Bioimaging based on Poly(ethylenimine)-Coated Carbon Dots and Gold Nanoparticles for pH Sensing and Metal Enhanced Fluorescence.

When exposed to specific light wavelengths, carbon dots (CDs), which tend to be fluorescent, can emit colorful light. It provides them with a lot of adaptability for different applications including bioimaging, optoelectronics, and even environmental sensing. Poly(ethylenimine) (PEI) coated carbon dots (PEI-CDs) with a long emission wavelength were synthesized via the hydrothermal method. The resultant CDs show strong fluorescence with quantum yield up to 20.2%. The PEI-CDs exist with distinct pH-sensitive features with pH values in the range of 2-14. The optical characteristics of CDs are pH-responsive due to the presence of different amine groups on PEI, which is a functional polycationic polymer. One of the most widely employed nanoparticles for improving the fluorescence plasmonic characteristics of a nanocomposite is gold. Gold nanoparticles were coupled with PEI-CDs in this assay by using the EDC-NHS coupling to increase the photoluminescence property of the PEI-CDs by using the metal-enhanced fluorescence approach. In the presence of gold nanoparticles, the fluorescence is enhanced 5-6 times. The likely mechanism in our investigation was primarily derived from enhancement of the intrinsic radiative decay rate rather than the local electric field impact. Moreover, PEI-CDs can be used as a bioimaging agent, as these molecules are nontoxic to the cells, and the positively charged PEI-CDs have the potential for nuclear targeting, allowing for electrostatic contact with DNA in the nucleus. This finding will expand the application that the PEI-CDs can be used in the future for targeted imaging applications.

Species-specific lipophilicities of fluorinated diketones in complex equilibria systems and their potential as multifaceted reversible covalent warheads.

Combined molecular, physicochemical and chemical properties of electrophilic warheads can be applied to create covalent drugs with diverse facets. Here we study these properties in fluorinated diketones (FDKs) and their multicomponent equilibrium systems in the presence of protic nucleophiles, revealing the potential of the CF2(CO)2 group to act as a multifaceted warhead for reversible covalent drugs. The equilibria compositions of various FDKs in water/octanol contain up to nine species. A simultaneous direct species-specific 19F-NMR-based log P determination of these complex equilibria systems was achieved and revealed in some cases lipophilic to hydrophilic shifts, indicating possible adaptation to different environments. This was also demonstrated in 19F-MAS-NMR-based water-membrane partitioning measurements. An interpretation of the results is suggested by the aid of a DFT study and 19F-DOSY-NMR spectroscopy. In dilute solutions, a model FDK reacted with protected cysteine to form two hemi-thioketal regioisomers, indicating possible flexible regio-reactivity of CF2(CO)2 warheads toward cysteine residues.

Harnessing Pillar[5]arene Host-Guest Complexation To Improve pH Stability and Affect Enzymatic Degradation of the Anticancer Prodrug Capecitabine: A 19 F NMR Study.

Cancer is a global health problem, and supramolecular chemotherapy is emerging as a novel strategy to battle the disease. Here, we first evaluated the thermodynamic and kinetic stability of the complexes formed between several water-soluble per-substituted pillar[5]arene derivatives and capecitabine (1), a widely used oral chemotherapeutic prodrug. The exchange rate was studied, for the first time in pillararene chemistry, by the 19 F guest exchange saturation transfer (GEST) NMR technique. Importantly, when we evaluated the effect of complexation on the characteristics of 1, we found that the complexation of 1 with such pillar[5]arene hosts increased capecitabine stability at acidic pH very significantly and slowed its enzymatic degradation by the carboxylesterase enzyme in a manner that depended on the host. These interesting findings could have implications on the clinical use of this heavily used prodrug and might affect the management of cancer patients.

Calcium Sulfate and Calcium Carbonate Scaling of Thin-Film Composite Polyamide Reverse Osmosis Membranes with Surface-Tethered Polyacrylic Acid Chains.

