Development of competitive ELISAs for 17beta-estradiol and 17beta-estradiol +estrone+estriol using rabbit polyclonal antibodies

Biomaterials and advanced technologies for the evaluation and treatment of ovarian aging

Ovarian aging is characterized by a progressive decline in ovarian function. With the increase in life expectancy worldwide, ovarian aging has gradually become a key health problem among women. Over the years, various strategies have been developed to preserve fertility in women, while there are currently no clinical treatments to delay ovarian aging. Recently, advances in biomaterials and technologies, such as three-dimensional (3D) printing and microfluidics for the encapsulation of follicles and nanoparticles as delivery systems for drugs, have shown potential to be translational strategies for ovarian aging. This review introduces the research progress on the mechanisms underlying ovarian aging, and summarizes the current state of biomaterials in the evaluation and treatment of ovarian aging, including safety, potential applications, future directions and difficulties in translation.

ELISA as an effective tool to determine spatial and seasonal occurrence of emerging contaminants in the aquatic environment

During the last two decades, studies related to the occurrence and fate of emerging contaminants in the aquatic environment have received great attention from the international scientific community. The monitoring of the presence of these compounds is particularly important since they are known to induce adverse effects in aquatic environments, even at extremely low concentrations. This work aimed to apply a simple and effective methodology, such as enzyme-linked immunosorbent assay (ELISA), in the monitoring of 17α-ethinylestradiol (EE2) and 17β-estradiol (E2) (a synthetic and a natural hormone, respectively), carbamazepine (CBZ, an antiepileptic), cetirizine (CET, an antihistamine) and caffeine (CAF, a stimulant) in water matrices with differing salinity and organic matter contents. ELISA was proven to be a valid and practical tool, especially for screening purposes in contrast to traditional chromatographic techniques which are prohibitively expensive for an application on a broader base. The main originality of this work was to establish seasonal and spatial effects on the occurrence of the referred contaminants by using the effectiveness of ELISA to screen those compounds in samples with different characteristics. This work reports both the seasonal and spatial quantification of the referred contaminants in the aquatic environment of the central region of Portugal, with concentrations ranging as follows: 5-87 ng L-1, for E2, 2-17 ng L-1, for EE2, 10-1290 ng L-1, for CBZ, 10-190 ng L-1, for CET, and 62-6400 ng L-1, for CAF.

Development and Application of Aptamer-Based Surface-Enhanced Raman Spectroscopy Sensors in Quantitative Analysis and Biotherapy

Surface-enhanced Raman scattering (SERS) is one of the most special and important Raman techniques. An apparent Raman signal can be observed when the target molecules are absorbed onto the surface of the SERS substrates, especially on the "hot spots" of the substrates. Early research focused on exploring the highly active SERS substrates and their detection applications in label-free SERS technology. However, it is a great challenge to use these label-free SERS sensors for detecting hydrophobic or non-polar molecules, especially in complex systems or at low concentrations. Therefore, antibodies, aptamers, and antimicrobial peptides have been used to effectively improve the target selectivity and meet the analysis requirements. Among these selective elements, aptamers are easy to use for synthesis and modifications, and their stability, affinity and specificity are extremely good; they have been successfully used in a variety of testing areas. The combination of SERS detection technology and aptamer recognition ability not only improved the selection accuracy of target molecules, but also improved the sensitivity of the analysis. Variations of aptamer-based SERS sensors have been developed and have achieved satisfactory results in the analysis of small molecules, pathogenic microorganism, mycotoxins, tumor marker and other functional molecules, as well as in successful photothermal therapy of tumors. Herein, we present the latest advances of the aptamer-based SERS sensors, as well as the assembling sensing platforms and the strategies for signal amplification. Furthermore, the existing problems and potential trends of the aptamer-based SERS sensors are discussed.

17β-Estradiol residues and estrogenic activities in the Hawkesbury River, Australia

Two highly sensitive ELISAs for the specific detection of 17β-estradiol (E2) residues were developed, showing the limits of detection (LOD, a concentration at 15% inhibition of color development) of 0.04 ± 0.02 μg/L and 0.05 ± 0.03 μg/L. The average recovery rate of the river water samples spiked with E2 at 1-50 ng/L range was 111.5% (68.6-252%) with the % relative standard deviation (RSD) of 0.5-86.3%. The ELISA demonstrated a good correlation with the GC-MS analyses of the spiked river water samples (r = 0.909). Applying the developed E2 ELISA assay to the monitoring of E2 residues in Hawkesbury River (New South Wales, Australia) found that all the tested creek samples contained E2 residues less than the biologically significant level of 10 ng/L. However, 25% of the water samples tested demonstrated the estrogen activity (determined by the yeast estrogen screening (YES) assay) above the levels that have been linked to the adverse effects in fish and other aquatic organisms (> 20 E2 Eq ng/L). It was apparent that the E2 residues together with the EE2 residues (reported in our previous study) contributed to most of the observed estrogenic activity in Hawkesbury River.

