Effect of water-soluble polymers on the transport of functional group-modified polystyrene nanoplastics in goethite-coated saturated porous media

The research on the impact of water-soluble polymers (WSPs) on the migration and fate of plastic particles is extremely limited. This article explored the effects of polyacrylic acid (PAA, a common WSP) and physicochemical factors on the transport of polystyrene nanoparticles (PSNPs-NH2/COOH) with different functional groups in QS (quartz sand) and FOS (goethite-modified quartz sand, simulates mineral colloids). Research has shown that PAA can selectively adsorb onto the surface of PSNPs-NH2, forming ecological corona heterogeneous aggregates. This process increased the spatial hindrance and elastic repulsion, resulting in the recovery of PSNPs-NH2 always exceeding that of PSNPs-COOH. Overall, PAA can hinder the migration of PSNPs in QS but can promote their migration in FOS. When multivalent cations coexist with PAA, the transport of PSNPs in the media is primarily affected by cation bridging and CH-cation-π interaction. The presence of oxyanions and PAA prevents PSNPs from following the Hofmeister rule and promotes their migration (PO43-: 82.34 ± 0.16% to 94.63 ± 2.82%>SO42-: 81.38 ± 2.73% to 91.15 ± 0.93%>NO3-: 55.85 ± 0.70%-87.16 ± 3.80%). The findings of this study contribute significantly to a better understanding of the migration of WSPs and group-modified NPs in complex saturated porous media.

Synergistic pervaporation dehydration of ethanol/water mixture: Exploring the potential of a covalently designed hybrid membrane structure of polyacrylic acid grafted carbon nitride and polyvinyl alcohol

Polyacrylic acid (PAA) grafted CN sheet (P-g-CN) was synthesized to enhance the dispersive properties of carbon nitride (CN) in the membrane. A successful PAA grafting to the CN was confirmed from FTIR, TGA, and Zeta potential and XRD analyses. The A PVA membrane embedded P-g-CN, including a covalently constructed polymer-filler network, was developed to separate ethanol-water mixtures using pervaporation (PV). XPS study has confirmed a covalent attachment of P-g-CN sheets to the PVA matrix. Thereby, a defect-free membrane matrix was observed in the FESEM analysis. A 10 wt% loaded PVA-P-g-CN10 composite membrane was compared to the pristine PVA membrane, demonstrating improved PV dehydration performance. The flux decreased from 0.21 kg/m2h of pristine PVA membrane to 0.17 kg/m2h of PVA-P-g-CN10 membrane, while the separation factor improved from 49 to 176 in a 90/10 wt % ethanol/water feed at 40 °C. This improvement can be attributed to the selective diffusion of water through the P-g-CN interlayer spacing and tiny triangular nanopores in the s-triazine network, along with their dispersibility in the PVA matrix, resulting in well-ordered membrane morphology. Furthermore, PVA-P-g-CN10 exhibited higher water permeance (43.31-86.07 GPU) than ethanol (1.18-10.47 GPU) as the feed temperature increased from 30 to 70 °C, suggesting P-g-CN successfully inhibits swelling in the feed solution through proper interaction with PVA. In a long-term PV test lasting 250 h, the PVA-P-g-CN10 membrane displayed excellent structural stability and maintained its performance.

Removal of cationic dyes from aqueous solution using polyacrylic acid modified hemp stem

Water pollution caused by dyes is a pressing environmental challenge due to their persistence and difficulty in degradation. Herein, an anionic adsorbent (HS-PAANa) was synthesized by grafting polyacrylic acid (PAA) onto the agricultural waste-hemp stem (HS). The obtained HS-PAANa adsorbent exhibited rapid adsorption kinetics, high adsorption capacity, and a favorable preference for cationic dyes, such as methylene blue (MB) and crystal violet (CV). The experimental data fit well with the pseudo-second-order kinetic model and Langmuir isotherm, demonstrating the efficiency of HS-PAANa in dye removal. Notably, the optimal adsorption capacities of HS-PAANa for MB and CV were found to be 1296.65 mg/g and 1451.43 mg/g, respectively. In the cationic/anionic dyes (MB/MO) binary systems, HS-PAANa exhibited enhanced selective adsorption of cationic dyes (MB), indicating its potential for targeted removal of specific dyes from mixed solutions. Moreover, HS-PAANa adsorption shows an excellent recyclability, after five cycles, HS-PAANa still maintained MB and CV removal rates of 93.85% and 95.08%, respectively. Therefore, the bioadsorbent HS-PAANa exhibits high potential as a highly efficient adsorbent for the effective treatment of cationic pollutants in wastewater.

Constructing amphipathic molecular layer to assists de-solvation process for dendrite-free Zn anode

Due to the excellent safety feature, substantial theoretical capacity and abundant zinc reserves in the earth's crust, Aqueous Zn-ion batteries (AZIBs) are promising as the next generation energy storage system. However, the problem of dendrite growth and the related side reactions in Zn surface limit their further development and application. Herein, an amphipathic molecular layer (Polyacrylic Acid, named as PAA) is constructed on Zn surface to hinder the side reactions and zinc dendrites by intervening the de-solvation process. It is found that the rich hydroxyl group in polyacrylic acid is very hydrophilic. On the contrary, hydrocarbon group on the other side is nearly hydrophobic. The amphiphilic PAA molecular layer on Zn surface results in lower de-solvation energy barrier, thus inhibits the decomposition of water and related side reactions. Additionally, the accumulate abundant negative charge at the interface of polyacrylic acid and Zn surface can attract homogeneous deposition of Zn atoms. Using only 0.01 M PAA as additive in 2.0 M ZnSO4 electrolyte. Zn||Zn symmetric cells expresses a superior cycling stability of 4643 h (5 mA cm-2, 1 mAh cm-2). This study provides new insights into the long-life AZIBs modulated by amphipathic molecular layer.

Facile synthesis of a novel polymer/covalent organic framework@silica composite material in deep eutectic solvent for mixed-mode liquid chromatographic separation

The solvothermal synthesis of covalent organic framework (COF) modified silica gel usually requires the use of harmful organic solvents, tedious steps, and harsh reaction conditions. In pursuit of green chemistry, a new strategy for the facile preparation of COF@SiO2 composite material was realized in this work by using a low-toxicity and low-cost deep eutectic solvent as the reaction medium. Additionally, a flexible polyacrylic acid (PAA) was introduced for the purpose of improving the hydrophilic selectivity and separation efficiency of COF@SiO2. Based on the above ideas, a novel PAA/COF@SiO2 composite was successfully developed as a liquid chromatographic packing material. Performance evaluation of the slurry-packed PAA/COF@SiO2 column showed that diverse types of analytes were effectively separated, and the retention behavior of polar nucleosides showed a U-shaped trend, indicating mixed-mode of hydrophobic/hydrophilic retention mechanisms. Thermodynamic studies revealed that the separation mechanism was largely independent of temperature. This work verifies the feasibility of synthesizing polymer/COF@SiO2 composite material in the deep eutectic solvent. This strategy provides a theoretical reference for the green and facile preparation of COF@SiO2 as an efficient liquid chromatographic stationary phase.

