A highly sensitive method for the detection of p-Aminophenol based on Cu-Au nanoparticles and KIO3

BACKGROUND

As a common industrial raw material and chemical intermediate, p-Aminophenol (pAP) is recognized as a serious pollutant that poses harm to both the environment and human health. The traditional detection methods for pAP have the advantages of good selectivity and high sensitivity, but their complex operation and time-consuming defects limit their application in on-site detection. Therefore, it is necessary to develop a simple, low-cost, rapid and high-sensitivity method for the detection of pAP.

RESULTS

Noble metal nanoparticles have been widely used in colorimetric sensing because of their simplicity and practicality. Herein, we presented a simple, excellent sensitive and selective colorimetric method for high-performance detection of pAP based on Cu-Au nanoparticles (Cu-Au NPs) and KIO3. In the presence of pAP, KIO3 was reduced to I2, which subsequently chemically adsorbed onto Cu-Au NPs surface and induced the dispersion and reorganization of Cu-Au NPs, along with prominent color change of the dispersion from gray-blue to pink and the transformation of Cu-Au NPs from chain-like aggregates to individual dispersed, irregular, subspherical nanoparticles. The mechanism was verified by TEM, DLS, Zeta potential, UV-vis and XPS. Meanwhile, Cu-Au NPs probe can rapidly detect pAP within 25 min, the limit of detection of pAP probe is 5 μM by the naked eyes and 0.03 μM by UV-vis absorption spectrum.

SIGNIFICANCE AND NOVELTY

This is the first colorimetric assay for pAP based on Cu-Au NPs probe. The satisfactory linearity (R2 = 0.9984) indicates that the colorimetric probe based on Cu-Au NPs and KIO3 can be utilized for quantitative detection of pAP. The detection results of pAP in real environmental water samples, urine samples and paracetamol tables demonstrate the practicability of pAP colorimetric probe.

Research progress in human biological monitoring of aromatic hydrocarbon with emphasis on the analytical technology of biomarkers

Aromatic hydrocarbons are unsaturated compounds containing carbon and hydrogen that form single aromatic ring, or double, triple, or multiple fused rings. This review focuses on the research progress of aromatic hydrocarbons represented by polycyclic aromatic hydrocarbons (including halogenated polycyclic aromatic hydrocarbons), benzene and its derivatives including toluene, ethylbenzene, xylenes (o-, m- and p-), styrene, nitrobenzene, and aniline. Due to the toxicity, widespread coexistence, and persistence of aromatic hydrocarbons in the environment, accurate assessment of exposure to aromatic hydrocarbons is essential to protect human health. The effects of aromatic hydrocarbons on human health are mainly derived from three aspects: different routes of exposure, the duration and relative toxicity of aromatic hydrocarbons, and the concentration of aromatic hydrocarbons which should be below the biological exposure limit. Therefore, this review discusses the primary exposure routes, toxic effects on humans, and key populations, in particular. This review briefly summarizes the different biomarker indicators of main aromatic hydrocarbons in urine, since most aromatic hydrocarbon metabolites are excreted via urine, which is more feasible, convenient, and non-invasive. In this review, the pretreatment and analytical techniques are compiled systematically for the qualitative and quantitative assessments of aromatic hydrocarbons metabolites such as gas chromatography and high-performance liquid chromatography with multiple detectors. This review aims to identify and monitor the co-exposure of aromatic hydrocarbons that provides a basis for the formulation of corresponding health risk control measures and guide the adjustment of the exposure dose of pollutants to the population.

Plasma-assisted in-situ preparation of L-cystine functionalized silver nanoparticle: An intelligent multicolor nano-sensing of cadmium and paracetamol from environmental sample

