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The associations between urinary phenol concentrations and markers of thyroid function and autoimmunity among potentially susceptible subgroups, such as subfertile women, have been understudied, especially when considering chemical mixtures. We evaluated cross-sectional associations of urinary phenol concentrations, individually and as a mixture, with serum markers of thyroid function and autoimmunity. We included 339 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2009-2015). We quantified four phenols in urine using isotope dilution high-performance liquid chromatography-tandem mass spectrometry, and biomarkers of thyroid function (thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4), and triiodothyronine (fT3, TT3)), and autoimmunity (thyroid peroxidase (TPO) and thyroglobulin (Tg) antibodies (Ab)) in serum using electrochemoluminescence assays. We fit linear and additive models to investigate the association between urinary phenols-both individually and as a mixture-and serum thyroid function and autoimmunity, adjusted for confounders. As a sensitivity analysis, we also applied Bayesian Kernel Machine Regression (BKMR) to investigate non-linear and non-additive interactions. Urinary bisphenol A was associated with thyroid function, in particular, fT 3 (mean difference for a 1 log unit increase in concentration: -0.088; 95% CI [-0.151, -0.025]) and TT 3 (-0.066; 95% CI [-0.112, -0.020]). Urinary methylparaben and triclosan were also associated with several thyroid hormones. The overall mixture was negatively associated with serum fT 3 concentrations (mean difference comparing all four mixture components at their 75th vs. 25th percentiles: -0.19, 95% CI [-0.35, -0.03]). We found no evidence of non-linearity or interactions. These results add to the current literature on phenol exposures and thyroid function in women, suggesting that some phenols may alter the thyroid system.

Background: Although previous epidemiological studies have explored associations of phthalate metabolites with thyroid function, no studies to date have assessed associations of mixtures with thyroid function and autoimmunity among potentially susceptible subgroups such as subfertile women., Objective: We aimed to explore associations of mixtures of urinary phthalate metabolites with serum markers of thyroid function and autoimmunity., Methods: This cross-sectional study included 558 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2005-2015). We quantified urinary concentrations of eight phthalate metabolites using mass spectrometry, and biomarkers of thyroid function [thyroid-stimulating hormone (TSH), free and total thyroxine ( fT 4 , TT 4 ) and triiodothyronine ( fT 3 , TT 3 ), and autoimmunity [thyroid peroxidase and thyroglobulin antibodies (TPOAb and TgAb, respectively)] in serum using electrochemiluminescence assays. We applied principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) to identify the main patterns of urinary phthalate metabolites. We used linear mixed models to assess the association between PCA-derived factor scores in quintiles and serum thyroid function and autoimmunity, adjusting for age, body mass index (BMI), specific gravity (SG), and, for the PCA, other factor scores., Results: We observed two factors using PCA, one representing the di(2-ethylhexyl) (DEHP) and another non-DEHP metabolites. Compared to women in the lowest quintile of the DEHP factor scores, women in the highest quintile had significantly lower serum concentrations of fT 4 , TT 4 , fT 3 , and TT 3 [absolute difference: - 0.62 ; 95% confidence interval (CI): - 0.12 , - 0.01 ; p = 0.04 ; absolute difference: - 8.31 ; 95% CI: - 13.8 , - 2.85 ; p = 0.003 ; absolute difference: - 0.37 ; 95% CI: 0.54, - 0.19 ; p < 0.0001 ; and absolute difference: - 0.21 ; 95% CI: - 0.32 , - 0.10 ; p = 0.003 , respectively]. Using BKMR, we observed that mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was the primary contributor to these negative associations. DEHP and non-DEHP factor scores were not associated with serum TSH, TgAb, or TPOAb., Conclusions: Mixtures of urinary DEHP metabolites were inversely associated with serum biomarkers of thyroid function but not with autoimmunity, which were within normal ranges for healthy adult women. https://doi.org/10.1289/EHP6740.

