Acid Pendant Groups Research Articles

Synthesis, characterization and applications of poly(styrene-co-divinylbenzene) functionalized with aminophosphinic acid pendant groups as high-performance adsorbents for acetylsalicylic acid

Synthesis, characterization and applications of poly(styrene-co-divinylbenzene) functionalized with aminophosphinic acid pendant groups as high-performance adsorbents for acetylsalicylic acid

Fabrication and characterization of tamarind seed gum based novel hydrogel for the targeted delivery of omeprazole magnesium

The tamarind seed gum based novel hydrogel was fabricated by varying concentration of polymer, monomer and crosslinker for the targeted delivery of omeprazole magnesium at stomach pH of 1.5. The free radical graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid with tamarind seed gum backbone resulted in hydrogel. The formation of sulfonic acid pendant groups in hydrogel was observed by the existence of an infrared absorption band at 1152 cm−1 for SO group. The conversion to semicrystalline nature on incorporation of drug evidenced by powder X-ray diffraction studies with peaks at 2θ = 20.4° 31.5° and 52.2°. The scanning electron microscopy images showed bigger voids which narrowed down for drug loaded matrix, supported by the presence of a peak for magnesium in the energy dispersive X-ray spectroscopy. The greatest swelling was observed at pH 7 with second-order rate constant 1.5371 (g/g)/min and drug release was found to be 97.85 ± 1 % over 1200 min at pH 1.5. The drug release transport was found combination of diffusion and erosion of polymer chain to be super case II diffusion and Hill equation model was good fit. The hydrogel drug conjugate found to be non-toxic at tested concentrations (17 mg/50 mg) on in-vivo testing in Drosophila model.

Effect of amino acid pendant groups on the helical configuration of polyphenylacetylene

In this study, several polyphenylacetylenes (PPAs) derivatives containing amino acid pendant groups were synthesized using a rhodium system catalyst (Rh(nbd)BPh4). The synthesized derivatives of PPAs included single chiral PPA with a single chiral center in the pendant groups and double chiral PPA' with two chiral centers in the pendant groups. The PPA and PPA' showed strong circular dichroism (CD) signals in the main chain absorption region of the UV-vis spectrum, while the monomer showed no CD signals. Furthermore, the PPA and PPA' with different chiral pendant groups showed different Cotton effects in the CD spectra. The results showed that these polymers existed in helical conformation, and the chiral center of the pendant groups affected the polymerization and helical structure of PPAs.

Boronic Acid-Tethered Silk Fibroin for pH-Dependent Mucoadhesion.

Mucus lines all surfaces of the human body not covered by skin and provides lubrication, hydration, and protection. The properties of mucus are influenced by changes in pH that may occur due to physiological conditions and pathological circumstances. Reinforcing the mucus barrier with biopolymers that can adhere to mucus in different conditions can be a useful strategy for protecting the underlying mucosae from damage. In this work, regenerated silk fibroin (silk) was chemically modified with phenyl boronic acid to form reversible covalent complexes with the 1,2- or 1,3-diols. The silk modified with boronic acid pendant groups has an increased affinity for mucins, whose carbohydrate component is rich in diols. These results offer new applications of silk in mucoadhesion, and the ability to bind diols to the silk lays the foundation for the development of silk-based sugar-sensing platforms.

Fully bio-based supramolecular gel based on cellulose nanowhisker gallate by cyclodextrin host-guest chemistry

Nowadays, supramolecular hydrogels have gained special importance and development of versatile approaches for their preparation as well as their new facile characterization strategies has elicited tremendous scientific interest. Herein, we demonstrate that modified cellulose nanowhisker with gallic acid pendant groups (CNW-GA) could effectively bind with CNW grafted with β-Cyclodextrin (CNW-g-β-CD) through HG interaction to form fully biocompatible and low-cost supramolecular hydrogel. Also, we reported an easy and efficient colorimetric characterization method for confirming HG complexation using naked eye. The possibility of this characterization strategy evaluated both experimentally and theoretically using DFT method. Also, phenolphthalein (PP) was used for visual detection of HG complexation. Interestingly, PP undergoes a rearrangement in its structure in presence of CNW-g-β-CD because of HG complexation that turns the purple molecule into a colorless compound in alkaline condition. Addition of CNW-GA to the resulting colorless solution turned the color to purple again which easily confirmed HG formation.

