Excellent Water Absorption Research Articles

Carboxymethyl Chitosan and Gelatin Hydrogel Scaffolds Incorporated with Conductive PEDOT Nanoparticles for Improved Neural Stem Cell Proliferation and Neuronal Differentiation

Tissue engineering scaffolds provide biological and physiochemical cures to guide tissue recovery, and electrical signals through the electroactive materials possess tremendous potential to modulate the cell fate. In this study, a novel electroactive hydrogel scaffold was fabricated by assembling poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles on a carboxymethyl chitosan/gelatin (CMCS/Gel) composite hydrogel surface via in situ chemical polymerization. The chemical structure, morphology, conductivity, porosity, swelling rate, in vitro biodegradation, and mechanical properties of the prepared hydrogel samples were characterized. The adhesion, proliferation, and differentiation of neural stem cells (NSCs) on conductive hydrogels were investigated. The CMCS/Gel-PEDOT hydrogels exhibited high porosity, excellent water absorption, improved thermal stability, and adequate biodegradability. Importantly, the mechanical properties of the prepared hydrogels were similar to those of brain tissue, with electrical conductivity up to (1.52 ± 0.15) × 10-3 S/cm. Compared to the CMCS/Gel hydrogel, the incorporation of PEDOT nanoparticles significantly improved the adhesion of NSCs, and supported long-term cell growth and proliferation in a three-dimensional (3D) microenvironment. In addition, under the differentiation condition, the conductive hydrogel also significantly enhanced neuronal differentiation with the up-regulation of β-tubulin III expression. These results suggest that CMCS/Gel-PEDOT hydrogels may be an attractive conductive substrate for further studies on neural tissue repair and regeneration.

Waste Cabbage-Integrated Nutritional Superabsorbent Polymers for Water Retention and Absorption Applications.

To alleviate soil impoverishment and water shortage in desert areas, as well as to reduce the impact of waste cabbage on the environment and human health, we used waste cabbage as a substrate, 2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS) and acrylic acid (AA) as polymerization units, and NH4Cl and KNO3 as nutriment to obtain two waste cabbage-superabsorbent polymers (CB-SAPNH4Cl and CB-SAPKNO3) by the one-pot method. The chemical structure, thermal stability, and morphology of the polymers were investigated by Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscope (SEM). Meanwhile, the water retention, water absorption, and salt resistance were compared with the purchased polymers. The results showed that the nutriment was successfully encapsulated inside the polymer, and CB-SAPNH4Cl and CB-SAPKNO3 at 1% nutrient concentration showed excellent water retention properties, salt resistance, and water absorption performance of 1546 and 1131 g/g (distilled water), 306 and 277 g/g (tap water), and 116 and 91 g/g (0.9% NaCl solution). Therefore, they are highly promising materials for the application.

Fenton-like redox-initiated synthesis of superabsorbent composites with excellent water retention and swelling properties based on green tea and oil shale semi-coke

Much increasing attention recently has been paid for the design of superabsorbent composites with superior adsorption/retention performances by economic and efficient preparation process. Herein, a facile and economic preparation strategy were employed for preparation of high-performance superabsorbent composites based on the redox-reaction between the components derived from natural green tea (GT) and calcined oil shale semi-coke (COSSC). The as-prepared chitosan-grafting-polyacrylic acid/green tea/calcined oil semi-coke (CS-g-PAA/GT/COSSC) superabsorbent composites showed the favorable water absorption capability and water uptake rate of 404 g/g in distilled water and 62 g/g in 0.9 wt% NaCl solution in 30 mins. After being buried for 90 days in soil, the superabsorbent composites indicated a 57 % biodegradation rate due to the presence of natural polymer of CS and GT residues. The superabsorbent composites also exhibited the perfect water retention capacity in soil, the total seed biomass and stem length of cabbage increased by 27.20 % and 30 %, after incorporation of 0.5 % of superabsorbent composites in soil, respectively. Based on the excellent water absorption, water retention and growth-promoting properties, the high efficient and economic superabsorbent composites prepared via low temperature-initiated polymerization presented a great potential in the charge of arid and semi-arid agriculture.