Background: Dibutyl phthalate (DBP) is an endocrine disruptor and used in some medication coatings, such as mesalamine for treatment inflammatory bowel disease (IBD)., Objectives: To determine whether high-DBP from some mesalamine medications alters thyroid function., Methods: Seventy men with IBD, without thyroid disease or any radiation history participated in a crossover-crossback prospective study and provided up to 6 serum samples (2:baseline, 2:crossover, 2:crossback). Men on non-DBP mesalamine (background exposure) at baseline crossed-over to DBP-mesalamine (high exposure) then crossed-back to non-DBP mesalamine (B 1 HB 2 -arm) and vice versa for men on DBP-mesalamine at baseline (H 1 BH 2 -arm). Serum concentrations of total triiodothyronine (T3), total thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb)., Results: After crossover in B 1 HB 2 -arm (26 men, 134 samples), T3 decreased 10% (95% confidence interval (CI): 14%,-5%), T3/T4 ratio decreased 8% (CI: 12%,-3%), TPOAb, and TgAb concentrations decreased, 11% (-20%, -2%) and 15% (-23%, -5%), respectively; after crossback, they increased. When men in the H 1 BH 2 -arm (44 men, 193 samples) crossed-over, T3 decreased 7% (CI: -11%, -2%) and T3/T4 ratio decreased 6% (CI: -9%, -2%). After crossback, only TgAb increased and FT4 decreased., Conclusions: High-DBP novel exposure or removal from chronic high-DBP exposure could alter elements of the thyroid system, and most probably alters the peripheral T4 conversion to T3 and thyroid autoimmunity, consistent with thyroid disruption. After exposure removal, these trends were mostly reversed., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: While overt thyroid disease is a well known risk factor for infertility, the potential consequences of mild thyroid dysfunction or thyroid autoimmunity remain unknown. Experimental studies suggest a considerable role for thyroid hormone in the physiological mechanisms of ovarian reserve, but translation of such findings to human studies remains rare. A potential role for thyroid function in female reproduction could be especially relevant when the cause of infertility remains unknown, such as in women with diminished ovarian reserve (DOR) or unexplained infertility. The aims of this study were to investigate the association of thyroid function and autoimmunity with markers of ovarian reserve day 3 follicle-stimulating hormone (FSH) concentrations and antral follicle count (AFC), and to investigate whether thyroid function or autoimmunity may have different effects in women with DOR or unexplained infertility., Methods: Thyrotropin, free thyroxine, thyroxine, free triiodothyronine (fT3), triiodothyronine, thyroid peroxidase antibodies (TPOAbs), and thyroglobulin antibodies (TgAbs), as well as AFC and the day 3 FSH concentration, were measured among women seeking fertility treatment at the Massachusetts General Hospital Fertility Center. Multiple linear or mixed regression models were used to study the association of thyroid function or autoimmunity with AFC or day 3 FSH., Results: In the total study population (436 women, 530 AFC measurements), there was no association of thyroid function or TPOAb positivity with AFC. However, TgAb positivity was associated with a higher AFC (mean difference = 3.4 [95% confidence interval (CI) 1.8-5.1], p < 0.001). In women with DOR or unexplained infertility, lower fT3 and TPOAb positivity were associated with a lower AFC (fT3: continuous nonlinear association, p = 0.009; TPOAb positivity: -2.3 follicles [confidence interval -3.8 to -0.5], p = 0.01), while TgAb positivity was not associated with AFC. Neither thyroid function nor thyroid antibody positivity was associated with the day 3 FSH concentration., Conclusions: This study found that lower fT3 and TPOAb positivity are associated with a lower AFC in women with DOR or unexplained infertility. Future studies are required to replicate these findings and further elucidate the role of TgAbs and underlying mechanisms through which thyroid function and autoimmunity is associated with ovarian reserve.