Highly soluble polythiophene-based strontium-doped NiO nanocomposite for effective electrochemical detection of catechol in contaminated water

Water-soluble conductive polymers are crucial for the development of sensor fabrication materials for the detection of water-soluble analytes. Polythiophene was considered as an excellent candidate because of its admirable optoelectronic properties. This work describes the synthesis of strontium-doped NiO nanocomposite (Sr-NiO) with water-soluble polythiophene (P3ThA). Improved interaction between Sr-NiO and polythiophene was achieved with acetic acid pendant group functionalization onto the polymer, and the resultant polymer nanocomposite was examined with various analytical tools. The as-synthesized Sr-NiO@P3ThA nanocomposite was employed as an effective nanocomposite electrode material for the electrochemical detection of ecotoxic catechol (CC). The modified screen-printed carbon electrode (SPCE) exhibited an exceptional electrocatalytic performance because of its synergistic effect of Sr-NiO nanoparticles with water-soluble P3ThA. The Sr-NiO@P3ThA-modified electrode showed the calibration curve for CC detection using the differential pulse voltammetry (DPV) technique, with a linear range of 0.009–14.1 and 14.1–404 µM and a detection limit of 6.5 nM (S/N = 3). Moreover, the Sr-NiO@P3ThA-modified electrode demonstrated good selectivity and sensitivity and was not influenced by interference moieties. The fabricated material was successfully utilized to detect catechol in river water and tap water in Taiwan. Overall, an eco-friendly, water-soluble, simple, sensitive, and selective approach was established to determine catechol contaminations in water resources.

Synthesis of poly(aryl ether)s bearing phosphonated side-chains from phosphonate ester-containing bisphenols

As part of our project research to design aromatic polymers with pendant acid groups, we have paid efforts to synthesize phosphonic acid-containing poly(aryl ether)s (PAEs) from functionalized monomers. To this end, two bisphenol monomers bearing phosphonic ester groups were synthesized. A study of the polymerization reaction via model compound preparation point out specific experimental conditions to prevent side reactions between phosphonic ester functions and phenolate monomers. Based on these experimental optimised conditions, different PAEs with high molecular weights were prepared. Free acid phosphonic groups-containing PAE were obtained by subsequent controlled hydrolysis of phosphonate ester groups.

Ionomers from Step-Growth Polymerization: Highly Ordered Ionic Aggregates and Ion Conduction

Precisely controlling the position of ionic groups along neutral polymer backbones in ionomers has led to novel nanoscale morphologies and promising properties, although the synthetic routes can be quite demanding. Here, we report a series of Li+-containing ionomers directly synthesized from step-growth polymerization of commercially available diol monomers (x = 6 or 12) and dianhydride monomers followed by neutralization with various amounts of lithium salts. The results are nearly precise linear polymers wherein nonpolar segments have precisely 6 or 12 methylene groups, as determined by the diol. The functional segment has two carboxylic acid pendant groups and 6–8 backbone atoms depending on the dianhydride addition. From X-ray scattering, these segmented ionomers exhibit well-defined nanostructures in contrast to the conventional random ionomers. The nearly precise nature of these segmented ionomers does not compromise the morphological ordering. The temperature-dependent ionic conductivities exhibit ...

Mutual influence of gold and silver nanoparticles on Tris-(2,2′bipyridine)-Ru(II) core complexes: Post-functionalization processes, optical and electrochemical investigations

The synthesis, reactivity and properties of a series of four polypyridyl ruthenium complexes have been studied. These complexes were used to post-functionalize preformed 3 nm silver and gold nanoparticles (NPs) in water and in dichloromethane (DCM). We studied the influence of the grafted complexes on the formation process and stability of the colloidal solutions and we investigated the optical and electrochemical properties of the final nanocomposites. Among the series of four ruthenium complexes, three novel heteroleptic complexes (1–3) bearing one pyridine, one amine or two carboxydithioic acid pendant groups were synthesized and reacted with preformed Au-NPs and Ag-NPs. Results were compared to those obtained with the model [Ru(bpy)3]2+ complex (4). The strength of the interaction between the anchoring group and the surface of NPs influenced the size, shape and stability of the final nanocomposites. Polar solvent such as water induced aggregation and lead to unstable nanocomposites. Stationary and time resolved luminescence of grafted nanocomposites (1–3) showed that the luminescence of complexes were completely quenched (lifetime and emission quantum yield) in water by electron transfer processes, moreover electrical measurements rationalize that Ag nanocomposites exhibit the stronger quenching due to a lower oxidation potential. It also showed a current enhancement associated with double layer charging of the metal nanoparticle cores.

