Search

Abstract: In this study, gold nanorods were firstly found to exhibit a tremendously higher catalytic activity towards luminol chemiluminescence (CL) than spherical gold nanoparticles. More importantly, ultra-trace aminothiols can cause a great CL decrease in the gold nanorod-catalyzed luminol system by the formation of Au–S covalent bonds on the ends of gold nanorods. Aminothiols can occupy the active sites of gold nanorods, and further interrupt the generation of the active oxygen intermediates. Other biomolecules including 19 standard amino acids, alcohols, organic acids and saccharides have no effect on gold nanorod-catalyzed luminol CL signals. Moreover, in order to evaluate the applicability and reliability of the proposed method, it was applied to the determination of glutathione in the cell extracts of Saccharomyces cerevisiae. Good agreements were obtained for the determination of glutathione in the cell extracts of S. cerevisiae between the present approach and a standard Alloxan method. The recoveries of glutathione were found to fall in the range between 96 and 105%. The calibration curve for glutathione was found to be linear from 0.05 to 100nM, and the detection limit (S/N=3) was 0.01nM. The relative standard deviation (RSD) for five repeated measurements of 5.0nM glutathione was 2.1%. [Copyright &y& Elsevier]

Abstract: Peroxymonocarbonate (HCO4 −) was produced by the online reaction of bicarbonate with hydrogen peroxide. A strong chemiluminescence (CL) was observed when HCO4 − reacted with AuCl4 − without any special CL reagent. When bisphenol A (BPA) was added to AuCl4 −–HCO4 − CL system, the CL emission was inhibited significantly. This new CL system was developed as a flow-injection method for the determination of BPA. Under the optimum experimental conditions, the inhibited CL intensity was linearly related to the concentration of BPA from 0.3 to 80μM (R =0.9958). The detection limit of BPA was 0.08μM. The relative standard deviation for 12 repeated measurements of 1.0μM BPA was 2.9%. The interferences of some cationic ions can be removed by an online cation-exchange column. The applicability of the present CL system was demonstrated for the sensitive and selective determination of BPA in real samples (mineral water bottle, baby bottle, beverage bottle and polycarbonate container). Based on the CL spectrum, UV–visible adsorption spectra, and the quenching effect of reactive oxygen species scavengers, a possible CL mechanism was proposed. [ABSTRACT FROM AUTHOR]

Abstract: The aggregation of gold nanoparticles (GNPs) capped with nonionic fluorosurfactant (FSN) could be induced rapidly and selectively by cephradine degradation products, but not by cephradine and other excipients in pharmaceutical formulations. A new detection method for cephradine has been developed based on the cephradine degradation products-induced aggregation of the GNPs. The present approach offers various advantages, such as simplicity and high selectivity. Under optimum conditions, the lowest detectable concentration of cephradine through this approach (S/N=3) is 0.8μgmL−1. The calibration curve was linear over the range of 2.0–10.0μgmL−1 for the detection of cephradine. The recoveries of cephradine were found to fall in the range between 97% and 105%. We have validated the applicability of our method through the analyses of cephradine in pharmaceutical formulations. Good agreements were obtained for the determination of cephradine between the present approach and official method. [Copyright &y& Elsevier]

Peroxynitrous acid (ONOOH) was produced by the on-line reaction of acidified hydrogen peroxide with nitrite in a flow system, and peroxynitrite (ONOO−) was generated from ONOOH in NaOH solution. A weak chemiluminescent (CL) emission was observed due to the production of singlet oxygen (1O2) during the decomposition of ONOO−. Bilirubin and its conjugate were found to enhance the CL emission of 1O2 in a suitable micellar medium. For the first time, the feasibility of employing the present CL system for the sensitive and selective determination of total bilirubin contents in human serum was demonstrated and the results were compared with certified values. The present method showed a great improvement on overcoming bis(2,4,6-trichlorophenyl)oxalate CL highly insolubility in aqueous solution and exhibiting higher tolerance towards interferences than redox reaction of bilirubin with various oxidizing agents such as sodium hypochlorite and iodine. The recoveries of bilirubin were found to fall in the range between 95 and 108%. The detection limits (S/N=3) for bilirubin and its conjugate were determined to be 10 and 8 ng ml−1, respectively. The relative standard deviations (R.S.D.) for the consecutive CL detection of a series of bilirubin (30 μg l−1) and bilirubin ditaurite (25 μg l−1) were 3.2 and 2.9% (n=11), respectively. [Copyright &y& Elsevier]