Objective: To investigate a dose dependency of thyroperoxidase antibody (TPOAb) concentrations in relation to thyroid function and premature delivery and define a population-based, pregnancy-specific, functional cutoff for TPOAb positivity., Design: Individual participant meta-analysis of three prospective birth cohorts: the Amsterdam Born Children and their Development study, and the Holistic Approach to Pregnancy., Setting: Population-based studies in the Netherlands (2002 to 2014)., Participants: A total of 11,212 pregnant women (<20 weeks' gestation)., Main Outcome Measures: Thyrotropin (TSH) and FT4 concentrations, premature delivery., Results: In all cohorts, there was a dose-dependent positive association of TPOAb concentrations with TSH concentrations, as well as a dose-dependent negative association with FT4 concentrations during early pregnancy (all P < 0.0001). There was a dose-dependent association of TPOAb concentrations with the risk of premature delivery, which was also modified by TSH concentrations. Women with TPOAb concentrations from the 92nd percentile upward had a higher TSH and a higher risk of a TSH >2.5 mU/L (range, 19.4% to 51.3%). Stratified analyses showed that women with TPOAb concentrations below manufacturer cutoffs already had a higher risk of premature delivery, especially when TSH concentrations were high or in the high-normal range., Conclusions: This study demonstrated a dose-dependent relationship between TPOAbs and thyroid function as well as the risk of premature delivery. Furthermore, our results indicate that the currently used cutoffs for TPOAb positivity may be too high. Furthermore, the use of a population-based cutoff for TPOAbs may identify women with a clinically relevant extent of thyroid autoimmunity and a higher risk of premature delivery but that would not be considered TPOAb positive or eligible for treatment otherwise., (Copyright © 2017 Endocrine Society)

Background: Though iodine deficiency in pregnancy is a matter of public-health concern, a functional measure of iodine status is lacking. The thyroid-specific protein thyroglobulin (Tg), which reflects thyroid size, has shown promise as a functional measure in studies of children and adults, but data in pregnancy are sparse. In a cohort of mildly to moderately iodine-deficient pregnant women, this study aimed to explore whether serum Tg is a sensitive functional biomarker of iodine status and to examine longitudinal change in Tg with gestational age., Method: A total of 230 pregnant women were recruited at an antenatal clinic at 12 weeks of gestation to the Selenium in PRegnancy INTervention study, in Oxford, United Kingdom. Repeated measures of urinary iodine-to-creatinine ratio, serum thyrotropin (TSH), and Tg at 12, 20, and 35 weeks of gestation were made. Women were dichotomized by their iodine-to-creatinine ratio (<150 or ≥150 μg/g) to group them broadly as iodine deficient or iodine sufficient. Women with thyroid antibodies were excluded; data and samples were available for 191 women., Results: Median Tg concentrations were 21, 19, and 23 μg/L in the first, second, and third trimesters, respectively. In a linear mixed model, controlling for confounders, Tg was higher in the <150 μg/g group than it was in the ≥150 μg/g group (p < 0.001) but there was no difference in TSH (p = 0.27). Gestational week modified the effect of iodine status on TSH (p = 0.01) and Tg (p = 0.012); Tg did not increase with gestational week in the ≥150 μg/g group, but it did in the <150 μg/g group, and TSH increased more steeply in the <150 μg/g group., Conclusions: Low iodine status (<150 μg/g) in pregnancy is associated with higher serum Tg, suggesting that the thyroid is hyperstimulated by iodine deficiency, which causes it to enlarge. Tg is a more sensitive biomarker of iodine status in pregnancy than is TSH.

Context: Thyroperoxidase antibody (TPOAb) positivity is the main risk factor for thyroid dysfunction during pregnancy and is consistently associated with premature delivery. However, the underlying mechanism is currently unknown. We hypothesized that TPOAb positivity may interfere with gestational thyroid stimulation induced by the pregnancy hormone human chorionic gonadotropin (hCG)., Design, Setting, and Participants: Thyrotropin (TSH), free thyroxine (FT4), TPOAbs, and/or hCG concentrations were measured in early and late pregnancy of 7587 pregnant women from 2 Dutch population-based prospective cohorts (n = 5924, Generation R study; n = 1663, Holistic Approach to Pregnancy and the First Postpartum Year study)., Interventions: None., Main Outcome Measure(s): Thyroidal response to hCG stimulation, premature delivery., Results: In TPOAb-negative women, hCG was positively associated with FT4 and negatively with TSH in both cohorts (P < 0.0001). In contrast, in TPOAb-positive women, hCG was not associated with FT4 or TSH in either cohort (all P > 0.40; P for interaction TPOAb positive vs negative ≤ 0.05). Overall, TPOAb positivity was associated with a 1.7-fold higher risk of premature delivery. TPOAb-positive women with an adequate response of FT4 to hCG (high FT4 concentration with high hCG concentration) did not have a higher risk of premature delivery. In contrast, TPOAb-positive women with an inadequate FT4 response to hCG (low FT4 concentration with high hCG concentration) had a 2.2- to 2.8-fold higher risk of premature delivery., Conclusion: TPOAb-positive women display an impaired thyroidal response to hCG and this may explain the higher risk of premature delivery in these women. This abnormal response in TPOAb-positive women might suggest that these women require a different treatment approach than TPOAb-negative women., (Copyright © 2017 by the Endocrine Society)