The gypsum and calcite scaling propensities of the thin-film composite polyamide (PA-TFC) reverse osmosis (RO) membrane, modified with a tethered surface layer of polyacrylic acid (PAA) chains, was evaluated and compared to the scaling of selected commercial RO membranes. The tethered PAA layer was synthesized onto a commercial polyamide membrane (i.e., base-PA) via atmospheric pressure plasma-induced graft polymerization (APPIGP). The PAA nano-structured (SNS) base-PA membrane (SNS-PAA-PA) was scaled to a lesser degree, as quantified by a lower permeate flux decline and surface imaging, relative to the tested commercial membranes (Dow SW30, Toray SWRO, and BWRO). The cleaning of gypsum-scaled membranes with D.I. water flushing achieved 100% water permeability recovery for both the SNS-PAA-PA and Dow SW30 membranes, relative to 92-98% permeability restoration for the Toray membranes. The calcium carbonate scaling of SNS-PAA-PA membranes was also lower relative to the commercial membranes, but permeability recovery after D.I. water cleaning was somewhat lower (94%) but consistent with the level of surface scale coverage. In contrast, the calcite and gypsum-scaled membrane areas of the commercial membranes post-cleaning were significantly higher than for the SNS-PAA-PA membrane but with 100% permeability recovery, suggesting the potential for membrane damage when mineral scaling is severe.

Diffusion NMR Reveals the Structures of the Molecular Aggregates of Resorcin[4]arenes and Pyrogallol[4]arenes in Aromatic and Chlorinated Solvents.

The hexameric assemblies of resorcinarenes and pyrogallolarenes are fascinating structures that can serve as nanoreactors in which new chemistry and catalysis occur. Recently, it was suggested based on SANS or SAXS that C11-resorcin[4]arene (1) forms octameric aggregates of a micellar rather than capsular structure in toluene. Here, using NMR spectroscopy, diffusion NMR, and DOSY performed on solutions of C11-resorcin[4]arene (1), C11-pyrogallol[4]arene (2), and mixtures thereof in protonated and deuterated solvents, we found that, in benzene and toluene, 1 primarily formed hexameric capsules accompanied by a minor product with diffusion characteristics consistent with an octameric assembly. In chloroform, 1 formed hexameric capsules. In toluene, 2D NMR revealed two populations of encapsulated toluene molecules in the same capsule of 1. The addition of tetrahexylammonium bromide to the assemblies of 1 in aromatic solvents drove the equilibrium toward the formation of the hexameric capsules. Interestingly, 2 formed only hexameric capsules in all solvents tested.

Female fragile X premutation carriers are at increased risk for metabolic syndrome from early adulthood.

BACKGROUND AND AIMS: Women with primary ovarian insufficiency exhibit an unfavorable cardiovascular risk profile. A common cause for primary ovarian insufficiency is fragile X premutation (FXPC), and data on the cardiovascular risk factors in women with FXPC are scarce. We aimed to assess the prevalences of abnormal metabolic components among FXPC. METHODS AND RESULTS: Clinical, anthropometric and laboratory data were collected from 71 women with FXPC and compared to 78 women referred for counseling in an in-vitro fertilization clinic (control group). The mean ± SD ages of the FXPC and control groups were 33.5 ± 5.6 and 36.2 ± 5.3 years, respectively (p = 0.003). In a logistic regression analysis, the FXPC group had increased risks for hyperglycemia, hypertriglyceridemia, central obesity and low high-density lipoprotein cholesterol, of 21.8-fold (95% CI 2.7-175, p = 0.004), 6.9-fold (95% CI 2.5-18.7, p < 0.0001), 3.1-fold (95% CI 1.4-6.9, p = 0.005) and 2.4-fold (95% CI 1.1-5.2, p = 0.03), compared to the control group. The FXPC group had 2.7-fold higher prevalence of two abnormal metabolic components; 19% met the full criteria of MetS, compared to 3% of the control group. Neither CGG repeats nor ovarian reserve markers were associated with metabolic risk. CONCLUSIONS: Carriers of fragile X premutation are at increased metabolic risk from early adulthood; waist circumference, glucose and lipid levels are particularly elevated. We recommend metabolic screening for all women with FMR1 premutation, to enable early interventions for prevention of long-term cardiovascular comorbidities.

