Quantitative measurement of 17 beta-estradiol and estriol in river water by time-resolved fluoroimmunoassay

Assessment of Xenoestrogens in Jordanian Water System: Activity and Identification

Sex hormone disruptors (xenoestrogens) are a global concern due to their potential toxicity. However, to date, there has been no study to investigate the presence of xenoestrogen pollutants in the Jordanian water system. Samples in triplicates were collected from six locations in Jordan, including dams, surface water, tap or faucet water, and filtered water (drinking water-local company). Xenoestrogens were then extracted and evaluated with a yeast estrogen screen utilizing Saccharomyces cerevisiae. Later, possible pollutants were mined using ultrahigh-performance liquid chromatography (UPLC) coupled with a Bruker impact II Q-TOF-MS. Possible hits were identified using MetaboScape software (4000 compounds), which includes pesticide, pharmaceutical pollutant, veterinary drug, and toxic compound databases and a special library of 75 possible xenoestrogens. The presence of xenoestrogens in vegetable samples collected from two different locations was also investigated. The total estrogen equivalents according to the YES system were 2.9 ± 1.2, 9.5 ± 5, 2.5 ± 1.5, 1.4 ± 0.9 ng/L for King Talal Dam, As-Samra Wastewater Treatment Plant, King Abdullah Canal, and tap water, respectively. In Almujeb Dam and drinking water, the estrogenic activity was below the detection limit. Numbers of identified xenoestrogens were: As-Samra Wastewater Treatment Plant 27 pollutants, King Talal Dam 20 pollutants, Almujeb Dam 10 pollutants, King Abdullah Canal 16 pollutants, Irbid tap water 32 pollutants, Amman tap water 30 pollutants, drinking water 3 pollutants, and vegetables 7 pollutants. However, a large number of compounds remained unknown. Xenoestrogen pollutants were detected in all tested samples, but the total estrogenic capacities were within the acceptable range. The major source of xenoestrogen pollutants was agricultural resources. Risk evaluations for low xenoestrogen activity should be taken into account, and thorough pesticide monitoring systems and regular inspections should also be established.

The application of rapid test paper technology for pesticide detection in horticulture crops: a comprehensive review

Background

The ever increasing pests and diseases occurring during vegetable crop production is a challenge for agronomists and farmers. One of the practices to avoid or control the attack of the causal agents is the use of pesticides, including herbicides, insecticides nematicides, and molluscicides. However, the use of these products can result in the presence of harmful residues in horticultural crops, which cause several human diseases such as weakened immunity, splenomegaly, renal failure, hepatitis, respiratory diseases, and cancer. Therefore, it was necessary to find safe and effective techniques to detect these residues in horticultural crops and to monitor food security.

Main body

The review discusses the use of conventional methods to detect pesticide residues on horticultural crops, explain the sensitivity of nanoparticle markers to detect a variety of pesticides, discuss the different methods of rapid test paper technology and highlight recent research on rapid test paper detection of pesticides.

Conclusions

The methodologies discussed in the current review can be used in a certain situation, and the variety of methods enable detection of different types of pesticides in the environment. Notably, the highly sensitive immunoassay, which offers the advantages of being low cost, highly specific and sensitive, allows it to be integrated into many detection fields to accurately detect pesticides.

Phosphorescent palladium-tetrabenzoporphyrin indicators for immunosensing of small molecules with a novel optical device

Small-molecule detection is important for many applications including clinical diagnostics, drug discovery, environmental screening, and food technology. Current techniques suffer from various limitations including cost, complex sample processing, massive instrumentation, and need for expertise. To overcome these limitations, a new optical immunosensing assay for the detection of small molecules was developed and assessed with the targets estrone (E1) and estradiol (E2). For this purpose, phosphorescent indicators were designed based on the tetrabenzoporphyrin skeleton directly linked to E1 or E2, or attached through a linker, with phosphorescence lifetimes in the range of ~100-~300 μs. The assay is an indicator displacement assay (IDA). The best performances of our optical immunosensor were obtained with the indicators E1-L-Por and E2-L-Por. As they bound to specific polyclonal antibodies, their phosphorescence (τ ~200 μs) was quenched. When an endogenous competitor was added, the indicator was displaced, and the phosphorescence was immediately recovered. These effects were measured with a new optical device, described here, and able to detect picograms of luminescent molecules emitting in the NIR range, simply by measuring phosphorescence decay. This radical switch-off/switch on process demonstrates that E1-L-Por and E2-L-Por are good candidates for in vivo and in vitro immunosensing of E1 and E2. Importantly, the present immunosensing assay can be easily adapted to other small molecules such as other hormones and drugs.