Double strand DNA functionalized Au@Ag Nps for ultrasensitive detection of 17β-estradiol using surface-enhanced raman spectroscopy

A detection method for 17β-estradiol (E2) using surface-enhanced Raman scattering (SERS)-based aptamer sensor was presented. Raman reporter molecule Cy3 labeled E2-aptamer and DNA functionalized gold-silver core-shell nanoparticles (Au@Ag CS NPs) offered SERS with high sensitivity and selectivity. Based on the fabricated double strand DNA-immobilized gold-silver core-shell nanoparticles (Au@Ag NPs), SERS signal intensity of Raman reporter changed with the number of Cy3-labeled aptamer attached to the core-shell nanoparticles due to the strong binding affinity between the aptamers and E2 with different concentrations. A wide linear range from 1.0 × 10^-13 to 1.0 × 10^-9 was obtained for the detection of E2, with a low detection limit of 2.75 fM. This proposed method showed highly sensitive and selective for detecting E2, and could be used to determine E2 in actual samples.

Estrogenic activity in Finnish municipal wastewater effluents

Effluents from wastewater treatment plants (WWTPs) are a major source of estrogenic compounds to the aquatic environment. In the present work, estrogenic activities of effluents from eight municipal WWTPs in Finland were studied. The main objectives of the study were to quantify the concentrations of selected estrogenic compounds, to evaluate their contribution to estrogenic potency and to test the feasibility of the commercial bioassays for wastewater analysis. The effluent samples were analyzed by two in vitro tests, i.e. ERα-CALUX(®) and ELISA-E2, and by liquid chromatography mass spectrometry for six estrogenic compounds: estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), 17α-estradiol and bisphenol A (BPA). Estrogenic effects were found in all of the effluent samples with both of the bioassays. The concentrations measured with ELISA-E2 (8.6-61.6 ng/L) were clearly higher but exhibited a similar pattern than those with chemical analysis (E2 <limit of quantification - 6.8 ng/L) and ERα-CALUX(®) (0.8-29.7 ng E2 EEQ/L). Due to the concentrations under limit of quantification, the evaluation of the chemical contribution to estrogenic potency was possible only for E1 and BPA, which contributed less than 10% to the observed effects, except in one sample with a high BPA contribution (17%). The contribution of E2 was significant in two samples where it was detected (28% and 67%). The results demonstrated that more comprehensive information on potential estrogenic activity of wastewater effluents can be achieved by using in vitro biotests in addition to chemical analysis and their use would be beneficial in monitoring and screening purposes.

Development of a real-time immuno-PCR assay for the quantification of 17β-estradiol in water

A competitive real-time (RT) immuno-polymerase chain reaction (iPCR) (RT-iPCR) assay was developed for the sensitive quantification of 17β-estradiol in water. Using a universal iPCR method and polyclonal antibodies, 17β-estradiol was accurately quantified at concentrations ranging from 1 pg mL(-1) to 10 µg mL(-1). The RT-iPCR assay's limit of detection was 0.7 pg mL(-1). The RT-iPCR assay provided an 800-fold increase in sensitivity as well as an expanded working range compared with the corresponding enzyme-linked immunosorbent assay. Assay cross-reactivity to estrone and estriol, two structurally related estrogens, was below 8%. Water samples spiked with 17β-estradiol were analyzed by RT-iPCR to determine the assay's potential as a rapid screen for the monitoring of manure-borne estrogens in the environment. The assay showed recoveries of 82, 102 and 103% for Milli-Q, tap, and irrigation water, respectively, without requiring sample extraction or concentration prior to analysis.

Evaluation of the anthropogenic input of caffeine in surface waters of the north and center of Portugal by ELISA

This study comprises the development of an enzyme-linked immunosorbent assay (ELISA) for the quantification of caffeine in complex aqueous matrices without any sample clean-up procedure. Salinity and dissolved organic matter were selected as potential interfering agents. The addition of a sample buffer containing bovine serum albumin (BSA) prior to the sample was found to decrease the influence of those interfering agents. The working range of the developed method was 0.1-100 μg L(-1). Quantification of caffeine was possible in 43 out of 51 real aqueous samples, at values between <LOD and 15 μg L(-1). Results correlate well with those obtained by LC-MS/MS. To the best of our knowledge this is the first study dealing with the quantification of caffeine in Portugal's surface waters.

Development of ELISA methodologies for the direct determination of 17β-estradiol and 17α-ethinylestradiol in complex aqueous matrices

This study comprises the development of enzyme-linked immunosorbent assays (ELISAs) for the quantification of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in complex aqueous matrices without any sample clean-up procedures. Salinity and dissolved organic matter were selected as potential interfering agents in the analysis of E2 and EE2. The optimization was performed in order to (i) overcome matrix effects, and to (ii) increase sensitivity. The addition of a sample buffer containing bovine serum albumin (BSA) prior to the sample was found to decrease the influence of matrix effects. Moreover, adjustments of this buffer's pH together with the optimization of tracer (T) dilution and incubation time were undertaken in order to lower the quantification range. The optimized methods allowed the quantification of E2 and EE2 in the ranges 0.03-200 μg L(-1) and 0.02-10 μg L(-1), respectively. The assays were applied to real aqueous samples. It was possible to do a first approach to the levels of E2 in Portuguese surface and waste waters; however, it was not feasible to detect EE2 in the samples tested.