Fabrication of hydrophilic polymer-hybrid octacalcium phosphate blocks under wet condition based on cement setting reactions

Bioceramics, while offering excellent biocompatibility, are often compromised by their fragility and brittleness, especially under wet conditions. Even though recent hybrid processes combining biocompatible polymers and bioceramics have shown promise, complete mitigation of these challenges remains elusive. In this research, a biomimetic process was employed to mimic the structure of biological bone tissue. This led to the development of block materials composed of octacalcium phosphate (OCP) and sodium polyacrylic acid (PAA-Na) that display flexibility and resilience in wet conditions. Adjusting the PAA-Na concentration enabled the OCP-PAA-Na blocks to demonstrate superior mechanical strength when dry and increased flexibility when wet. Notably, these blocks expanded in aqueous solutions while preserving their structure, making them ideal for oral surgeries by preventing issues like blood flooding from implanted areas.

Randomized controlled field trial to assess the efficacy of an intranasal Moraxella bovis cytotoxin vaccine against naturally occurring infectious bovine keratoconjunctivitis

Background

Infectious bovine keratoconjunctivitis (IBK; pinkeye) is generally considered to be caused by corneal infections with Moraxella bovis. Previous studies demonstrated that M. bovis cytotoxin-specific mucosal immune responses in the bovine eye can be stimulated by intranasal vaccination with a recombinant M. bovis cytotoxin subunit adjuvanted with polyacrylic acid.

Methods

A randomized controlled field trial (two-arm parallel design with blinding) was conducted in beef steers in Northern California to determine if this vaccine could prevent naturally occurring IBK and/or reduce morbidity rates associated with this disease. Beef steers were vaccinated intranasally on days 0 and 21 with either a recombinant M. bovis cytotoxin subunit adjuvanted with polyacrylic acid (Vaccine group) or adjuvant alone (Control group). Eye examinations were performed on all steers every 7 days for 16 weeks to document the occurrence of IBK and to determine sizes of corneal ulcers. Serum and tear samples were collected on days 0, 42, and 112 from a subset of animals to measure changes in systemic and ocular immune responses to M. bovis cytotoxin.

Results

The cumulative proportion of steers that developed IBK after 16 weeks did not differ between groups. Variables related to disease severity were numerically lower in steers that received the experimental vaccine. IBK-affected Vaccine group steers had a significantly lower number of observation weeks with severe ulcers versus Control group steers. Cytotoxin-specific tear IgA was significantly higher in Vaccine group compared to Control group steers on day 112. Conclusion: Although the proportion of animals that developed corneal ulcers associated with IBK did not differ between groups, the lowered metrics of disease severity in vaccinated steers suggests that intranasal vaccination with recombinant M. bovis cytotoxin can reduce the severity of IBK in cattle.

Synthesis & fabrication of O-linked polymeric hybrids for recovery of textile dyes: Closed loop economy

Dyes are an important resource employed for the production systems in textile, paper, paint and leather industry. An estimate of 200,000 tons of dyes are discharged as textile effluent each year worldwide. It becomes imperative to recover these dyes by treating the effluents using economically viable routes. The present research was undertaken with the objective to attain zero emission and zero waste through development of novel polymeric hybrids as adsorbents. For this purpose, metal moieties (Al3+, Si4+, Ti4+ and Zr4+) were hybridized with polyacrylic acid, and cellulose acetate for the uptake of selected dyes under optimized parameters. The structural elucidation of four synthesized hybrids (MP-Al, MP-Si, MP-Ti and MP-Zr) by FTIR, EDX and TGA confirmed O-linked grafting of metal moieties with polymers and thermally stable porous materials. SEM micrographic images displayed void spaces providing channels for effective adsorption. The batch experiments demonstrated removal of malachite green (77-96%) and congo red (70-82%) upon contact of initial 45 min on polymeric hybrids On the other hand, pristine polyacrylic acid and cellulose acetate showed remarkably low removal of dyes. The adsorption mechanism is proposed as physical in nature following type II isotherm. Further, Langmuir and Ho's pseudo second order fitness was evaluated. In order to determine the economic viability of the present research, the real textile dyes were recovered in three consecutive cycles of adsorption and chemical treatment of hybrids. The results propose a system with positive impact on economy by maximum utilization of hybrids as adsorbents and recovery of textile dyes for reuse in textile processing.

Chitosan/polyacrylic acid/octadecene double-crosslinked network hydrogel functionalized porous silica microspheres for multimode liquid chromatographic separation

In this study, chitosan (CS) and polyacrylic acid (PAA) were used to construct a double-crosslinked network hydrogel, which was employed as the functional material for silica microspheres to prepare a CS/PAA hydrogel modified liquid chromatographic stationary phase. During preparation, octadecene (ODE) was introduced into the CS/PAA hydrogel to improve its hydrophobicity and separation ability. The electrostatic interaction between the amino group of CS and the carboxyl group of PAA effectively prevented the swelling of the CS/PAA hydrogel, which ensured the successful application of the obtained CS/PAA hydrogel@SiO2 in chromatographic analysis. Polar nucleosides/bases and B-vitamins were selectively separated using hydrophilic interaction liquid chromatography. Hydrophobic polycyclic aromatic hydrocarbons and alkylphenols were effectively separated through reversed-phase liquid chromatography. Moreover, the effective separation of aromatic positional isomers and chiral enantiomers was achieved. This study confirms the potential application of the CS/PAA hydrogel in chromatographic separation. What is noteworthy is that the method developed in this study also provides a feasible strategy to solve the swelling issue associated with the hydrogel-based liquid chromatographic stationary phase.

Green synthesis of chitosan/polyacrylic acid/graphitic carbon nitride nanocarrier as a potential pH-sensitive system for curcumin delivery to MCF-7 breast cancer cells

A novel pH-sensitive nanocarrier containing chitosan (CS), polyacrylic acid (PAA), and graphitic carbon nitride (g-C₃N₄) was designed via water/oil/water (W/O/W) emulsification to administer curcumin (CUR) drug. g-C₃N₄ nanosheets with a high surface area and porous structure were produced via simple one-step pyrolysis process using thiourea as precursor, and incorporated into CS/PAA hydrogel. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were used to assess the crystalline structure of the nanocarrier and the interactions between its components, respectively. Scanning electron microscopy (SEM) images revealed a spherical structure and confirmed the g-C₃N₄ impregnation into the CS/PAA matrix. Zeta potential and dynamic light scattering (DLS) provided information about the surface charge and average size distribution. High CUR loading and entrapment efficiencies were obtained, which were further improved upon addition of g-C₃N₄. The release kinetics of drug-loaded CS/PAA/g-C₃N₄ nanocomposites were investigated at pH = 5.4 and pH = 7.4, and the results showed an excellent controlled pH-sensitive release profile. Cell apoptosis and in vitro cytotoxicity were investigated using flow cytometry and MTT analyses. CS/PAA/g-C₃N₄/CUR resulted in the highest rate of apoptosis in MCF-7 breast cancer cells, demonstrating the excellent nanocomposite efficacy in eliminating cancerous cells. CS/PAA hydrogel coated with g-C₃N₄ shows great potential for pH-sensitive controlled drug release.