Superabsorbent Polymer with Excellent Water/Salt Absorbency and Water Retention, and Fast Swelling Properties for Preventing Soil Water Evaporation

In arid areas, the rapid evaporation of water leads to severe water shortage for plant growth. Superabsorbent polymers have the prospect of preventing water evaporation because of its excellent water absorbency. However, insufficient in salt resistance, water retention, and swelling rate limit its application. Herein, we fabricated Hydroxyethyl cellulose-g-(Acrylic acid-co-2-Acrylamido-2-methyl-1-propane sulfonic acid)/laterite (HEC-g-P (AA-co-AMPS)/laterite) with exceptional abovementioned performances by aqueous solution polymerization. Under optimal synthesis conditions, the water absorbency of the superabsorbent polymer were 1294 g/g, 177 g/g, and 119 g/g in distilled water, tap water, and 0.9 wt% NaCl solution, respectively. The water retention of the superabsorbent polymer was still as high as 97.7% after 16 h at 25 ℃, the water absorbency was up to 832 g/g after re-swelling for 5 times at 40 ℃, and the water absorption reached swelling equilibrium was only 5 min. We investigated the effect of the mount of swollen hydrogel on the water evaporation rate in soil, and the results showed that hydrogels were effective in inhibiting soil water evaporation. Our study provides a new horizon for the application of superabsorbent polymer.

Fully bio-based poly (pentamethylene glutaramide) with high molecular weight and less glutaric acid cyclization via direct solid-state polymerization

Poly (pentamethylene glutaramide) (PA55) has broad application prospects because all the polymeric monomers can be obtained from biomass fermentation. However, it is very difficult to obtain PA55 with high molecular weight by conventional melt polymerization (MP) due to the cyclization of glutaric acid. Thermodynamics and kinetics studies illustrated that the cyclization activity of glutaric acid increased with increasing temperature. Solid-state polymerization can be carried out at a low temperature and effectively avoid the occurrence of side reactions. Herein, we successfully inhibited the cyclization ratio of glutaric acid at low polymerization temperature via direct solid-state polymerization (DSSP) and obtained high molecular weight PA55 (ηr = 1.99, Mn = 19 kg·mol−1), which was much higher than that of MP (ηr = 1.52, Mn = 6 kg·mol−1). PA55 possessed a high melting temperature (Tm = 241 °C), excellent thermal stability (Td5 = 408 °C) and high water absorption (>13 wt%). Besides, the cyclization of glutaric acid related to polymerization methods, temperature and time was studied systematically, the ratio of imide ring could be controlled at <3 mol% via DSSP.

Biocompatible Carboxymethyl Chitosan/GO-Based Sponge to Improve the Efficiency of Hemostasis and Wound Healing.

Sponges with highly absorptive properties have been widely used in emergency hemostasis. Graphene oxide (GO) has been extensively investigated in biomedical applications and is a promising candidate for hemostatic sponges. However, GO has been demonstrated to have adverse effects on the human body. To overcome this problem, a hemostatic sponge based on modified GO and carboxymethyl chitosan (CMCS) is successfully prepared, which has excellent water absorption ability and mechanical strength. Importantly, hemostasis assays showed that the composite sponge exhibited high hemostatic efficiency, and the possible hemostatic mechanism is also discussed in this study. Moreover, the results of in vitro antibacterial tests reveal that the composite sponge also presents strong antimicrobial effects against Staphylococcus aureus and Escherichia coli. Significantly, the composited sponge used as hemostatic dressing can effectively promote cell proliferation, achieving a wound closure rate of 95% on day 12. Such a graphene-based sponge with multiple advantageous features would hold broad prospects in the hemostatic field.

