The analysis of estrone and 17β-estradiol by stir bar sorptive extraction–thermal desorption–gas chromatography/mass spectrometry: Application to urine samples after oral administration of conjugated equine estrogens

Competitive ECL immunosensor for ultrasensitive 17β-estradiol detection based on synergistic promotion strategy using CdSe-ZnSe nanocomposites

A novel competitive ECL immunosensor for detection of 17β-Estradiol (E2) has been fabricated successfully. CdSe-ZnSe nanocomposites (CdSe-ZnSe NCs) with high catalytic properties, large surface area and good conductivity were used synergistically as the ECL nanocarriers of Pt nanoparticles (PtNPs). The ECL intensity of CdSe-ZnSe NCs increased and stabilized with luminol-PtNPs (luminol-PtNPs@CdSe-ZnSe NCs) because of electron transfer. To achieve the successful assembling of competitive ultrasensitive ECL immunosensor with high sensitivity and synergistic effect, Ag@TiO2 core-shell was introduced as label. Ag@TiO2 acted as a signal amplifier and also exhibited the high catalytic activity towards H2O2. This firmly anchored the E2 Antigen with covalent bond and converted the longer wavelength radiations to shorter wavelength. Under optimized conditions, our proposed strategy quantify the selective and reliable analysis of E2 with detection limit of 2.51 fg/mL (S/N = 3) within the linear range of 0.0001-30 ng/mL. The assembled synergistic strategy-based ECL immunosensor manifested the promising sensitivity, selectability along with high level of repeatability. Thus, the fabricated ECL immunosensor has potential valuable application for E2 detection along with many other environmental pollutants.

A magnetic relaxation switch sensor for determination of 17β-estradiol in milk and eggs based on aptamer-functionalized Fe3 O4 @Au nanoparticles

BACKGROUND

A simple and rapid detection method for 17β-estradiol (E₂ ) in complex food matrix is greatly desirable. A magnetic relaxation switch (MRS) sensor for detecting E₂ based on the aptamer-functionalized gold-coated iron oxide (Fe₃ O₄ @Au) nanocomposite was designed in this study. Fe₃ O₄ @Au nanoparticles (NPs) played as a 'switch' between dispersed and aggregated states, while aptamer served as the recognition unit.

RESULTS

According to the sensing effect of monocomponent relaxation time (T_2W ) for E₂ , the volume ratio of aptamers to Fe₃ O₄ @Au, the sodium chloride (NaCl) concentration, the concentration of Fe₃ O₄ @Au@Apt, and reaction time were optimized to be 4:1, 0.03 mol L^-1 , 4 μmol L^-1 and 15 min, respectively. For the analysis of food sample, the E₂ was quantified over a concentration range of 1 to 100 nmol L^-1 with a detection limit of 7.6 nmol L^-1 for milk samples, while a linearity range of 20 to 100 nmol L^-1 and a detection limit of 8.57 nmol L^-1 for egg samples.

CONCLUSION

These results exhibited that the MRS sensor could be a promising platform for the rapid detecting of E₂ in food sample. © 2021 Society of Chemical Industry.

Quantitation of estradiol by competitive light-initiated chemiluminescent assay using estriol as competitive antigen

Background

Light‐initiated chemiluminescent assays (LICA) are homogeneous assays that are sensitive, specific, and free of separation and washing steps and have high throughput and high precision.

Methods

In this research, we developed a competitive method by LICA to achieve accurate quantification of estradiol (E2) in human serum. E2 competed with estriol (E3) for binding to anti‐human E2 antibodies. E3 was linked to biotin via bovine serum albumin as a linker. As this assay used competition between the labeled tracer and the analyte, an increase in E2 concentration will cause a signal decrease.

Results

The expected detection range of E2 was 20‐5000 pg/mL. The analytical and functional sensitivities were 7.16 and 13.7 pg/mL, respectively. The intra‐ and inter‐assay coefficients of variation were both below 15%, and the recovery rate ranged from 97.5% to 106.8%. The interference rates ranged from −3.6% to 5.4% and met detection requirements for E2 in hyperbilirubinemia, hemolysis, and lipemia in clinical samples. In addition, the cross‐reactivity rates between E2 and structural analogs and some reproductive hormones varied from 1.9% to 10.6% which showed that LICA is highly specific for E2. Moreover, our results showed high accordance with the IMMULITE 2000 (y = 0.6695x + 47.92, r² = .843) and VIDAS systems (y = 1.099x − 821.5, r² = .9392).

Conclusion

Our data show that the LICA, which is easy to automate, is a promising technique for quantification of E2 in human serum and could be used for clinical detection.