A green approach for preparation of polyacrylic acid/starch incorporated with titanium dioxide nanocomposite as a biocompatible platform for curcumin delivery to breast cancer cells

Curcumin (Cur) is a polyphenolic hydrophobic molecule with several biological uses, including cancer therapy. However, its widespread use in cancer treatment faces limitations due to its low solubility in acidic and neutral conditions, rapid removal from the circulatory system, and poor bioavailability. In order to overcome these challenges, a biocompatible and pH-sensitive carrier nanoplatform was designed for the specific delivery of curcumin to breast cancer cells. This nanocomposite containing polyacrylic acid (PAA), starch, and titanium dioxide (TiO₂) was synthesized with a specific morphology through the water-in-oil-in-water green emulsification strategy. The nanocomposite structure was confirmed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and field-emission scanning electrom microscopy (FE-SEM) imaging tests. The mean particle size of 151 nm for the PAA-Starch-TiO₂ nanocomposite ensures specific entry into cancer cells and minimal damage to healthy cells. Loading efficiency (LE) and encapsulation efficiency (EE) for curcumin obtained 49.50 % and 87.25 %, which are desirable for a carrier nanoplatform. Compared to the physiological medium, the in-vitro release of curcumin was higher in the acidic conditions in all time intervals, which indicates the possibility of targeted drug release from the PAA-Starch-TiO₂ nanocomposite around the tumor tissue. Furthermore, for better understanding of the release mechanism, the cumulative release data in both media were fitted with common mathematical kinetic models. Cytotoxicity tests against the MCF-7 cell line were performed using in vitro MTT and flow cytometry tests. The results showed that the PAA-Starch-TiO₂ carrying Cur was more effective through increasing the bioavailability and controlled release of the drug compared to the free Cur. Also, the death of cancer cells in the presence of this nanocomposite compared to free Cur occurred mainly through the induction of apoptosis, which indicates the programmed death of cancer cells and the high efficiency of the designed nanocarrier.

4D Printing of Body Temperature-Responsive Hydrogels Based on Poly(acrylic acid) with Shape-Memory and Self-Healing Abilities

Additive manufacturing of smart materials that can be dynamically programmed with external stimuli is known as 4D printing. Among the 4D printable materials, hydrogels are the most extensively studied materials in various biomedical areas because of their hierarchical structure, similarity to native human tissues, and supreme bioactivity. However, conventional smart hydrogels suffer from poor mechanical properties, slow actuation speed, and instability of actuated shape. Herein, we present 4D-printed hydrogels based on poly(acrylic acid) that can concurrently possess shape-memory and self-healing properties. The printing of the hydrogels is achieved by solvent-free copolymerization of the hydrophilic acrylic acid (AAc) and hydrophobic hexadecyl acrylate (C16A) monomers in the presence of TPO photoinitiator using a stereolithography-based commercial resin printer followed by swelling in water. The printed hydrogels undergo a reversible strong-to-weak gel transition below and above human body temperature due to the melting and crystallization of the hydrophobic C16A domains. In this way, the shape-memory and self-healing properties of the hydrogels can be magically actuated near the body temperature by adjusting the molar ratio of the monomers. Furthermore, the printed hydrogels display a high Young's modulus (up to ∼215 MPa) and high toughness (up to ∼7 MJ/m³), and their mechanical properties can be tuned from brittle to ductile by reducing the molar fraction of C16A, or the deformation speed. Overall, the developed 4D printable hydrogels have great potential for various biomedical applications.

Nose-to-brain delivery of galantamine loaded nanospray dried polyacrylic acid/taurodeoxycholate mixed matrix as a protective therapy in lipopolysaccharide-induced Alzheimer's in mice model

One of the promising drug delivery approaches is performed by nanosizing the administered drug product using the nanospray drying technique. In this study, a combination of several formulation factors was integrated and exploited to augment the bioavailability of galantamine hydrobromide (GAL) via the intranasal route. Nanosized polymeric particles were fabricated using the mucoadhesive polymer, polyacrylic acid (PAA), and the permeability booster, sodium taurodeoxycholate (TDC). First, a preliminary study was conducted to adjust the nanospray drying conditions. Then, formulations were prepared on the basis of a mixed factorial experimental design and further analyzed using Design Expert® software. Different responses were investigated: particle size, polydispersity index, spray rate, drying efficiency, and percent yield. The optimized formulation was further assessed for physical morphology using the scanning electron microscope, flowability, in vitro drug release, and in vivo brain cell uptake using confocal laser scanning microscopy. The promising formulation (F6), composed of equal ratio of PAA and TDC and 20 mg GAL, exhibited a particle size of 185.55 ± 4.3 nm, polydispersity index of 0.413 ± 0.02, and yield-value of 69.58 ± 5.82 %. It also displayed good flowability, complete drug release within 2 h, and enhanced in vivo fluorescent dye uptake and penetration in brain cells. The efficacy of the optimized formulation was examined using lipopolysaccharide-induced Alzheimer's in mice. Results revealed the advantageous influence of the optimized formulation (F6) through downregulation of NF-κβ, IL-1β and GFAP as well as upregulating TGF-1β in adult mice.

Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange

In soil and water, metal complexation by humic substances has been demonstrated to have great importance in determining the bioavailability of many trace metals including lead. The binding of lead by humic acids has important implications for lead toxicity, and remediation. In this study we demonstrate the use of 4-(2-pyridylazo)-resorcinol (PAR) as a competitive ligand for the purposed of determining sorption isotherms for Pb²⁺ on humic acids and humic acid analogs. Equilibration rates at pH 8 were very rapid and the sorption isotherms measured were fit to the Langmuir isotherm equation and values for the stability constants (K_HA) and complexing site concentrations (L_t) are reported. At a PAR concentration of 0.24 mM and humic acid concentrations of 25-200 mg/L, the mass normalized log K_HA values for the humic substances ranged from 7.2 to 7.9, while the log L_t values ranged from -2.8 to -3.8. At lower PAR concentrations both K_HA and L_t tended to increase in magnitude indicating the role of the PAR concentration in establishing the measurement window for the interaction of Pb²⁺ with humic materials.

Topical application of sustained released-carbon monoxide promotes cutaneous wound healing in diabetic mice

Clinical incidences of pressure ulcers in the elderly and intractable skin ulcers in diabetic patients are increasing because of the aging population and an increase in the number of diabetic patients worldwide. Although various agents are used to treat pressure and skin ulcers, these ulcers are often refractory and deteriorate the patients' quality of life. Therefore, a novel therapeutic agent with a novel mechanism of action is required. Carbon monoxide (CO) contributes to many physiological and pathophysiological processes, including anti-inflammatory activity; therefore, it can be a therapeutic gaseous molecule. Recent studies have revealed that CO accelerates wound healing in gastrointestinal tract injuries. However, it remains unclear whether CO promotes cutaneous wound healing. Therefore, we aimed to evaluate the therapeutic effects of topical application of a CO-containing solution and elucidate the underlying mechanism. A full-thickness skin wound generated on the back of diabetic mice was treated topically with CO or vehicle. Sustained release of CO was achieved using polyacrylic acid (PAA) as a thickener. The administration of CO-containing PAA aqueous solution resulted in a significant acceleration in wound recovery without elevating serum CO levels in association with increased angiogenesis and supported by elevated expression of vascular endothelial growth factor mRNA in the wound granulomatous tissues. These data suggest that CO might represent a novel therapeutic agent for the treatment of cutaneous wounds.

