Acid Monomers Research Articles

Fabrication of pH responsive hydrogel blends of chondroitin sulfate/pluronic F-127 for the controlled release of ketorolac: its characterization and acute oral toxicity study

Objective Ketorolac tromethamine (KT), selected as a model drug, is used in management of moderate to severe acute pain. It has a short half-life (∼5.5 h) and requires frequent dose administration when needed for longer period of time. In our current project, we designed pH responsive hydrogel blends of chondroitin sulfate/pluronic F-127 (CS/Pl) for the controlled release of ketorolac. Methods Hydrogel blends were fabricated using free radical polymerization reaction technique utilizing different ratios of chondroitin sulfate (CS) (polymer) and pluronic F-127 (polymer), acrylic acid (monomer), N,N′-methyl-bisacrylamide (MBA) (cross-linker), initiator ammonium persulfate (APS) and tween-80 (surfactant). The fabricated hydrogel blends were studied and evaluated for pH responsiveness, swelling, water absorbency, in vitro drug release, and morphological characteristics such as SEM, XRD, FTIR, and TGA/DSC. Acute toxicity study was performed on rabbits. Results Maximum swelling and water absorbency were shown by CS/Pl blends being significantly greater at 7.4 (basic pH) than in 1.2 (acidic pH). In vitro dissolution demonstrated pH responsive controlled KT release following zero order at higher pH (7.4) medium up to 36 h. FTIR studies confirmed the structures of our blends; SEM results showed porous framework; thermal studies revealed higher stability of hydrogels than the individual polymers; and XRD confirmed the nature of our blends. Toxicity study revealed the nontoxic nature of the hydrogel blends. Conclusion The prepared CS/Pl hydrogels demonstrated stimuli-controlled release with delivery of drug for prolonged period of time and thus can minimize dosing frequency, safe drug delivery, increased patient compliance and easiness.

Hollow natural rubber latex particles as bio-based alternative white pigment for coating applications

Due to the broad particle size distribution as well as non-spherical shape of natural rubber (NR) latex particles, the non-collapse hollow NR latex particles (HL-NRPs) with well-defined void structure were developed aiming to use as an eco-friendly white pigment/additive for coatings. These hybrid HL-NRPs were prepared via the seeded emulsion polymerization of methyl methacrylate/divinylbenzene/acrylic acid (MMA/DVB/AA) monomers on NR core particles in one-pot. Using cumene hydroperoxide (CHP)/tetraethylene pentamine (TEPA) as a redox initiator, the copolymerization occurred at the particle/water interface. Without seed removal, a single void inside NRP was in situ formed by the phase separation process. Hydrophobic and elastic NR became the inner wall which strengthened the HL particles. Whereas its indigenous stabilizers, i.e., proteins-lipids, allowed the osmosis from the aqueous medium to further expand the void. The proposed mechanism was illustrated using oleic acid (OA) as a model fatty acid for non-rubber substances. Since the multiple light scattering inside the hollow structure could enhance their refractive index, the optical performance of HL-NRPs as a low-density opacifying agent in poly(vinyl alcohol) matrix, was examined using UV-Vis spectroscopy. Results showed that the HL-NRPs-based films exhibited high blocking ability over UV and visible regions. Moreover, the HL-NRPs coated with chitosan (CS) enabled these nanocomposites to adsorb the formaldehyde vapor. For sustainable development, HL-NRPs/CS could potentially be a green alternative white pigment/additive for coatings.

Study on the synthesis and properties of an environmentally friendly water treatment agent

An environment-friendly and effective polymer IA/SMAS was synthesized via a green method, the IA/SMAS as an effective scale inhibitor. In addition, explained its possible scale inhibition mechanism. The long-term application of phosphorus-containing or nitrogen-containing water treatment agents can easily lead to the eutrophication of water bodies. Here, a random copolymer IA/SMAS was synthesized by itaconic acid (IA) and sodium methacrylate sulfonate (SMAS) monomer by the aqueous polymerization method. The optimal synthesis conditions were as follows: a raw material mass ratio (IA:SMAS) of 2:1, a temperature of 95 °C and a reaction time of 6 h. In addition, ammonium persulfate and isopropanol were both added at 5 % of the total raw material mass. The copolymer IA/SMAS was characterized by infrared spectroscopy (IR), elemental analysis, nuclear magnetic resonance (NMR), field emission scanning electron microscopy (FESEM), and EDS. Its molecular weight and distribution were analyzed by gel chromatography (GPC). Static methods were used to evaluate copolymers and their performance in synergy with electrostatic fields. The scale inhibition mechanism of the copolymer and its synergistic effect with electrostatic field were also studied by a scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the copolymer had excellent scale inhibition performance for calcium carbonate and good dispersion effect on iron oxide. The addition of the electrostatic field improved the scale inhibition performance of IA/SMAS copolymer by 16 %. Thus, the copolymer is a phosphorus-free and nitrogen-free water treatment agent that achieves excellent performance and can significantly disrupt the surface morphology and crystalline structures of crystals.