Fluorescent aptasensor for 17β-estradiol determination based on gold nanoparticles quenching the fluorescence of Rhodamine B

In this paper, we developed a fluorescent aptasensor for 17β-estradiol (E2) determination in aqueous solution using label-free E2-specific aptamer, gold nanoparticles (AuNPs) and Rhodamine B (RhoB) as sensing probe, fluorescent quencher and fluorescent indicator respectively. In the absence of E2, AuNPs were wrapped by E2 aptamer and maintained dispersed in NaCl solution basically. These dispersed AuNPs could effectively impair the originally high fluorescence of RhoB. Contrarily, in the presence of E2, E2 aptamer could specifically combine with E2 to form E2-aptamer complex, so the AuNPs were released by E2 aptamer and aggregated under the influence of NaCl. The aggregated AuNPs have a weak influence on RhoB fluorescence. Therefore, the E2 concentration can be determined by the change of fluorescence intensity of RhoB. This fluorescent assay has a detection limit as low as 0.48 nM, a linear range from 0.48 to 200 nM, and high selectivity over other disrupting chemicals. It was applied to determine E2 in water samples with recoveries in the range of 94.3-111.7%. The fluorescent aptasensor holds great potential for E2 detection in environmental water samples.

Highly efficient detection of paclobutrazol in environmental water and soil samples by time-resolved fluoroimmunoassay

A fast and ultrasensitive indirect competitive time-resolved fluoroimmunoassay (TRFIA) was developed for the analysis of paclobutrazol in environmental water and soil samples. Paclobutrazol hapten was synthesized and conjugated to bovine serum albumin (BSA) for producing polyclonal antibodies. Under optimal conditions, the 50% inhibitory concentration (IC50 value) and limit of detection (LOD, IC20 value) were 1.09μgL(-1) and 0.067μgL(-1), respectively. The LOD of TRFIA was improved 30-fold compared to the already reported ELISA. There was almost no cross-reactivity of the antibody with the other structural analogues of triazole compounds, indicating that the antibody had high specificity. The average recoveries from spiked samples were in the range from 80.2% to 104.7% with a relative standard deviation of 1.0-9.5%. The TRFIA results for the real samples were in good agreement with that obtained by high-performance liquid chromatography analyses. The results indicate that the established TRFIA has potential application for screening paclobutrazol in environmental samples.

Analytical methods for the endocrine disruptor compounds determination in environmental water samples

The potential risk of exposure to different xenobiotics, which can modulate the endocrine system and represent a treat for the wellness of an increasing number of people, has recently drawn the attention of international environmental and health agencies. Several agents, characterized by structural diversity, may interfer with the normal endocrine functions that regulate cell growth, homeostasis and development. Substances such as pesticides, herbicides, plasticizers, metals, etc. having endocrine activity (EDCs) are used in agriculture and industry and are also used as drugs for humans and animals. A difficulty in the analytical determination of these substances is the complexity of the matrix in which they are present. In fact, the samples most frequently analyzed consist of groundwater and surface water, including influent and effluent of wastewater treatment plants and drinking water. In this review, several sample pretreatment protocols, assays and different instrumental techniques recently used in the EDCs determination have been considered. This review concludes with a paragraph in which the most recent hyphenated-instrument techniques are treated, highlighting their sensitivity and selectivity for the analyses of environmental water samples.