Polyacrylic acid and β-cyclodextrin polymer cross-linking binders to enhance capacity performance of silicon/carbon composite electrodes in lithium-ion batteries

Binders play a key role in maintaining the integrity of high-capacity silicon anodes, which otherwise experience serious capacity decay during cycling caused by huge volume variation of the silicon. With an aim to developing a highly efficient polymeric binder to mitigate this capacity decay, we present a novel binder synthesized from polyacrylic acid (PAA) and polymerized β-cyclodextrin (β-CDp) for Si anodes for the lithium-ion batteries. This PAA-β-CDp binder has a 3D network structure, which provides strong adhesion between the active material and the current collector. PAA-β-CDp binder makes silicon anode achieve a specific capacity of 2326.4 mAhg^-1 at the current density of 0.2 A g^-1 with a capacity retention of 64.6% after 100 cycles. The experimental results show that the PAA-β-CDp binder can effectively mitigate the huge volume change and improve the capacity and cycling performance of Si anodes.

Removed heavy metal ions from wastewater reuse for chemiluminescence: Successive application of lignin-based composite hydrogels

The novel sulfomethylated lignin-grafted-polyacrylic acid (SL-g-PAA) hydrogel was fabricated in this work via a facile and green synthetic strategy for the efficient removal of heavy metal ions from wastewater, and then successively reused for chemiluminescence (CL). The sulfomethylation of lignin was first performed to improve its water solubility and introduce numerous active sites for adsorption of heavy metal ions. The as-synthesized SL-g-PAA hydrogel with high content of lignin exhibited the highly efficient and rapid removal of various metal ions from simulated wastewater. More importantly, the spent hydrogel (M²⁺@SL-g-PAA) after adsorption was reused for the first time to develop a new CL system by an ingenious strategy, in which these metal ions adsorbed on M²⁺@SL-g-PAA act as heterogeneous catalytic sites to catalyze the CL reaction between N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and H₂O₂. The resultant CL system displayed high CL intensity and long duration time, which could be observed by naked eye in the dark and lasted for > 24 h. The combination of facile fabrication process, renewable raw materials, and ingenious strategy for successive application in adsorption and CL endows this lignin-based composite hydrogel with a great potential for application in wastewater treatment, biological imaging and cold light sources.

The first comprehensive study evaluating the ecotoxicity and biodegradability of water-soluble polymers used in personal care products and cosmetics

Water-soluble polymers (WSPs) are organic materials that have been used for decades in various applications as part of paints, coatings, adhesives, washing agents, pharmaceuticals, personal care products and cosmetics. However, their ecotoxicity, biodegradability, and overall impact on the environment are still unknown. In this study four polyacrylic acid- based WSPs (three in the solid state and one in the liquid state), which are widely used in cosmetic industry, were tested in terms of their ecotoxicity and biodegradability. The ecotoxicity tests were performed using aquatic plant Lemna minor, microalga Pseudokirchneriella subcapitata, crustacean Daphnia magna, bacterium Allivibrio fischeri, and a mixed bacterial culture of activated sludge (with heterotrophic and nitrifying microorganisms tested separately). All four WSPs had low or moderate effects on the tested organisms at several endpoints. However, the liquid WSP had a specific toxic effect on the bioluminescence of Allivibrio fischeri and the oxygen consumption of nitrifying microorganisms - 100 mg/L caused 73% and 88% inhibition, respectively. Therefore, some WSPs capable of inhibiting nitrifying microorganisms could have implications for the nitrification process in wastewater treatment plants and aquatic ecosystems, despite 100 mg/L being a high tested concentration and probably difficult to reach in wastewater. All investigated WSPs were not biodegradable; therefore, their persistence in the environment could be expected.

Gamma radiation-induced polymerization of polyacrylic acid-dolomite composite and applications for removal of cesium, cobalt, and zirconium from aqueous solutions

Gamma-irradiation initiated polymerization was utilized to prepare polyacrylic acid dolomite P(AA/D) nanocomposites. Different analytical techniques have been applied to investigate the structure of the new materials. XRD and TEM revealed the crystalline phase with an average particle size ranging from 2 to 4 nm. The ability of the prepared materials to remove cesium, cobalt, and zirconium ions from aqueous solutions was evaluated. The adsorption capacity of studied nanocomposites has an affinity sequence; Zr⁴⁺>Co²⁺≫Cs⁺ with values 77.8, 72.4, and 34.9 mg/g respectively. The effect of the interfering species reveals that the rate of adsorption of cesium, cobalt, and zirconium ions decreases with increasing concentrations of the interfering species. The investigation proved that the prepared nanocomposite is suitable material for the removal of the studied metals from aqueous solutions and could be considered as potential material for purification of effluent polluted with these metal ions.

New method for the protection and restoration of calcareous cultural heritage stones by polyelectrolytes and hydroxyapatite nanocrystals

We have investigated the feasibility of a new two-step protocol for the restoration of marbles. The process employs a polyelectrolyte multilayer film that enhances the chemical affinity between the treated stone and restorative material (hydroxyapatite nanocrystals), through functionalization, while at the same time it attributes an acid resistant property to the resulting system. Surface functionalization and material deposition is achieved through spraying; a simple and versatile application method suitable for objects of various sizes and geometries. Polyelectrolyte (polyethylenimine and polyacrylic acid) deposition was examined through Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and Atomic Force Microscopy (AFM), and tested through contact angle, water absorption and dissolution experiments. The hydroxyapatite nanocrystals were studied by ATR-FTIR, z-potential, AFM and Scanning Electron Microscopy (SEM), and characterized via contact angle and color alteration measurements. Our results show that the polyelectrolyte multilayer was stable in an aqueous environment with increased acid resistance (up to 46% decrease in mass weight loss when compared with untreated samples) and decreased water absorption (up to 39%). Color measurements of the outer hydroxyapatite layer showed a minimal color alteration for one type of the tested substrates showing low color difference values (ΔΕ* < 5). The results suggest that the proposed method holds great potential for marble restoration as it attributes multi-functionality and is easy to apply.

