Introduction of electropolymerization of pyrrole as a coating method for stir bar sorptive extraction of estradiol followed by gas chromatography

Exploring the optimal electropolymerization strategy for the preparation of solid-phase microextraction fibers using pyrrole-dopamine copolymers

In-situ electropolymerization of conductive polymers on the surface of stainless-steel substrates is a well-established but promising procedure for the preparation of solid-phase microextraction (SPME) tools. Herein, different electrochemical methods including constant potential (CP), constant potential pulse (CPP), and cyclic voltammetry (CV) were utilized to fabricate SPME fibers by in-situ electropolymerization of pyrrole-dopamine copolymers (PPY/PDA) on the surface of stainless-steel fibers. The coated fibers were characterized and applied for the direct-immersion SPME (DI-SPME) sampling of ultra-trace amounts of plant hormones including abscisic acid (ABA), gibberellic acid (GA3), and indole acetic acid (IAA) in fruit juices, followed by HPLC-UV determination. The results showed that CV electropolymerization is significantly more efficient than the two other methods. The coatings created by the CV method were satisfactorily uniform, adhesive, and durable and exhibited higher extraction performance compared to the CP and CPP procedures. The important experimental variables of the proposed DI-SPME-HPLC method were evaluated and optimized using response surface methodology with a Box-Behnken design. The developed method showed wide-range linearities, spanning from 0.05 to 20μg mL-1 for GA3, and 0.02 to 20μg mL-1 for ABA and IAA. The limits of detection were obtained 0.01μg mL-1 for GA3, and 0.005μg mL-1 for ABA and IAA. The fiber was successfully employed for the simultaneous DI-SPME-HPLC analysis of plant hormones in fruit juice samples.

Development of matrix-based reference materials for 17 beta-estradiol by the recommended reference method of ID-LC-MS/MS

We developed and evaluated two-level, namely 2017011 and 2017012, serum-based reference materials (RMs) for 17 beta-estradiol (17 β-E2) by the reference method of isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) from the remaining serum samples after routine clinical tests, to help improve clinical routine testing and provide the traceability of results. This paper describes the development process of these RMs. The National Metrology Institute of Japan (NMIJ) certified reference material (CRM) 6004-a was used as the primary RM for the measurement of 17 β-E2. These serum-based RMs showed satisfactory homogeneity and stability. They also assessed the commutability between the reference method and the three routine clinical immunoassay systems. Besides, a collaborative study was carried out in five reference laboratories, all of which had been accredited by the China National Accreditation Service for Conformity Assessment (CNAS) in accordance with ISO/WD 15725-1. Statistical analysis of raw results and uncertainty assessment obtained certified values: 2017011 was 445.2 ± 39.0 pmol/L, and 2017012 was 761.9 ± 35.5 pmol/L.

Electrochemical biosensors for monitoring of selected pregnancy hormones during the first trimester: A systematic review

The hormones human chorionic gonadotropin, progesterone, estrogen and four of its metabolites (estradiol, estrone, estriol, estetrol), as well as relaxin play an essential role in the development of the fetus during the first trimester. Imbalances in these hormones during the first trimester have been directly linked to miscarriages. However, frequent monitoring of the hormones is limited by the current conventional centralized analytical tools that do not allow a rapid response time. Electrochemical sensing is considered an ideal tool to detect hormones owing to its advantages such as quick response, user-friendliness, low economic costs, and possibility of use in point-of-care settings. Electrochemical detection of pregnancy hormones is an emerging field that has been demonstrated primarily at research level. Thus, it is timely with a comprehensive overview of the characteristics of the reported detection techniques. This is the first extensive review focusing on the advances related to electrochemical detection of hormones linked to the first trimester of pregnancy. Additionally, this review offers insights into the main challenges that must be addressed imminently to ensure progress from research to clinical applications.

Isolation of a Monoclonal Antibody and its Derived Immunosensor for Rapid and Sensitive Detection of 17β-Estradiol

Estrogens are effective for stimulating several functions in living organisms and for regulating cancer development by promoting cell proliferation. Estradiol can disrupt the reproductive and endocrine systems, leading to the development of various diseases. In this study, the monoclonal antibody ESC9 was developed by immunizing mice with a 17β-estradiol (E2) conjugate, preparing an antibody phage display library, and screening monoclonal antibodies from the prepared library. An antibody with the same sequence as that of ESC9 has not been reported previously. The equilibrium dissociation constant between ESC9 and E2 was found to be 43.3 nM. Additionally, we generated an ESC9-derived immunosensor named as the ESC9 Quenchbody (Q-body), which can rapidly and sensitively detect E2. The assay can be completed within 2 min with a limit of detection of 3.9 pg/ml and half-maximal effective concentration of 154.0 ng/ml. Serum E2 levels were measured using the ESC9 Q-body without pretreatment with serum and with a high recovery rate of 83.3–126.7%. The Q-body immunosensor shows potential for clinical applications based on its excellent detection speed and sensitivity.

Preparation, characterization and application of double yolk–shell structure magnetic molecularly imprinted polymers for extraction of 17β-estradiol

Novel double yolk–shell structure molecularly imprinted polymers were synthesized by surface polymerization with 17β-estradiol as the template, followed by chemical etching.

Visual-afterglow dual-mode immunochromatographic strip for 17β-estradiol detection in milk

The continuous intake of 17β-estradiol (E2) residue from animal-derived food may pose a threat to the health of consumers, so the rapid screen and detection of E2 is very necessary. Although visual immunochromatographic strip (ICS) has played a great role in food safety control such as the screen of many food contaminants, it cannot meet the requirements for E2 detection due to the insufficient sensitivity of traditional visual ICS and the low concentration range of estrogen in food. Here, we developed a dual-mode ICS strategy to achieve rapid and highly sensitive detection of E2. Based on the visual detection mode of a competitive ICS, the afterglow detection mode working in fluorescence resonance energy transfer mechanism was introduced by using the afterglow particles (APs) as energy donor and gold nanoparticles (AuNPs) as energy acceptor. In this method, large APs of micron size with superior afterglow were applied as the test zone-fixed fluorescence signal source, thus the contradiction between migration and afterglow characteristics was skillfully resolved. In addition, a 6 W UV lamp was used as the light source to excite APs, and a smartphone was used to capture an image of 0.5 s after the UV light was turned off to effectively remove the autofluorescence from the strips and improve the signal-to-noise ratio. The limit of detection of this afterglow mode was 0.5 ng/mL, twenty times more sensitive than that of visual mode (10 ng/mL). The strategy has been successfully applied to the detection of estradiol in milk and verified by HPLC-FLD.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.