Deformation-induced morphology evolution of precise polyethylene ionomers

The morphology evolution during deformation was characterized for a series of lithium neutralized acrylic acid containing linear polyethylenes (PEs). In situ X-ray scattering measurements simultaneously captured the changes in the inter-ionic aggregate peak and amorphous halo during uniaxial elongation. The effects of spacer length between pendant acid groups on the linear PE backbone, fraction of neutralized acid groups, and temperature were examined. This study indicates that the neutralization of the acid-functionalized precise polymers with metal salts significantly increases the melting and glass transition temperatures and improves mechanical properties, while the accessible morphologies remain controlled by the underlying polymer structure. During deformation above the thermal transitions, an anisotropic layered morphology similar to that found in the acid forms with 15 and 21 carbon spacers was observed in the precise ionomers with 9, 15, and 21 carbon spacers. Precise polymers with the highest acid and ionic content corresponding to a 9-carbon spacer have the highest ultimate tensile strength in the melt state due to persistent ionic aggregates. At elevated temperatures strain hardening was observed when significant chain orientation occurred corresponding to an anisotropic layered morphology, indicating some chain mobility through facile aggregate exchange.

Solution-grown crystals of precise acid- and ion-containing polyethylenes

Crystals of precise acid- and ion-containing polyethylenes were prepared from solution. While large pendant groups on polyethylene backbones are typically excluded from the crystalline domain, the precisely-placed acid and ionic functional groups are accommodated into the solution-grown crystals. Polyethylene containing carboxylic acid pendant groups on every 21st carbon atom (p21AA) grows into rectangular shaped crystals with an average thickness of 9 nm, which is 3–4 times the all-trans chain length between the functional groups. This thickness indicates that the carboxylic acid groups are incorporated within the crystals. Electron diffraction images and Raman spectra indicate that p21AA backbones are hexagonally packed with more gauche chain conformations than the polyethylene orthorhombic phase. The precise polyethylene containing geminal carboxylic acid groups placed every 21 carbon atoms (p21gAA) forms irregular-shaped crystals with an average thickness 8 nm. Similar to p21AA, p21gAA incorporates the geminal acid groups into its solution-grown crystals. Surprisingly, the polymer with imidazolium bromide groups on every 21st carbon (p21ImBr) produces remarkably large crystals with thicknesses of 200–900 nm, and widths of 6–12 μm. Finally, we propose a multi-layer stack of adjacent reentry structures that is consistent with the incorporation of large functional groups into the solution-growth crystals of these precise polyethylenes. Interestingly, this stacked structure is distinct from our recent results in melt-crystallized p21AA, where the layers are nearly transverse to the lamellae.

Rapidly Responding pH- and Temperature-Responsive Poly (N-Isopropylacrylamide)-Based Microgels and Assemblies.

Rapidly responding stimuli-responsive materials can have a benefit in a myriad of applications, for example, sensing and biosensing, actuation, and in drug delivery systems. Thermo- and pH-responsive materials have been among the most widely studied, and can be triggered at physiologically relevant temperatures and pH. Here, we have used a “homologous series” of acids based on the acrylic acid (AAc) backbone and incorporated them into N-isopropylacrylamide (NIPAm)-based microgels. Specifically, the acids used were AAc, methacrylic acid (MAAc), ethylacrylic acid (EAAc), and butylacrylic acid (BAAc), which have pKa’s in the range of 4.25–7.4. The resultant microgels were characterized by optical microscopy, and their responsivity to temperature and pH studied by dynamic light scattering. The microgels were subsequently used to generate optical devices (etalons) and their pH and temperature response was also investigated. We found that the devices composed of BAAc-modified microgels exhibit unusually fast response kinetics relative to those of the rest of the devices. We also found that the speed of the response decreased as the length of the acid pendant group decreased, with AAc-modified microgel-based devices exhibiting the slowest response kinetics. Finally, we showed that the kinetics of the device’s temperature response also decreased as the length of the acid pendant group decreased, which we hypothesize is a consequence of the hydrophobicity of the acid groups, that is, increased hydrophobicity leads to faster responses. Understanding this behavior can lead to the rational design of fast responding materials for the applications mentioned above.

Heterogeneous Chain Dynamics and Aggregate Lifetimes in Precise Acid-Containing Polyethylenes: Experiments and Simulations

Melt state dynamics for a series of strictly linear polyethylenes with precisely spaced associating functional groups were investigated. The periodic pendant acrylic acid groups form hydrogen-bonded acid aggregates within the polyethylene (PE) matrix. The dynamics of these nanoscale heterogeneous morphologies were investigated from picosecond to nanosecond timescales by both quasi-elastic neutron scattering (QENS) measurements and fully atomistic molecular dynamics (MD) simulations. Two dynamic processes were observed. The faster dynamic processes which occur at the picosecond timescales are compositionally insensitive and indicative of spatially restricted local motions. The slower dynamic processes are highly composition dependent and indicate the structural relaxation of the polymer backbone. Higher acid contents, or shorter PE spacers between pendant acid groups, slow the structural relaxation timescale and increase the stretching parameter (β) of the structural relaxation. Additionally, the dynamics ...

