Glycol Derivatives Research Articles

Tandem Acid/Pd-Catalyzed Reductive Rearrangement of Glycol Derivatives.

Herein, we describe the acid/Pd‐tandem‐catalyzed transformation of glycol derivatives into terminal formic esters. Mechanistic investigations show that the substrate undergoes rearrangement to an aldehyde under [1,2] hydrogen migration and cleavage of an oxygen‐based leaving group. The leaving group is trapped as its formic ester, and the aldehyde is reduced and subsequently esterified to a formate. Whereas the rearrangement to the aldehyde is catalyzed by sulfonic acids, the reduction step requires a unique catalyst system comprising a PdII or Pd0 precursor in loadings as low as 0.75 mol % and α,α′‐bis(di‐tert‐butylphosphino)‐o‐xylene as ligand. The reduction step makes use of formic acid as an easy‐to‐handle transfer reductant. The substrate scope of the transformation encompasses both aromatic and aliphatic substrates and a variety of leaving groups.

Transmission Electron Microscopy Characterization of IONPs Modified with Polyethylene Glycol Derivatives

Transmission Electron Microscopy Characterization of IONPs Modified with Polyethylene Glycol Derivatives

Encoding Information into Polyethylene Glycol Using an Alcohol-Isocyanate "Click" Reaction.

In this article, the capability of encoding information using a homologous series of monodisperse monomethoxypolyethylene glycols (mPEG), with a number of ethylene oxide units ranging from nEO = 5 to 8, and monodisperse linear aliphatic isocyanates containing a number of CH2 units from 3 to 7, is demonstrated. The “click” reaction of the two corresponding homologous series yielded 20 different isocyanate end-capped polyethylene glycol derivatives (mPEG-OCONHR) whose sodiated adduct ion’s nominal m/z values spanned from 360 to 548, providing an average ca. 8 m/z unit for the storage of one-bit information. These mPEG-OCONHR oligomers were then used to encode information in binary sequences using a 384-well MALDI sample plate and employing the common dried-droplet sample preparation method capable of encoding 20 bit, i.e., 2.5 byte information in one spot, was employed. The information stored in the spots was read by MALDI-TOF MS using the m/z value of the corresponding mPEG-OCONHR oligomers. The capability of the method to store data was demonstrated by writing and reading a text file, visualizing a small picture and capturing a short audio file written in Musical Instrument Digital Interface (MIDI) sequence. Due to the very large similarities in the chemical structures of the encoding oligomers and their “easy to be ionized” property, as well as their very similar ionization efficiencies, the MALDI-TOF MS signal intensities from each compound was so strong and unambiguous that complete decoding could be performed in each case. In addition, the set of the proposed encoding oligomers can be further extended to attain higher bit “densities”.

UV Spectra of Glycolic Acid Derivatives – A Time-Dependant Density Functional Theory Examination

One of the serious health issues faced by people throughout the world in recent years is Skin cancer, which is caused by harmful UV radiations from the sun. To protect the human skin from direct exposure to these ultraviolet radiations, preventive measures have to be taken and once such solution is the application of suitable and safer sunscreen. It is the need of the hour to develop better and harmless sunscreens to protect the skin. One such material which plays a major role in dermatology and cosmetics industry is Glycolic acid, CH2OHCOOH, a precursor of a-hydroxy carboxylic acids. Our present study is to find out if the glycolic acid conformers and its derivatives are capable of absorbing harmful radiations in the UVB and UVA ranges. To understand this property the UV absorption spectra is calculated using Time dependant density functional theory (TD-DFT). Further, our TDDFT calculations have shown that o-Nitromandelic acid, a glycolic acid derivative shows absorption in both UVB and UVA regions. This indicates that o-Nitromandelic acid can be probably used as a UV filter in sunscreen lotions.

