Search

A label-free non-aggregation colorimetric sensor has been designed for the detection of Cu2+, based on Cu2+ catalyzing etching of gold nanorods (AuNRs) along longitudinal axis induced by dissolve oxygen in the presence of S2O3 2−, which caused the aspect ratio (length/width) of AuNRs to decrease and the color of the solution to distinctly change. The linear range and the detection limit (LD, calculated by 10 Sb/k, n=11) of this sensor were 0.080–4.8µM Cu2+ and 0.22µM Cu2+, respectively. This sensor has been utilized to detect Cu2+ in tap water and human serum samples with the results agreeing well with those of inductively coupled plasma-mass spectroscopy (ICP-MS), showing its remarkable practicality. In order to prove the possibility of catalyzing AuNRs non-aggregation colorimetric sensor for the detection of Cu2+, the morphological structures of AuNRs were characterized by high resolution transmission electron microscopy (HRTEM) and the sensing mechanism of colorimetric sensor for the detection of Cu2+ was also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Fe3+ can catalyze H2O2 to oxidize along on the longitudinal axis of gold nanorods (AuNRs), which caused the aspect ratio of AuNRs to decrease, longitudinal plasmon absorption band (LPAB) of AuNRs to blueshift (Δλ) and the color of the solution to change obviously. Thus, a rapid response and highly sensitive non-aggregation colorimetric sensor for the determination of Fe3+ has been developed based on the signal amplification effect of catalyzing H2O2 to oxidize AuNRs. This simple and selective sensor with a wide linear range of 0.20–30.00μM has been utilized to detect Fe3+ in blood samples, and the results consisted with those obtained by inductively coupled plasma-mass spectroscopy (ICP–MS). Simultaneously, the mechanism of colorimetric sensor for the detection of Fe3+ was also discussed. [Copyright &y& Elsevier]

Abstract: The CdS/TiO2–fluorescein isothiocyanate (FITC) luminescent nanoparticles (CdS/TiO2–FITC) with the particle size of 20nm have been synthesized by sol–gel method. CdS/TiO2–FITC could emit the fluorescence of both FITC and CdS/TiO2. The fluorescence resonance energy transfer (FRET) occurred between the donor CdS/TiO2 and the acceptor FITC in the CdS/TiO2–FITC. Taking advantages of the excellent characteristics of FRET, a new CdS/TiO2–FITC FRET labeling reagent and a CdS/TiO2–FITC–wheat germ agglutinin (CdS/TiO2–FITC–WGA) fluorescent probe have been developed. The FRET occurring between the donor CdS/TiO2 and the acceptor FITC in the labelled product CdS/TiO2–FITC–WGA–AP, formed in the affinity adsorption reaction between the WGA in this CdS/TiO2–FITC–WGA fluorescent probe and alkaline phosphatase (AP), sharply enhanced the fluorescence signal of FITC and quench the fluorescence signal of CdS/TiO2. Moreover, the ΔF (the change of the fluorescence signal) of FITC and CdS/TiO2 were proportional to the content of AP, respectively. Thus, a new method that CdS/TiO2–fluorescein isothiocyanate nanoparticles for the determination of trace AP based on FRET-affinity adsorption assay has been established. The limit of quantification (LOQ) of the method was 1.3×10−17 g AP mL−1 for CdS/TiO2 and 1.1×10−17 g AP mL−1 for FITC, respectively. This sensitive, rapid, high selective and precise method has been applied to the determination of AP in human serum and the prediction of human disease with the results agreed well with enzyme-linked immunosorbent assay (ELISA) in Zhangzhou Municipal Hospital of Fujian Province. Simultaneously, the reaction mechanism for the determination of AP was also discussed. [Copyright &y& Elsevier]