Photophysical Properties of Linear, Net-structured and Branched Polybenzimidazoles.

Polybenzimidazoles with three different network structures are synthesized by condensation polymerization between the conventional monomer 3,3'-Diaminobenzidine and three different acid monomers. The synthesised polymer networks are characterized using several characterization techniques such as FT-IR, powder XRD, HR-SEM and TG-DTA analyses. The polybenzimidazoles are amorphous in nature with excellent thermal stability up to 450 ºC. The photophysical properties of polybenzimidazoles are studied using UV-visible absorption and Emission spectral techniques. Further, the excited state photoluminescence decay time measurement shows a functional group dependant decay behaviour. All the three polymers display narrow optical band gap energy and could be applied as a material for solar energy conversion and semiconductors.

An Overview into Polyethylene Terephthalate (PET) Hydrolases and Efforts in Tailoring Enzymes for Improved Plastic Degradation.

Plastic or microplastic pollution is a global threat affecting ecosystems, with the current generation reaching as much as 400 metric tons per/year. Soil ecosystems comprising agricultural lands act as microplastics sinks, though the impact could be unexpectedly more far-reaching. This is troubling as most plastic forms, such as polyethylene terephthalate (PET), formed from polymerized terephthalic acid (TPA) and ethylene glycol (EG) monomers, are non-biodegradable environmental pollutants. The current approach to use mechanical, thermal, and chemical-based treatments to reduce PET waste remains cost-prohibitive and could potentially produce toxic secondary pollutants. Thus, better remediation methods must be developed to deal with plastic pollutants in marine and terrestrial environments. Enzymatic treatments could be a plausible avenue to overcome plastic pollutants, given the near-ambient conditions under which enzymes function without the need for chemicals. The discovery of several PET hydrolases, along with further modification of the enzymes, has considerably aided efforts to improve their ability to degrade the ester bond of PET. Hence, this review emphasizes PET-degrading microbial hydrolases and their contribution to alleviating environmental microplastics. Information on the molecular and degradation mechanisms of PET is also highlighted in this review, which might be useful in the future rational engineering of PET-hydrolyzing enzymes.

Synthesis of Polylactic Acid Oligomers for Broad-Spectrum Antimicrobials.

Infectious microbial diseases are a major public health hazard, calling for more innovative antimicrobials. Herein, polylactic acid (PLA) oligomers have been explored and reported as a bio-safe and eco-friendly functional antimicrobial agent against pathogens, such as viruses (H1N1, H3N2, and SARS-CoV-2), bacteria (E. coli, S. aureus, K. pneumoniae, MRSA), and fungi (C. albicans). The PLA oligomers were prepared by direct catalyst-free condensation polymerization of l-lactic acid monomers and characterized by FT-IR and 1H-NMR. The antiviral results demonstrate that PLA oligomers possess robust (inhibiting rate > 99%) and rapid (<20 min) antiviral activity against two pandemic ssRNA viruses, including influenza A virus (IAV) and coronavirus (CoV). Furthermore, the PLA oligomers exhibit high antibacterial activities against both Gram negative (G−) and Gram positive (G+) bacteria. The PLA oligomers also perform efficiently in killing a large amount of C. albicans as high as 105 cfu/mL down to zero at the concentration of 10 mg/mL. Thus, the broad-spectrum antimicrobial activity endowed the PLA oligomers with a promising biocidal option, except antibiotics in a wide range of applications, such as medical textiles, food preservation, water disinfection, and personal hygiene, in light of their unique biodegradability and biocompatibility.

