A critical and comprehensive review of the current status of 17ß-estradiol hormone remediation through adsorption technology.

Even at low concentrations, steroid hormones pose a significant threat to ecosystem health and are classified as micropollutants. Among these, 17ß-estradiol (molecular formula: C18H24O2; pKa = 10.46; Log Kow = 4.01; solubility in water = 3.90 mg L-1 at 27 °C; molecular weight: 272.4 g mol-1) is extensively studied as an endocrine disruptor due to its release through natural pathways and widespread use in conventional medicine. 17ß-estradiol (E2) is emitted by various sources, such as animal and human excretions, hospital and veterinary clinic effluents, and treatment plants. In aquatic biota, it can cause issues ranging from the feminization of males to inhibiting plant growth. This review aims to identify technologies for remediating E2 in water, revealing that materials like graphene oxides, nanocomposites, and carbonaceous materials are commonly used for adsorption. The pH of the medium, especially in acidic to neutral conditions, affects efficiency, and ambient temperature (298 K) supports the process. The Langmuir and Freundlich models aptly describe isothermal studies, with interactions being of a low-energy, physical nature. Adsorption faces limitations when other ions coexist in the solution. Hybrid treatments exhibit high removal efficiency. To mitigate global E2 pollution, establishing national and international standards with detailed guidelines for advanced treatment systems is crucial. Despite significant advancements in optimizing technologies by the scientific community, there remains a considerable gap in their societal application, primarily due to economic and sustainable factors. Therefore, further studies are necessary, including conducting batch experiments with these adsorbents for large-scale treatment along with economic analyses of the production process.

Rational evolution for altering the ligand preference of estrogen receptor alpha.

Estrogen receptor α is commonly used in synthetic biology to control the activity of genome editing tools. The activating ligands, estrogens, however, interfere with various cellular processes, thereby limiting the applicability of this receptor. Altering its ligand preference to chemicals of choice solves this hurdle but requires adaptation of unspecified ligand-interacting residues. Here, we provide a solution by combining rational protein design with multi-site-directed mutagenesis and directed evolution of stably integrated variants in Saccharomyces cerevisiae. This method yielded an estrogen receptor variant, named TERRA, that lost its estrogen responsiveness and became activated by tamoxifen, an anti-estrogenic drug used for breast cancer treatment. This tamoxifen preference of TERRA was maintained in mammalian cells and mice, even when fused to Cre recombinase, expanding the mammalian synthetic biology toolbox. Not only is our platform transferable to engineer ligand preference of any steroid receptor, it can also profile drug-resistance landscapes for steroid receptor-targeted therapies.

A 4-year study of bovine reproductive hormones that are induced by pharmaceuticals and appear as steroid estrogenic pollutants in the resulting slurry, using in vitro and instrumental analytical methods.

The main objective of the research was to study the environmental "price" of the large-scale, milk production from a rarely known perspective, from the mapping of the estrogenic footprint (the amount of oestrus-inducer hormonal products, and the generated endoestrogens) in the resulting slurry in a dairy cow farm. These micropollutants are endocrine-disrupting chemicals (EDCs) and can be dangerous to the normal reproductive functions even at ng/kg concentration. One of them, 17ß-estradiol, has a 20,000 times stronger estrogenic effect than bisphenol-A, a widely known EDC of industrial origin. While most studies on EDCs are short-term and/or laboratory based, this study is longitudinal and field-based. We sampled the slurry pool on a quarterly basis between 2017 and 2020. Our purpose was testing the estrogenic effects using a dual approach. As an effect-based, holistic method, we developed and used the YES (yeast estrogen screen) test employing the genetically modified Saccharomyces cerevisiae BJ3505 strain which contains human estrogenic receptor. For testing exact molecules, UHPLC-FLD was used. Our study points out that slurry contains a growing amount of EDCs with the risk of penetrating into the soil, crops and the food chain. Considering the Green Chemistry concept, the most benign ways to prevent of the pollution of the slurry is choosing appropriate oestrus-inducing veterinary pharmaceuticals (OIVPs) and the separation of the solid and liquid parts with adequate treatment methods. To our knowledge, this is the first paper on the adaptation of the YES test for medicine and slurry samples, extending its applicability. The adapted YES test turned out to be a sensitive, robust and reliable method for testing samples with potential estrogenic effect. Our dual approach was successful in evaluating the estrogenic effect of the slurry samples.