Background: Given the excellent performance of modern mass spectrometers, their clinical application for the analysis of macromolecules is a growing field of interest. This principle is explored by hemoglobin analysis, which is a representative example by its molecular weight and clinical relevance in e.g. screening programs for thalassemia and hemoglobin variants. Considering its abundance and cellular containment, pre-analysis is significantly reduced allowing for essential rapid acquisitions., Methods: By parallel analysis of routine diagnostics for hemoglobin variants and thalassemia, we acquired samples of adults who were consented for hemoglobinopathy screening in our clinical laboratory. The pre-analytical process comprised of red cell lysis only; without further digestion and purification steps, the samples were directly injected in an electrospray ionization quadrupole time-of-flight setup and the intact proteins were analyzed by flow injection analysis. After optimization of process parameters, the deconvoluted mass spectra revealed the presence of α- and β-globulins. The reference ranges for the average mass of both globulins and their intensity ratio (α/β-ratio) were deduced from a disease-free subgroup and patients with a hemoglobinopathy were compared., Results: The α/β-ratio is a poor marker for thalassemia patients, yet deviant α/β-ratios are found for patients with a hemoglobin variant. Mass deviations down to 1Da can be resolved; even if the patient suffers from a heterozygotic disorder, the average mass is found outside the established reference interval., Conclusions: Although subjects with mild thalassemia were not detected, all patients with a hemoglobin variant were resolved by top-down mass spectrometry using the average globulin mass and the α/β-ratio as screening parameters., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Therapeutic drug monitoring (TDM) of infliximab (IFX, Remicade®) can aid to optimize therapy efficacy. Many assays are available for this purpose. However, a reference standard is lacking. Therefore, we evaluated the analytical performance, agreement and clinically relevant differences of three commercially available IFX ELISA kits on an automated processing system., Methods: The kits of Theradiag (Lisa Tracker Infliximab), Progenika (Promonitor IFX) and apDia (Infliximab ELISA) were implemented on an automated processing system. Imprecision was determined by triplicate measurements of patient samples on five days. Agreement was evaluated by analysis of 30 patient samples and four spiked samples by the selected ELISA kits and the in-house IFX ELISA of Sanquin Diagnostics (Amsterdam, The Netherlands). Therapeutic consequences were evaluated by dividing patients into four treatment groups using cut-off levels of 1, 3 and 7 μg/mL and determining assay concordance., Results: Within-run and between-run imprecision were acceptable (≤12% and ≤17%, respectively) within the quantification range of the selected ELISA kits. The apDia assay had the best precision and agreement to target values. Statistically significant differences were found between all assays except between Sanquin Diagnostics and the Lisa Tracker assay. The Promonitor assay measured the lowest IFX concentrations, the apDia assay the highest. When patients were classified in four treatment categories, 70% concordance was achieved., Conclusions: Although all assays are suitable for TDM, significant differences were observed in both imprecision and agreement. Therapeutic consequences were acceptable when patients were divided in treatment categories, but this could be improved by assay standardization.