Aggregation Mode, Host-Guest Chemistry in Water, and Extraction Capability of an Uncharged, Water-Soluble, Liquid Pillar[5]arene Derivative.

An uncharged, water-soluble per-ethylene-glycol pillar[5]arene derivative (1) was synthesized and its aggregation mode, host-guest chemistry in water and extraction ability was explored. Compound 1 is a liquid at room temperature; in water, limited self-aggregation occurred at high concentrations as deduced from diffusion NMR and dynamic light scattering. Compound 1 forms pseudo-rotaxane-like 1 : 1 host-guest complexes with 1,ω-di-substituted alkanes with association constants on the order of 103 -104  m-1 . Interestingly, NMR experiments showed that the guest location relative to the host ring system differs among the different complexes. In proof-of-concept experiments, compound 1 was shown to extract structurally related organic compounds from benzene into water with significant selectivity. Compound 1, which is a liquid at room temperature and has only limited interactions with its side arms, can, in principle, be regarded as a complement to or as a kind of type I porous liquid.

Solution NMR of synthetic cavity containing supramolecular systems: what have we learned on and from?

NMR has been instrumental in studies of both the structure and dynamics of molecular systems for decades, so it is not surprising that NMR has played a pivotal role in the study of host-guest complexes and supramolecular systems. In this mini-review, selected examples will be used to demonstrate the added value of using (multiparametric) NMR for studying macrocycle-based host-guest and supramolecular systems. We will restrict the discussion to synthetic host systems having a cavity that can engulf their guests thus restricting them into confined spaces. So discussion of selected examples of cavitands, cages, capsules and their complexes, aggregates and polymers as well as organic cages and porous liquids and other porous materials will be used to demonstrate the insights that have been gathered from the extracted NMR parameters when studying such systems emphasizing the information obtained from somewhat less routine NMR methods such as diffusion NMR, diffusion ordered spectroscopy (DOSY) and chemical exchange saturation transfer (CEST) and their variants. These selected examples demonstrate the impact that the results and findings from these NMR studies have had on our understanding of such systems and on the developments in various research fields.

Dysregulation of anti-Mullerian hormone expression levels in mural granulosa cells of FMR1 premutation carriers.

FMR1 premutation (55-200 CGG repeats) results in fragile X-associated primary ovarian insufficiency (FXPOI). We evaluated expression levels of folliculogenesis-related mediators, follicle-stimulating hormone (FSH) receptor and anti-Mullerian hormone (AMH), to gain insights into the mechanisms underlying the reduced ovarian function. Mural granulosa cells (MGCs) were collected from FMR1 premutation carriers and noncarriers undergoing IVF treatments. At baseline, MGCs of carriers demonstrated significantly higher mRNA expression levels of AMH (3.5 ± 2.2, n = 12 and 0.97 ± 0.5, n = 17, respectively; p = 0.0003) and FSH receptor (5.6 ± 2.8 and 2.7 ± 2.8, respectively; p = 0.02) and higher AMH protein expression on immunostaining. Accordingly, FMR1 premutation-transfected COV434 cells exhibited higher AMH protein expression than COV434 cells transfected with 20 CGG repeats. We conclude that FMR1 premutation may lead to dysregulation of AMH expression levels, probably due to a compensatory mechanism. Elucidating the pathophysiology of FXPOI may help in early detection of ovarian dysfunction and tailoring IVF treatments to FMR1 premutation carriers.

Design Guidelines for Cationic Pillar[n]arenes that Prevent Biofilm Formation by Gram-Positive Pathogens.