Trace analysis of estrogens in milk samples by molecularly imprinted solid phase extraction with genistein as a dummy template molecule and high-performance liquid chromatography-tandem mass spectrometry

Dummy molecularly imprinted polymer microspheres (DMIPMS) towards estrogens were synthesized by Pickering emulsion polymerization employing genistein (GEN) as a dummy template molecule. The FTIR analysis indicated the successful preparation of the imprinted polymers, and the characterization results of scanning electron microscopy and nitrogen adsorption desorption measurement indicated that the obtained DMIPMS are in possess of regular spherical shapes, porous structures and narrow diameter distribution, a BET surface area of 402.74 m² g^-1, a total pore volume of 0.568 cm³ g^-1 and a pore diameter of 3.62 nm. The binding capacity and selectivity of DMIPMS were investigated in equilibrium binding experiments and chromatographic evaluation experiments through scatchard analysis and molecular imprinting factor (IF) analysis, respectively. The MIPs showed high binding capacity and excellent selectivity towards seven selected natural and synthetic estrogens, which are Estrone (E1), 17β-estradiol (βE2), estriol (E3), ethinylestradiol (EE2), dienestrol(DS), diethylstilbestrol (DES), and hexestrol (HEX). A method for selective determination of seven estrogens in milk samples via dummy molecularly imprinted solid phase extraction coupled with HPLC-MS/MS was developed, which showed good linearity from 2 to 500 µg L^-1 with a correlation coefficient (R2) of more than 0.999. The detection limits were within the range of 0.10-0.35 µg L^-1 and the recoveries of the seven estrogens at three spiking levels (10,100,250 µg L^-1) ranged from 88.9% to 102.3% with relative standard deviation (RSD, n = 5) for intra-day and inter-day assays varied from 0.8% to 4.5%. The developed method is thus proven to be efficient and reliable for regular monitoring of trace estrogens in complex matrices such as milk samples.

Highly Sensitive Detection of Hormone Estradiol E2 Using Surface-Enhanced Raman Scattering Based Immunoassays for the Clinical Diagnosis of Precocious Puberty

The hormone estradiol (17β-estradiol, E2) plays an important role in sexual development and serves as an important diagnostic biomarker of various clinical conditions. Particularly, the serum E2 concentration is very low (<10 pg/mL) in prepubertal girls. Accordingly, many efforts to develop a sensitive method of detection and quantification of E2 in human serum have been made. Nonetheless, current clinical detection methods are insufficient for accurate assessment of E2 at low concentrations (<10 pg/mL). Thus, there is an urgent need for new technologies with efficient and sensitive detection of E2 for use in routine clinical diagnostics. In this study, we introduce a new E2 assay technique using a surface-enhanced Raman scattering (SERS)-based detection method. The SERS-based assay was performed with 30 blood samples to assess its clinical feasibility, and the results were compared with data obtained using the ARCHITECT chemiluminescence immunoassay. Whereas the commercial assay system was unable to quantify serum levels of E2 lower than 10 pg/mL, the limit of detection of E2 using the novel SERS-based assay described in this study was 0.65 pg/mL. Thus, the proposed SERS-based assay has a strong potential to be a valuable tool in the early diagnosis of precocious puberty due to its excellent analytical sensitivity.

In situ aqueous derivatization as sample preparation technique for gas chromatographic determinations

The use of derivatization reactions is a common practice in analytical laboratories. Although in many cases it is tedious and time-consuming, it does offer a good alternative for the determination of analytes not compatible to gas chromatography. Many of the reactions reported in the literature occur in organic medium. However, in situ aqueous derivatization reactions, which can be performed directly in aqueous medium, offer important advantages over those mentioned above, such as no need of a previous extraction step and easy automation. Here we review the most recent developments and applications of in situ aqueous derivatization. The discussion focuses on the derivatization reactions used for the determination of alcohols and phenols, carboxylic acids, aldehydes and ketones, nitrogen-containing compounds and thiols in different aqueous matrices, such as environmental, biological and food samples. Several reactions are described for each functional group (acylation, alkylation, esterification, among others) and, in some cases, the same reagents can be used for several functional groups, such that there is an unavoidable overlap between sections. Finally, attention is also focused on the techniques used for the introduction of the derivatives formed in the aqueous medium into the chromatographic system. The implementation of in situ aqueous derivatization coupled to preconcentration techniques has permitted the enhancement of recoveries and improvements in the separation, selectivity and sensitivity of the analytical methods.