Objective: In current literature and guidelines, there is a tendency to define absolute TSH concentrations at which patient follow-up or even pharmaceutical intervention should be initiated. As TSH concentrations depend on the analytical method/platform used for TSH quantification, absolute cut-off values may pose threats for uniform clinical decision-making. In this study we therefore set out to clarify to what extent the method/platform and the reference values applied for TSH influence the clinical interpretation of thyroid parameters., Design and Methods: We retrospectively analyzed anonymous TSH results from the Dutch external quality assessment program (EQAS) in relation to reference values advised by different manufacturers. We also examined TSH/free thyroxin (fT4) reference ranges and prevalence of thyroid pathology among different Dutch laboratories, including four cases in which a switch in the measuring platform was made., Results: Our data show that interpretation of thyroid parameters is not only influenced by between-method/platform variation, but is also substantially affected by the variation in TSH/fT4 reference intervals applied in individual laboratories. Additionally, we show that the transition to a novel analytical method/platform can result in a shift in the prevalence of thyroid pathology, especially for subclinical hypothyroidism., Conclusions: Subclinical hypothyroidism can be a 'laboratory-induced' condition. This is an undesirable situation in regard to the clinical implications such a diagnosis can have for patients., (© 2015 European Society of Endocrinology.)

Background: The HAPPY study is a large prospective longitudinal cohort study in which pregnant women (N ≈ 2,500) are followed during the entire pregnancy and the whole first year postpartum. The study collects a substantial amount of psychological and physiological data investigating all kinds of determinants that might interfere with general well-being during pregnancy and postpartum, with special attention to the effect of maternal mood, pregnancy-related somatic symptoms (including nausea and vomiting (NVP) and carpal tunnel syndrome (CTS) symptoms), thyroid function, and human chorionic gonadotropin (HCG) on pregnancy outcome of mother and foetus., Methods/design: During pregnancy, participants receive questionnaires at 12, 22 and 32 weeks of gestation. Apart from a previous obstetric history, demographic features, distress symptoms, and pregnancy-related somatic symptoms are assessed. Furthermore, obstetrical data of the obstetric record form and ultrasound data are collected during pregnancy. At 12 and 30 weeks, thyroid function is assessed by blood analysis of thyroid stimulating hormone (TSH), free thyroxine (FT4) and thyroid peroxidase antibodies (TPO-Ab), as well as HCG. Also, depression is assessed with special focus on the two key symptoms: depressed mood and anhedonia. After childbirth, cord blood, neonatal heel screening results and all obstetrical data with regard to start of labour, mode of delivery and complications are collected. Moreover, mothers receive questionnaires at one week, six weeks, four, eight, and twelve months postpartum, to investigate recovery after pregnancy and delivery, including postpartum mood changes, emotional distress, feeding and development of the newborn., Discussion: The key strength of this large prospective cohort study is the holistic (multifactorial) approach on perinatal well-being combined with a longitudinal design with measurements during all trimesters of pregnancy and the whole first year postpartum, taking into account two physiological possible markers of complaints and symptoms throughout gestation: thyroid function and HCG. The HAPPY study is among the first to investigate within one design physiological and psychological aspects of NVP and CTS symptoms during pregnancy. Finally, the concept of anhedonia and depressed mood as two distinct aspects of depression and its possible relation on obstetric outcome, breastfeeding, and postpartum well-being will be studied.

The rise in antimicrobial resistance has become a serious global health problem. Restrictive use of antibiotics seems the only option to temper this accession since research in new antibiotics has halted. Antimicrobial stewardship programmes rely on quick access to susceptibility data. This study evaluated the concept of bacterial cell count monitoring as a fast method to determine susceptibility. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains were tested for amoxicillin/piperacillin and gentamicin by three conventional methods (VITEK2(®) , Etest(®) and broth-macrodilution). Bacterial cell count monitoring reliably predicted susceptibility after 90 min for Escherichia coli and after 120 min for Pseudomonas aeruginosa and Staphylococcus aureus without any minor, major or very major discrepancies. Time-to-result was reduced by 74%, 83% and 76%, respectively. Bacterial cell count monitoring shows great potential for rapid susceptibility testing., (© 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.)

