Presence Of Crosslinker Research Articles

Efficient drug delivery potential and antimicrobial activity of biocompatible hydrogels of dextrin/Na-alginate/PVA

Ceftriaxone sodium belongs to the third-generation cephalosporin group and is used intramuscular and intravenous route as a broad-spectrum antibiotic. This research aims to prepare biocompatible hydrogels for targeted delivery of ceftriaxone sodium by parental route. Different proportions of polymers (natural and synthetic) in the presence of cross-linker were synthesized by solvent casting method. Ceftriaxone sodium was loaded in hydrogels in different concentrations and its drug release behavior was evaluated along with swelling and biodegradation analysis. The characterization of hydrogel was done by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) to analyze surface morphology and functional groups involved in the formation of dextrin/Na-alginate/PVA hydrogels loaded with the drug. Thermogravimetric analysis (TGA) was confirmed by thermal stability and degradation pattern of loaded and unloaded hydrogels. The drug-loaded samples presented promising antimicrobial activity against S. aureus and P. multocida and their cytotoxic nature was also studied. Drug release analysis using simulated intestinal fluid (SIF) and phosphate buffer saline(PBS) for the circulatory system shows the consistent release of the drug. The findings unveiled the development of a biocompatible and innovative hydrogel, which has potential advantages for biomedical application, particularly in enhancing the therapeutic efficacy of ceftriaxone sodium drug.

Formulation and In Vitro Assessment of Polymeric pH-Responsive Nanogels of Chitosan for Sustained Delivery of Madecassoside.

Madecassoside, a triterpenoid saponin compound mainly isolated from the gotu kola herb (Centella asiatica), shows an extensive range of biological activities, including antiapoptotic, antioxidant, anti-inflammatory, moisturizing, neuroprotective, and wound healing effects. It has been highly used in the management of eczema, skin wounds, and other diseases. Due to poor oral bioavailability, membrane permeability, and intestinal absorption, the clinical application of the madecassoside is limited. Hence, a drug carrier system is needed that not only sustains the release of the madecassoside but also overcomes the drawbacks associated with its administration. Therefore, the authors prepared novel pH-responsive chitosan-based nanogels for the sustained release of madecassoside. Free radical polymerization technique was used for cross-linking of polymer chitosan and monomer methacrylic acid in the presence of cross-linker N',N'-methylene bis(acrylamide). The decrease in polymer crystallinity after polymerization and development of nanogels was demonstrated by XRD and FTIR analysis. The effects of nanogel contents on polymer volume, sol-gel analysis, swelling, drug loading, and release were investigated. Results indicated that high swelling and maximum release of the drug occurred at pH 7.4 compared to pH 1.2 and 4.6, indicating the excellent pH-sensitive nature of the engineered nanogels. High swelling and drug release were perceived with the integration of a high quantity of chitosan, while a decline was observed with the high integration of N',N'-methylene bis(acrylamide) and methacrylic acid contents. The same effects of nanogel contents were shown for drug loading too. Sol fraction was reduced, while gel fraction was enhanced by increasing the chitosan load, N',N'-methylene bis(acrylamide), and methacrylic acid. The Korsmeyer-Peppas model of kinetics was trailed by all nanogel formulations with non-Fickian diffusion. The results demonstrated that prepared nanogels can be employed for sustained release of the madecassoside.

Zwitterionic functionalization of polysaccharide gum by graft copolymerization to develop 3-D network materials for anticancer drug delivery applications

Herein, functionalization of polysaccharide gum has been carried out to develop network copolymeric materials for use in sustained anticancer drug delivery. Grafting reaction of poly[2-(methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSAH) onto sterculia gum has been done in the presence of crosslinker. Copolymeric materials were characterized by scanning electron micrographs (SEMs), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 13C-nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). SEM, AFM and XRD displayed heterogeneous morphology with a rough surfaces of amorphous copolymeric materials. Peaks at 173.822 ppm (carbonyl carbon) and at 60.653 ppm (methylene carbon attached to a quaternary ammonium group) confirmed the addition of poly(MEDSAH) during the grafting reaction. Mesh size in network hydrogel was found between 14.54 nm to 36.32 nm. Sustained release of doxorubicin was found with non-Fickian diffusion and was best demonstrated by the kinetic model Hixson Crowell. The biocompatibility of material was revealed in a haemolytic index (1.74 ± 0.26%) less than two percent during the copolymer-blood interaction. The material exhibited antioxidant and mucoadhesion properties. Free radical scavenging ability of copolymers was 49.41 ± 0.97% in 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay of the antioxidant test. These properties of copolymeric hydrogels demonstrated their suitability for use in sustained drug delivery systems for cancer chemotherapy.