Quantum Dot-Sensitised Estrogen Receptor-α-Based Biosensor for 17ß-Estradiol.

17ß-estradiol (E2) is an important natural female hormone that is also classified as an estrogenic endocrine-disrupting compound (e-EDC). It is, however, known to cause more damaging health effects compared to other e-EDCs. Environmental water systems are commonly contaminated with E2 that originates from domestic effluents. The determination of the level of E2 is thus very crucial in both wastewater treatment and in the aspect of environmental pollution management. In this work, an inherent and strong affinity of the estrogen receptor-α (ER-α) for E2 was used as a basis for the development of a biosensor that was highly selective towards E2 determination. A gold disk electrode (AuE) was functionalised with a 3-mercaptopropionic acid-capped tin selenide (SnSe-3MPA) quantum dot to produce a SnSe-3MPA/AuE electroactive sensor platform. The ER-α-based biosensor (ER-α/SnSe-3MPA/AuE) for E2 was produced by the amide chemistry of carboxyl functional groups of SnSe-3MPA quantum dots and the primary amines of ER-α. The ER-α/SnSe-3MPA/AuE receptor-based biosensor exhibited a formal potential (E0') value of 217 ± 12 mV, assigned as the redox potential for monitoring the E2 response using square-wave voltammetry (SWV). The response parameters of the receptor-based biosensor for E2 include a dynamic linear range (DLR) value of 1.0-8.0 nM (R2 = 0.99), a limit of detection (LOD) value of 1.69 nM (S/N = 3), and a sensitivity of 0.04 µA/nM. The biosensor exhibited high selectivity for E2 and good recoveries for E2 determination in milk samples.

Identification of Biologically Diverse Tetrahydronaphthalen-2-ols through the Synthesis and Phenotypic Profiling of Chemically Diverse, Estradiol-Inspired Compounds.

Combining natural product fragments to design new scaffolds with unprecedented bioactivity is a powerful strategy for the discovery of tool compounds and potential therapeutics. However, the choice of fragments to couple and the biological screens to employ remain open questions in the field. By choosing a primary fragment containing the A/B ring system of estradiol and fusing it to nine different secondary fragments, we were able to identify compounds that modulated four different phenotypes: inhibition of autophagy and osteoblast differentiation, as well as potassium channel and tubulin modulation. The latter two were uncovered by using unbiased morphological profiling with a cell-painting assay. The number of hits and variety in bioactivity discovered validates the use of recombining natural product fragments coupled to phenotypic screening for the rapid identification of biologically diverse compounds.

Development of a competitive ELISA based on estrogen receptor and weak competitive molecule for the screening of potential estrogens in foods.

Enzyme labeled competitive molecules are generally homologous with competitors in competitive broad-spectrum enzyme-linked immunosorbent assays (ELISA). It is speculated that the detectability will be improved when the competitiveness of competitive molecule is weak. Herein, common small molecule food hazard-estrogen disrupting chemicals (EDCs) were used as target model for verification. The dual-estrogen receptor (ER) and three estrogen-enzyme conjugates with various responses were used as recognizers and competitive molecules in ELISA. ELISA based on bisphenol (BPA)-horseradish peroxidase (HRP) has the highest detectability and can screen all six EDCs, in which BPA-HRP showed the weakest ER excitatory activity (Ka = 1.39 × 10-2 nmol·L-1) among three conjugates. The proposal showed good practicability with spiked recovery of 80.0-110 % for estrogens (17ß-estradiol, 17α-estradiol, BPA) in foodstuffs, and revealed biomarkers with weak competitiveness may be applied to other competitive procedures to improve detectability, and it provides sensitive pre-screening strategy for follow-up screening tool.

Split aptamer regulated CRISPR/Cas12a biosensor for 17ß-estradiol through a gap-enhanced Raman tags based lateral flow strategy.