The diagnosis of urinary tract infection (UTI) by urine culture is time-consuming and can produce up to 60 to 80% negative results. Fast screening methods that can reduce the necessity for urine cultures will have a large impact on overall turnaround time and laboratory economics. We have evaluated the detection of bacteria and leukocytes by a new urine analyzer, the UF-1000i, to identify negative urine samples that can be excluded from urine culture. In total, 1,577 urine samples were analyzed and compared to urine culture. Urine culture showed growth of ≥10(3) CFU/ml in 939 samples (60%). Receiver operating characteristics (ROC) curves and ROC decision plots were been prepared at three different gold standard definitions of a negative urine culture: no growth, growth of bacteria at <10(4) CFU/ml, and growth of bacteria at <10(5) CFU/ml. Also, the reduction in urine cultures and the percentage of false negatives were calculated. At the most stringent gold standard definition of no growth, a chosen sensitivity of 95% resulted in a cutoff value of 26 bacteria/μl, a specificity of 43% and a reduction in urine cultures of only 20%, of which 14% were false negatives. However, at a gold standard definition of <10(5) CFU/ml and a sensitivity of 95%, the UF-1000i cutoff value was 230 bacteria/μl, the specificity was 80%, and the reduction in urine cultures was 52%, of which 0.3% were false negatives. The applicability of the UF-1000i to screen for negative urine samples strongly depends on population characteristics and the definition of a negative urine culture. In our setting, however, the low workload savings and the high percentage of false-negative results do not warrant the UF-1000i to be used as a screening analyzer.

Details of the forces between nanoparticles determine the ways in which the nanoparticles can self-assemble into larger structures. The use of directed interactions has led to new concepts in self-assembly such as asymmetric dendrons, Janus particles, patchy colloids and colloidal molecules. Recent models that include attractive regions or 'patches' on the surface of the nanoparticles predict a wealth of intricate modes of assembly. Interactions between such particles are also important in a range of phenomena including protein aggregation and crystallization, re-entrant phase transitions, assembly of nanoemulsions and the organization of nanoparticles into nanowires. Here, we report the synthesis of 6-nm nanoparticles with dynamic hydrophobic patches and show that they can form reversible self-assembled structures in aqueous solution that become topologically more connected upon dilution. The organization is based on guest-host supramolecular chemistry with the nanoparticles composed of a hydrophobic dendrimer host molecule and water-soluble hydrophilic guest molecules. The work demonstrates that subtle changes in hierarchal composition and/or concentration can dramatically change mesoscopic ordering.

We provide detailed insight into complex supramolecular assembly processes by fully characterizing a multicomponent model system using dynamic light scattering, cryogenic transmission electron microscopy, atomic force microscopy, and various NMR techniques. First, a preassembly of a host molecule (the fifth-generation urea-adamantyl poly(propylene imine) dendrimer) and 32 guest molecules (a water- and chloroform-soluble ureidoacetic acid guest) was made in chloroform. The association constant in chloroform is concealed by guest self-association and is therefore higher than 10(3) M(-1). Via the neat state the single-host complex was transferred to water, where larger dendrimer-based assemblies were formed. The core of these assemblies, consisting of multiple host molecules (on average three), is kinetically trapped upon dissolution in water, and its size is constant irrespective of the concentration. The guest molecules forming the corona of the assemblies, however, stay dynamic since they are still in rapid exchange on the NMR time scale, as they were in chloroform. A stepwise noncovalent synthesis provides a means to obtain metastable dynamic supramolecular assemblies in water, structures that cannot be formed in one step.

The multiple monovalent binding of adamantyl-urea poly(propyleneimine) dendrimers with carboxylic acid-urea guests was investigated using molecular dynamics simulations and X-ray crystallography to better understand the structure and behavior of the dynamic multivalent complex in solution. The results from the two methods are consistent and suggest a preferred molecular picture of this complicated aggregate of multiple components. The guest molecules can bind to the dendrimer in a variety of ways although most involve hydrogen-bonding interactions between urea groups of the dendrimer with urea and/or carboxylic acid groups of the guest. In addition, acid-base interactions between the carboxylic acid of the guest and the tertiary amine in the interior of the dendritic host are present. Our proposed structure gives important information about the predominant dynamic interactions between the host and guest and illustrates how they fit together and interact with each other.