From Peptide Nucleic Acids to Supramolecular Structures of Nucleic Acid Derivatives.

Nucleic acids play a pivotal role in life processes. The endeavours to shed light on the essential properties of these intriguing building blocks led us to the synthesis of different analogues and the investigation of their properties. First various peptide nucleic acid monomers and oligomers have been synthesized, using an Fmoc/acyl protecting group strategy, and their properties studied. The serendipitous discovery of a side reaction of coupling agents led us to the elaboration of a peptide sequencing method. The capricious behaviour of guanine derivatives spurred the determination of their substitution pattern using 13 C, 15 N NMR, and mass spectrometric methods. The properties of guanines initiated the logical transition to the study of supramolecular systems composed of purine analogues. Thus, xanthine and uracil derivatives have been obtained and their supramolecular self-assembly properties scrutinized in gas, solid, and liquid states and at solid-liquid interfaces.

Influence of the graft-copolymerized hydrophilic lignin content on the structure and mechanical properties of gel-spun poly(vinyl alcohol) composite fibers

Lignin is a cost-effective, biobased filler for the fabrication of high-performance poly(vinyl alcohol) (PVA) composite fibers that increases fiber performance and sustainability. However, amorphous and hydrophobic lignin often have poor compatibility with semi-crystalline and hydrophilic PVA matrixes. Moreover, aggregation of the filler at high content could occur to impede the effectiveness of lignin as a reinforcing filler. To address these issues, modified organosolv lignin (OL24) with hydrophilicity was obtained from the graft copolymerization of organosolv lignin and acrylic acid monomers after 24 h of reaction and later used as a reinforcing filler at different ratios of 0%, 5%, 10%, 20% and 30% in PVA to achieve composite fibers with better compatibility between the filler and matrix, and enhanced sustainability. The influence of the graft-copolymerized hydrophilic lignin content on the structure and mechanical performance of gel-spun PVA composite fibers was fundamentally investigated. The results showed that 10% OL24/PVA fiber had outstanding mechanical properties with an average tenacity of 7.8 cN/dtex (tensile strength of 1.02 GPa), average specific modulus of 143.21 cN/dtex (Young’s modulus of 18.62 GPa) and toughness of 20.90 J/g. It was concluded that the higher orientation, larger crystal size and stronger hydrogen bonding in the composite fiber structure contributed to the good fiber mechanical performance. These results offer technical support for the mechanical performance optimization of lignin-reinforced polymeric high-performance fibers.

Macrocyclic Triazolopeptoids: A Promising Class of Extended Cyclic Peptoids.

Head-to-tail cyclization of linear oligoamides containing 4-benzylaminomethyl-1H-1,2,3-triazol-1-yl acetic acid monomers afforded a novel class of "extended macrocyclic peptoids". The identification of the conformation in solution for a cyclodimer and the X-ray crystal structure of a cyclic tetraamide are reported.

Enone as TFO Linker: Synthesis and Parallel DNA Triplex Stability Evaluation

AbstractTwo new intercalated nucleic acid monomers, X and Y, possessing enone as linker have been synthesized. The monomers were incorporated into 14‐mer polypyrimidine strand to act as triplex‐forming oligonucleotide (TFO). The thermal stabilities of the formed parallel triplexes, parallel and antiparallel duplexes were evaluated to show high stability of its parallel triplexes at pH 5.0 and pH 7.2, while limited stability at pH 6.0 compared to unmodified triplex. The architectures of enone linker are shown to disturb the planarity of its parallel and antiparallel duplexes and consequently the π‐π stacking ability with the neighboring nucleobases. The data was confirmed by molecular dynamics simulation and binding energy calculations. Characteristic fluorescence spectra were also investigated to show the ability of X and Y containing TFO to discriminate parallel triplex from parallel and antiparallel duplex.

A Strand Entangled Supramolecular PANI/PAA Hydrogel Enabled Ultra-Stretchable Strain Sensor.