It is significant to exploit the full potential of CRISPR/Cas based biosensor for non-nucleic-acid targets. Here, we developed a split aptamer regulated CRISPR/Cas12a and gap-enhanced Raman tags based lateral flow biosensor for small-molecule target, 17ß-estradiol. In this assay, one split aptamer of 17ß-estradiol was designed to complement with crRNA of Cas12a so that the trans-cleavage ability of CRISPR/Cas12a can be regulated by the competitive binding of 17ß-estradiol and split aptamers. Through integration of the signal amplification ability of CRISPR/Cas12a and the ultra-sensitive gap-enhanced Raman tags based lateral flow assay, a visible-SERS dual mode determination of 17ß-estradiol can be established. 17ß-estradiol can be visibly recognized as low as 10 pM and accurately quantified with a detection limit of 180 fM by SERS signals, which is at least 103-fold lower than that of the previous immunoassay lateral flow strategies. Our assay provides a novel perspective to develop split aptamer regulated CRISPR/Cas12a coupling with SERS lateral flow strips for ultrasensitive and easy-to-use non-nucleic-acid targets detection.

Kinetic Study of 17α-Estradiol Mechanism during Rat Sperm Capacitation.

17α-Estradiol (αE2) is a natural diastereoisomer of 17ß-estradiol (E2). It is well known that αE2 can bind to estrogen receptors. However, its biological activity is less than that of E2 and is species and tissue specific. The goal of our study was to propose the mechanism of αE2 hormonal response in rat sperm during their capacitation in vitro and compare it with a previously studied mouse model. Concentration changes in externally added αE2 during capacitation of rat sperm were monitored by the high-performance liquid chromatographic method with tandem mass spectrometric detection (HPLC-MS/MS). The calculated values of relative concentrations Bt were subjected to kinetic analysis. The findings indicated that αE2 in rat sperm did not trigger autocatalytic reaction, in contrast to the mouse sperm, and that the initiation of the hormone penetration through the sperm plasma membrane was substantially faster in rats.

An irreversible inhibitor of 17ß-hydroxysteroid dehydrogenase type 1 inhibits estradiol synthesis in human endometriosis lesions and induces regression of the non-human primate endometriosis.

Endometriosis is a gynecological disorder affecting about 10% of women and can lead to invalidating painful symptoms and infertility. Since there is no current definitive cure for this disease, new therapeutic options are necessary. 17ß-Hydroxysteroid dehydrogenase type 1 (17ß-HSD1) is involved in the production of estradiol (E2), the most potent estrogen in women, and of 5-androstene-3ß,17ß-diol (5-diol), a weaker estrogen than E2, but whose importance increases after menopause. 17ß-HSD1 is therefore a pharmacological target of choice for the treatment of estrogen-dependent diseases such as endometriosis. We developed a targeted-covalent (irreversible) and non-estrogenic inhibitor of 17ß-HSD1, a molecule named PBRM, and herein evaluated its efficiency for the treatment of endometriosis. In a cell-free assay containing estrone (E1), the natural substrate of 17ß-HSD1, PBRM was able to block the formation of E2 in a collection of 50 human endometriosis lesions from a different clinical feature type, location, and phase. When given orally by gavage at 15 mg/kg to baboons, the resulting plasmatic concentration of PBRM was found to be sufficiently high (up to 125 ng/mL) for an efficacy study in a non-human primate (baboon) endometriosis model. After 2 months of treatment, the number of lesions/adhesions decreased in 60% of animals (3/5) in the PBRM-treated group, compared to the placebo group which showed an increase in the number of lesion/adhesions in 60% (3/5) of animals. Indeed, the total number of lesions/adhesions decreased in treated group (-6.5 or -19% when excluding one animal) while it increased in the control group receiving a placebo (+11%). Analysis of specific endometriotic lesions revealed that PBRM decreased the number of red lesions (-67%; 8/12) and white lesions (-35%; 11/31), but not of blue-black lesions. Similarly, PBRM decreased the surface area of dense adhesions and filmy adhesions, as compared to placebo. Also, PBRM treatment did not significantly affect the number of menstrual days. Finally, this targeted covalent inhibitor showed no adverse effects and no apparent toxicity for the duration of the treatment. These data indicate that 17ß-HSD1 inhibitor PBRM is a promising candidate for therapy targeting endometriosis and supports the need of additional efforts toward clinical trials.