Highly sensitive impedimetric glycosensor for the determination of a ricin surrogate, Ricinus communis agglutinin I (RCA120)

A highly sensitive impedimetric glycosensor has been developed for the label-free detection of Ricinus communis Agglutinin I (RCA120) - a surrogate of potential security threat toxin ricin. In order to accomplish strong binding of RCA120 onto the glycosensor surface, the coverage of self-assembled monolayers of thiolated β-galactose derivative on gold electrode was optimized with varying ratios of thiolated ethylene glycol derivative. The association constant between the RCA120 and the β-galactose derivative with 10% coverage on gold electrode surface has been determined to be ca. 1.54 × 109 M−1, implying that the β-galactose derivative can be used as an effective recognition element for RCA120. The increase in electron transfer resistance through the selective binding of RCA120 onto the glycosensor measured by electron impedance spectroscopy was directly dependent upon the amount of RCA120 in sample solution. The present glycosensor can detect RCA120 from 8.33 × 10−11 M to 4.17 × 10−6 M with a limit of detection (S/N = 3) of 1.23 × 10−11 M, which is much lower than those of the previous reports. Since the proposed glycosensor does not need time-consuming labeling or signal amplification steps commonly carried out in sandwich-type RCA120 immunoassays, it provides the potential for a simple and rapid detection of a security threat toxin ricin.

Fabrication of Hollow Fiber Membranes Using Highly Viscous Liquids as Internal Coagulants

Ethylene glycol (EG) and its derivatives were proposed as internal coagulants to spin hollow fiber membranes of the commercial polymer poly(ether imide) (PEI) and compared with water. The thermodynamic and kinetic characteristics of the polymer–solvent–nonsolvent systems were analyzed. The morphology and ultrafiltration performance of the resultant membranes were investigated. Water leads to a fast precipitation rate while a slow process is obtained for EG derivatives because of their high viscosity, large molecular size, and weak nonsolvent capability. The hollow fibers prepared with EG derivatives as bore fluids have thinner walls, which promote less resistance to the permeant transport. High rejections of bovine serum albumin (66 kg/mol), ovalbumin (45 kg/mol), and α-lactalbumin (14 kg/mol) were detected. The good performance combined with the nontoxicity of the EG derivatives makes them promising coagulants for membrane fabrication.

Biofunctionalized Polyelectrolyte Microcapsules Encoded with Fluorescent Semiconductor Nanocrystals for Highly Specific Targeting and Imaging of Cancer Cells

Fluorescent semiconductor nanocrystals or quantum dots (QDs) are characterized by unique optical properties, including a high photostability, wide absorption spectrum, and narrow, symmetric fluorescence spectrum. This makes them attractive fluorescent nanolabels for the optical encoding of microcarriers intended for targeted drug delivery, diagnosis, and imaging of transport processes on the body, cellular, and subcellular levels. Incorporation of QDs into carriers in the form of polyelectrolyte microcapsules through layer-by-layer adsorption of oppositely charged polyelectrolyte polymers yields microcapsules with a bright fluorescence signal and adaptable size, structure, and surface characteristics without using organic solvents. The easily modifiable surface of the microcapsules allows for its subsequent functionalization with capture molecules, such as antibodies, which ensures specific and selective interaction with cells, including tumor cells, with the use of the bioconjugation technique developed here. We obtained stable water-soluble nanolabels based on QDs whose surface was modified with polyethylene glycol (PEG) derivatives and determined their colloidal and optical characteristics. The obtained nanocrystals were used to encode polyelectrolyte microcapsules optically. The microcapsule surface was modified with humanized monoclonal antibodies (Abs) recognizing a cancer marker, epidermal growth factor receptor (EGFR). The possibility of effective, specific, and selective delivery of the microcapsules to tumor cells expressing EGFR has been demonstrated. The results show that the QD-encoded polyelectrolyte microcapsules functionalized with monoclonal Abs against EGFR can be used for targeted imaging and diagnosis.

Nanoassembly and Multiscale Computation of Multifunctional Optical-Magnetic Nanoprobes for Tumor-Targeted Theranostics.