Preliminary evaluation of PARACEST MRI agents for the detection of nitric oxide synthase

Several paramagnetic chemical exchange saturation transfer magnetic resonance imaging (PARACEST MRI) agents for the potential detection of nitric oxide synthase (NOS) have been synthesized and evaluated. These agents are based on an amino acid- or dipeptide-decorated DOTAM (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid amide) chelator possessing either Tm3+ or Dy3+. The amino acid and dipeptide decorated DOTAMs were designed such that the terminal amino acid pendant group was l-arginine, which may be converted to l-citrulline by NOS. Preliminary evaluation has revealed that some of the l-arginine-decorated complexes are recognized and metabolized by the NOS. Differences in the CEST properties between Dy3+-metallated l-arginine- and l-citrulline-modified complexes suggest that these might be suitable for imaging of the NOS enzymatic activity.

Preparation and Characterization of Succinyl‐Chitosan Nanoparticles for Drug Delivery

SummarySuccinyl‐Chitosan (SCS), a water soluble CS derivative, exhibits biocompatibility, low toxicity and long‐term retention in the body. SCS offers unique characteristics as polymer for obtaining drug delivery nanosystems, due to its many reactive amino, hydroxyl, and carboxylic acid pendant groups. Chemical modifications of SCS with antibodies and other active species are easily achieved through bonding with these groups, allowing targeting and detection. In this work, SCS was obtained by amidation of primary amine groups of CS with succinic anhydride. The succinylation degree, determined by 1H‐NMR, was 28%. Evaluation by zeta potential measurements of SCS showed a pH‐dependent charge profile, which can be conveniently exploited to prepare pH‐sensitive nanoparticles. Colloidal stable SCS/CS and SCS nanoparticles, useful in drug delivery, were prepared by ionic crosslinking from mixtures of CS and SCS in different weight percentages. Nanoparticles with sizes between 140–250 nm (after purification process) are obtained, which through further surface functionalization are suitable for application in drug delivery. The colloidal stability of the particles in water was studied by particle size measurements during 30 days and aggregation or formation of larger particles was not observed.

The influence of the combination of carboxylate and phosphinate pendant arms in 1,4,7-triazacyclononane-based chelators on their 68Ga labelling properties.

In order to compare the coordination properties of 1,4,7-triazacyclononane (tacn) derivatives bearing varying numbers of phosphinic/carboxylic acid pendant groups towards 68Ga, 1,4,7-triazacyclononane-7-acetic-1,4-bis(methylenephosphinic) acid (NOPA) and 1,4,7-triazacyclononane-4,7-diacetic-1-[methylene(2-carboxyethyl)phosphinic] acid (NO2AP) were synthesized using Mannich reactions with trivalent or pentavalent forms of H-phosphinic acids as phosphorus components. Stepwise protonation constants logK1–3 12.06, 3.90 and 1.95, and stability constants with GaIII and CuII, logKGaL 24.01 and logKCuL 16.66, were potentiometrically determined for NOPA. Both ligands were labelled with 68Ga and compared with NOTA (tacn-N,N′,N″-triacetic acid) and NOPO, a TRAP-type [tacn-N,N′,N″-tris(methylenephosphinic acid)] chelator. At pH 3, NOPO and NOPA showed higher labelling efficiency (binding with lower ligand excess) at both room temperature and 95 °C, compared to NO2AP and NOTA. Labelling efficiency at pH = 0–3 correlated with a number of phosphinic acid pendants: NOPO >> NOPA > NO2AP >> NOTA; however, it was more apparent at 95 °C than at room temperature. By contrast, NOTA was found to be labelled more efficiently at pH > 4 compared to the ligands with phosphinic acids. Overall, replacement of a single phosphinate donor with a carboxylate does not challenge 68Ga labelling of TRAP-type chelators. However, the presence of carboxylates facilitates labelling at neutral or weakly acidic pH.