Evaluation of physiochemical and biomedical properties of psyllium-poly(vinyl phosphonic acid–co-acrylamide)-cl-N,N-methylene bis acrylamide based hydrogels

Present investigation deals with the synthesis of psyllium based copolymeric hydrogels and evaluation of their physiochemical and biomedical properties. These copolymers have been prepared by grafting of poly(vinyl phosphonic acid) (poly (VPA)) and poly(acrylamide) (poly(AAm)) onto psyllium in the presence of crosslinker N,N-methylene bis acrylamide (NNMBA). These copolymers [psyllium-poly(VPA-co-AAm)-cl-NNMBA] were characterized by field emission-scanning electron micrographs (FE-SEM), electron dispersion X-ray analysis (EDAX), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA)- differential thermal analysis (DTG). FESEM, AFM and XRD demonstrated heterogeneous morphology with a rough surface and an amorphous nature. Diffusion of ornidazole occurred with a non-Fickian diffusion mechanism, and the release profile data was fitted in the Korsemeyer-Peppas kinetic model. Biochemical analysis of hydrogel properties confirmed the blood-compatible nature during blood-polymer interactions and revealed haemolysis value 3.95 ± 0.05 %. The hydrogels exhibited mucoadhesive character during biomembrane-polymer interactions and demonstrated detachment force = 99.0 ± 0.016 mN. During 2,2-diphenyl-1-picrylhydrazyl reagent (DPPH) assay, free radical scavenging was observed 37.83 ± 3.64 % which illustrated antioxidant properties of hydrogels. Physiological and biomedical properties revealed that these hydrogels could be explored for drug delivery uses.

Controlling the morphology of polystyrene dumbbell particles

Controlling colloidal particles’ shape is one of the new frontiers in colloidal science. Methods that permit synthesizing polymer particles with a non-spherical shape are increasing and advancing. Of all the non-spherical particles, spheres with protrusions are one of the best investigated, and many recipes have been developed to prepare them. One of the best-developed methods, initially proposed by Park et al. (JACS, 2010), starts with linear polystyrene seed particles, which are swelled and subsequently polymerized with a mixture of styrene and 3-(trimethoxysilyl)propyl methacrylate (MPS). The latter monomer’s hybrid nature creates a hydrophilic and partially crosslinked coating. This prevents the formation of core-shell structure upon further swelling and polymerization with styrene and leads to one or more new lobes. In this work, we investigate many parameters affecting the outcome of this method, including the pH, the duration of the hydrolysis of MPS, its concentration, the presence of crosslinkers in the seed particles, and the use of a different monomer in the last step. The investigation shows the importance of pH control during MPS hydrolysis in the coating step. It also demonstrates that its concentration can effectively be used to control the morphology of the resulting particles, which range from simple one-lobed dumbbells with variable roughness to multilobed particles. Furthermore, a shorter version of the dumbbell synthesis protocol has been obtained.

Preparation, characterization, and performance evaluation of composite films of polyvinyl alcohol/ cellulose nanofiber extracted from Imperata cylindrica