Abstract: In this work, with the assistance of the additivity of surface plasmon resonance band of nonionic fluorosurfactant-stabilized gold nanoparticles, we developed a new colorimetric assay approach of cysteine (Cys) and homocysteine (Hcy) in biological fluids, requiring no use of separation techniques. The detection limits of Cys and Hcy can be as low as 0.4μM. The applicability of the method was validated by spiking known amount of Cys and Hcy in human urine and plasma samples. Recoveries were in the range of 97.2–106.7%. The present approach is simple, high selective and reproducible. In addition, the universality of the additivity of surface plasmon resonance band was demonstrated by virtue of silver nanoparticles. Therefore, the proposed method has a great potentiality in disease diagnosis associated with Cys and Hcy. [Copyright &y& Elsevier]

Water in organic solvents is a prevalent impurity that significantly influences chemical reactions and industrial processes. Carbon dots (CDs) gained attention as promising tools for chemosensing due to their advantageous characteristics, including easy synthesis, cost-effectiveness, and excellent adjustability and stability. However, limited solubility in water and turn off fluorescence response mode hinder the practical utilization of CDs for water sensing. To tackle such dilemma, a highly water-soluble CDs with distinctive hydrogen-bond-induced emission (HBIE) was rationally designed through introducing sulfone group into the widely employed p -phenylenediamine precursor. The inclusion of sulfone group imparts the CDs with notable water solubility, as well as distinctive ratiometric fluorescent response towards water content, exhibiting high sensitivity and selectivity. Upon exposure to water, the emission color of CDs undergoes a real-time transition from blue to yellow-green, which can be readily discerned by naked eyes. The CDs have been successfully applied in detecting water in commercially available alcohol. This study presents a straightforward yet efficacious approach for rationally design of CDs with unique HBIE characteristics and ratiometric fluorescent response, offering great potential for practical chemosensing applications. [Display omitted] • A water-soluble CDs was synthesized by introducing sulfone group into the p-phenylenediamine precursor. • Hydrogen-bond-induced emission between CDs and water contributes to ratiometric fluorescent detection of water content. • The CDs have been successfully applied in detecting water in commercially available alcohol. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we utilize the triangular gold nanoparticles (AuNPs) prepared by trisodium citrate reduction of HAuCl4 in presence of nonionic fluorosurfactant (FSN) as a novel chemiluminescence (CL) probe for the determination of captopril. Captopril can induce a sharp decrease in CL intensity from the triangular AuNPs-catalyzed luminol system. Under the selected experimental conditions, a linear relationship was obtained between the logarithm of CL intensity and the logarithm of concentration of captopril in the range of 23.0–920nM, and the detection limit at a signal-to-noise ratio of 3 for captopril was 4.6nM. The as-prepared triangular AuNPs were easier to synthesize, stable at a wider pH range and high ionic strength, and exhibited a high selectivity and an excellent sensitivity toward captopril. The applicability of the proposed method has been validated by determining captopril in commercial pharmaceutical formulations and human urine samples with satisfactory results. The recoveries for captopril in spiked samples were found to be between 95.0% and 103.5%. The method shows promise for routine control analysis of pharmaceutical preparations and human urine samples. Moreover, based on the CL spectra, UV–vis spectra and transmission electron microscope (TEM) measurements, a possible CL mechanism was proposed. The mechanism of high selectivity toward captopril is supposed to originate from the tight binding of the sulphydryl groups of captopril to the active site of the as-prepared triangular AuNPs, leading to oxygen-related radicals cannot easily be generated from H2O2 on the surface of triangular AuNPs. [Copyright &y& Elsevier]