Quaternary Ammonium Salt를 도입한 방오도료용 폴리우레탄 수지

최근 해양 산업에서는 해양환경에 잔류성은 없으면서 방오성능은 우수한 새로운 종류의 방오도료 수지 개발이 해결해야 할 시급한 과제로 대두되고 있다. 본 연구에서는 폴리우레탄계 수지를 방오도료용 수지로 적용하여 평가하였다. Polyethylene glycol(PEG), 4,4'-diphenylmethane diisocyanate(MDI) 2,2'-bis(hydroxyl methyl)propionic acid(DMPA)를 사용하여 중합한 후 방오성능을 발휘하는 치환기로서 quaternary ammonium salt를 치환시켰다. 합성된 수지는 최종적으로 필름화하여 해수 내에서의 마모특성을 확인하였다. 그 결과, PEG의 분자량이 600인 방오도료용 폴리우레탄 수지의 기계적 물성이 가장 양호함을 알 수 있었으며, quaternary ammonium salt의 함량이 일정 이상으로 많은 경우에는 수지에 대한 부착력이 저하됨을 확인하였다. Recently, the development of a new class of anti-fouling paint resin which has excellent anti-fouling performance and no persistence in the marine ecology is necessary. In this study, we first polymerized polyurethanes (PUs) as the other type of matrix which have carboxylic acid groups by using poly(ethylene glycol) (PEG), 4,4'-diphenylmethane diisocyanate (MDI), and 2,2'-bis(hydroxyl methyl)-propionic acid (DMPA). And next, we synthesized final resins having quaternary ammonium salts on pendant acid groups of PUs. After synthesis, the physical self-polishing property of resin by the measurement of reduced thickness in sea water was tested. The mechanical property of antifouling paint resin was good when the molecular weight of PEG was 600 or less. It was confirmed that the adhesion of PU resin was deteriorated when the content of quaternary ammonium salt was incorporated over specific value.

Ultraefficient homogeneous catalyst for the CO 2 -to-CO electrochemical conversion

A very efficient electrogenerated Fe(0) porphyrin catalyst was obtained by substituting in tetraphenylporphyrin two of the opposite phenyl rings by ortho-, ortho'-phenol groups while the other two are perfluorinated. It proves to be an excellent catalyst of the CO2-to-CO conversion as to selectivity (the CO faradaic yield is nearly quantitative), overpotential, and turnover frequency. Benchmarking with other catalysts, through catalytic Tafel plots, shows that it is the most efficient, to the best of our knowledge, homogeneous molecular catalyst of the CO2-to-CO conversion at present. Comparison with another Fe(0) tetraphenylporphyrin bearing eight ortho-, ortho'-phenol functionalities launches a general strategy where changes in substituents will be designed so as to optimize the operational combination of all catalyst elements of merit.

Thermoresponsiveness of copolymers bearing cholic acid pendants induced by complexation with β-cyclodextrin.

Copolymers of N-alkylacrylamides and methacrylate bearing cholic acid pendant groups were synthesized via radical polymerization. The cholic acid pendant groups of such copolymers can form complexes with β-cyclodextrin, and the effect of complexation on their thermoresponsive properties was studied. The phase transition temperatures (transition from hydrophilic to hydrophobic state) of the copolymers gradually increase with the addition of β-cyclodextrin, due to the complexation of the cholic acid guest with the β-cyclodextrin host. The increase of the phase transition temperature may be reversed by the addition of a competing guest molecule, potassium 1-adamantylcarboxylate. The host-guest complexation provides a straightforward way to vary the thermoresponsive properties of such copolymers.

Block and random copolymers bearing cholic acid and oligo(ethylene glycol) pendant groups: aggregation, thermosensitivity, and drug loading.

A series of block and random copolymers consisting of oligo(ethylene glycol) and cholic acid pendant groups were synthesized via ring-opening metathesis polymerization of their norbornene derivatives. These block and random copolymers were designed to have similar molecular weights and comonomer ratios; both types of copolymers showed thermosensitivity in aqueous solutions with similar cloud points. The copolymers self-assembled into micelles in water as shown by dynamic light scattering and transmission electron microscopy. The hydrodynamic diameter of the micelles formed by the block copolymer is much larger and exhibited a broad and gradual shrinkage from 20 to 54 °C below its cloud point, while the micelles formed by the random copolymers are smaller in size but exhibited some swelling in the same temperature range. Based on in vitro drug release studies, 78% and 24% paclitaxel (PTX) were released in 24 h from micelles self-assembled by the block and random copolymers, respectively. PTX-loaded micelles formed by the block and random copolymers exhibited apparent antitumor efficacy toward the ovarian cancer cells with a particularly low half-maximal inhibitory concentration (IC50) of 27.4 and 40.2 ng/mL, respectively. Cholic acid-based micelles show promise as a versatile and potent platform for cancer chemotherapy.