In recent years, production of cellulose nanofiber (CNF) from waste materials has achieved great interest owing to their renewable nature, biodegradability, high mechanical properties, economic value, and low density. Because Polyvinyl alcohol (PVA) is a synthetic biopolymer with good water solubility and biocompatibility, the composite material formed of CNF and PVA, is a sustainable way of monetizing to address environmental and economic issues. In this work pure PVA, PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5, and PVA/CNF2.0 nanocomposite films were produced using the solvent casting approach with the addition of 0, 0.5, 1.0, 1.5, and 2.0 wt% of CNF concentrations respectively. The strongest water absorption behaviour was found as 25.82% for pure PVA membrane, followed by PVA/CNF0.5 (20.71%), PVA/CNF1.0 (10.26%), PVA/CNF1.5 (9.63%), and PVA/CNF2.0 (4.35%). The water contact angle of 53.1°, 47.8°, 43.4°, 37.7°, and 32.3° was formed between water droplet and the solid-liquid interface of pure PVA, PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5, PVA/CNF2.0 composite films respectively. The SEM image clearly shows that a network structure like a tree form at the PVA/CNF0.5 composite film, where the sizes and number of pores are apparent. XRD analysis suggested that unique peaks found at 2θ = 17.5°, 28.1°, 33.4°, and 38° for nanocomposites indicating new crystal plane generated upon cross-linking in presence of malic acid. The maximum loss rate temperature (Td,max) for PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5 was determined by TG analysis to be around 273.4 °C. FTIR studies suggested that PVA/CNF0.5 composite film showed the highest peak at 1428 cm−1 as compared to other PVA/CNF composite films representing the presence of higher crystalline band in the composite film matrix. PVA/CNF0.5 composite film was found to have a surface porosity and mean pore size of 27.35% and 0.19 μm respectively, classifying it in the MF membrane category. The maximum tensile strength (TS) of 5.27 MPa was found for PVA/CNF0.5, followed by PVA/CNF1.0, PVA/CNF1.5, pure PVA, and PVA/CNF2.0. The maximum young's modulus (111 MPa) was found for PVA/CNF1.0, followed by PVA/CNF0.5, PVA/CNF2.0, PVA/CNF1.5, and pure PVA, which could be attributed to the cyclization of the molecular structures by cross-linking. PVA/CNF0.5 exhibits greater elongation at break (21.7) than the other polymers, indicating a material's ability to undergo significant deformation before failure. Performance evaluation of the PVA/CNF0.5 composite film showed that 46.3% and 92.8% yield were found in the retentate for 200 mg/L of BSA, and 5 × 107 CFU/mL respectively. However, more than 90% E. coli was retained by PVA/CNF0.5 composite film, therefore absolute rating of this membrane is 0.22 μm. The size of this composite film may be therefore considered in the range of MF.

Sustainable, processable and cytocompatible bioelastomers based on polycaprolactone and biobased polyester elastomer via dynamic vulcanization

AbstractBioelastomers (bio‐thermoplastic vulcanizate, bio‐TPV) with tunable elasticity, high strength and satisfactory cytocompatibility were fabricated via an in situ dynamic vulcanizing strategy, i.e. melt blending of biobased polyester elastomer (BPE) and polycaprolactone (PCL) in the presence of crosslinker with the occurrence of phase inversion. A large amount of the BPE, which provides flexibility and elasticity, was quickly crosslinked and finely dispersed in the PCL matrix, which provides strength and processability. Bio‐TPV with a BPE/PCL weight ratio of 70/30 exhibited good tensile properties, such as a tensile strength of 11.2 MPa and elongation at break of 414%. Additionally, the bio‐TPV demonstrated satisfactory processability and reprocessability. Moreover, the as‐prepared bio‐TPV promotes MC3T3 cell adhesion and proliferation. The combination of improved sustainability, processability, cytocompatibility and mechanical performance makes these bio‐TPVs potential candidates for both biomedical and engineering materials. © 2023 Society of Industrial Chemistry.

Optimization of Partially Hydrolyzed Polyacrylamide (HPAM) Utilized in Water-Based Mud While Drilling