Hydrogel electronics have attracted growing interest for emerging applications in personal healthcare management, human-machine interaction, etc. Herein, a "doping then gelling" strategy to synthesize supramolecular PANI/PAA hydrogel with a specific strand entangled network is proposed, by doping the PANI with acrylic acid (AA) monomers to avoid PANI aggregation. The high-density electrostatic interaction between PAA and PANI chains serves as a dynamic bond to initiate the strand entanglement, enabling PAA/PANI hydrogel with ultra-stretchability (2830%), high breaking strength (120kPa), and rapid self-healing properties. Moreover, the PAA/PANI hydrogel-based sensor with a high strain sensitivity (gauge factor = 12.63), a rapid responding time (222ms), and a robust conductivity-based sensing behavior under cyclic stretching is developed. A set of strain sensing applications to precisely monitor human movements is also demonstrated, indicating a promising application prospect as wearable devices.

A Novel Chronoimpedimetric Cytosine Modified Molecularly Imprinted Sensor for Label-Free Detection of 8-Hydroxydeoxyguanosine in Urine Samples

First time in the literature, we imprinted 8-hydroxyguanosine (8OHG) to engineer an impedimetric sensor on a polymer from three different main non-covalent structures. Considering the chemical structure of the molecule and its potential non-covalent bonding behaviors, we designed a special electrode with molecular imprinting technology (MIT). Therefore, 8OHG, which serves as an important biomarker of oxidative stress, was imprinted on an electrode to form an 8OHG sensor. In this imprinting method, firstly, a gold electrode was modified with Cytosine-1yl-acetic acid (CAA) to increase selectivity and form DNA hydrogen bond-like structures. Afterward, pyrrole and aminophenyl boronic acid monomers were polymerized from three different points by electropolymerization, and a selective and sensitive sensor technology was developed. 8OHG measurement was carried out impedimetrically in six minutes (R2 value in the range of 500–10000 pg ml−1 is 0.9928 ± 0.006). LOD and LOQ was calculated 155.8 pg ml−1 and 472 pg ml−1, respectively. In conclusion, a sensitive, low-cost, fast and innovative technique with higher selectivity has been introduced. We believe that novel imprinting techniques will provide the important potential for MIP techniques for medical diagnostics.

Synthesis and Characterization of a Novel Dual-Responsive Nanogel for Anticancer Drug Delivery.

In this study, to reduce the side effects of anticancer drugs and also to increase the efficiency of current drug delivery systems, a pH and temperature-responsive polymeric nanogel was synthesized by copolymerization of N-vinylcaprolactam (VCL) and acrylic acid (AA) monomers (P(VCL-co-AA)) with a novel cross-linker, triethylene glycol dimethacrylate (TEGDMA), as a biocompatible and nontoxic component. The structural and physicochemical features of the P(VCL-co-AA) nanogel were characterized by FT-IR, DLS/Zeta potential, FE-SEM, and 1HNMR techniques. The results indicated that spherical polymeric nanogel was successfully synthesized with a 182 nm diameter. The results showed that the polymerization process continues with the opening of the carbon-carbon double bond of monomers, which was approved by C-C band removing located at 1600 cm−1. Doxorubicin (Dox) as a chemotherapeutic agent was loaded into the P(VCL-co-AA), whit a significant loading of Dox (83%), and the drug release profile was investigated in the physiological and cancerous site simulated conditions. P(VCL-co-AA) exhibited a pH and temperature-responsive behavior, with an enhanced release rate in the cancerous site condition. The biocompatibility and nontoxicity of P(VCL-co-AA) were approved by MTT assay on the normal human foreskin fibroblasts-2 (HFF-2) cell line. Also, Dox-loaded P(VCL-co-AA) had excellent toxic behavior on the Michigan Cancer Foundation-7 (MCF-7) cell line as model cancerous cells. Moreover, Dox-loaded P(VCL-co-AA) had higher toxicity in comparison with free Dox, which would be a vast advantage in reducing Dox side effects in the clinical cancer treatment applications.

КОМПОЗИЦИОННЫЕ МАТЕРИАЛЫ НА ОСНОВЕ АЛЮМОФТОРСИЛИКАТНОГО СТЕКЛА

The article presents the results of an analytical review of the literature on glass ionomer (glass polyalkenate) cements, which are widely used in dentistry. This materials consist from the powder and liquid, which form a plastic mass at mix that sets to form a solid. The composition of the powder and liquid components of glass ionomer cement has been analyzed. The solid component is powdered calcium or strontium aluminofluorosilicate glass, the liquid component is an aqueous solution of acrylic acid homopolymer or its copolymer with methylene-succinic acid, maleic acid and other monomers. Information about the range of compositions of aluminofluorosilicate glass, raw materials and melting process parameters are represented. An analysis of the curing mechanism of this dental material is also carried out. Acid-base interaction and cross-linking of polymeric acid molecules with ions extracted from glass occur at mixing the powder and liquid components. The final microstructure of the hardened glass ionomer cement is partially decomposed glass particles embedded in a matrix of calcium and aluminum polyalkenoates and coated with a layer of silica gel. The information presented in this review may be useful for a comprehensive understanding by dentists, developers of dental materials and scientific groups conducting research in this subject area of the physicochemical process of curing this material.