Preparation and characterization of polyacrylic acid-hydroxyapatite nanocomposite by microwave-assisted synthesis method

Polyacrylic acid, polyalkenoic acids in general, form the liquid ionomer phase of glass ionomer cements, which are frequently used in root restorations in dentistry. It is possible to obtain these ionomers with a fast, energy-efficient, high reaction efficiency and a clean method with microwave irradiation method. In this study, polyacrylic acid and its composite with nano HAp have been synthesized by microwave (MW) irradiation. The two-process parameters that were tested are MW intensity and reaction time. The polymerization was carried out at 110 °C up to 40 min and yield over 92% was produced in 30 min. The average molar mass of PAA was found as 11960 Da using a high-resolution mass spectrometer (TOF-MS). On the other hand, hydroxyapatite (HAp) nanoparticles have been prepared via the sol-gel procedure using potassium dihydrogen phosphate and calcium nitrate tetrahydrate as the precursors for phosphorus and calcium, respectively. XRD, EDS analysis revealed that the particles contain calcium deficient hydroxyapatite (Ca_10-x(HPO₄)_x(PO₄)_6-x(OH)_2-x (HAp) crystals with beta-TCP phase. Morphological observation by SEM measurement proved that the crystal particles of the HAp are very regular and granular, and their size is 25-45 nm in the longitudinal section. These particles were used in composite preparation with PAA. The yield of the composite obtained by heating at 500 W, 30 min was found to be 90%. From the FTIR and ¹H-NMR results, it was observed that there was not only a physical but also an electrostatic interaction between HAp and PAA. The thermal behavior of PAA and its composite with nano HAp were determined by the thermogravimetric analyzer (TGA). The results showed that anhydride formation or decarboxylation occurred at a lower temperature, confirming the interaction between PAA and HAp. The polymerization rate is much faster with microwave heating than conventional heating. Microwave irradiation enables rapid energy transfer and high-energy efficiency, hence, a faster reaction rate.

Fabrication of pH-Responsive Polyimide Polyacrylic Acid Smart Gating Membranes: Ultrafast Method Using 248 nm Krypton Fluoride Excimer Laser

pH-responsive smart gating membranes were developed using a two-step fabricating process. In the first step, a porous polyimide (PI) support membrane with ordered, regular, and well-defined pores was obtained with a 248 nm KrF excimer laser using a lithography technique. The porous membranes were then grafted with poly(acrylic acid) (PAAc) hydrogel by free radical polymerization using the same excimer laser. The number of pulses and frequency could be varied to obtain a range of water permeabilities. Permeability of membrane changed significantly due to swelling and deswelling of PAAc inside the pores at pH 7 and pH 3, respectively. These hydrogel networks were firmly grafted inside pores and remained mechanically intact even after using high pressure during permeability studies. PAAc grafting was confirmed using ATR-FTIR. PAAc hydrogel distribution inside membrane pores was analyzed using SEM and fluorescence microscopy. To quantify the amount of polymer grafted, TGA studies were carried out. Diffusion studies were also carried out using caffeine as a drug molecule to evaluate the application of membrane in drug delivery devices. The linear drug release profile obtained from the study confirmed the potential application of membrane for drug delivery purposes. Results obtained also suggest that the fabrication method developed is fast, efficient, solvent-free, and economical.

A drug delivery system based on nanocomposites constructed from metal-organic frameworks and Mn3O4 nanoparticles: Preparation and physicochemical characterization for BT-474 and MCF-7 cancer cells

An integrated nanocomposite system comprising of manganese oxide (Mn₃O₄) nanoparticles, functioning as a tumor diagnostic agent, in conjunction with polyacrylic acid (PAA) and ZIF-8, as pH-sensitive drug delivery agents, and methotrexate (MTX), operating as a tumor biomarker and a therapeutic agent (dual mechanism of action), is applied for both diagnostic intentions and controlled delivery of the drug. Physicochemical characteristics of the constructed system, Mn₃O₄@PAA@ZIF-8/MTX, are investigated by several methods, including X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and electrochemical techniques. The in-vitro magnetic resonance imaging measurements was performed to show the efficiency of Mn₃O₄@PAA@ZIF-8 nanocomposite as a contrast agent where a relaxivity (r₁) of 3.3 mM^-1 s^-1 is found. The loading ratio was found as 161 % which is four times larger than the value obtained for Mn₃O₄@PAA system in the same conditions, indicating high capability of the system for MTX delivery. The application of the nanocomposite as a dual pH-sensitive nanocarrier for MTX is studied through in-vitro drug release experiments at pHs of 5.4, 6.8 and 7.4. Interestingly, the results show that a large amount of loaded MTX drug (53 %) is released from the system during incubation and dialysis at pH 5.4, compared with that (20 % and 15 %), respectively, released at pHs 6.8 and 7.4 at the same conditions. The affinity of Mn₃O₄@PAA@ZIF-8/MTX nanocomposite for capturing of BT-474 and MCF-7 cancer cells was evaluated via impedance spectroscopy measurements. The results show that GC-Mn₃O₄@PAA@ZIF-8/MTX electrode captures the BT-474 and MCF-7 cancer cells, respectively, by factors of ∼2 and 196 compared with L929 normal cells. This affinity also shows the high selectivity of the system for MCF-7 cancer cells compared with BT-474.

Nylon mesh-based 3D scaffolds for the adherent culture of neural stem/progenitor cells

We developed novel scaffolds for the adherent culture of neural stem/progenitor cells on the woven mesh. Nylon mesh (NM) is an inert material for cell adhesion. We prepared polyacrylic acid-grafted nylon mesh (PAA-NM) by graft polymerization method using gamma-irradiation. Matrigel was covalently immobilized to the carboxyl groups in PAA-NM by chemical conjugation using 1-ethyl-3-(3-dimethylamino propyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to prepare the Matrigel-immobilized PAA-grafted nylon mesh (M-PAA-NM). Cell adhesion property of mouse neural stem/progenitor cells (NSPCs) between the NM, PAA-NM, and M-PAA-NM was different from each other. The neurosphere-like clusters of NSPCs were weakly bound to NM and PAA-NM without spreading. The NSPCs were firmly adhered to, spread, and covered the surface of M-PAA-NM. We evaluated the state of differentiation by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immnocytochemistry. A neuronal marker β III tubulin, a glial marker glial fibrillary acidic protein (GFAP) and a mature glial marker S100β were expressed at a low level in the cultured cells while immature NSPCs marker Nestin and Sox2 were slightly lower without significant statistical difference. We concluded that the M-PAA-NM is a good substrate for adherent culture of NSPCs without triggering their cell differentiation, and also provides the maintenance of their growth with fewer passages in comparison with the conventional suspension culture of NSPCs in neurospheres.

Fabricating acid-sensitive controlled PAA@Ag/AgCl/CN photocatalyst with reversible photocatalytic activity transformation

Achieving the intelligent controllability of the photocatalyst to the surrounding environment is a very meaningful work. Here, the polyacrylic acid (PAA) modified Ag/AgCl-40/CN composite was constructed to achieve an intelligent response of pH value. PAA exhibits hydrophilic properties at high pH value, increasing the adsorption capacity to tetracycline (TC) molecules. The morphology of PAA from contracted state to diastolic state, releasing the Ag/AgCl-40/CN catalyst. In addition, PAA modified Ag/AgCl-40/CN can prevent the loss of AgCl. The g-C₃N₄ nanosheets (CN) as a carrier enhance the dispersibility of the AgCl particles. The LSPR effects of Ag nanoparticles produce more electrons acting on photocatalytic degradation. On the results of experiment, the degradation of TC by PAA@Ag/AgCl-40/CN shows an excellent degradation activity when the high pH value. Photoluminescence spectroscopy and photocurrent demonstrate that carrier separation efficiency of PAA@Ag/AgCl-40/CN is higher than CN and Ag/AgCl-40/CN. The detection of the main active substances •O₂^- and h⁺, revealing a reasonable mechanism for the PAA@Ag/AgCl-40/CN hybrid system. This work provides a procedure to obtain smart materials that can switch photocatalytic processes.