Water-soluble polymers are becoming increasingly important in various applications, such as stabilizer fluids and drilling muds. These materials are used as viscosifiers and filtration control agents, flocculants, and deflocculants due to their superior properties in increasing viscosity and gelling ability in the presence of crosslinkers. In general, studying the rheological behavior of drilling fluids is of paramount importance to ensure successful well drilling operations. Partially hydrolyzed polyacrylamide is one of the polymers widely used in water-based muds. The main objective of this study is to optimize the rheological properties of drilling muds through a characterization study of various parameters, including rheological behavior, viscosity, temperature (23 °C, 40 °C, and 60 °C), salinity using KCl and NaCl contents, aging, pH, solubility, and structural analysis using infrared of partially hydrolyzed polyacrylamide. The study aims to demonstrate the importance of using polymers in drilling muds. The findings revealed that a rate of 3% of HPAM gave better rheological behavior, the influence of KCl (1.5%, 3%, and 4.5%) was greater than that of NaCl (1.5%, 3%, and 4.5%) on polymers, and the aging test showed that the different formulations are stable and maintain their behavior up to 110 °C. The solubility test results confirmed the maximum amount absorbed by polyacrylamide ([CHPAM] = 66.42 g/L) in order to avoid aggregation, gelification, and enhance the drilling mud by utilizing the prescribed contents.

Application of Molecularly Imprinted Electrochemical Sensor for Selective Non-Labelled Detection of Acetamiprid Insecticide in Fruits

Acetamiprid (ACP) is a widely used systemic insecticide as a replacement for organophosphorus compounds to control sucking-type insects on leafy vegetables, fruits, and tea trees. In this work, bulk polymerized molecularly imprinted polymer was developed using ACP as template, 4-Vinyl pyridine as monomer and ethylene glycol dimethyl acrylate (EGDMA) as cross-linker in presence of acetone as porogen. The polymers were then tested as a template recognition modifiers for carbon paste electrode in cooperation with multiwalled carbon nanotubes as a signal enhancer. The optimum response towards ACP was attained on using 10% of polymer ratio (1: 3: 40) and 5% MW-CNT in the electrode composition at pH 6.2 of 0.1 phosphate buffer as supporting electrolyte. The developed electrode was morphologically and electrochemically characterized and was found to show a linear response for differential pulse voltammetry of 1 × 10−12–5 × 10−6 M equivalent to 0.222–111.3 ×104 ng l−1 with limits of detection and quantification of 7.35 × 10−3 and 0.022 ng l−1, respectively. The electrode was efficiently applied for ACP detection in its pure solutions, commercial insecticide formulation and spiked apple, tomato, and watermelon samples with recoveries from 95.55%-101.66% indicating its efficiency for application in regulatory units for hazardous food contaminants.

Biosynthesis of silver-based nanoparticles on polypropylene non-woven material for efficient antimicrobial activity

The outbreak of the COVID 19 pandemic confirmed the importance of personal protective equipment including the respiratory face masks as barriers to pathogens. Taking into account that face masks are mainly composed of polypropylene (PP) non-woven materials this study explores the possibility of in situ biosynthesis of silver-based nanoparticles as an antimicrobial agent on PP material. A pomegranate peel extract was used as a ?green? agent for synthesis and stabilization of nanoparticles. Hydrophobicity of PP fibers was overcome by modification with corona discharge at atmospheric pressure. In order to improve the binding of silver ions, corona modified PP material was impregnated with biopolymer chitosan in the presence of crosslinker 1,2,3,4-butanetetracarboxylic acid. SEM analysis revealed the presence of spherical Ag-based nanoparticles on the fiber surface with an average size of approximately 69 nm. The higher the concentration of the precursor salt, the higher the silver content after the reduction. Larger amounts of Ag-based nanoparticles provided stronger antimicrobial activity against bacteria Escherichia coli and Staphylococcus aureus, and yeast Candida albicans.

Specific Binding of Ligand-Functionalized Thermoresponsive Microgels: Effect of Architecture, Ligand Density, and Hydrophobicity.

The biomolecular interaction of ligand-presenting switchable microgels is studied with respect to the polymer type, composition, and structure of the microgels. Monodisperse microgels are prepared through precipitation polymerization of N-isopropylacrylamide (PNIPAM microgels) or oligo(ethylene glycol methacrylamide)s (POEGMA microgels) in the presence of crosslinkers or in their absence (self-crosslinked). Functionalization with mannose or biotin as model ligands and affinity measurements upon heating/cooling are conducted to obtain mechanistic insights into how the microgel phase transition affects the specific interactions. In particular, we are interested in adjusting the crosslinking, swelling degree, and ligand density of mannose-functionalized microgels to reversibly catch and release mannose binding Escherichia coli by setting the temperature below or above the microgels' volume phase transition temperature (VPTT). The increased mannose density for collapsed microgels above the VPTT results in stronger E. coli binding. Detachment of E. coli by reswelling the microgels below the VPTT is achieved only for self-crosslinked microgels showing a stronger decrease in ligand density compared to microgels with dedicated crosslinkers. Owing to a reduced mannose density in the shell of POEGMA microgels, their E. coli binding was lower compared to PNIPAM microgels, as supported by ultraresolution microscopy. Importantly, an inverse temperature-controlled binding of microgels decorated with hydrophilic mannose and hydrophobic biotin ligands is observed. This indicates that hydrophobic ligands are inaccessible in the collapsed hydrophobic network above the VPTT, whereas hydrophilic mannose units are then enriched at the microgel-water interface and thus are more accessible.