Simultaneous determination of three naturally occurring estrogens in environmental waters by high-performance liquid chromatography

A simple, sensitive and accurate reversed-phase high-performance liquid chromatographic (HPLC) method for simultaneous determination of three naturally occurring estrogenic steroids including estrone (E1), 17β-estradiol (E2) and estriol (E3) in environmental water samples was developed. Analytes were extracted with ethyl acetate solvents and preconcentrated prior to HPLC analysis. Separations were accomplished in <20 min using a reversed-phase C(18) column (4.6×250 mm id, 5 μm) with a gradient elution of mobile phase containing 3.0 mM ammonium acetate/acetonitrile mixtures (flow rate, 1.0 mL/min). UV light absorption responses at 205 nm were linear over a wide concentration range from 100,000 μg/L to the detection limits of 0.96 μg/L E1, 0.64 μg/L E2 and 0.78 μg/L E3. Quantitation was carried out by the peak area method. The relative standard deviation for the analysis of three estrogens was <3.0%. This method was applied for the simultaneous determination of estrogens in environmental water samples collected in Zhejiang, China. The higher concentrations of both E2 and E3 were found in Tang River and West Lake waters, and E1 was detected in lake water only. All three estrogens were below the detection limits in rain waters.

Determination of 17beta-oestradiol by fluorescence immunoassay with streptavidin-conjugated quantum dots as label

A sensitive and selective method for the determination of 17beta-oestradiol by fluorescence immunoassay (FIA) was established on the basis of quantum dots (QDs) as label. The complex of biotin-labelled anti-rabbit IgG and strepavidin conjugated by quantum dots (QD-SA) was regarded as a probe in this system and the strepavidin-biotin system as signal amplification system. After optimising the conditions of the immunoreaction, such as the concentration of the reagent and the pH of the buffer solution, the linear range and the limit of detection of 17beta-oestradiol were 0.01-10,000ngml(-1) and 0.00542ngml(-1), respectively. This method was applied to determine oestradiol in water samples, with the percent recoveries in the range of 86-113%.

Time-resolved fluoroimmunoassay as an advantageous approach for highly efficient determination of sulfonamides in environmental waters

Using monoclonal antibodies labeled with Eu(3+) chelates, time-resolved fluoroimmunoassay (TRFIA) methods were developed for the determination of trace sulfamethazine (SMZ), sulfa-methoxazole (SMX), and sulfadiazine (SDZ) in environmental waters. Under the optimized conditions, the developed methods offered (i) low detection limits (9.8 ng/L SMZ, 6.1 ng/L SMX, and 5.4 ng/L SDZ, based on 90% inhibition) which were about 1 order of magnitude lower than that of the enzyme-linked immunosorbent assay (ELISA), (ii) high selectivity with no cross-reactivity (<0.05%) to similarly structured sulfonamides; (iii) high tolerance to variation of the sample pH (6.0-9.0) and salinity (0-100 mM), as well as the presence of humic acid (0-100 mg/L DOC) and heavy metals (0-1 mg/L concentration each of Cu(2+), Cd(2+), Hg(2+), Pb(2+), and As(V)) in the samples, and (iv) direct determination with low cost, high sample throughput, and low sample consumption (50-100 microL). The proposed TRFIA procedures were applied to determine sulfonamides in a variety of surface water and wastewater samples without sample pretreatment other than filtration. The satisfactory recoveries (64-127%) and reproducibilities (CV = 0.2-16%) achieved, as well as the good agreement with those given by liquid chromatography-tandem mass spectroscopy and ELISA methods, demonstrated the applicability of the proposed TRFIA methods for routine screening/quantification of sulfonamides in environmental waters.

Development of magnetic particle-based chemiluminescence enzyme immunoassay for the detection of 17beta-estradiol in environmental water

In the present work, a simple, fast, and highly sensitive chemiluminescence enzyme immunoassay for 17beta-estradiol (E2) in environmental water samples was developed, using magnetic particles (MPs) labeled with secondary antibody as both the immobilization matrix and the separation tools. The specific anti-E2 polyclonal antibody (PcAb) was produced against a conjugate of estradiol-bovine serum albumin. The specificity of the anti-E2 antibody was studied. The results showed that the antibody did not cross-react with the structurally related endocrine-disrupting compounds, including estrone, ethinyl E2, estriol, E2-17-glucuronide, E2-3-sulfate-17-glucuronide, androstenedione, and dihydrotestosterone. The water samples were pretreated with solid-phase extraction using C18 cartridges for the removal of matrix effects. Several physicochemical parameters including the dilution ratios of E2-6-horseradish peroxidase conjugate and anti-E2 PcAb, immunoreaction time, volume of chemiluminescent substrate and MPs, chemiluminescence reaction time, and pH of assay solution were studied and optimized. At optimal experimental conditions, it was found that the proposed method exhibited high performance with detection limit of 2.0 pg/mL, linear range of 20-1,200 pg/mL, and total assay time of 45 min. Both inter- and intra-assay coefficient of variation were less than 10%. The average recoveries of three different spiked concentration samples ranged from 86.3% to 108%. The method was successfully applied to the determination of E2 in river, waste, and tap water, and showed a good correlation with the commercially available radioimmunoassay kit.

