Biocidal Nano-Silver Reinforced Activated Charcoal in Water Treatment

<div><p>Improvements in nanotechnology make eco-friendly and cost-effective solutions to the drinking water contamination problem feasible. Activated charcoal, which is widely used for water purification, can be more effectively employed when reinforced with nanoparticles. For antimicrobial water treatment activated charcoal can be reinforced with silver nanoparticles (SNPs) for best results. Among various methods for the synthesis of nanoparticles, green synthesis mediated by phytoconstituents is preferable, as it is both cost-effective and environmentally friendly. Here we report a green method for synthesizing SNPs from musk melon fruit extract and activated charcoal from coconut shells. The prepared activated charcoal was reinforced with the green-synthesized SNPs and used in microbial water filtration. The efficiency of nanosilver reinforced activated charcoal was higher than virgin activated charcoal proving improved filtration against microbes after successful reinforcement.</p></div

Green Synthesis and Antimicrobial Activity of Monodispersed Silver Nanoparticles Synthesized Using Lemon Extract

<div><p>A simple, environmentally benign green synthesis of silver nanoparticles was achieved using lemon fruit extract (<i>Citrus lemon</i>). The synthesized silver nanoparticles were characterized using UV-Vis spectroscopy, infrared spectroscopy, powder X-ray diffraction, and transmission electron microscopy. The predominantly spherical monodispersed 2–10 nm sized silver nanoparticles were obtained for the first time using lemon extract. The antimicrobial activity of silver nanoparticles was also explored. Lemon extract–mediated synthesis is cost efficient, eco-friendly and an easy alternative to conventional methods of silver nanoparticles synthesis.</p></div

Selective Detection of H₂S by Copper Complex Embedded in Vesicles through Metal Indicator Displacement Approach

A new approach for the detection of hydrogen sulfide (H₂S) was constructed within vesicles comprising phospholipids and amphiphilic copper complex as receptor. 1,2-Distearoyl-<i>sn</i>-glycero-3-phosphocholine (DSPC) vesicles with embedded metal complex receptor (<b>1.Cu</b>) sites have been prepared. The vesicles selectively respond to H₂S in a buffered solution and show colorimetric as well as spectral transformation. Other analytes such as reactive sulfur species, reactive nitrogen species, biological phosphates, and other anions failed to induce changes. The H₂S detection is established through a metal indicator displacement (MIDA) process, where Eosin-Y (EY) was employed as an indicator. Fluorescence, UV–vis spectroscopy, and the naked eye as the signal readout studies confirm the high selectivity, sensitivity, and lower detection limit of the vesicular receptor. The application of vesicular receptors for real sample analysis was also confirmed by fluorescence live cell imaging

Binding interaction of a fluoranthene–thiol on gold nanoparticles with β-cyclodextrin and DNA

<p>In this paper, we report the preparation of a fluoranthene–thiol derivative, the assembly of the compound onto gold nanoparticles, and their binding to β-cyclodextrin and DNA. The synthesised fluoranthene–thiol is characterised using infra-red (IR), nuclear magnetic resonance (NMR), and mass spectrometric techniques. The gold nanoparticles are characterised using transmission electron microscopy and energy dispersive X-ray spectroscopy microanalysis. The size of the nanoparticles is 5 ± 1 nm. The thiol–gold nanoparticles bind to β-cyclodextrin, and DNA and the fluorescence spectra show enhancement of fluorescence on the binding. The thiol–gold nanoparticles form a host–guest complex with β-cyclodextrin and the binding constant of the complex is 1330 mol⁻¹ dm³. This reveals the openness of the thiol on the surface of the gold nanoparticles.</p