Development of hydrogel based on Carboxymethyl cellulose/poly(4-vinylpyridine) for controlled releasing of fertilizers

A novel Carboxymethyl cellulose (CMC) and poly (4-vinylpyridine) (P4VP) hydrogel system is synthesized with different ratios, in the presence of cross-linker N, N,- methylene bis-acrylamide (MBA). The hydrogel is characterized via FTIR spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The FTIR results showed a strong interaction between both CMC, P4VP and the loaded fertilizer. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, biodegradability was investigated in soil to simulate real-world conditions. To determine the best release behavior of urea and calcium nitrate from the hydrogel, fertilizers were loaded with different ratios onto the hydrogel during its formation. Fertilizers release was followed by Atomic absorption spectroscopy to study the release of calcium nitrate and urea. Release kinetic parameters were obtained based on different mathematical models as Zero order, First order, Korsmeyer–Peppas and Higuchi models. The suitable proportionality between the mathematical models used and the fertilizers release was determined based on the correlation coefficients (R2). According to Zero order model urea release showed independent concentration. Based on Korsmeyer-Pappas and Higuchi models with high n value and R2 equals to 0.97. Compared to urea, Ca2+, Zero order and Higuchi have been ignored due to their poor correlation coefficients values as proportion with Ca2+ fertilizer release.

Assisted Compatibility, and Balanced Regulation of the Mechanical, Thermal, and Antioxidant Activity of Polyvinyl Alcohol-Chinese Bayberry Tannin Extract Films Using Different Di-Aldehydes as Cross-Linkers

Polyvinyl alcohol (PVA)-based films containing Chinese bayberry tannin (BT) were prepared by cross-linking using glyoxal, glutaraldehyde and dialdehyde starch, individually. The presence of cross-linkers was evident to promote the transparency and decrease the moisture content of PVA/BT films, while the water solubility stayed almost unchanged in the cross-linked PVA/BT films. All cross-linkers provided promotion of the water vapor permeability, mechanical property and thermal stability of PVA/BT films. The best water vapor barrier capacity was found in case of glutaraldehyde cross-linked PVA/BT film, while the highest tensile strength was encountered in case of glyoxal cross-linked PVA/BT films, compared with the uncross-linked films. The scavenging action of the films towards DPPH radical activity was influenced by the nature of each cross-linker. Namely, the PVA/AT film cross-linked by glutaraldehyde acquired the lowest radical scavenging activity in a certain time, suggesting that glutaraldehyde decreased the release rate of BT from PVA. Based on the experimental data, glutaraldehyde and dialdehyde starch could be more suitable for PVA/BT film preparation since they can promote the intermolecular interaction of PVA and BT to a reasonable extent.

Quick and sensitive colorimetric detection of amino acid with functionalized-silver/copper nanoparticles in the presence of cross linker, and bacteria detection by using DNA-template nanoparticles as peroxidase activity