L-cystine (L-cys) functionalized plasmonic silver nanomaterial (Ag NPs) was fabricated toward the selective and sensitive detection of paracetamol and cadmium. The prepared L-cys-Ag nanoparticles (NPs) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) and fourier transform infrared spectroscopy (FTIR) analyses. SEM imaging show that Ag NPs was decorated on the surface of L-cysteine 3D cubic nanosheet. L-cys-Ag NPs showed selective and sensitive detection towards paracetamol and cadmium. The interference study confirms that the presence of other metal ions didn't inhibit the detection of cadmium by L-cys-Ag NPs. The limit of detection of paracetamol and cadmium by L-cys-Ag NPs was calculated to be 1.2 and 2.82 nM respectively. In addition, the real sample detection of paracetamol on blood serum and urine, and cadmium on STP were performed and the recovery percentage was above 97%. Further, the real sample analysis was performed in tap and drinking water and the recovery percentage was more than 98%. The analytic logic gate on the multicolour detection of cadmium and paracetamol was performed for the semi-quantitative monitoring of paracetamol and cadmium by L-cys-Ag NPs. The developed L-cys-Ag NPs were found to be an effective tool for the monitoring of cadmium in environmental water bodies and paracetamol in blood and urine.

Salt-template preparation of Mo5N6 nanosheets with peroxidase- and catalase-like activities and application for colorimetric determination of 4-aminophenol

Mo₅N₆ nanosheets were synthesized by a nickel-induced growth method and were found to possess peroxidase-like activity in acidic condition and catalase-like activity in weak basic condition. In acidic condition, Mo₅N₆ nanosheets can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H₂O₂ to form a blue color product (TMB_OX). At the co-existence of 4-aminophenol (4-AP), 4-AP can react with H₂O₂ and TMB_OX, resulting in the decrease of TMB_OX and the fading of blue color. Therefore, a facile, sensitive colorimetric method for the quantitative detection of 4-AP was developed. The linear range for 4-AP was 1.0 to 80.0 μmol⋅L^‒1 (R² = 0.999), and the detection limit was 0.56 μmol⋅L^‒1 based on 3σ/k. Resorcinol, aniline, humic acid, and common ions and anions in surface water did not interfere the determination of 4-AP. This colorimetric method was applied to measure the 4-AP in real water sample from Wulong River in Fujian Province of China. The relative standard deviation for the determination of 4-AP was ranged from 0.03 to 1.88%, and the recoveries from spiked samples were ranged between 99.2 and 107.6%. The determination results were consistent with those obtained by HPLC.

Application of ultrasound-assisted emulsification microextraction for simultaneous determination of aminophenol isomers in human urine, hair dye, and water samples using high-performance liquid chromatography

Aminophenol isomers (2-, 3-, and 4-aminophenols) are typically classified as industrial pollutants with genotoxic and mutagenic effects due to their easy penetration through the skin and membranes of human, animals, and plants. In the present study, a simple and efficient ultrasound-assisted emulsification microextraction procedure coupled with high-performance liquid chromatography with ultraviolet detector was developed for preconcentration and determination of these compounds in human fluid and environmental water samples. Effective parameters (such as type and volume of extraction solvent, pH and ionic strength of sample, and ultrasonication and centrifuging time) were investigated and optimized. Under optimum conditions (including sample volume: 5 mL; extraction solvent: chloroform, 80 µL; pH: 6.5; without salt addition; ultrasonication: 3.5 min; and centrifuging time: 3 min, 5000 rpm min−1), the enrichment factors and limits of detection were ranged from 42 to 51 and 0.028 to 0.112 µg mL−1, respectively. Once optimized, analytical performance of the method was studied in terms of linearity (0.085–157 µg mL−1, r2 > 0.998), accuracy (recovery = 88.6– 101.7%), and precision (repeatability: intraday precision < 3.98%, and interday precision < 5.12%). Finally, applicability of the method was evaluated by the extraction and determination of these compounds in human urine, hair dye, and real water samples.