Abstract: Luminescent particles of lead carboxymethyl cellulose (Pb(CMC)2), which contains salicyl fluorones (THBF), Pb(CMC)2-THBF, were synthesized by sol–gel method. Pb(CMC)2-THBF can emit intense and stable solid substrate room temperature phosphorescence (SS-RTP) on filter paper. EDTA can chelate the Pb2+ in Pb(CMC)2-THBF, causing it decompose into aqueous soluble components PbY2-, CMC- and THBF, and these components can react with Hg2+ to form (CMC)2Hg-THBF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS-RTP quenching method was established. The linear range of this method is 2.0–40.0fgspot-1 (5.0–100.0pgml-1) of Hg2+, with a detection limit (LD) of 0.26fgspot-1, and the regression equation of working curve is (fgspot-1, 0.4μl spot-1), r = 0.9994. This method has been applied to the determination of trace mercury in water sample with satisfactory results. The mechanism of SS-RTP emission is also discussed. [Copyright &y& Elsevier]

A new solid substrate-room temperature phosphorimetry method for the determination of trace mercury has been established. It bases on the fact that in acetic acid medium, Hg2+ ion can catalyze the substitute reaction of CN− ligand in [Fe(CN)6]4− by 2,2′-bipyridyl (bipy), and the resultant [Fe(bipy)3]2+ cation can react with FinBr4− anion of tetrabromofluorescein (HFinBr4) to form ion association complex [Fe(bipy)3]2+⋅[(FinBr4)2]2− which can emit phosphorescent signal on filter paper substrate. Under the optimum condition, the linear dynamic range of this method is 1.6–16 fg per spot with a detection limit (LD) of 0.18 fg per spot (0.4 μl sample solution per spot), and the regression equation of working curve is ΔIp=1.058+7.671 CHg2+ (fg per spot ), n=7, correlation coefficient is 0.9990. This method has been applied to the determination of trace mercury in hair and cigarette samples with satisfactory result. The reaction mechanism for formation of the ion association complex is also discussed. [Copyright &y& Elsevier]

Luminescent particles of lead carboxymethyl cellulose (Pb(CMC)(2)), which contains salicyl fluorones (THBF), Pb(CMC)(2)-THBF, were synthesized by sol-gel method. Pb(CMC)(2)-THBF can emit intense and stable solid substrate room temperature phosphorescence (SS-RTP) on filter paper. EDTA can chelate the Pb(2+) in Pb(CMC)(2)-THBF, causing it decompose into aqueous soluble components PbY(2-), CMC(-) and THBF, and these components can react with Hg(2+) to form (CMC)(2)Hg-THBF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS-RTP quenching method was established. The linear range of this method is 2.0-40.0fgspot(-1) (5.0-100.0pgml(-1)) of Hg(2+), with a detection limit (LD) of 0.26fgspot(-1), and the regression equation of working curve is [Formula: see text] (fgspot(-1), 0.4mul spot(-1)), r = 0.9994. This method has been applied to the determination of trace mercury in water sample with satisfactory results. The mechanism of SS-RTP emission is also discussed.

A new solid substrate-room temperature phosphorimetry method for the determination of trace mercury has been established. It bases on the fact that in acetic acid medium, Hg(2+) ion can catalyze the substitute reaction of CN(-) ligand in [Fe(CN)(6)](4-) by 2,2'-bipyridyl (bipy), and the resultant [Fe(bipy)(3)](2+) cation can react with FinBr(4)(-) anion of tetrabromofluorescein (HFinBr(4)) to form ion association complex [Fe(bipy)(3)](2+)[(FinBr(4))(2)](2-) which can emit phosphorescent signal on filter paper substrate. Under the optimum condition, the linear dynamic range of this method is 1.6-16fg per spot with a detection limit (LD) of 0.18fg per spot (0.4mul sample solution per spot), and the regression equation of working curve is DeltaI(p)=1.058+7.671 C(Hg(2+)) (fg per spot ), n=7, correlation coefficient is 0.9990. This method has been applied to the determination of trace mercury in hair and cigarette samples with satisfactory result. The reaction mechanism for formation of the ion association complex is also discussed.