Preparation and hemostatic mechanism of bioactive glass-based membrane-like structure camouflage composite particles

Powder hemostatic particles have no limitation on wound type and a wide application prospect in the treatment of wound hemostasis. In this study, bioactive glass-based membrane-like structure camouflage composite particles (MBG@BSA/CS) were prepared by Layer-by-layer (LBL) method to coat bovine serum albumin (BSA) and chitosan (CS) on the surface of the synthesized macroporous and mesoporous bioactive glass (MBG). The results showed that MBG@BSA/CS particles significantly improved the coagulation effect of MBG and could activated both endogenous and exogenous physiological coagulation pathways. MBG@BSA/CS had the excellent water absorption quality and could immediately release Ca2+ to participate in the coagulation pathway. The main hemostatic mechanism of MBG@BSA/CS was that the membrane-like of BSA/CS could form a fibrin network by aggregating erythrocytes and activating platelets, thus rapidly aggregating coagulation factors. In addition, MBG@BSA/CS particles had a significant hemostatic effect on surface bleeding (tail-amputation model) and internal bleeding (liver injury model) in SD rats, which could shorten the bleeding time and reduce the amount of blood loss effectively. This research work stated that the MBG-based membrane-like structure camouflage composite particles might be with the potential applications as a hemostasis biomaterial for the emergency bleeding.

Gelatin-based nanofiber membranes loaded with curcumin and borneol as a sustainable wound dressing

Infection is a huge obstacle to wound healing. Thus, to enhance the healing of infected wounds, wound dressings that permit the dual delivery of antimicrobials and antioxidants are highly desirable. In this study, a series of gelatin-based nanofiber membranes with different curcumin contents were fabricated via solution electrospinning. The obtained membranes were characterized in terms of their morphologies, in addition to their physical, mechanical, and in vitro properties. The results showed that the membranes maintained an integrated morphology, excellent water absorption capability, satisfactory mechanical properties, and a high dissolution rate of curcumin. The addition of curcumin and borneol conferred the membranes the ability to inhibit Staphylococcus aureus and eliminate free radicals. Furthermore, cytocompatibility testing using the L929 cell line confirmed the excellent biocompatibility of the membranes. These gelatin-based nanofiber membranes loaded with curcumin and borneol can therefore be considered as promising materials for dressing wounds. Moreover, the use of biodegradable polymers and environmentally sustainable production techniques in this system render it suitable for the commercial manufacture of composite membranes.

Assembling a multi-component and multifunctional integrated filament scaffold based on triaxial 3D bioprinting technology

Currently, most scaffolds produced by 3D printing is based on a single material which limits their wide application in the medical field. In this study, a multi-component and multifunctional shell-core filament 3D scaffold was designed and subsequently produced by triaxial bioprinting technology using sodium alginate, gelatin, collagen, chitosan and platelet-rich plasma (PRP) as biological raw materials. The resulting filamentous 3D scaffold exhibited excellent water absorption and retention capacity, good biocompatibility as well as antibacterial effects. In addition, compared with clinically-used PRP-gel, the filamentous 3D stent could effectively reduce the frequency of PRP administration by 50–75% during wound treatment while also showing better therapeutic effects.

A chitosan based multimodal “soft” hydrogel for rapid hemostasis of non-compressible hemorrhages and its mode of action

Uncontrolled hemorrhages during accidents or surgery require non-compressible dressings to halt bleeding and avoid damage to soft tissue and organs. Here, we report the synthesis of a sodium tripolyphosphate crosslinked chitosan-based hemostatic hydrogel dressing incorporating hemostasis agonists like aluminum chloride, an aggregation enhancer and silica nanoparticles, a contact activator, as confirmed by FTIR analyses. Rheology studies displayed G” > G’ values confirming typical soft gel-like behavior that was maintained upto shear rate 10/s. Further, composite had excellent water absorption capacity (737 ± 50%) and showed 6-fold enhanced in vitro hemostasis as compared to bare hydrogel. Platelet aggregation was enhanced with composite as compared to SFLLRN peptide (a thrombin mimic) and adenosine diphosphate (calcium release activator) while it was absent with heparin (thrombin inhibitor). Enhanced activation and release of calcium were observed by composite with a specific fluorescent calcium dye in A549 cell model. The composite was biocompatible and in vivo evaluation of hemostatic efficiency in rat liver injury revealed enhanced blood clotting (16 ± 2.1 s) of hydrogel composite as compared to commercial HemoStat Clear gel (55 ± 5 s). Thus, developed soft hydrogel composite has potential for application as a safe, easy-to-apply, rapid, non-compressible hemostatic agent.