In this project, poly (citric acid) (PCA) functionalized on nano Ag/Cu was synthesized by chemical analysis method. The nano probe was applied to detection of cysteine by using the magnesium (II) ions as a cross linker. The characterization of Ag/Cu/PCA nano probe was studied by using the UV–visible, morphological microscopy, dynamic light scattering, and zeta potential analyzer. The zeta potential and size of Ag/Cu/PCA were −38.0 mV and 18.0 nm, respectively. The prepared nano probe shows rapid response for detection of cysteine. The detection limit of Ag/Cu/PCA nano probe was 0.07 nM. Additional, the Ag/Cu/PCA nanoparticles was applied to cysteine detection from real samples in the presence of amino acids compounds. Rapidly and sensitive determination of Streptococcus pneumoniae is substantial for food safety and human health. The DNA-Ag/Cu/PCA were prepared as a template in chemical method and experimented as a bio-receptor for the cell bacteria detection as peroxidase-like catalytic process. The DNA-Ag/Cu/PCA nano probe shows a linear dynamic concertation range of Streptococcus pneumoniae via detection limit about 65 CFU/mL. The project presents that the DNA-Ag/Cu/PCA could detect the biological and bacterial samples via high accuracy.

A novel clean biopolymer-based additive to improve mechanical and microstructural properties of clayey soil

Conventional soil additives can cause serious environmental problems due to the greenhouse gas emission, consumption of huge amounts energy in their production process and threatening plant cover and underground water quality. To eliminate these destroying effects, environmentally friendly additives have gained great consideration. Although polysaccharides are considered as powerful biocompatible soil additives in recent studies, the effect of their crosslinked hydrogel with elevated rheological and adhesive properties has been very rarely investigated. In this paper, calcium chloride was used as ionic crosslinker to enhance recently proposed Persian gum biopolymer. A group of macro and micro scale tests including unconfined compressive strength, direct shear test, freeze thaw durability, scanning electron microscopy, stereo zoom microscopy, Brunauer, Emmett and Teller and x-ray diffraction were conducted. The tests were also performed on soil treated with xanthan gum as a common hydrocolloid of soil stabilization. Combination of 2% Persian gum and 2 molar ionic crosslinker was determined as optimum additive content. The superior compressive strength improvement of crosslinked hydrogel (about 201.1%) than xanthan gum (83.5%) shows its powerful strengthening performance. In terms of durability, crosslinked hydrogel has reduced mass loss of pure Persian gum treated soil from 19.1 to 10.25% that is comparable with xanthan gum. Consumption of lower amounts of Persian gum at presence of crosslinker can make stabilization projects economical efficient. Microscale tests also confirmed the powerful impact of optimum modified hydrogel on soil interstructure by filling the pores, agglomeration of soil particles and formation of new cementitious compounds.

A Review on Molecularly Imprinted Polymers Preparation by Computational Simulation-Aided Methods.

Molecularly imprinted polymers (MIPs) are obtained by initiating the polymerization of functional monomers surrounding a template molecule in the presence of crosslinkers and porogens. The best adsorption performance can be achieved by optimizing the polymerization conditions, but this process is time consuming and labor-intensive. Theoretical calculation based on calculation simulations and intermolecular forces is an effective method to solve this problem because it is convenient, versatile, environmentally friendly, and inexpensive. In this article, computational simulation modeling methods are introduced, and the theoretical optimization methods of various molecular simulation calculation software for preparing molecularly imprinted polymers are proposed. The progress in research on and application of molecularly imprinted polymers prepared by computational simulations and computational software in the past two decades are reviewed. Computer molecular simulation methods, including molecular mechanics, molecular dynamics and quantum mechanics, are universally applicable for the MIP-based materials. Furthermore, the new role of computational simulation in the future development of molecular imprinting technology is explored.

A Comprehensive Review on Alginate as Wound Dressing Biomaterial

Background: The design and characteristics of alginate biomaterial have a significant role in wound dressing and tissue regeneration. The ideal biomaterial for wound dressing must be biodegradable, biocompatible, non-inflammatory, and non-toxic. Objective: Wound dressing should promote the re-epithelization process and protect the wound from further infection by creating a moist environment. The physical and mechanical nature of the alginate biopolymer has the potential to influence the pathophysiological mechanisms in the chronic wound. The application of this biomaterial provides ample advantages than synthetic polymers. Methods: The wound healing process is a critical step involved in different phases. The presence of cross-linkers, various drugs along with alginate leads to a decrease in the mechanical property of dressing. Hence the choice of an effective material for dressing along with alginate is a very critical decision. The therapeutic efficacy of the alginate dressing system (film, hydrogel, wafer, etc.) is influenced by the incorporation of different materials such as bioactive agents, nanoparticles, crosslinkers, nature of the excipients, etc. Results: The ion exchange occurring between dressing and exudates results in the formation of a gel, due to the presence of glucuronic acid in alginate. This gel absorbs moisture and maintains an appropriate moist environment and actively influences the pathophysiological mechanisms of the chronic wound. Conclusion: This review provides detailed knowledge to researchers to work with alginate and also knowledge about the incorporation of an appropriate material and its therapeutic efficacy in wound dressing.