Gold nanorods, mesoporous silica, gadolinia, folic acid, and polyethylene glycol (PEG) derivatives have been investigated due to their own advantages in cancer theranostics. However, it remains a great challenge to assemble these components into a stable unity with the diverse and enhanced functionality for more potential applications. Herein, as inspired by the first-principles calculation, a highly stable and safe all-in-one nanoprobe is fabricated via a novel nanoassembly strategy. Multiscale calculations were performed to address the atomistic bonding of a nanoprobe, heat necrosis of a tumor adjacent to the vasculature, and thermal diffusion in a photothermal circumstance, respectively. The nanoprobe gains an 8-fold increase in magnetic resonance imaging (MRI) relaxivity compared to the clinical gadolinium diethylenetriaminepentaacetate, achieving a significant MRI signal in vivo. Conjugated with folate-PEG, the nanoprobe can be effectively absorbed by tumoral cells, obtaining a vivid two-photon cell imaging. A specific multisite scheme for photothermal therapy of a solid tumor is proposed to improve low photothermal efficacy caused by thermal diffusion in a large tumor, leading to the successful cure of the mice with xenograft tumor sized 10-12 mm. In vitro and in vivo toxicity, long-term excretion data, and the recovery of the treated mice demonstrate that the theranostic nanoprobe possesses good biocompatibility and metabolism efficacy.

Pharmacokinetic study of intravenously administered artemisinin-loaded surface-decorated amphiphilic γ-cyclodextrin nanoparticles.

Artemisinin and its derivatives are currently recommended by World Health Organization for the treatment of malaria. Severe malaria requires a parenteral administration of artemisinin-based formulations. However, the effective use of artemisinin is limited by the pharmacokinetic characteristics of the drug (low water solubility, poor bioavailability and short half-life). To overcome some of these drawbacks, artemisinin-loaded surface-decorated nanoparticles were prepared by co-nanoprecipitation of γ-cyclodextrin bioesterified with C10 alkyl chains and polyethylene glycol (PEG) derivatives (polysorbate 80 and DMPE-mPEG2000). Using a single dose (1.5 mg kg-1 or 2 mg kg-1) by intravenous administration, we investigated the in vivo pharmacokinetic properties in healthy rats of two types of artemisinin-loaded nanoparticle formulations, namely, nanosphere and nanoreservoir systems versus an ethanolic-aqueous solution of artemisinin as reference. Significantly enhanced pharmacokinetic parameters were obtained with artemisinin-loaded nanoparticles. In comparison to reference formulation, the geometric mean exposures in plasma (AUC0-t) exhibited 2.35 and 3.26-fold increases when artemisinin was loaded in nanoreservoir and nanosphere systems, respectively. Its plasma half-life increased 4.00 and 6.25-fold and its clearance decreased up to 2.5 and 4.72-fold. Artemisinin was successfully administered intravenously by means of surface-decorated amphiphilic γ-cyclodextrin nanostructures and showed a longer elimination half-life with respect to an artemisinin solution in ethanol. Therefore, these systems are likely to provide significant advantages for the intravenous treatment of severe malaria.

Ruthenium-catalyzed selective hydrosilylation reaction of allyl-functionalized PEG derivatives

Reactions of allyl-functionalized poly(ethylene glycol) (PEG) derivatives with alkoxysilanes proceeded efficiently to furnish the corresponding hydrosilylated products in good to excellent yields using a ruthenium catalyst, [RuCl2(nbd)]n. A preliminary mechanistic study supported the pivotal role of the PEG moiety, which coordinated to the ruthenium atom during the reaction to achieve high reaction selectivity. This method may be applicable to the synthesis of various PEGs with a silyl terminus, which is useful as biocompatible and low toxic silane coupling agents.

Allergic Contact Dermatitis to Operating Room Scrubs and Disinfectants.