Bacterial biofilms are a major threat to human health, causing persistent infections that lead to millions of fatalities worldwide every year. Biofilms also cause billions of dollars of damage annually by interfering with industrial processes. Recently, cationic pillararenes were found to be potent inhibitors of biofilm formation in Gram-positive bacteria. To identify the structural features of pillararenes that result in antibiofilm activity, we evaluated the activity of 16 cationic pillar[5]arene derivatives including that of the first cationic water-soluble pillar[5]arene-based rotaxane. Twelve of the derivatives were potent inhibitors of biofilm formation by Gram-positive pathogens. Structure activity analyses of our pillararene derivatives indicated that positively charged head groups are critical for the observed antibiofilm activity. Although certain changes in the lipophilicity of the substituents on the positively charged head groups are tolerated, dramatic elevation in the hydrophobicity of the substituents or an increase in steric bulk on these positive charges abolishes the antibiofilm activity. An increase in the overall positive charge from 10 to 20 did not affect the activity significantly, but pillararenes with 5 positive charges and 5 long alkyl chains had reduced activity. Surprisingly, the cavity of the pillar[n]arene is not essential for the observed activity, although the macrocyclic structure of the pillar[n]arene core, which facilitates the clustering of the positive charges, appears important. Interestingly, the compounds found to be efficient inhibitors of biofilm formation were nonhemolytic at concentrations that are ∼100-fold of their MBIC50 (the minimal concentration of a compound at which at least 50% inhibition of biofilm formation was observed compared to untreated cells). The structure-activity relationship guidelines established here pave the way for a rational design of potent cationic pillar[n]arene-based antibiofilm agents.

Ethnicity has a multiplex impact upon the risk of a full mutation expansion among female heterozygotes for FMR1 premutation.

PURPOSE: To evaluate whether ethnicity affects the risk of full mutation expansion among females heterozygous for FMR1 premutation. METHODS: Women who carry the FMR1 premutation alelle of Jewish origin who underwent fragile X prenatal diagnosis between 2011 and 2018 in two medical centers in Israel were included. The heterozygote women and fetuses were analyzed for the number of CGG repeats and AGG interruptions. RESULTS: Seven hundred sixty-six subjects were included. Parental ethnicity was fully concordant in 592 cases (Jewish, Ashkenazi, and non-Ashkenazi). Ashkenazi compared with non-Ashkenazi heterozygotes have a significantly higher mean number of CGG repeats (68 ± 8.7, 64 ± 6.4 respectively, P = 0.03) and a lower mean number of AGG interruptions (0.89 ± 0.83, 1.60 ± 1.18 respectively, p = 0.0001). Overall, 56/198 (28.2%) fetuses of Ashkenazi heterozygotes had an expansion to a full mutation compared with 6/98 among the non-Ashkenazi (6.1%) (p = 0.001). Multivariate analysis demonstrated that, in addition to CGG repeats and AGG interruptions (which contributed 68.3% of variance), ethnicity is an independent risk factor for a full mutation expansion (odds ratio [OR] = 2.04, p < 0.001) and accounted for 9% of the variation of a full mutation expansion. CONCLUSION: Apart from significant differences regarding the number of CGG repeats and AGG interruptions between Ashkenazi and non-Ashkenazi heterozygotes, ethnicity independently affects the risk of a full mutation.

Desupersaturation of RO concentrate and gypsum removal via seeded precipitation in a fluidized bed crystallizer.