Rapid and accurate detection of rare circulating tumor cells (CTCs) in human blood still remains a challenge. We present a surface enhanced Raman spectroscopy (SERS) method based on aptamer-SERS bio-probe recognition coupled with micropore membrane filtration capture for the detection of CTCs at single cell level. The parylene micropore membrane with optimized micropore size installed on a filtration holder could capture bio-probe labeled CTCs by gravity in less than 10 s, and only with very less white blood cells (WBCs) residual. In order to facilitate the synthesis of the aptamer-SERS bio-probe, ethyl acetate dehydration method was established. The bio-probe can be rapidly synthesized within 2 h by binding SH-aptamer to 4- mercaptobenzoic acid (4-MBA) modified AuNPs with the help of ethyl acetate. The SERS bio-probe with selected specific aptamer could distinguish single human non-small cell lung cancer A549 cells from residual WBCs on membrane efficiently and reliably based on their Raman signal intensity difference at 1075 cm−1. Through the filter membrane coupled with aptamer-SERS bio-probe system, even 20 A549 cells in blood solution simulating CTCs sample can be detected, which the recovery rate and recognition rate are more than 90%. This method is rapid, reliable and cost-effective, which indicates a good prospect in clinical application for CTCs detection. An aptamer-SERS bio-probe was fabricated by binding specific aptamer of A549 tumor cell to Raman reporter 4-MBA modified AuNPs. CTCs sample labeled by the bio-probes can be captured on micropore parylene membrane with optimized micropore size by quick filtration. Single CTC on filter membrane was identified by SERS mapping method. [Display omitted] • Parylene membrane with suitable pore size capture CTCs rapidly and remove most WBCs. • Bioprobe synthesis with ethyl acetate dehydration in 2 h and keep Raman signal. • Selected aptamer ensure specificity for A549 cells compared to other cell and WBCs. • Low cost, time-saving, high capture efficiency and detection specificity for CTCs. [ABSTRACT FROM AUTHOR]

Abstract: In this work, Mg–Al CO3-layered double hydroxides (LDHs) were used as adsorbent materials for sodium dodecyl benzene sulfonate (SDBS) in aqueous solutions, the enriched SDBS can be directly detected by IO4 −–H2O2 chemiluminescence (CL) system. The commonly existing cations cannot be enriched by Mg–Al CO3-LDHs due to the structurally positively charged layers of LDHs, while other adsorbed anionic interferents had no effect on the IO4 −–H2O2 CL reaction. The corresponding linear regression equation was established in the range of 0.1–10μM for SDBS. The detection limit at a signal-to-noise (S/N) ratio of 3 for SDBS was 0.08μM. The relative standard deviation (RSD) for nine repeated measurements of 0.5μM SDBS was 2.6%. This proposed method has been successfully applied to the determination of SDBS in river water samples. To the best of our knowledge, we have first time coupled the high enrichment capacity of LDHs towards anions with CL detection for analytes. [Copyright &y& Elsevier]

The rapid and sensitive visualization of 2,6-dipicolinic acid (DPA, a unique anthrax biomarker) is essential to prevent anthrax disease or biological terrorist attack. In this study, a Eu3+-labeled ethylenediaminetetraacetic acid loaded hyperbranched polyethyleneimine carbon nanodot (hPEI-CD-EDTA-Eu3+) nanoprobe has been proposed for the ratiometric DPA detection. The sensing mechanism is based on the rapid DPA-Eu3+ chelation within 30 s and subsequent enhanced fluorescence emission through the antenna effect. With the introduction of EDTA chelating unit, the resulted fluorescence of Eu3+-complex is greatly enhanced, which endows sensitive DPA perception. By employing hPEI-CD as the internal reference, ratiometric DPA sensing is realized with a good linearity in the concentration range from 1.0 to 100 nM, with a limit of detection of 190 pM (S/N = 3). The specific chelation affinity between Eu3+ and DPA provides satisfying selectivity over other amino acids and ions. Using nanoprobe-loaded polyvinylidene fluoride paper as the analytical device, point-of-care DPA visualization is achieved. Furthermore, the practical application of designed paper device is validated by the visual detection of metabolic DPA-release from Bacillus subtilis spores. Image 1 • EDTA chelation can greatly enhance the fluorescence of Eu3+‒DPA complex. • Eu3+-labeled carbon nanodot fluorescence nanoprobe for sensitive DPA detection was fabricated. • Other metal ions or amino acids had no interference on DPA sensing. • The point-of-care DPA detection was achieved using nanoprobe-loaded PVDF paper device. • The visualization of metabolic DPA-release from Bacillus subtilis spores was realized. [ABSTRACT FROM AUTHOR]