Both surgical personnel and patients undergoing procedures are exposed regularly to different antiseptic chemicals in various forms. Little is known about the ingredients in these antiseptics and the risk these products may provoke allergic contact dermatitis. The aim of the study was to identify and characterize common allergens in surgical scrubs and patient surgical cleansers that health care workers and surgical patients may encounter in the perioperative period. DailyMed website was searched using numerous terms for surgical disinfectants. Products used for health care worker handwashing/scrubbing or patient surgical cleansing/disinfecting were included. Each product's ingredients were recorded; those found on the 2017 American Contact Dermatitis Society (ACDS) Core Allergen Series were noted from each product. A total of 1940 products were identified, of which 267 were included in the analysis. A total of 66.3% contained iodine, 25.8% contained chlorhexidine digluconate, and 2.6% contained chloroxylenol. Within the group analyzed, 1586 ingredients were identified. Of these, 241 were ACDS Core Series allergens. Most products contained a single ACDS allergen. There were significant differences in allergens based on product type and active ingredient, with iodine-containing products having the fewest number of allergens. The most common ACDS allergens found were cocamide diethanolamide (22.5%), fragrance (21.7%), lanolin (19.5%), propylene glycol (6.7%), alkyl glucosides (6.0%), and sorbic acid derivatives (5.6%).

Nanoparticles With a Specific Size and Surface Charge Promote Disruption of the Secondary Structure and Amyloid-Like Fibrillation of Human Insulin Under Physiological Conditions.

Nanoparticles attract much interest as fluorescent labels for diagnostic and therapeutic tools, although their applications are often hindered by size- and shape-dependent cytotoxicity. This cytotoxicity is related not only to the leak of toxic metals from nanoparticles into a biological solution, but also to molecular cytotoxicity effects determined by the formation of a protein corona, appearance of an altered protein conformation leading to exposure of cryptic epitopes and cooperative effects involved in the interaction of proteins and peptides with nanoparticles. In the last case, nanoparticles may serve, depending on their nature, as centers of self-association or fibrillation of proteins and peptides, provoking amyloid-like proteinopathies, or as inhibitors of self-association of proteins, or they can self-assemble on biopolymers as on templates. In this study, human insulin protein was used to analyze nanoparticle-induced proteinopathy in physiological conditions. It is known that human insulin may form amyloid fibers, but only under extreme experimental conditions (very low pH and high temperatures). Here, we have shown that the quantum dots (QDs) may induce amyloid-like fibrillation of human insulin under physiological conditions through a complex process strongly dependent on the size and surface charge of QDs. The insulin molecular structure and fibril morphology have been shown to be modified at different stages of its fibrillation, which has been proved by comparative analysis of the data obtained using circular dichroism, dynamic light scattering, amyloid-specific thioflavin T (ThT) assay, transmission electron microscopy, and high-speed atomic force microscopy. We have found important roles of the QD size and surface charge in the destabilization of the insulin structure and the subsequent fibrillation. Remodeling of the insulin secondary structure accompanied by remarkable increase in the rate of formation of amyloid-like fibrils under physiologically normal conditions was observed when the protein was incubated with QDs of exact specific diameter coated with slightly negative specific polyethylene glycol (PEG) derivatives. Strongly negatively or slightly positively charged PEG-modified QDs of the same specific diameter or QDs of bigger or smaller diameters had no effect on insulin fibrillation. The observed effects pave the way to the control of amyloidosis proteinopathy by varying the nanoparticle size and surface charge.

High-Pressure Studies on the Chain and Segmental Dynamics of a Series of Poly(propylene glycol) Derivatives

In this paper, we report comprehensive studies on the molecular dynamics of a series of poly(propylene glycol) (PPG) derivatives characterized by three different terminal groups and various molecul...

Understanding the Influence of a Bifunctional Polyethylene Glycol Derivative in Protein Corona Formation around Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles are one of the most prominent agents used in theranostic applications, with MRI imaging the main application assessed. The biomolecular interface formed on the surface of a nanoparticle in a biological medium determines its behaviour in vitro and in vivo. In this study, we have compared the formation of the protein corona on highly monodisperse iron oxide nanoparticles with two different coatings, dimercaptosuccinic acid (DMSA), and after conjugation, with a bifunctional polyethylene glycol (PEG)-derived molecule (2000 Da) in the presence of Wistar rat plasma. The protein fingerprints around the nanoparticles were analysed in an extensive proteomic study. The results presented in this work indicate that the composition of the protein corona is very difficult to predict. Proteins from different functional categories—cell components, lipoproteins, complement, coagulation, immunoglobulins, enzymes and transport proteins—were identified in all samples with very small variability. Although both types of nanoparticles have similar amounts of bonded proteins, very slight differences in the composition of the corona might explain the variation observed in the uptake and biotransformation of these nanoparticles in Caco-2 and RAW 264.7 cells. Cytotoxicity was also studied using a standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Controlling nanoparticles’ reactivity to the biological environment by deciding on its surface functionalization may suggest new routes in the control of the biodistribution, biodegradation and clearance of multifunctional nanomedicines.