The feasibility of a continuous chemically-enhanced seeded precipitation (CCESP) process was evaluated for desupersaturation of primary reverse osmosis (PRO) concentrate generated from RO desalting of inland agricultural drainage (AD) water with high gypsum scaling potential. The CCESP approach, comprised of partial lime treatment (PLT) followed by gypsum seeded precipitation (GSP), was assessed via laboratory and field tests, along with model simulations. PLT effectiveness was confirmed for residual antiscalant removal from the PRO concentrate, which otherwise would suppress gypsum crystallization. GSP was carried out in a fluidized bed crystallizer (FBC) demonstrating the feasibility of continuous PRO concentrate desupersaturation with suitable solids management. FBC operation was stable, with respect to desupersaturation performance, when operating over a sequence of periodic solids purge-only mode with intermittent seeds replenishment. The study suggests that CCESP integration with primary and secondary RO desalting (i.e., PRO-CCESP-SRO) can provide for significant enhancement of product water recovery for inland water of high gypsum scaling propensity. For example, source water of high salinity (14,347 mg/L total dissolved solid) AD water, nearly saturated with respect to gypsum, could be desalted up to a recovery of 88-96% (relative to merely 66% recovery feasible via PRO desalting. Moreover, net salt harvesting of 2.6-3.6 kg per m3 RO concentrate (with concentrate recycle) can be obtained from high recovery desalting of the above PRO concentrate.

Reading Akkadian cuneiform using natural language processing.

In this paper we present a new method for automatic transliteration and segmentation of Unicode cuneiform glyphs using Natural Language Processing (NLP) techniques. Cuneiform is one of the earliest known writing system in the world, which documents millennia of human civilizations in the ancient Near East. Hundreds of thousands of cuneiform texts were found in the nineteenth and twentieth centuries CE, most of which are written in Akkadian. However, there are still tens of thousands of texts to be published. We use models based on machine learning algorithms such as recurrent neural networks (RNN) with an accuracy reaching up to 97% for automatically transliterating and segmenting standard Unicode cuneiform glyphs into words. Therefore, our method and results form a major step towards creating a human-machine interface for creating digitized editions. Our code, Akkademia, is made publicly available for use via a web application, a python package, and a github repository.

QSAR without borders.

Prediction of chemical bioactivity and physical properties has been one of the most important applications of statistical and more recently, machine learning and artificial intelligence methods in chemical sciences. This field of research, broadly known as quantitative structure-activity relationships (QSAR) modeling, has developed many important algorithms and has found a broad range of applications in physical organic and medicinal chemistry in the past 55+ years. This Perspective summarizes recent technological advances in QSAR modeling but it also highlights the applicability of algorithms, modeling methods, and validation practices developed in QSAR to a wide range of research areas outside of traditional QSAR boundaries including synthesis planning, nanotechnology, materials science, biomaterials, and clinical informatics. As modern research methods generate rapidly increasing amounts of data, the knowledge of robust data-driven modelling methods professed within the QSAR field can become essential for scientists working both within and outside of chemical research. We hope that this contribution highlighting the generalizable components of QSAR modeling will serve to address this challenge.

Correction: QSAR without borders.

Correction for 'QSAR without borders' by Eugene N. Muratov et al., Chem. Soc. Rev., 2020, DOI: 10.1039/d0cs00098a.

NanoSolveIT Project: Driving nanoinformatics research to develop innovative and integrated tools for in silico nanosafety assessment.

Nanotechnology has enabled the discovery of a multitude of novel materials exhibiting unique physicochemical (PChem) properties compared to their bulk analogues. These properties have led to a rapidly increasing range of commercial applications; this, however, may come at a cost, if an association to long-term health and environmental risks is discovered or even just perceived. Many nanomaterials (NMs) have not yet had their potential adverse biological effects fully assessed, due to costs and time constraints associated with the experimental assessment, frequently involving animals. Here, the available NM libraries are analyzed for their suitability for integration with novel nanoinformatics approaches and for the development of NM specific Integrated Approaches to Testing and Assessment (IATA) for human and environmental risk assessment, all within the NanoSolveIT cloud-platform. These established and well-characterized NM libraries (e.g. NanoMILE, NanoSolutions, NANoREG, NanoFASE, caLIBRAte, NanoTEST and the Nanomaterial Registry (>2000 NMs)) contain physicochemical characterization data as well as data for several relevant biological endpoints, assessed in part using harmonized Organisation for Economic Co-operation and Development (OECD) methods and test guidelines. Integration of such extensive NM information sources with the latest nanoinformatics methods will allow NanoSolveIT to model the relationships between NM structure (morphology), properties and their adverse effects and to predict the effects of other NMs for which less data is available. The project specifically addresses the needs of regulatory agencies and industry to effectively and rapidly evaluate the exposure, NM hazard and risk from nanomaterials and nano-enabled products, enabling implementation of computational 'safe-by-design' approaches to facilitate NM commercialization.