Microtubule Self-Organization in Presence of Cross-Linkers and Crowders

Microtubule Self-Organization in Presence of Cross-Linkers and Crowders

Preparations of Tough and Conductive PAMPS/PAA Double Network Hydrogels Containing Cellulose Nanofibers and Polypyrroles.

To afford an intact double network (sample abbr.: DN) hydrogel, two-step crosslinking reactions of poly(2-acrylamido-2-methylpropanesulfonic acid) (i.e., PAMPS first network) and then poly(acrylic acid) (i.e., PAA second network) were conducted both in the presence of crosslinker (N,N′-methylenebisacrylamide (MBAA)). Similar to the two-step processes, different contents of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) oxidized cellulose nanofibers (TOCN: 1, 2, and 3 wt.%) were initially dispersed in the first network solutions and then crosslinked. The TOCN-containing PAMPS first networks subsequently soaked in AA and crosslinker and conducted the second network crosslinking reactions (TOCN was then abbreviated as T for DN samples). As the third step, various (T–)DN hydrogels were then treated with different concentrations of FeCl3(aq) solutions (5, 50, 100, and 200 mM). Through incorporations of ferric ions into (T–)DN hydrogels, notably, three purposes are targeted: (i) strengthen the (T–)DN hydrogels through ionic bonding, (ii) significantly render ionic conductivity of hydrogels, and (iii) serve as a catalyst for the forth step to proceed with in situ chemical oxidative polymerizations of pyrroles to afford polypyrrole-containing (sample abbr.: Py) hydrogels [i.e., (T–)Py–DN samples]. The characteristic functional groups of PAMPS, PAA, and Py were confirmed by FT–IR. Uniform microstructures were observed by cryo scanning electron microscopy (cryo-SEM). These results indicated that homogeneous composites of T–Py–DN hydrogels were obtained through the four-step process. All dry samples showed similar thermal degradation behaviors from the thermogravimetric analysis (TGA). The T2–Py5–DN sample (i.e., containing 2 wt.% TOCN with 5 mM FeCl3(aq) treatment) showed the best tensile strength and strain at breaking properties (i.e., σTb = 450 kPa and εTb = 106%). With the same compositions, a high conductivity of 3.34 × 10−3 S/cm was acquired. The tough T2–Py5–DN hydrogel displayed good conductive reversibility during several “stretching-and-releasing” cycles of 50–100–0%, demonstrating a promising candidate for bioelectronic or biomaterial applications.

Preparation of multifunctional cellulosic fabric based on graphene/TiO2 nanocoating

Photocatalysts in powder form commonly cannot have a high photocatalytic efficiency without strong agitation in traditional photocatalytic process. It is also inconvenient for recovery of the photocatalysts in powder form after usage. This consequently, results in a secondary pollution which limits their application in water treatment for heavily polluted natural waterways. In this work, coating GO and TiO2 nanomaterials over large-scale cellulose substrates which can easily float on water was performed in the presence of crosslinker by applying a simple dip-coating method. The photocatalytic activities were evaluated by studying the degradation of two models of organic pollutants, methylene blue and glyphosate under visible light irradiation. The nanomaterial wrapped substrates endured over 40 times reuse at an optimum photocatalyst concentration of 0.1 g/L GO and 15% TiO2 based on fabric weight. The highest degradation rate was obtained at this point and a further increase in concentration decreased the degradation rate. The efficient degradation of glyphosate by the nanomaterial loaded substrate confirms its industrial application in treating pesticide and herbicide polluted waters. Remarkably, this study has established a feasible practical way for direct degradation of pollutants in lakes or rivers using mechanically floating large-scale cellulose-supported photocatalysts.