Not always what closes best opens better: mesoporous nanoparticles capped with organic gates

ABSTRACT Four types of calcined MCM-41 silica nanoparticles, loaded with dyes and capped with different gating ensembles are prepared and characterized. N1 and N2 nanoparticles are loaded with rhodamine 6G and capped with bulky poly(ethylene glycol) derivatives bearing ester groups (1 and 2). N3-N4 nanoparticles are loaded with sulforhodamine B and capped with self-immolative derivatives bearing ester moieties. In the absence of esterase enzyme negligible cargo release from N1, N3 and N4 nanoparticles is observed whereas a remarkable release for N2 is obtained most likely due to the formation of an irregular coating on the outer surface of the nanoparticles. In contrast, a marked delivery is found in N1, N3, and N4 in the presence of esterase enzyme. The delivery rate is related to the hydrophilic/hydrophobic character of the coating shell. The use of hydrophilic poly(ethylene glycol) derivatives as gating ensembles on N1 and N2 enables an easy access of esterase to the ester moieties with subsequent fast cargo release. On the other hand, the presence of a hydrophobic monolayer on N3 and N4 partially hinders esterase enzyme access to the ester groups and the rate of cargo release was decreased.

Influence of synthesized pyridine and tetra ethylene glycol derivatives in poly (vinylidene fluoride)/poly (ethylene oxide) with Ti coated back contact dye-sensitized solar cells

A newly designed back contact dye-sensitized solar cells (BCDSSC) with back contact electrode (BCE) of Ti for electron collection, is placed on the side opposite to side of light irradiation on TiO2 with synthesized organic compound doped poly (ethylene oxide)/poly (vinylidene fluoride)/potassium iodide/Iodine polymer electrolyte was introduced for the application of solar energy to electric energy conversion. The surface morphology of the polymer electrolyte study was carried out by SEM, XRD, DSC, DTA, TGA and it proves that the synthesized organic compounds enhances the amorphous nature of the polymer due to well coordinate with redox couple. The movement of I−/I3− characterized with UV–vis spectroscopy proves of organic compound with Iodine in the redox couple to decrease the sublimation of iodine. The conductivity of polymer/potassium iodide/iodine/organic compound shows high conductivity of 4.9 × 10−4 S cm−1 and it confirms that the importance of synthesized organic compounds in polymer electrolyte. The TiO2/Ti (BCE)/N3dye/PEO/PVdF/Potassium iodide/Iodine/PDSD/Pt compounds yielded an efficiency of 8.9% under illumination of 70 mW cm−2 at A.M. 1.5.

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole-cyclodextrin interaction.

We propose a two-step ligand exchange for the selective end-functionalization of gold nanorods (AuNR) by thiolated cyclodextrin (CD) host molecules. As a result of the complete removal of the precursor capping agent cetyltrimethylammonium bromide (CTAB) by a tetraethylene glycol derivative, competitive binding to the host cavity was prevented, and reversible, light-responsive assembly and disassembly of the AuNR could be induced by host–guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four cycles. By the introduction of AAP, previous disassembly limitations based on the photostationary states of azobenzenes could be solved. The combination photoresponsive interaction and selectively end-functionalized nanoparticles shows significant potential in the reversible self-assembly of inorganic–organic hybrid nanomaterials.