Analysis of the structure-function relationship of alpha amylase complexed with polyacrylic acid

Alpha-amylase is frequently used in technologies that require its immobilization, stabilization or encapsulation. Polyacrylic acid is a very suitable polymer for these purposes because it can bind to enzymes and then be released under certain conditions without altering the functional capacity of enzymes. The consequences produced by polyacrylic acid on alpha-amylase structure and function have been investigated through various techniques. Calorimetric measurements allowed examining the nature of the binding reaction, stoichiometry and affinity, while spectroscopic techniques provided additional information about functional and structural perturbations of the enzyme. Isothermal titration calorimetry (ITC) revealed a mixed interaction and a binding model with a large number of molecules of protein per molecule of polyacrylic acid. One the one hand circular dichroism (CD) spectroscopy showed that alpha-amylase loses its secondary structure in the presence of increasing concentrations of polyacrylic acid, while it is stabilized by the polyelectrolyte at low pH. On the other hand, fluorescence spectra revealed that the three-dimensional enzyme structure was not affected in the microenvironment of tryptophan residues. Differential scanning calorimetry (DSC) thermograms showed that only one domain of alpha-amylase is affected in its conformational stability by the polymer. The unfolding process proved to be partially reversible. Finally, the enzyme retained more than 90 % of its catalytic activity even in excess of the polymer.

Evaluating the circadian rhythm and response to glucose addition in dispersed growth cultures of Neurospora crassa

Work on the filamentous fungus Neurospora crassa has contributed to or pioneered many aspects of research on circadian clock mechanism, a process that is functionally conserved across eukaryotes. Biochemical assays of the fungal circadian clock typically involve growth in liquid medium where Neurospora forms a spherical ball of submerged mycelium. Here, we revive a method for dispersed growth of Neurospora in batch culture using polyacrylic acid as an additive to the medium. We demonstrate that dispersed growth cultures utilize more carbon than mycelial balls, but nonetheless retain a functional circadian clock. This culturing method is suited for use in circadian experiments where uniform exposure to nutrients and/or increased biomass is required.

Polyacrylic acid-functionalized graphene oxide for high-performance adsorption of gallium from aqueous solution

Graphene oxide (GO) has great potential in metal recovery and water purification owing to their high surface area, abundant hydroxyl (OH) and carboxyl (COOH) groups. To fully understand the influence of the dispersity of GO on the adsorption capacity of metal ions, a series of polyacrylic acid (PAA) functionalized GO (PAA/GO) composites with different dispersity were prepared. The charge density of the PAA/GO composites were much higher than that of the untreated GO in acidic conditions, demonstrating a significant improvement of dispersibility by introducing PAA on the surfaces. Moreover, recovery of gallium by employing the PAA/GO composites as adsorbent were studied. The maximum adsorption capacity towards gallium ions of the adsorbent can reach 196.84 mg·g^-1, much higher than that of other commercially available resins (CL-P204, P507). This superiority could be attributed to the abundant COOH groups on the surfaces and the good dispersity of the PAA/GO composites. These results revealed that the PAA/GO composites could be promising adsorbents for selective adsorption and efficient recovery of Ga(III).

Plasma assisted-synthesis of magnetic TiO2/SiO2/Fe3O4-polyacrylic acid microsphere and its application for lead removal from water

Hybrid microsphere of polyacrylic acid (PAA) grafted TiO₂/SiO₂/Fe₃O₄ (TSF-PAA) was synthesized via coating polyacrylic acid on the core-shell-shell TiO₂/SiO₂/Fe₃O₄ (TSF) structure with the aid of plasma technique. The synthesized microsphere was applied to remove Pb²⁺ from water. The state-of-the techniques including TEM, FTIP, TGA, and XPS were used to characterize the morphology and the surface functionalities of the microsphere and confirmed that PAA was successfully grafted on TSF surfaces and active functional groups were introduced. A combination of the BET, VSM, and XRD results showed that plasma treatment decreased surface area of TSF by 36%, whereas its magnetic property and crystalline structure were not significantly altered. Both the Pb²⁺-sorbed magnetic TSF and TSF-PAA can be separated with a magnet from the aqueous phase. The pH and dosage changes of the microspheres exerted an intense influence on their lead removal efficiency. Compared to TSF, the removal capacity of Pb²⁺ by TSF-PAA was considerably improved from 65% to 95%, attributable to the fact that PAA coating induced by plasma treatment additionally introduced carboxylic and hydroxyl groups to TSF. Their introduction greatly enhanced the interaction between Pb²⁺ and TSF-PAA relative to that with TSF, which had hydroxyl groups only as supported by XPS analysis.

A theranostic system based on nanocomposites of manganese oxide nanoparticles and a pH sensitive polymer: Preparation, and physicochemical characterization

A multifunctional nanocomposite theranostic system is constructed of manganese oxide (Mn₃O₄) nanoparticles (NPs), as a tumor diagnostic agent, in conjunction with polyacrylic acid (PAA), as a pH-sensitive drug delivery agent, and methotrexate (MTX), as a model of targeting agent and anticancer drug. Physicochemical characteristics of the Mn₃O₄@PAA/MTX system is studied in detail by several techniques, including X-ray and Auger photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and electrochemical methods. The system performance is studied based on (i) in-vitro MRI measurements to support efficiency of the Mn₃O₄@PAA NPs as a diagnostic agent, (ii) drug release performance of the Mn₃O₄@PAA/MTX NPs at pHs of 5.4 and 7.4 through in-vitro method to evaluate application of the NPs as pH-sensitive nanocarriers for MTX, and (iii) impedance spectroscopy measurements to show Mn₃O₄@PAA/MTX NPs affinity for capturing of cancer cells. The results show that (i) Mn₃O₄@PAA NPs can be used as a contrast agent in MRI measurements (r₁ ≅ 6.5 mM^-1 s^-1), (ii) the MTX, loaded on Mn₃O₄@PAA NPs, is released faster and more efficient at pH 5.4 than 7.4, and (iii) the GC-Mn₃O₄@PAA/MTX electrode system captures the 4T1 cells 3.32 times larger than L929 cells.