Comparison of 17ß-Estradiol Adsorption on Corn Straw- and Dewatered Sludge-Biochar in Aqueous Solutions.

Removal of steroid hormones from aqueous environment is of prevailing concern because of their adverse impact on organisms. Using biochar derived from biomass as adsorbent to remove pollutants has become more popular due to its low cost, effectiveness, and sustainability. This study evaluated the feasibility of applying corn straw biochar (CSB) and dewatered sludge biochar (DSB) to reduce 17ß-estradiol (E2) from aquatic solutions by adsorption. The experimental results showed that the adsorption kinetics and isotherm behavior of E2 on the two biochars were well described by the pseudo-second-order (R2 > 0.93) and Langmuir models (R2 > 0.97). CSB has higher E2 adsorption capacity than DSB, and the maximum adsorption capacity was 99.8 mg/g obtained from Langmuir model at 298 K, which can be attributed to the higher surface area, porosity, and hydrophobicity of this adsorbent. Higher pH levels (>10.2) decreased the adsorption capacities of biochar for E2, while the ionic strength did not significantly affect the adsorption process. The regeneration ability of CSB was slightly better than that of DSB. The possible adsorption mechanism for E2 on biochar is suggested as π−π interactions, H−bonding, and micropores filling. These results indicated that CSB has more potential and application value than DSB on reducing E2 from aqueous solutions when considering economy and removal performance.

Phenol and 17ß-estradiol removal by Zoogloea sp. MFQ7 and in-situ generated biogenic manganese oxides: Performance, kinetics and mechanism.

The pollution of multifarious pollutants such as heavy metal, organic compounds, and nitrate are a hot research topic at present. In this study, the functions of Zoogloea sp. MFQ7 and its biological precipitation formed during bacterial manganese oxidation on the removal of phenol and 17ß-estradiol (E2) were investigated. Strain MFQ7, a manganese-oxidizing bacteria, can remove 98.34% of phenol under pH of 7.1, a temperature of 30 â„ƒ and Mn2+ concentration of 24.34 mg L-1, additionally, the optimum E2 removal by strain MFQ7 was 100.00% at pH of 7.1, temperature of 28 â„ƒ and Mn2+ concentration of 28.45 mg L-1 by using response surface methodology (RSM) based on Box-Behnken design (BBD) model. The maximum adsorption capacity of bio-precipitation for phenol and E2 was 201.15 mg g-1 and 65.90 mg g-1, respectively. Furthermore, adsorption kinetics and isotherms analysis, XPS, FTIR spectra, Mn(III) trapping experiments elucidated chemical adsorption and Mn(III) oxidation contribute to the removal of phenol and E2 by biogenic manganese oxides. These findings indicated that the adsorption and oxidation of manganese are expected to be one of the effective means to remove these typical organic pollutants containing phenol and E2.

A signal-off photoelectrochemical aptasensor for ultrasensitive 17ß-estradiol detection based on rose-like CdS@C nanostructure and enzymatic amplification.

Carbon-coated cadmium sulfide rose-like nanostructures (CdS@C NRs) were prepared via a facile solvothermal approach and used as the photoelectrochemical (PEC) sensing platform for the integration of functional biomolecules. Based on this, a novel "signal-off" PEC aptasensor mediated by enzymatic amplification was proposed for the sensitive and selective detection of 17ß-estradiol (E2). In the presence of E2, alkaline phosphatase-modified aptamer (ALP-apta) were released from the electrode surface through the specific recognition with E2, which caused the negative effect on PEC response due to the decrease of ascorbic acid (AA) produced by the ALP in situ enzymatic catalysis. The developed PEC aptasensor for detection of E2 exhibited a wide linear range of 1.0-250 nM, with the low detection limit of 0.37 nM. This work provides novel insight into the design of potential phoelectroactive materials and the application of signal amplification strategy in environmental analysis field.