Starch and itaconic acid-based superabsorbent hydrogels for agricultural application

Biobased superabsorbent is considered as an interesting polymeric material with excellent water absorption capacity. It can act as an active agent carrier and soil conditioner along with others. Howsoever, extensive usage of polymeric superabsorbent derived from conventional petroleum sources is posing serious threats to sustainability of the ecosystem. In this facet, a high biobased content (63 %) superabsorbent was synthesized using starch and itaconic acid as renewable resources. The prepared superabsorbent polymer was authenticated by its high-water absorption capacity (650 g/g) due to the presence of porous morphology as supported by SEM image analysis and the presence of various polar groups in its structure as confirmed by Fourier transform infrared (FTIR) spectral analysis. The superabsorbent hydrogels with different compositions were prepared and their performance was evaluated towards water absorption with and without load, and in salt solutions. The swelling kinetic studies of the hydrogels revealed faster water absorption with higher itaconic acid content. The urea encapsulated hydrogels were used in soil to judge their abilities for water holding capacity, seed germination rate, soil porosity enhancement, etc. Moreover, the hydrogels possess good biodegradability as confirmed by the soil burial study, and thereby endowing the environmentally benign characteristic which can overcome the shortcomings of petroleum-based hydrogels. Thus, they have great potential to be used in agricultural applications, especially as environmentally friendly superabsorbent.

Tetra functional epoxy/polyhedral oligomeric silsesquioxane (POSS) nanocomposites with enhanced mechanical, thermal, anticorrosion and dielectric properties

Tetra functional epoxy resin namely tetraglycidyl 1,4’-bis (4-amine-phenoxy) sulphone benzene epoxy (TGBAPSB) was developed via 1,4’-bis (4-amine-phenoxy) sulphone benzene (BAPSB) and epichlorohydrin. TGBAPSB was reinforced with polyhedral oligomeric silsesquioxane (POSS) nanomaterial in various weight percentages (1–2 wt%) and polyamidoimidazoline (Aradur 140) was used as curing agent. FT-IR results validated the molecular structure of the synthesized POSS. Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) evaluated the thermo-mechanical and thermal behaviour of TGBAPSB epoxy matrix and its organic-inorganic hybrid epoxy nanocomposites (TGBAPSB/POSS). X-Ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) investigated the surface morphological behaviour of the organic-inorganic hybrid epoxy nanocomposites. TGBAPSB epoxy resin with optimized POSS reinforcement exhibited excellent thermo-mechanical, thermal, mechanical, dielectric, and water absorption properties, making it a suitable material for advanced high-performance applications.

In-situ forming hydrogel incorporated with reactive oxygen species responsive and antibacterial properties for diabetic infected chronic wound healing

Chronic diabetic wounds are often characterized by oxidative damage due to bacterial infection or pathological interference, representing a major clinical challenge. An in-situ gelled and shape-adaptable hydrogel with antibacterial and reaction oxygen species (ROS) scavenging properties was developed in this study. It was designed and synthesized via progressively adding dl-Dithiothreitol, Poly (ethylene glycol) diacrylate and phenylboronic acid modified ε‑Poly-Lysine to obtain a stock solution before use. Through local light-induced in-situ gelling, this hydrogel can provide a physical barrier that fills wound defects and protects the wounds from bacteria. Moreover, the EPL-PBA modified DPEs exhibited excellent water absorption and outstanding consumption of H2O2, which could respond to an overdose of the oxidative micro-environment to promote wound healing. Moreover, the hydrogel displayed great biocompatibility and antibacterial activity, enabling the wound dressing to effectively inhibit bacterial growth and accelerate infected wound healing. Furthermore, an infected diabetic chronic full-thickness skin defect healing test revealed that the wound dressing promoted wound contraction and healing via inflammatory adjustment and collagen deposition. All of these in vitro and in vivo results revealed the capability of DPE2 to the acceleration of infected diabetic wound healing, presenting a viable material for chronic wound healing.