Conformers of Vanillic Acid and Its Monohydrate: A Rotational Spectroscopic and Theoretical Study.

Organic acids are released during wildfire combustion and can influence aerosol formation and growth. Conformational flexibility is thought to be advantageous in stabilizing the precritical nucleus in the process of aerosol particle formation and allowing for further complexation with other atmospheric constituents. We describe here a study of the conformational flexibility of vanillic acid and its monohydrate using electronic structure calculations and Fourier transform microwave spectroscopy. Computationally, 12 and 28 conformers were found for the monomer and monohydrate, respectively. The two lowest energy conformers of both the vanillic acid monomer and the vanillic acid-water complex could be experimentally identified. The deviation between experimental and theoretical rotational constants determined at the MP2/aug-cc-pVTZ and DFT B3LYP-D3(BJ)/def2-TZVP levels of theory is less than 1%. No tunneling splittings were observed, which suggests a relatively high barrier to methyl internal rotation, in agreement with other, previously studied vanillin derivatives. Furthermore, no c-type transitions could be observed for the vanillic acid monomer, in agreement with the computed zero c-dipole moment component of the two lowest energy structures. For the monohydrate the absence of c-type transitions is rationalized by averaging over a large amplitude motion involving the free H atom of the water unit. From the theoretical structures, it is apparent that intramolecular hydrogen bonds play a significant role in stabilizing the lowest energy conformers. To further characterize the intramolecular interactions in the monomer and intra- and intermolecular interactions in the monohydrate, quantum theory of atoms-in-molecules (QTAIM), noncovalent interactions (NCI), and intrinsic bond strength index (IBSI) analyses were performed. The atmospheric abundance of the vanillic acid monohydrate relative to the monomer was evaluated to assess its atmospheric significance.

Methane Production by Facultative Anaerobic Wood-Rot Fungi via a New Halomethane-Dependent Pathway.

ABSTRACTThe greenhouse gas methane (CH4) is of pivotal importance for Earth’s climate system and as a human energy source. A significant fraction of this CH4 is produced by anaerobic Archaea. Here, we describe the first CH4 production by facultative anaerobic wood-rot fungi during growth on hydroxylated/carboxylated aromatic compounds, including lignin and lignite. The amount of CH4 produced by fungi is positively correlated with the amount of CH3Cl produced during the rapid growth period of the fungus. Biochemical, genetic, and stable isotopic tracer analyses reveal the existence of a novel halomethane-dependent fungal CH4 production pathway during the degradation of phenol and benzoic acid monomers and polymers and utilization of cyclic sugars. Even though this halomethane-dependent pathway may only play a side role in anaerobic fungal activity, it could represent a globally significant, previously overlooked source of biogenic CH4 in natural ecosystems.IMPORTANCE Here, we demonstrate that wood-rot fungi produce methane anaerobically without the involvement of methanogenic archaea via a new, halomethane-dependent pathway. These findings of an anaerobic fungal methane formation pathway open another avenue in methane research and will further assist with current efforts in the identification of the processes involved and their ecological implications.