Triazole-estradiol analogs: A potential cancer therapeutic targeting ovarian and colorectal cancer.

1,2,3-triazoles have continuously shown effectiveness as biologically active systems towards various cancers, and when used in combination with steroid skeletons as a carrier, which can act as a drug delivery system, allows for a creation of a novel set of analogs that may be useful as a pharmacophore leading to a potential treatment option for cancer. A common molecular target for cancer inhibition is that of the Epidermal Growth Factor Receptor/Mitogen Activated Protein Kinase pathways, as inhibition of these proteins is associated with a decrease in cell viability. Estradiol-Triazole analogs were thus designed using a molecular modeling approach. Thirteen of the high scoring analogs were then synthesized and tested in-vitro on an ovarian cancer cell line (A2780) and colorectal cancer cell line (HT-29). The most active compound, Fz25, shows low micromolar activity in both the ovarian (15.29 ± 2.19 µM) and colorectal lines (15.98 ± 0.39 µM). Mechanism of action studies proved that Fz25 moderately arrests cells in the G1 phase of the cell cycle, specifically inhibiting STAT3 in both cell lines. Additionally, Fz57 shows activity in the colorectal line (24.19 ± 1.37 µM). Inhibition studies in both cell lines show inhibition against various proteins in the EGFR pathway, namely EGFR, STAT3, ERK, and mTOR. To further study their effects as therapeutics, Fz25 and Fz57 were studied against drug efflux proteins, which are associated with drug resistance, and were found to inhibit the ABC transporter P-glycoprotein. We can conclude that these estradiol-triazole analogs provide a key for future studies targeting protein inhibition and drug resistance in cancer.

Partial Agonistic Actions of Sex Hormone Steroids on TRPM3 Function.

Sex hormone steroidal drugs were reported to have modulating actions on the ion channel TRPM3. Pregnenolone sulphate (PS) presents the most potent known endogenous chemical agonist of TRPM3 and affects several gating modes of the channel. These includes a synergistic action of PS and high temperatures on channel opening and the PS-induced opening of a noncanonical pore in the presence of other TRPM3 modulators. Moreover, human TRPM3 variants associated with neurodevelopmental disease exhibit an increased sensitivity for PS. However, other steroidal sex hormones were reported to influence TRPM3 functions with activating or inhibiting capacity. Here, we aimed to answer how DHEAS, estradiol, progesterone and testosterone act on the various modes of TRPM3 function in the wild-type channel and two-channel variants associated with human disease. By means of calcium imaging and whole-cell patch clamp experiments, we revealed that all four drugs are weak TRPM3 agonists that share a common steroidal interaction site. Furthermore, they exhibit increased activity on TRPM3 at physiological temperatures and in channels that carry disease-associated mutations. Finally, all steroids are able to open the noncanonical pore in wild-type and DHEAS also in mutant TRPM3. Collectively, our data provide new valuable insights in TRPM3 gating, structure-function relationships and ligand sensitivity.

Safety and Effectiveness of F-18 Fluoroestradiol Positron Emission Tomography/Computed Tomography: a Systematic Review and Meta-analysis.

BACKGROUND: We conducted a pooled analysis of the diagnostic accuracy of F-18 fluoroestradiol (F-18 FES) positron emission tomography/computed tomography (PET/CT) assessing estrogen receptor expression of patients who have recurrent or metastatic breast cancer. METHODS: Two investigators and seven related experts (from the departments of nuclear medicine, hematological oncology, surgery, and evidence-based medicine) evaluated the effectiveness of F-18 FES PET/CT according to diagnostic accuracy and correlation with immunohistochemistry tests via systematic literature review, and safety according to test-related side effects. The present study was conducted in accordance with the Scottish Intercollegiate Guidelines (SIGN), and the Cochrane, and Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines. The SIGN tools were used for quality assessment. RESULTS: Of the 512 articles retrieved in the literature search, 8 were deemed to be eligible for inclusion. Results of the evaluation indicated that the F-18 FES PET/CT test was safe because patients who reported pain in the injection site in the analyzed articles are most likely to be caused by mechanical injury from needle injection not by administration of radioactive materials. Assessment of diagnostic accuracy based on data from seven studies revealed a pooled sensitivity and specificity of 0.86 and 0.85, respectively. CONCLUSION: As such, the test was evaluated to be a safe and effective and, considering the anatomical site where only invasive tests are possible, the test was deemed to have high clinical utility.

