Silver nanoparticles (Ag-NPs) were bio-synthesized using Camellia sinensis (green tea) aqueous extract. Nanoparticles prepared with 10 -3 M AgNO 3 solution, using 3mL of green tea extract and at 60˚C, have spherical shape with a mean diameter of 7nm. The formation of the nanoparticles was confirmed by UV-Vis spectrophotometry through studies of the surface plasmon resonance (SPR). The morphology, size and crystalline structure of the Ag-NPs were determined using high definition transmission electron microscopy (TEM). Moreover, these green synthesized Ag-NPs were found to exhibit good sensing properties to war d s Cu 2+ and Pb 2+ ions in aqueous solutions. This metal ions-sensing ability of the biogenic Ag-NPs was monitored by UV-Vis spectrophotometry (SPR analyses) and fluorescence spectroscopy.
The chemical interaction between biogenic gold nanoparticles (AuNPs) and several metal (II) ions can be regarded as a practical, twofold, colorimetric, and plasmon resonance sensing method for the recognition of some divalent metal ions in aqueous solutions. The green synthesized AuNPs, using Camellia sinensis as a reducing agent, were characterized by a surface plasmon resonance (SPR) using UV-Vis spectroscopy, infrared spectroscopy, and transmission electron microscopy. The AuNP colloidal solutions obtained have a pink-reddish color with SPRs centered between 529 and 536 nm. AuNPs with spherical, triangular, and hexagonal shapes were found by TEM analyses. Despite their divergent morphologies, these AuNPs can be employed as colorimetric and plasmon resonance sensors for detection of Ca2+, Sr2+, Cu2+, and Zn2+, primarily, in aqueous solutions. Sensibility studies based on molar concentrations were also performed for these metal ions. Furthermore, solid biogenic AuNPs/cellulosic biocomposites were prepared with the aim of developing portable, fast, and dependable colorimetric sensors; nevertheless, these biocomposites resulted to be good adsorbent materials of metal ions.
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