Self-assembled three-dimensional double network graphene oxide/polyacrylic acid hybrid aerogel for removal of Cu2+ from aqueous solution

Three-dimensional (3D) double network graphene oxide/polyacrylic acid (GO/PAA) hybrid aerogels were fabricated under mild conditions from the mixture of GO and acrylic acid (AA) monomers using a one-pot in situ solution polymerization process which included the polymerization of AA and the self-assembly of functional GO sheets. The PAA chains served as not only binder to assemble GO sheets into 3D framework but also modifier to provide more active functional groups. The adsorbents based on such material exhibited superior adsorption performance towards Cu²⁺ ions in aqueous media due to rich mesopores, high specific surface area, and abundant active sites. This work brings a new vision for assembling 3D porous graphene-based nanomaterials as adsorbents in environmental protection.

The effect of dentine pre-treatment using bioglass and/or polyacrylic acid on the interfacial characteristics of resin-modified glass ionomer cements

OBJECTIVE

To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied onto dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning.

METHODS

RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (μTBS) testing or 6 months in AS immersion and subsequently μTBS tested. Results were analysed statistically by two-way ANOVA and Student-Newman-Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMGIC-bonded specimens were surveyed for interfacial ultramorphology characterisation (dye-assisted nanoleakage) using confocal microscopy.

RESULTS

RMGIC applied onto dentine air-abraded with BAG regardless PAA showed no significant μTBS reduction after 6 months of AS storage and/or load cycling (p > 0.05). RMGIC-dentine interface showed no sign of degradation/nanoleakage after both aging regimens. Conversely, interfaces created in PAA-conditioned SiC-abraded specimens showed significant reduction in μTBS (p < 0.05) after 6 months of storage and/or load cycling with evident porosities within bonding interface.

CONCLUSIONS

Dentine pre-treatment using BAG air-abrasion might be a suitable strategy to enhance the bonding performance and durability of RMGIC applied to dentine. The use of PAA conditioner in smear layer-covered dentine may increase the risk of degradation at the bonding interface.

CLINICAL SIGNIFICANCE

A combined dentine pre-treatment using bioglass followed by PAA may increase the bond strength and maintain it stable over time. Conversely, the use of PAA conditioning alone may offer no significant contribute to the immediate and prolonged bonding performance.

Covalent immobilization of acetylcholinesterase on a novel polyacrylic acid-based nanofiber membrane

In this study, polyacrylic acid-based nanofiber (NF) membrane was prepared via electrospinning method. Acetylcholinesterase (AChE) from Electrophorus electricus was covalently immobilized onto polyacrylic acid-based NF membrane by demonstrating efficient enzyme immobilization, and immobilization capacity of polymer membranes was found to be 0.4 mg/g. The novel NF membrane was synthesized via thermally activated surface reconstruction, and activation with carbonyldiimidazole upon electrospinning. The morphology of the polyacrylic acid-based membrane was investigated by scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and thermogravimetric analysis. The effect of temperature and pH on enzyme activity was investigated and maxima activities for free and immobilized enzyme were observed at 30 and 35°C, and pH 7.4 and 8.0, respectively. The effect of 1 mM Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Mg²⁺, Ca²⁺ ions on the stability of the immobilized AChE was also investigated. According to the Michaelis-Menten plot, AChE possessed a lower affinity to acetylthiocholine iodide after immobilization, and the Michaelis-Menten constant of immobilized and free AChE were found to be 0.5008 and 0.4733 mM, respectively. The immobilized AChE demonstrated satisfactory reusability, and even after 10 consecutive activity assay runs, AChE maintained ca. 87% of its initial activity. Free enzyme lost its activity completely within 60 days, while the immobilized enzyme retained approximately 70% of the initial activity under the same storage time. The favorable reusability of immobilized AChE enables the support to be employable to develop the AChE-based biosensors.

A new approach for development of vaccine against visceral leishmaniasis: Lipophosphoglycan and polyacrylic acid conjugates

OBJECTIVE

To determine the antileishmanial vaccine effectiveness of lipophosphoglycan (LPG) and polyacrylic acids (PAA) conjugates on in vivo mice models.

METHODS

LPG molecule was isolated and purified from large-scale Leishmania donovani parasite culture. Protection efficacies of LPG alone, in combination with Freund's adjuvant, in a physical mixture and in conjugate (consisting of various LPG concentrations) with PAA, were comparatively determined by various techniques, such as cultivation with the micro-culture method, assessment of in vitro infection rates of peritoneal macrophages, determination of parasite load in liver with Leishman-Donovan Units, and detection of cytokine responses.

RESULTS

Obtained results demonstrated that the highest vaccine-mediated immune protection was provided by LPG-PAA conjugate due to all parameters investigated. According to the Leishman-Donovan Units results, the sharpest decline in parasite load was seen with a ratio of 81.17% when 35 μg LPG containing conjugate was applied. This value was 44.93% for the control group immunized only with LPG. Moreover, decreases in parasite load were 53.37%, 55.2% and 65.8% for the groups immunized with 10 μg LPG containing LPG-PAA conjugate, a physical mixture of the LPG-PAA, and a mixture of LPG + Freund's adjuvant, respectively. Furthermore, cytokine results supported that Th1 mediated protection occurred when mice were immunized with LPG-PAA conjugate.

CONCLUSIONS

It has been demonstrated in this study that conjugate of LPG and PAA has an antileishmanial vaccine effect against visceral leishmaniasis. In this respect, the present study may lead to new vaccine approaches based on high immunogenic LPG molecule and adjuvant polymers in fighting against Leishmania infection.

Intensification of depolymerization of polyacrylic acid solution using different approaches based on ultrasound and solar irradiation with intensification studies

Depolymerization of polyacrylic acid (PAA) as sodium salt has been investigated using ultrasonic and solar irradiations with process intensification studies based on combination with hydrogen peroxide (H2O2) and ozone (O3). Effect of solar intensity, ozone flow and ultrasonic power dissipation on the extent of viscosity reduction has been investigated for individual treatment approaches. The combined approaches such as US+solar, solar+O3, solar+H2O2, US+H2O2 and US+O3 have been subsequently investigated under optimum conditions and established to be more efficient as compared to individual approaches. Approach based on US (60W)+solar+H2O2 (0.01%) resulted in the maximum extent of viscosity reduction as 98.97% in 35min whereas operation of solar+H2O2 (0.01%), US (60W), H2O2 (0.3%) and solar irradiation resulted in about 98.08%, 90.13%, 8.91% and 90.77% intrinsic viscosity reduction in 60min respectively. Approach of US (60W)+solar+ozone (400mg/h flow rate) resulted in extent of viscosity reduction as 99.47% in 35min whereas only ozone (400mg/h flow rate), ozone (400mg/h flow rate)+US (60W) and ozone (400mg/h flow rate)+solar resulted in 69.04%, 98.97% and 98.51% reduction in 60min, 55min and 55min respectively. The chemical identity of the treated polymer using combined approaches was also characterized using FTIR (Fourier transform infrared) spectra and it was established that no significant structural changes were obtained during the treatment. Overall, it can be said that the combination technique based on US and solar irradiations in the presence of hydrogen peroxide is the best approach for the depolymerization of PAA solution.