Mechanistic Investigation of Drug Supersaturation in the Presence of Polysorbates as Solubilizing Additives by Solution Nuclear Magnetic Resonance Spectroscopy.

The introduction of solubilizing additives has historically been an attractive approach to address the ever-growing proportion of poorly water-soluble drug (PWSD) compounds within the modern drug discovery pipeline. Lipid-formulations, and more specifically micelle formulations, have garnered particular interest because of their simplicity, size, scalability, and avoidance of solid-state limitations. Although micelle formulations have been widely utilized, the molecular mechanism of drug solubilization in surfactant micelles is still poorly understood. In this study, a series of modern nuclear magnetic resonance (NMR) methods are utilized to gain a molecular-level understanding of intermolecular interactions and kinetics in a model system. This approach enabled the understanding of how a PWSD, 17ß-Estradiol (E2), solubilizes within a nonionic micelle system composed of polysorbate 80 (PS80). Based on one-dimensional (1D) 1H chemical shift differences of E2 in PS80 solutions, as well as intermolecular correlations established from 1D selective nuclear Overhauser effect (NOE) and two-dimensional NOE spectroscopy experiments, E2 was found to accumulate within the palisade layer of PS80 micelles. A potential hydrogen-bonding interaction between a hydroxyl group of E2 and a carbonyl group of PS80 alkane chains may allow for stabilizing E2-PS80 mixed micelles. Diffusion and relaxation NMR analysis and particle size measurements using dynamic light scattering indicate a slight increase in the micellar size with increasing degrees of supersaturation, resulting in slower mobility of the drug molecule. Based on these structural findings, a theoretical orientation model of E2 molecules with PS80 molecules was developed and validated by computational docking simulations.

Elucidation of Agonist and Antagonist Dynamic Binding Patterns in ER-α by Integration of Molecular Docking, Molecular Dynamics Simulations and Quantum Mechanical Calculations.

Estrogen receptor alpha (ERα) is a ligand-dependent transcriptional factor in the nuclear receptor superfamily. Many structures of ERα bound with agonists and antagonists have been determined. However, the dynamic binding patterns of agonists and antagonists in the binding site of ERα remains unclear. Therefore, we performed molecular docking, molecular dynamics (MD) simulations, and quantum mechanical calculations to elucidate agonist and antagonist dynamic binding patterns in ERα. 17ß-estradiol (E2) and 4-hydroxytamoxifen (OHT) were docked in the ligand binding pockets of the agonist and antagonist bound ERα. The best complex conformations from molecular docking were subjected to 100 nanosecond MD simulations. Hierarchical clustering was conducted to group the structures in the trajectory from MD simulations. The representative structure from each cluster was selected to calculate the binding interaction energy value for elucidation of the dynamic binding patterns of agonists and antagonists in the binding site of ERα. The binding interaction energy analysis revealed that OHT binds ERα more tightly in the antagonist conformer, while E2 prefers the agonist conformer. The results may help identify ERα antagonists as drug candidates and facilitate risk assessment of chemicals through ER-mediated responses.

Electrochemical Microfluidic Paper-Based Aptasensor Platform Based on a Biotin-Streptavidin System for Label-Free Detection of Biomarkers.