Analysis of multiplex endogenous estrogen metabolites in human urine using ultra-fast liquid chromatography-tandem mass spectrometry: a case study for breast cancer

A rapid, sensitive, specific and accurate analytical method of ultra-fast liquid chromatography combined with tandem mass spectrometry (UFLC-MS/MS) was established for simultaneous quantitative analysis of 16 distinct endogenous estrogens and their metabolites (EMs) in postmenopausal female urine. The quantitative method utilized a hydrolysis/extraction/derivatization step and a UFLC system to achieve separation in 16 min. The lower limit of quantitation for each estrogen metabolite was 2 pg mL(-1) with the percent recovery of a known added amount of estrogen at 93.2-109.3%. The intra-batch accuracy and precision for all analytes were 87.5-107.7% and 0.6-11.7%, respectively, while inter-batch accuracy and precision were 87.0-105.8% and 1.2-10.2%, respectively. Using this developed and validated method, the comprehensive metabolic profiling of 16 EMs in urine samples of 86 postmenopausal female breast cancer patients and 36 healthy controls was investigated by systematic statistical analysis. As a result, the circulating levels of 6 EMs were found to be different by a comparison of patients and healthy controls. The parent estrogens, estrone (E1) and 17β-estradiol (E2), as well as 2-hydroxyestradiol (2-OHE2) and 4-hydroxyestradiol (4-OHE2) were produced in higher abundance, whereas 16α-hydroxyestrone (16α-OHE1) and 2-methoxyestradiol (2-MeOE2) were decreased in the breast cancer group. 2-OHE2 and 4-OHE2 in particular showed significant elevation in patients, which are consistent with the carcinogenic mechanism hypothesis that catechol estrogens can react with DNA via quinones, resulting in mutations to induce breast cancer. Thus, 2,4-hydroxylation may be the dominant metabolic pathway for parent estrogens rather than 16α-hydroxylation. The lower level of 2-MeOE2 in the breast cancer group was believed to correlate with its protective effect against tumor formation. This study could provide valuable information on the association of the EM metabolic pathway with carcinogenesis as well as identify potential biomarkers for estrogen-induced breast cancer risk.

Profiling oestrogens and testosterone in human urine by stable isotope dilution/benchtop gas chromatography-mass spectrometry

Oestrogens, such as oestrone (E(1)), 17β-oestradiol (E(2)), oestriol (E(3)) and their biologically active metabolites 2-methoxyoestrone (2-MeOE(1)), 2-hydroxyoestradiol (2-OHE(2)) 16-ketooestradiol (16-OE(2)), 16-epioestriol (16-epiE(3)), as well as testosterone (T) play an important role in physiological and pathological developmental processes during human development. We therefore aimed at developing an isotope dilution/bench top gas chromatography-mass spectrometry (ID/GC-MS) method, based on benchtop GC-MS, for the simultaneous determination ('profiling') of the above analytes in children. The method consisted of equilibration of urine (5 ml) with a cocktail containing stable isotope-labelled analogues of the analytes as internal standards ([2,4-(2)H(2)]E(1), [2,4,16,16-(2)H(4)]E(2), [2,4,17-(2)H(3)]E(3), [16,16,17-(2)H(3)]T, [1,4,16,16-(2)H(4)]2-MeOE(1), [1,4,16,16,17-(2)H(5)]2-OHE(2), [2,4,15,15,17-(2)H(5)]16-OE(2) and [2,4-(2)H(2)]16-epiE(3)). Then, solid-phase extraction (C(18) cartridges), enzymatic hydrolysis (sulphatase from Helix pomatia (type H-1)), re-extraction, purification by anion exchange chromatography and derivatisation to trimethylsilyl ethers followed. The samples were analysed by GC-MS (Agilent GC 6890N/5975MSD; fused silica capillary column 25 m × 0.2 mm i.d., film 0.10 μm). Calibration plots were linear and showed excellent reproducibility with coefficients of determination (r(2)) between 0.999 and 1.000. Intra- and inter-assay coefficients of variation (CV) were <2.21% for all quantified metabolites. Sensitivity was highest for 2-OHE(2) (0.25 pg per absolute injection: signal-to-noise ratio (S/N)=3) and lowest for 16-epiE(3) (2 pg per absolute injection: S/N=2.6), translating into corresponding urine sample analyte concentrations of 0.025 ng ml(-1) and 0.2 ng ml(-1), respectively. Accuracy - determined in a two-level spike experiment - showed relative errors ranging between 0.15% for 16-OE(2) and 11.63% for 2-OHE(2). Chromatography showed clear peak shapes for the components analysed. In summary, we describe a practical, sensitive and specific ID/GC-MS assay capable of profiling the above-mentioned steroids in human urine from childhood onwards.