Field study using two immunoassays for the determination of estradiol and ethinylestradiol in the aquatic environment

The effluent of four sewage treatment plants (STP) and eight surface water samples from the river Rhine in Germany and two smaller rivers were monitored for the hormones estradiol (E2) and ethinylestradiol (EE2). The studied STPs are using different treatment processes. Two facilities include an activated sludge treatment, one is a constructed wetland, and one is just an aerated lagoon. For analysis of E2 and EE2 in the aquatic environment two immunoassays have been developed allowing a very cost-effective screening for both hormones in environmental samples. Detection limits could be established at 0.05 ng L(-1) for E2 and 0.01 ng L(-1) for EE2, taking a 50-fold enrichment into account. Median concentrations for E2 and EE2 in effluent samples were 12 and 1.8 ng L(-1), in surface water 4.0 and 0.7 ng L(-1), respectively. The highest estrogen concentrations were found in the effluent of the lagoon, equipped with very basic means of wastewater treatment.

Analytical approach for monitoring endocrine-disrupting compounds in urban waste water treatment plants

The presence of endocrine-disrupting compounds in influent and effluent water samples from four waste water treatment plants located in Italy was studied. The estrogen-like activity of the water samples was measured using a chemiluminescent recombinant yeast assay which is based on genetically engineered yeast cells that express the human estrogen receptor. This receptor, once activated, elicits the expression of the reporter gene lac-Z and, consequently, the production of beta-galactosidase, which is then measured by chemiluminescence. To control and minimize sample matrix effects, an external control based on a modified yeast strain stably expressing beta-galactosidase was developed and also used in the assay. Rapid and sensitive chemiluminescent enzyme immunoassays were also developed and validated for the quantification of 17beta-estradiol, estrone, and estriol in waste water samples. Results from both methods were compared with a reference high-performance liquid chromatography and electrospray ionization tandem mass spectrometry (HPLC ESI-MS-MS) method developed for the quantification of natural estrogens. The recombinant yeast assay revealed a significant estrogenic activity in the influent samples, ranging from 80 to 400 pmol/L 17beta-estradiol equivalents (EEQ), which was reduced by 70-95% in the effluent samples. The yeast assay also showed a systematic 20-30% overestimation of estrogenic activity relative to the HPLC ESI-MS-MS method, suggesting the presence of other compounds in the samples with estrogenic activity. The chemiluminescent enzyme immunoassays showed the presence of estrogens in the influent samples (mean concentrations: 350-450 pmol/L for estrone, 5-100 pmol/L for 17beta-estradiol, 25-300 pmol/L for estriol), with significantly lower concentrations detected in the respective effluent samples. The waste water treatment was able to reduce natural estrogen concentrations by 40-95%, although a high variability was observed. The enzyme immunoassay data correlated well with data obtained by the HPLC ESI-MS-MS method. Although the recombinant yeast assay represents a useful tool for a first-level screening of estrogenic activity due to its simplicity and high analytical throughput, sample matrix effects observed in waste water of industrial origin were found to strongly affect the yeast cells response, even when properly corrected for using the external control, thereby limiting its use to urban waste water. Its integration with chemiluminescent enzyme immunoassays would improve its performance by reducing false negative results, thereby enabling its use in extensive studies monitoring for the presence of endocrine-disrupting compounds in urban treatment plant effluents.