[Structure: see text] A novel procedure for catalyst recycling is described. Copper(I)-based catalysts, equipped with an affinity tag, are isolated from crude reaction mixtures on the basis of quadruple hydrogen-bonding interactions using a resin functionalized with complementary affinity tags. Recycled catalysts were successfully used to catalyze a tandem Sonogashira coupling/5-endo-dig cyclization and a Cu-catalyzed [3+2] Huisgen cycloaddition reaction in high yields.

Host-guest interactions between the periphery of adamantylurea-functionalized dendrimers (host) and ureido acetic acid derivatives (guest) were shown to be specific, strong and spatially well-defined. The binding becomes stronger when using phosphonic or sulfonic acid derivatives. In the present work we have quantified the binding constants for the host-guest interactions between two different host motifs and six different guest molecules. The host molecules, which resemble the periphery of a poly(propylene imine) dendrimer, have been fitted with an anthracene-based fluorescent probe. The two host motifs differ in terms of the length of the spacer between a tertiary amine and two ureido functionalities. The guest molecules all contain an acidic moiety (either a carboxylic acid, a phosphonic acid, or a sulfonic acid) and three of them also contain an ureido moiety capable of forming multiple hydrogen bonds to the hosts. The binding constants for all 12 host-guest complexes have been determined by using fluorescence titrations by monitoring the increase in fluorescence of the host upon protonation by the addition of the guest. The binding constants could be tuned by changing the design of the acidic part of the guest. The formation of hydrogen bonds gives, in all cases, higher association constants, demonstrating that the host is more than a proton sensor. The host with the longer spacer (propyl) shows higher association constants than the host with the shorter spacer (ethyl). The gain in association constants are higher when the urea function is added to the guests for the host with the longer spacer, indicating a better fit. Collision-induced dissociation mass spectrometry (CID-MS) is used to study the stability of the six motifs using the corresponding third generation dendrimer. A similar trend is found when the six different guests are compared.

A new way to analyze supramolecular dendritic architectures is reported by making use of (13)C NMR and (31)P NMR. Two ethylene glycol guest molecules have been synthesized containing a (13)C labeled carboxylic acid headgroup (2) and a phosphonic acid headgroup (3). The binding of these guests to urea-adamantyl modified poly(propylene imine) dendrimers has been investigated with (13)C NMR and (31)P NMR next to 1D and 2D (1)H NMR techniques. Different amounts of guest 2 have been added to fifth generation dendrimer 1e, and the observed chemical shift values in (13)C NMR were fitted to a model that assumes 1:1 binding between guest and binding site. An association constant of 400 +/- 95 M(-)(1) is obtained for guest 2 with 41 binding sites per dendrimer. When different amounts of phosphonic acid guest 3 are added to dendrimer 1e, two different signals are observed in (31)P NMR. Deconvolution gives the fractions of free and bound guest, resulting in an association constant of (4 +/- 3) x 10(4) M(-)(1) and 61 +/- 1 binding sites. A statistical analysis shows that guest 2 forms a "polydisperse supramolecular aggregate", while guest 3 is able to form a "monodisperse supramolecular aggregate" when the amount of guest is high enough. The NMR results are compared with dynamic light scattering experiments, and a remarkable agreement is found. Phosphonic acid guest 3 is able to exchange with guest 2, which is in agreement with the obtained association constants, and shows that these techniques can be used to analyze multicomponent dendritic aggregates.

Boc-protected L-phenylalanine has been connected to a spacer-armed ureido-acetic acid derivative, which can form multiple supramolecular complexes with urea-adamantyl modified poly(propylene imine) dendrimers in chloroform. Complexes of this guest with several generations of urea-adamantyl dendrimers were prepared. The dendrimer-guest complexes were characterized in detail by (1)H-NMR, (1)H-(1)H-NOESY spectroscopy and mass spectrometry to prove their formation. Optical rotation experiments performed on different generations of dendrimer-guest complexes showed a constant positive value. These observations indicate that, though guest molecules decrease the flexibility at the periphery of the dendrimer upon binding, the amino acid at the terminus of the guest molecule retains its high local conformational freedom. This is in agreement with values found for covalently modified spacer-armed dendrimers.