2 is showing the presence of spherical and ellipsoidal nanoparticles whereas doped samples showing nanobulk, pentagons and rods. The absorption edge of the doped samples are blue shifted with increasing concentration of dopants indicates the control of optical absorption property of TiO2. The visible light assisted photocatalytic degradation of fish processing waste water by doped and undoped samples are found to be established as 0.0076/min and 0.0071/min respectively. Visible light assisted degradation of commercially available dyes and fish processing waste water is assessed. Methyl blue showed enhanced photocatalytic activity under visible light irradiation compared to Methyl orange. It is observed that all the prepared particles show good antimicrobial activity against Staphylococcus aureus.

Antimicrobial and catalytic activities of biosynthesized gold, silver and palladium nanoparticles from Solanum nigurum leaves.

The field of nanobiotechnology and nanomedicine paves way for the use of several nanoparticles. Especially, in biomedical applications, the silver nanoparticles (AgNPs), gold nanoparticles (AuNPs) and palladium nanoparticles (PdNPs) are found most vital and promising, among other nanoparticles. The biomedical activities of these particles mostly depend on their shape, size and distribution. Preparation of these particles in an eco-friendly method is an immediate need of the society. Herein, AuNPs, AgNPs and PdNPs (MNPS) were synthesized by Solanum nigrum Leaves (SNL) extract. The structural and morphological studies were carried out by using TEM, XRD and EDAX, while the optical and chemical properties were studied using UV-visible spectrum and FTIR spectroscopy. The particles obtained were found to possess a FCC (Face Centered Cubic) structure. TEM images of Ag, Au and PdNPs showed spherical well dispersed nanoparticles with average size of 3.46 nm, 9.39 nm and 21.55 nm respectively. The FTIR spectra confirmed polyphenols and antioxidants in SNL extract act as reducing and capping agents respectively in the synthesis of MNPs. The EDX technique confirmed the presence of silver, gold and palladium nanoparticles. Antimicrobial studies noted that the AgNPs have effective inhibition against E. coli. The complete reduction of 4-Nitrophenol and the formation of 4-Aminophenol with the presence of NaBH4 was chosen for the study of catalytic activities of the prepared MNPs. The reduction time of Au and Pd catalyst were smaller compared to that of Ag. This viable preparation method for producing small spherical shaped nanoparticles expected to the applied to the fields of nanomedicine.