Lanthanide complex-based fluorescence label for time-resolved fluorescence bioassay

Different from organic fluorescence dyes, fluorescent lanthanide complexes have the fluorescence properties of long fluorescence lifetime, large Stokes shift and sharp emission profile, which makes them favorable be used as the fluorescent labeling reagents for microsecond time-resolved fluorescence bioassay. Lanthanide complex-based fluorescence labels have been successfully used for highly sensitive time-resolved fluorescence immunoassay, DNA hybridization assay, cell activity assay, and bio-imaging microscopy assay. Since the technique allows easy distinction of the specific fluorescence signal of the long-lived label from short-lived background noises associated with biological samples, scattering lights (Tyndall, Rayleigh and Raman scatterings) and the optical components (cuvettes, filters and lenses), the sensitivity of fluorescence bioassay has been remarkably improved. This paper summarized the recent developments of lanthanide complex-based fluorescence labels and their applications in time-resolved fluorescence bioassays mainly based on the authors' researches and relative publications.

Development of a micro-plate magnetic chemiluminescence enzyme immunoassay (MMCLEIA) for rapid- and high-throughput analysis of 17β-estradiol in water samples

A novel method of micro-plate magnetic chemiluminescence enzyme immunoassay (MMCLEIA) for the screening of 17beta-estradiol in water samples was proposed. It used the micro-plate magnetic separator designed by ourselves which can achieve the high-throughput analysis without the samples pre-treatment and the sensitive chemiluminescence system of AMPPD-ALP system. The method showed specific recognition of estrogen, without cross-reactions for three other major estrogenic compounds (17beta-estradiol (E2), estriol (E3), ethinyl (E2)) commonly found in water. The MMCLEIA was also especially suitable for the large-scale samples processing. The working range for 17beta-estradiol was 10-3000 pg/ml. The assay sensitivity was 5.4 pg/ml. Both intra- and inter-assay had relative standard deviation of less 15%. The effect of several physico-chemical parameters, such as the ratio of antibody versus antigen, incubation time and the concentration of detergent were studied. This method has been successfully applied to the preliminary detection of the sea-water. Compared with the chemiluminescence enzyme-linked immunosorbed assay, the correlation was good.

Development of a screen-printed carbon electrochemical immunosensor for picomolar concentrations of estradiol in human serum extracts

Investigations into the development of a prototype electrochemical immunosensor for estradiol (E(2)) are described. After optimising reagent loadings in a 96-well enzyme-linked immunosorbent assay (ELISA), antibodies (rabbit anti-mouse IgG and monoclonal mouse anti-E(2)) were immobilised by passive adsorption onto the surface of screen-printed carbon electrodes (SPCEs). A competitive immunoassay was then performed using an alkaline-phosphatase (ALP)-labelled E(2) conjugate. Calibration plots for E(2) buffer standards, performed colorimetrically on the SPCEs using a para-nitrophenyl phosphate substrate solution, were in good agreement with ELISA calibration plots. Electrochemical measurements were then performed using differential pulse voltammetry (DPV) following the production of 1-naphthol from 1-naphthyl phosphate. The calibration plot of DPV peak current versus E(2) concentration showed a measurable range of 25-500 pg/ml with a detection limit of 50 pg/ml. A coefficient of variation of between 13.0 and 15.6% was obtained for repeat measurements. The immunosensor was applied to the determination of E(2) in spiked serum, following an extraction step with diethyl ether. A mean recovery for the method of 102.5% was obtained with a CV of 19.1%. The options available for further development of the sensor regarding precision, limit of detection and direct sample analysis are discussed.

Degradation of estrogen conjugates using titanium dioxide as a photocatalyst

Estrogen conjugates (estradiol-3-glucuronide, -17-glucuronide, estrone-glucuronide and -sulfate) were subjected to photodegradation using titanium dioxide immobilized on glass beads as a catalyst. Their time courses were measured by HPLC and compared with those of the unconjugated estrogens. Estradiol, its 17-glucuronide and estrone, which have an unconjugated phenolic hydroxy group at the C-3 position, were almost completely degraded by UV irradiation within 4 h. On the other hand, significant amounts of estradiol- and estrone-3-glucuronide (ca. 20%, 25%) and estrone sulfate (ca. 90%), which were conjugated at the 3-hydroxy group, remained after a 6.5 h irradiation. These results supported the hypothesis that the photodegradation of estrogens was initiated at the phenolic hydroxy group.