A facile, cost-effective and sensitive colorimetric detection method for Pb(2+) has been developed by using glutathione functionalized gold nanoparticles (GSH-GNPs). The sensitivity and selectivity of detection were investigated in detail. The GSH-GNPs could be induced to aggregate immediately in the presence of Pb(2+), especially after the addition of 1 M NaCl aqueous solution. The Pb(2+) could be detected by colorimetric response of GNPs that could be monitored by a UV-vis spectrophotometer or even naked eyes, and the detection limit could reach 100 nM. The GSH-GNPs bound by Pb(2+) showed excellent selectivity compared to other metal ions (Hg(2+), Mg(2+), Zn(2+), Ni(2+), Cu(2+), Co(2+), Ca(2+), Mn(2+), Fe(2+), Cd(2+), Ba(2+), and Cr(3+)), which led to prominent color change. This provided a simple and effective colorimetric sensor (no enzyme or DNA) for on-site and real-time detection of Pb(2+). Most importantly, this probe was also applied to determine the Pb(2+) in the lake samples with low interference and high sensitivity.

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A simple, cost-effective yet rapid and sensitive colorimetric sensor for the detection of Hg(2+) using L-cysteine functionalized gold nanoparticles induced by ultraviolet radiation was developed. The sensitivity and selectivity of detection was also investigated. The L-cysteine modified gold nanoparticles can be induced to aggregate quickly in the presence of Hg(2+), especially with the assistance of ultraviolet radiation. The presence of Hg(2+) can be monitored by the colorimetric response of gold nanoparticles. The detection of Hg(2+) could be realized, after measuring the UV-vis spectra, with a detection limit of 100 nM. The selectivity of this method has been investigated by other divalent metal ions. The effective colorimetric sensor can be used for on-site and real-time Hg(2+) detection.

A clean, facile, and ecologically friendly method for the production of biodiesel has been developed. A solid acid, namely the heteropolyacid (HPA) Cs 2.5 H 0.5 PW 12 O 40 , has been used as a heterogeneous catalyst for the production of biodiesel from Eruca sativa Gars. oils (ESG oil) with methanol at a certain temperature. A study for optimizing the reaction conditions such as the reaction time, temperature, the oil to methanol ratio, the amount of catalyst, and the usage times of the catalyst, has been performed. The Cs 2.5 H 0.5 PW 12 O 40 heterogeneous acid catalyst shows almost the same activity under the optimized reaction conditions as compared to a conventional homogeneous catalyst such as sodium hydroxide or sulfuric acid, and can easily be separated from the products and can be used for several more runs. The most important features of this catalyst are that the catalytic activity is not effected by the content of free fatty acids and content of water in the vegetable oil and that the esterification can occur at a lower temperature (room temperature) and be finished within a shorter time. The results illustrate that the Cs 2.5 H 0.5 PW 12 O 40 is an excellent, water-tolerant and environmentally benign solid acid catalyst for the production of biodiesel. The fuel properties of ESG biodiesel were found to be in agreement with the ASTM standard.

Rapid and sensitive detection of 2,4,6-trinitrotoluene (TNT) and 4-nitrophenol (4-NP) has attracted considerable attention due to their wide applications as nitroaromatic explosive materials. A novel fluorescence method for TNT and 4-NP based on bovine serum albumin functionalized fluorescent gold nanoclusters (BSA Au-NCs) has been developed. The detection probe BSA Au-NCs can be used as a fluorescent probe for the sensitive and selective detection of TNT and 4-NP simultaneously. A good linearity of fluorescence detection using BSA Au-NCs as a fluorescent probe was observed for TNT and 4-NP concentrations in the range of 10(-8)-5 × 10(-5) M and 10(-9)-5 × 10(-5) M, with a detection limit of 10 nM and 1 nM, respectively. The high specificity of TNT and 4-NP with BSA Au-NCs interactions provided excellent selectivity towards detecting TNT and 4-NP over other relevant nitroaromatic compounds. This system can be applied to test strips to detect TNT and 4-NP with high sensitivity and selectivity. The vapour of TNT and 4-NP can be detected using BSA Au-NCs test paper within 1 min with a detection limit of 10 pM and 1 pM.

A kind of biocompatible fluorescent nitrogen doped carbon quantum dots (NCDs) has been synthesized using uric acid as raw material through a facile, effective and green thermal treatment method in one pot. The surface morphology and optical properties of the synthesized NCDs were characterized. Without further chemical modification, the NCDs emit bright blue fluorescence with a high quantum yield of 56% due to the enhancement effect of N dopant atoms on a surface of carbon quantum dots. Owing to the strong blue fluorescence, negligible toxicity and the special response of heavy metal ions, the NCDs have been used as a fluorescence probe for sensitive and selective detection of Hg 2+ and Ag + ions with detection limit of 4.8 nM and 1 nM, respectively. Moreover, it was successfully applied to determination of Hg 2+ and Ag + in real environmental water samples, which offers the advantages of simplicity and cost efficiency.

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A facile synthetic route under mild conditions to the preparation of gold nanostars (GNSs) with Fe3O4 cores (Fe3O4@GNSs), possessing magnetization and tunable optical properties from the visible to near-infrared (NIR) region, was developed. Additionally, the resulting Fe3O4@GNSs described here show good catalytic activity for the reduction of potassium ferricyanide as a model reaction. Importantly, the catalyst, Fe3O4@GNSs, can be easily recycled with an external magnet and exhibits long-life, good reusability and stability. We also anticipated that Fe3O4@GNSs may provide a platform for broad potential diagnostic and therapeutic biomedical applications due to its magnetization and tunable optical properties from the visible to NIR region.