Biological Activity and Optical Sensor Properties of Green Synthesis Polymer

AbstractIn this study, 4‐amino‐3‐hydroxy‐1‐naphthalene sulfonic acid (Monomer) was converted to its enzyme‐catalyzed oxidative polymerization (Poly‐enz) in dioxane solvent by horseradish peroxidase enzyme (HRP) in the presence of hydrogen peroxide as oxidant. For the analysis of the monomer and its synthesized Poly‐enz, 1H‐NMR, 13C‐NMR, FT‐IR, TGA, and SEM measurements were determined. In addition, the optical ion sensor properties of Poly‐enz against metals such as Ag+, Cd2+, Co2+, Hg2+, Ni2+, Pb2+, Zn2+, Cu2+ were examined with UV‐Vis spectrophotometer. It was observed that Cu metal showed sensory properties. DNA cleavage and DNA binding activities of monomer and Poly‐enz were done using by agarose gel electrophoresis and UV‐Vis methods, respectively. It was seen that the Poly‐enz interacted with DNA electrostatically. This enzymatic polymer was found to cleave pBR322 plasmid DNA both hydrolytically and oxidatively as well. The antioxidant activities of the compounds were examined by three different methods (DPPH, ABTS, FRAP) and it was found that the Poly‐enz showed high antioxidant activity compared to its monomer. Antimicrobial activities were studied against various bacterial and yeast cultures by the minimum inhibition concentration (MIC) method. It was observed that the antimicrobial activities of the enzymatic polymer in different microorganisms increased depending on the concentration.

Direct Observation and Quantitative Measurement of OH Radical Desorption During the Ultraviolet Photolysis of Liquid Nonanoic Acid.

Ultraviolet (UV) photolysis of fatty acid surfactants─which cover the surfaces of atmospheric liquid aerosols and are found in the oceans─such as nonanoic acid (NA) has recently been suggested as a source of hydroxyl (OH) radicals in the troposphere. We used laser-induced fluorescence to directly observe OH radicals desorbed from the surface of neat liquid NA as a primary photoproduct following 213 nm irradiation. The upper limit of photoreaction cross section for the OH radical desorption was estimated to be 9.0(4.1) × 10-22 cm2, which is only 1.2 ± 0.8% of the photoreaction cross section established for the photolysis of gas-phase acetic acid monomers. Vibrational sum-frequency generation spectroscopy for liquid NA revealed the hydrogen-bonded, cyclic, dimer structure of the NA molecules at the liquid surface. This dimerization can inhibit the formation of OH radicals and lead the present low photochemical reactivity of liquid NA.

Tyrosine, Phenylalanine, and Tryptophan Undergo Self-Aggregation in Similar and Different Manners

Phenylalanine, tyrosine, and tryptophan are aromatic amino acids, and they are of high interest in both health science and biotechnology. These amino acids form organized structures, like fibrils and nanotubes. Although these amino acids belong to the same family, they still differ from each other with respect to polarity, hydrophobicity as well as internal structures. In this work, we performed extensive molecular dynamics simulations to investigate the dynamics of the self-aggregations of these amino acids and studied the details of the formed structures. The amino acid monomers placed in water were simulated at a constant temperature. It has been observed that they compose nanostructures with similarities and differences.

Microwave and Computational Study of Pivalic Sulfuric Anhydride and the Pivalic Acid Monomer: Mechanistic Insights into the RCOOH + SO3 Reaction.

The microwave spectrum of pivalic sulfuric anhydride, (CH3)3CCOOSO2OH (PivSA), has been observed by rotational spectroscopy. The compound was formed by the reaction of SO3 with (CH3)3CCOOH (pivalic acid) in a supersonic jet in a manner analogous to that previously observed with other carboxylic acids. Computational analysis indicates that the reaction is best described as a pericyclic process coupled with a 60° rotation of the t-butyl group. Product formation can occur through either a sequential (two-step) or a concerted (one-step) pathway. The former involves an internal rotation of the t-butyl group through a 0.11 kcal/mol barrier followed by the pericyclic reaction that joins the moieties. The latter passes through a second-order saddle point in which the internal rotation and pericyclic reaction occur simultaneously. This path is the most energetically favorable, as the zero-point corrected energy at the saddle point structure is 0.16 kcal/mol below that of a putative (CH3)3CCOOH-SO3 precursor complex. Additional computational work involving a series of carboxylic acids is reported, which explores the effects of gas-phase acidity and basicity of the RCOOH reactant on reaction energetics. These calculations, together with prior experimental and theoretical studies of the acetic and trifluoroacetic derivatives, demonstrate that the basicity of the carbonyl oxygen, not the acidity of the COOH proton, is the important driving factor for the reaction. As a precursor to the experimental work on the title molecule, microwave spectra of the parent and OD forms of the pivalic acid monomer were recorded and are reported here as well. A convenient synthesis of SO3 is also described.