Temperature-Dependent and pH-Responsive Pillar[5]arene-Based Complexes and Hydrogen-Bond-Based Supramolecular Pentagonal Boxes in Water.

Supramolecular systems in water are of paramount importance and those based on hydrogen bonds are both intriguing and scarce. Here, after studying the peculiar host-guest complexes formed between per-dimethylamino-pillar[5]arene (1) and the bis-sulfonates 2 a-c, we describe the formation of the first hydrogen-bond-based supramolecular pentagonal boxes (SPBs), which are stable in water. These pH-responsive SPBs are constructed from 1 as a body, benzene polycarboxylic acids 3 a,b as lid compounds, and 2 a-c as guests. We demonstrate that encapsulation of 2 a-c in pillar[5]arene 1 and in the highly stable water-soluble SPBs, that is, 1(3 a)2 and 1(3 b)2 , is both temperature and pH dependent and, quite interestingly, depends, on the nature of the lid compounds used for capping the boxes even at high pH. We also highlight the difference in the 1 H NMR characteristics of 2 b and 2 c in the cavity of 1 and the SPBs.

Kinetic Stabilities and Exchange Dynamics of Water-Soluble Bis-Formamide Caviplexes Studied Using Diffusion-Ordered NMR Spectroscopy (DOSY).

A deep cavitand binds long-chain trans,trans- and trans,cis-bis-formamide isomers in water solution giving a pair of caviplexes in a ca. 60:40 ratio. Both caviplexes display in/out guest exchange dynamics that are slow on the 1 H NMR chemical shift timescale, but fast on the EXSY timescale. We apply diffusion-ordered NMR spectroscopy (DOSY) to characterize the caviplexes. On the diffusion timescale, the guest in/out exchange processes feature intermediate dynamics allowing the assessment of their kinetic stabilities. We found that the trans,cis-bis-formamide isomers form kinetically more stable caviplexes than the trans,trans-counterparts. We also show that the kinetic stabilities of the bis-formamide caviplexes relate well with their relative thermodynamic stabilities. Fortunately, the tuning of the DOSY parameters allowed the observation of the exchange dynamics as slow processes on the experiment timescale.

Constant gradient FEXSY: A time-efficient method for measuring exchange.

Filter-Exchange NMR Spectroscopy (FEXSY) is a method for measurement of apparent transmembranal water exchange rates. The experiment is comprised of two co-linear sequential pulsed-field gradient (PFG) blocks, separated by a mixing period in which exchange takes place. The first block remains constant and serves as a diffusion-based filter that removes signal coming from fast-diffusing water. The mixing time and the gradient area (q-value) of the second block are varied on repeated iterations to produce a 2D data set that is analyzed using a bi-compartmental model which assumes that intra- and extra-cellular water are slow and fast diffusing, respectively. Here we suggest a variant of the FEXSY method in which measurements for different mixing times are taken at a constant gradient. This Constant Gradient FEXSY (CG-FEXSY) allows for the determination of the exchange rate by using a smaller 1D data set, so that the same information can be gathered during a considerably shorter scan time. Furthermore, in the limit of high diffusion weighting, such that the extra-cellular water signal is removed while the intra-cellular signal is retained, CG-FEXSY also allows for determination of the intra-cellular mean residence time (MRT). The theoretical results are validated on a living yeast cells sample and on a fixed porcine optic nerve, where the values obtained from the two methods are shown to be in agreement.