Ipso-hydroxylation and subsequent fragmentation: a novel microbial strategy to eliminate sulfonamide antibiotics

Sulfonamide antibiotics have a wide application range in human and veterinary medicine. Because they tend to persist in the environment, they pose potential problems with regard to the propagation of antibiotic resistance. Here, we identified metabolites formed during the degradation of sulfamethoxazole and other sulfonamides in Microbacterium sp. strain BR1. Our experiments showed that the degradation proceeded along an unusual pathway initiated by ipso-hydroxylation with subsequent fragmentation of the parent compound. The NADH-dependent hydroxylation of the carbon atom attached to the sulfonyl group resulted in the release of sulfite, 3-amino-5-methylisoxazole, and benzoquinone-imine. The latter was concomitantly transformed to 4-aminophenol. Sulfadiazine, sulfamethizole, sulfamethazine, sulfadimethoxine, 4-amino-N-phenylbenzenesulfonamide, and N-(4-aminophenyl)sulfonylcarbamic acid methyl ester (asulam) were transformed accordingly. Therefore, ipso-hydroxylation with subsequent fragmentation must be considered the underlying mechanism; this could also occur in the same or in a similar way in other studies, where biotransformation of sulfonamides bearing an amino group in the para-position to the sulfonyl substituent was observed to yield products corresponding to the stable metabolites observed by us.

Annotation of the human adult urinary metabolome and metabolite identification using ultra high performance liquid chromatography coupled to a linear quadrupole ion trap-Orbitrap mass spectrometer

Metabolic profiles of biofluids obtained by atmospheric pressure ionization mass spectrometry-based technologies contain hundreds to thousands of features, most of them remaining unknown or at least not characterized in analytical systems. We report here on the annotation of the human adult urinary metabolome and metabolite identification from electrospray ionization mass spectrometry (ESI-MS)-based metabolomics data sets. Features of biological interest were first of all annotated using the ESI-MS database of the laboratory. They were also grouped, thanks to software tools, and annotated using public databases. Metabolite identification was achieved using two complementary approaches: (i) formal identification by matching chromatographic retention times, mass spectra, and also product ion spectra (if required) of metabolites to be characterized in biological data sets to those of reference compounds and (ii) putative identification from biological data thanks to MS/MS experiments for metabolites not available in our chemical library. By these means, 384 metabolites corresponding to 1484 annotated features (659 in negative ion mode and 825 in positive ion mode) were characterized in human urine samples. Of these metabolites, 192 and 66 were formally and putatively identified, respectively, and 54 are reported in human urine for the first time. These lists of features could be used by other laboratories to annotate their ESI-MS metabolomics data sets.

Whole-body distribution and brain tumor imaging with (11)C-4DST: a pilot study

Recently, we developed [methyl-(11)C]4'-thiothymidine ((11)C-4DST) as an in vivo cell proliferation marker. The present study was performed to determine the safety, distribution, radiation dosimetry, and initial brain tumor imaging of (11)C-4DST in humans.

METHODS

Multiorgan biodistribution and radiation dosimetry of (11)C-4DST were assessed in 3 healthy humans, who underwent 2-h whole-body PET scanning. Radiation dosimetry was estimated from the residence times of source organs using the OLINDA program. Six brain tumor patients underwent dynamic (11)C-4DST scans with arterial blood sampling. These patients were also evaluated with (11)C-methionine PET on the same day (n = 4) as, or 3 wk before (n = 2), (11)C-4DST PET studies. Metabolites in plasma and urine samples were analyzed by high-performance liquid chromatography. Breakdown of the blood-brain barrier in tumor tissue was confirmed by gadolinium-enhanced T1-weighted MRI.

RESULTS

There were no serious adverse events in any subjects at any time during the study period. (11)C-4DST PET demonstrated selective uptake in the bone marrow, which has a high rate of proliferation. In addition, high-level uptake was also seen in the liver. The highest absorbed organ dose was in the urinary bladder wall (17.6 μGy/MBq). The estimated effective dose for (11)C-4DST was 4.2 μSv/MBq. (11)C-4DST showed little uptake in normal brain tissues, resulting in low background activity for imaging of brain tumors. In contrast, (11)C-4DST PET demonstrated rapid uptake in aggressive tumor masses, whereas no signal of (11)C-4DST was seen in clinically stable disease in which (11)C-methionine uptake was high. The distribution pattern of (11)C-methionine in tumor regions was not always identical to that of (11)C-4DST. Analysis of plasma samples by high-performance liquid chromatography indicated that more than 60% of the radioactivity was present as unchanged (11)C-4DST at 20 min.

CONCLUSION

The initial findings of the present study in a small group of patients indicated that (11)C-4DST PET is feasible for imaging of brain tumors. Dosimetry and pharmacologic safety were acceptable at the dose required for adequate PET images.