Polyacrylic acid attenuates ethylene glycol induced hyperoxaluric damage and prevents crystal aggregation in vitro and in vivo

The study explores calcium oxalate crystal inhibiting characteristic of polyacrylic acid (pAA), an anionic polymer in in vitro and in vivo. Animals were divided into 5 groups where group 1 served as control, group 2 were made hyperoxaluric by supplementing with Ethylene glycol (EG) 0.75% (v/v) for 30 days. Group 3, 4 & 5 were also given with EG and treated simultaneously with 2.5, 5 & 10 mg of pAA/kg of body weight, respectively. Urine, serum and tissue analyses along with histological studies were performed at the end of the 30 days study. In vitro crystallization was significantly inhibited by pAA and further it was supported by particle size analyses, XRD and FT-IR studies. Toxicological analyses showed that pAA was safe to use in animals at concentrations below 100 mg/kg BW. In vivo anti-urolithic study showed significant improvement in urinary lithogenic factors (calcium, oxalate, phosphate, citrate & magnesium) and renal function parameters (creatinine, urea and protein). Tissue analyses on anti-oxidant enzyme activity and lipid peroxides showed maintenance of tissue antioxidant status in the pAA supplemented rats and histological studies demonstrated the nephroprotection offered by pAA and were concurrent to the biochemical analyses. Supplementation of pAA not only reduces the crystal aggregation but also regulates the expression and localization of crystal inhibiting proteins and gene expression of inflammatory cytokines in experimental animals. In summary, pAA is a potent anti-urolithic agent in rats and we can propose that 10 mg/kg body weight is the effective dosage of pAA and this concentration can be used for further studies.

Graphene-polyelectrolyte multilayer film formation driven by hydrogen bonding

A method for preparing hydrogen bonded multilayer thin films comprised of layer pairs of surfactant stabilized graphene and an anionic polyelectrolyte is described. The films were constructed at low pH using the Layer-By-Layer (LbL) technique, where the adsorption of the cationic polyelectrolyte, polyethyleneimine (PEI) is followed by the sequential alternating adsorption of the anionic polyelectrolyte, polyacrylic acid (PAA) and anionic graphene sheets modified with Pluronic® F108, a polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) surfactant. Quartz Crystal Microbalance (QCM) measurements indicate that film formation was driven by hydrogen bonding between the carboxylic acid group of the PAA and ethylene oxide unit present in the surfactant. QCM measurements and Raman spectra showed evidence of non-linear and linear growth at low and high numbers of adsorbed layers respectively, suggesting overall superlinear film growth. Atomic Force Microscopy (AFM) Quantitative Nanomechanical Mapping (QNM) measurements of the films indicated that the reduced Young's Modulus of the films decreased with increasing numbers of adsorbed layers, reaching a bulk value of 6.07-32.3 MPa for samples with greater than 300 layers of surfactant stabilized graphene and PAA. The films were also shown to deteriorate partially with aqueous solutions at neutral and basic pH. The thin films exhibited features advantageous for use in coatings, such as pH responsiveness in addition to different mechanical properties, surface roughness, and internal structures based on the number of layers adsorbed.

Fabrication of interfacial functionalized porous polymer monolith and its adsorption properties of copper ions

The interfacial functionalized poly (glycidyl methacrylate) (PGMA) porous monolith was fabricated and applied as a novel porous adsorbent for copper ions (Cu(2+)). PGMA porous material with highly interconnected pore network was prepared by concentrated emulsion polymerization template. Then polyacrylic acid (PAA) was grafted onto the interface of the porous monolith by the reaction between the epoxy group on PGMA and a carboxyl group on PAA. Finally, the porous monolith was interfacial functionalized by rich amount of carboxyl groups and could adsorb copper ions effectively. The chemical structure and porous morphology of the porous monolith were measured by Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the effects of pore size distribution, pH value, co-existing ions, contacting time, and initial concentrations of copper ions on the adsorption capacity of the porous adsorbents were studied.

Controlled release of tinidazole and theophylline from chitosan based composite hydrogels

Several composite hydrogels were synthesized by free radical crosslink copolymerization of acrylic acid (AA) and N' methylene bis-acrylamide (MBA) in the presence of chitosan (CS). During polymerization CS was incorporated in situ in the crosslinked polyacrylic acid gel to produce composite hydrogels. The structure and properties of the hydrogels were characterized by FTIR, (13)C NMR, DTA-TGA, XRD, swelling and diffusion characteristic and also network parameters. The loading and the in vitro release behaviours of theophylline and tinidazole model drugs were studied with these hydrogels. The wt% of CS and MBA and pH of the medium was found to strongly influence the drug release behaviour of the gels. Accordingly, the release rate of these two drugs was much faster at pH of 7.6 than at pH 1.5.

Comparison of adsorption affinity of polyacrylic acid for surfaces of mixed silica-alumina

The influence of solution pH (in the range 3–9) on the adsorption of polyacrylic acid (PAA) on the mixed silica–alumina surface (SA-3: SiO₂ 97 %–Al₂O₃ 3 % and SA-96: SiO₂ 4 %–Al₂O₃ 96 %) was investigated. The following methods were applied in experiments: spectrophotometry, viscosimetry, potentiometric titration, and microelectrophoresis, which enable determination of adsorbed amount of the polymer, thickness of its adsorption layers, surface charge density, and zeta potential of solid particles in the presence and absence of PAA, respectively. The obtained results indicate that rise of solution pH causes the decrease of PAA adsorption and the increase of its adsorption layer thickness on surfaces of both solids. Moreover, significantly higher adsorption of polyacrylic acid was obtained on the SA-96 surface. This is a result of more favorable electrostatic interactions occurring between the adsorbing polymer chains and the SA-96 surface and formation of a greater number of adsorbate-adsorbent connections through hydrogen bridges.

Mobility of nanosized cerium dioxide and polymeric capsules in quartz and loamy sands saturated with model and natural groundwaters

The environmental and health risks posed by emerging engineered nanoparticles (ENPs) released into aquatic environments are largely dependent on their aggregation, transport, and deposition behavior. Herein, laboratory-scale columns were used to examine the mobility of polyacrylic acid (PAA)-coated cerium dioxide nanoparticles (nCeO2) and an analogous nanosized polymeric capsule (nCAP) in water saturated quartz sand or loamy sand. The influence of solution ionic strength (IS) and cation type (Na(+), Ca(2+), or Mg(2+)) on the transport potential of these ENPs was examined in both granular matrices and results were also compared to measurements obtained using a natural groundwater. ENP suspensions were characterized using dynamic light scattering and nanoparticle tracking analysis to establish aggregate size, and laser Doppler electrophoresis to determine ENP electrophoretic mobility. Regardless of IS, virtually all nCeO2 particles suspended in NaNO3 eluted from the quartz sand-packed columns. In contrast, heightened nCeO2 and nCAP particle retention and dynamic (time-dependent) transport behavior was observed with increasing concentrations of the divalent salts and in the presence of natural groundwater. Enhanced particle retention was also observed in loamy sand in comparison to the quartz sand, emphasizing the need to consider the nature of the aqueous matrix and granular medium in evaluating contamination risks associated with the release of ENPs in natural and engineered aquatic environments.