The Impact of Molecular Weight on the Behavior of Poly(propylene glycol) Derivatives Confined within Alumina Templates

In this paper, we explored the influence of both the variation in the molecular weight (Mn = ∼400, 2000, 4000 g/mol) and the terminal groups (hydroxyl, amino, and methoxy) on the molecular dynamics of poly(propylene glycols) confined within anodic aluminum oxide membranes of different pore diameters. All confined samples revealed the presence of two glass transition temperatures related to the vitrification of two, core and interfacial, fractions of polymers. As found, the glass transition temperature of PPG adsorbed on the pore walls increases with a decrease in polymer Mn and scales with the H-bonding ability of a given material. Surprisingly, the glass transition temperature of the core macromolecules decreases with respect to the bulk sample with increasing Mn. To gain insight into the observed quite unexpected anti-correlated behavior of both Tg values, we performed the additional contact angle and surface tension measurements together with the annealing experiments. As shown, there were no differenc...

Nanocarriers of Fe3O4 as a Novel Method for Delivery of the Antineoplastic Agent Doxorubicin Into HeLa Cells in vitro.

Here we report the synthesis and in vitro characterization of a redox-sensitive, magnetically inducible nanoparticle carrier system based on the doxorubicin (DOX) drug delivery model. Each quantal nanocarrier unit consists of a magnetite Fe3O4 nanoparticle core that is further encapsulated in self-assembled micelles of the redox-responsive polyethylene glycol derivative, DSPE-SS-mPEG. The nanocarrier system was prepared using a combination of ultrasonication and dialysis to produce the microenvironment sensitive delivery system. The final synthesized and DOX-loaded magnetic nanocarriers had an average size of ~150 nm when assembled with a 6.9% DOX payload. The release rate of DOX from these redox-responsive magnetic nanocarriers was shown to be accelerated in vitro when in the presence of glutathione (GSH). Furthermore, we demonstrated that more redox-responsive magnetic nanocarriers could be taken up by HeLa cells when a local magnetic field was applied. Once internalized within a cell, the micelles of the outer nanocarrier complex were broken down in the presence of higher concentrations of GSH, which accelerated the release of DOX. This produces a particle with dual operating characteristics that can be controlled via a specific cellular environment coupled with an exogenously applied signal in the form of a magnetic field triggering release.

Stereoselective Aldol Additions of Glycolic Acid and Its Derivatives

This review gives a comprehensive overview of aldol additions of glycolic acid derivatives to achiral aldehydes and acetals affording α,β-dihydroxycarboxylic acids or derivatives thereof. The focus is on simple diastereoselectivity. A selection of related aldol additions is also presented: aldol additions of glycolic acid derivatives to ketones with two different substituents and aldol additions of α-substituted glycolic acid derivatives.1 Introduction1.1 Organization of this Review1.2 Outside the Scope of this Review: Aldol Additions Giving α,β-Dihydroxyaldehydes and α,β-Dihydroxyketones Diastereoselectively1.3 Non-Aldol Routes to Diastereomerically Pure α,β-Dihydroxycarboxylic Acid Derivatives2 Aldol Additions of Glycolic Acid (Derivative) Enolates to Aldehydes2.1 Aldol Additions of Glycolate Enolates (‘Glycolic Acid Dianions’)2.2 Aldol Additions of Glycolic Ester Enolates2.3 Aldol Additions of Glycolic Thioester Enolates2.4 Aldol Additions of Glycolimide Enolates2.5 Aldol Additions of Glycolamide Enolates2.6 Mukaiyama Aldol Additions of Silyl Ketene Acetals of Glycolic Esters­ and Thioesters2.7 Aldol Additions of Glycoloyl Chlorides via Acyl Ammonium Enolates3 Aldol-Providing Substitutions of Glycolimide Enolates in Acetals4 Additions Related to Aldol Additions of Glycolic Acid Derivative Enolates to Aldehydes4.1 Selected Simply Diastereoselective Aldol Additions of Enolates of Glycolic Acid Derivatives to Ketones with Two Different Substituents4.2 Simply Diastereoselective Aldol Additions of Enolates of Glycolic Acid Derivatives with a Methyl Substituent at C-α (Lactic Acid Derivatives)5 Conclusion