Timely and rapid detection of biomarkers is extremely important for the diagnosis and treatment of diseases. However, going to the hospital to test biomarkers is the most common way. People need to spend a lot of money and time on various tests for potential disease detection. To make the detection more convenient and affordable, we propose a paper-based aptasensor platform in this work. This device is based on a cellulose paper, on which a three-electrode system and microfluidic channels are fabricated. Meanwhile, novel nanomaterials consisting of amino redox graphene/thionine/streptavidin-modified gold nanoparticles/chitosan are synthesized and modified on the working electrode of the device. Through the biotin-streptavidin system, the aptamer whose 5'end is modified with biotin can be firmly immobilized on the electrode. The detection principle is that the current generated by the nanomaterials decreases proportionally to the concentration of targets owing to the combination of the biomarker and its aptamer. 17ß-Estradiol (17ß-E2), as one of the widely used diagnostic biomarkers of various clinical conditions, is adopted for verifying the performance of the platform. The experimental results demonstrated that this device enables the determination of 17ß-E2 in a wide linear range of concentrations of 10 pg mL-1 to 100 ng mL-1 and the limit of detection is 10 pg mL-1 (S/N = 3). Moreover, it enables the detection of targets in clinical serum samples, demonstrating its potential to be a disposable and convenient integrated platform for detecting various biomarkers.

Remote-controllable bone-targeted delivery of estradiol for the treatment of ovariectomy-induced osteoporosis in rats.

BACKGROUND: Osteoporosis (OP) is a systemic skeletal disease marked by bone mass reduction and bone tissue destruction. Hormone replacement therapy is an effective treatment for post-menopausal OP, but estrogen has poor tissue selectivity and severe side effects. RESULTS: In this study, we constructed a poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs)-based drug delivery system to co-load 17ß estradiol (E2) and iron oxide (Fe3O4) together, modified with alendronate (AL) to achieve bone targeting and realize a magnetically remote-controllable drug release. The NPs were fabricated through the emulsion solvent diffusion method. The particle size was approximately 200 nm while the encapsulation efficiency of E2 was 58.34 ± 9.21%. The NPs were found to be spherical with a homogenous distribution of particle size. The NPs showed good stability, good biocompatibility, high encapsulation ability of E2 and excellent magnetic properties. The NPs could be effectively taken up by Raw 264.7 cells and were effective in enriching drugs in bone tissue. The co-loaded NPs exposed to an external magnetic field ameliorated OVX-induced bone loss through increased BV/TV, decreased Tb.N and Tb.Sp, improved bone strength, increased PINP and OC, and downregulated CTX and TRAP-5b. The haematological index and histopathological analyses displayed the NPs had less side effects on non-skeletal tissues. CONCLUSIONS: This study presented a remote-controlled release system based on bone-targeted multifunctional NPs and a new potential approach to bone-targeted therapy of OP.

17ß-Estradiol-Induced Conformational Changes of Human Microsomal Triglyceride Transfer Protein: A Computational Molecular Modelling Study.

Human microsomal triglyceride transfer protein (hMTP) plays an essential role in the assembly of apoB-containing lipoproteins, and has become an important drug target for the treatment of several disease states, such as abetalipoproteinemia, fat malabsorption and familial hypercholesterolemia. hMTP is a heterodimer composed of a larger hMTPα subunit and a smaller hMTPß subunit (namely, protein disulfide isomerase, hPDI). hPDI can interact with 17ß-estradiol (E2), an endogenous female sex hormone. It has been reported that E2 can significantly reduce the blood levels of low-density lipoprotein, cholesterol and triglyceride, and modulate liver lipid metabolism in vivo. However, some of the estrogen's actions on lipid metabolism are not associated with estrogen receptors (ER), and the exact mechanism underlying estrogen's ER-independent lipid-modulating action is still not clear at present. In this study, the potential influence of E2 on the stability of the hMTP complex is investigated by jointly using multiple molecular dynamics analyses based on available experimental structures. The molecular dynamics analyses indicate that the hMTP complex in the presence of E2 has reduced interface contacts and surface areas. A steered molecular dynamics analysis shows that the forces required to separate the two subunits (namely, hPDI and hMTPα subunit) of the hMTP complex in the absence of E2 are significantly higher than the forces required to separate the complex in which its hPDI is already bound with E2. E2 makes the interface between hMTPα and hPDI subunits more flexible and less stable. The results of this study suggest that E2-induced conformational changes of the hMTP complex might be a novel mechanism partly accounting for the ER-independent lipid-modulating effect of E2.