High-sensitivity electrochemical enzyme-linked assay on a microfluidic interdigitated microelectrode

A novel enzyme-linked DNA hybridization assay on an interdigitated array (IDA) microelectrode integrated into a microfluidic channel is demonstrated with sub-nM detection limit. To improve the detection limit as compared to conventional electrochemical biosensors, a recyclable redox product, 4-aminophenol (PAP) is used with an IDA microelectrode. The IDA has a modest and easily fabricated inter-digit spacing of 10 μm, yet we were able to demonstrate 97% recycling efficiency of PAP due to the integration in a microfluidic channel. With a 70 nL sample volume, the characterized detection limit for PAP of 1.0 × 10⁻¹⁰ M is achieved, with a linear dynamic range that extends from 1.0 × 10⁻⁹ to 1.0 × 10⁻⁵ M. This detection limit, which is the lowest reported detection limit for PAP, is due to the increased sensitivity provided by the sample confinement in the microfluidic channel, as well as the increased repeatability due to perfectly static flow in the microchannel and an additional anti-fouling step in the protocol. DNA sequence detection is achieved through a hybridization sandwich of an immobilized complementary probe, the target DNA sequence, and a second complementary probe labeled with β-galactosidase (β-GAL); the β-GAL converts its substrate, 4-aminophenyl-d-galactopyranoside (PAPG), into PAP. In this report we present the lowest reported observed detection limit (1.0 × 10⁻¹⁰ M) for an enzyme-linked DNA hybridization assay using an IDA microelectrode and a redox signaling paradigm. Thus, we have demonstrated highly sensitive detection of a targeted DNA sequence using a low-cost easily fabricated electrochemical biosensor integrated into a microfluidic channel.

Spectrophotometric Determination of Paracetamol in Urine with Tetrahydroxycalix[4]arene as a Coupling Reagent and Preconcentration with Triton X-114 Using Cloud Point Extraction

In the present paper, conventional spectrophotometry in conjunction with cloud point extraction-preconcentration were investigated as alternative methods for paracetamol (PCT) assay in urine samples. Cloud point extraction (CPE) was employed for the preconcentration of p-aminophenol (PAP) prior to spectrophotometric determination using the non-ionic surfactant Triton X-114 (TX-114) as an extractant. The developed methods were based on acidic hydrolysis of PCT to PAP, which reacted at room temperature with 25,26,27,28-tetrahydroxycalix[4]arene (CAL4) in the presence of an oxidant (KIO(4)) to form an blue colored product. The PAP-CAL4 blue dye formed was subsequently entrapped in the surfactant micelles of Triton X-114. Cloud point phase separation with the aid of Triton X-114 induced by addition of Na(2)SO(4) solution was performed at room temperature as an advantage over other CPE assays requiring elevated temperatures. The 580 nm-absorbance maximum of the formed product was shifted bathochromically to 590 nm with CPE. The working range of 1.5-12 microg ml(-1) achieved by conventional spectrophotometry was reduced down to 0.14-1.5 microg ml(-1) with cloud point extraction, which was lower than those of most literature flow-through assays that also suffer from nonspecific absorption in the UV region. By preconcentrating 10 ml sample solution, a detection limit as low as 40.0 ng ml(-1) was obtained after a single-step extraction, achieving a preconcentration factor of 10. The stoichiometric composition of the dye was found to be 1 : 4 (PAP : CAL4). The impact of a number of parameters such as concentrations of CAL4, KIO(4), Triton X-100 (TX-100), and TX-114, extraction temperature, time periods for incubation and centrifugation, and sample volume were investigated in detail. The determination of PAP in the presence of paracetamol in micellar systems under these conditions is limited. The established procedures were successfully adopted for the determination of PCT in urine samples. Since the drug is rapidly absorbed and excreted largely in urine and its high doses have been associated with lethal hepatic necrosis and renal failure, development of a rapid, sensitive and selective assay of PCT is of vital importance for fast urinary screening and antidote administration before applying more sophisticated, but costly and laborious hyphenated instrumental techniques of HPLC-SPE-NMR-MS.