Eco-friendly superabsorbent composites based on calcined semicoke and polydimethylourea phosphate: Synthesis, swelling behavior, degradability and their impact on cabbage growth

In this work, novel eco-friendly superabsorbent composites of chitosan-grafted-polyacrylic acid/polydimethylourea phosphate/calcined semicoke (CS-g-PAA/PDUP/CSC) with the semi-interpenetrating network (semi-IPN) were developed via a convenient redox polymerization at room temperature. The redox polymerization was triggered by the calcined oil shale semicoke (CSC) under air atmosphere, in which the iron-compounds of CSC and Na2S2O3 were employed as oxidizing agent and reducing agent, respectively. The CS-g-PAA/PDUP/CSC composites prepared at the optimal conditions exhibited the maximum water absorption capacity of 412.89 and 51.30 g/g in deionized water and 0.9 wt% NaCl solution within 60 min, respectively. The excellent water absorption and retention performance were related to the introduction of CSC, which could be served as an inorganic component weakening the hydrogen-bond interaction between the functional groups in the polymer matrix and the semi-IPN. The superabsorbent composites also showed the favorable degradability, and 42.35 % of superabsorbent was degraded at 90 days. Interestingly, the nitrogen element provided by urea and chitosan could be released during degradation and directly absorbed by the plant to promote the growth. Integration of the above performance, the prepared composites may be used for better water resources management in agriculture taken into account of the corresponding environmental benefits.

Slow Release and Water Retention Performance of Poly(acrylic acid-co-acrylamide)/Fulvic Acid/Oil Shale Semicoke Superabsorbent Composites.

In order to achieve the low cost and multifunction of superabsorbent composites, poly(acrylic acid-co-acrylamide)/fulvic acid/oil shale semicoke (PAMFS) were prepared by free radical copolymerization of fulvic acid (FA), oil shale semicoke (OSSC), acrylic acid (AA) and acrylamide (AM). The characterization results revealed that FA and OSSC were involved in the construction of a three-dimensional (3D) polymeric network via hydrogen bonding and covalent bonding. The water absorbency of PAMFS in distilled water and 0.9 wt% NaCl solution were 724 and 98 g/g, respectively. The FA slow release of PAMFS in distilled water and soil was achieved due to the interaction between FA and the functional groups of polymer matrix by hydrogen bonds and covalent bonds. Furthermore, the potted experiment indicated that the addition of PAMFS to soil can significantly promote plant growth compared with the pure soil, regardless of water stress. Therefore, this superabsorbent composite showed an excellent water absorption and salt resistance performance, as well as nice slow release performance. It has a broad application prospect.

A Multifunctional Microspheric Soil Conditioner Based on Chitosan-Grafted Poly(acrylamide-co-acrylic acid)/Biochar.

A multifunctional microspheric soil conditioner based on chitosan-grafted poly(acrylamide-co-acrylic acid)/biochar [CS-g-P(AM-co-AA)/BC] was prepared. First, the P(AM-co-AA) was synthesized and successfully grafted onto CS, and the three-dimensional network structure of microspheres was formed with N,N-methylenebis(acrylamide) as the cross-linking agent according to the inverse suspension polymerization method. Meanwhile, BC and urea were encapsulated into the body of microspheres during the polymerization. The structure of the microspheres was analyzed by Fourier transform infrared spectroscopy, polarized optical microscopy, and scanning electron microscopy, and the mechanism of adsorption of Cu2+ on the microspheres was investigated by X-ray photoelectron spectroscopy. Furthermore, the experimental results demonstrated the excellent water absorption and retention capabilities of microspheres, and the release rate of urea was dramatically reduced. Importantly, the introduction of BC significantly enhanced the adsorption performance of the microspheres with respect to heavy metal ions. Consequently, the multifunctional soil conditioner held promise for use in soil improvement and agricultural production.

Wood-Inspired Compressible Superhydrophilic Sponge for Efficient Removal of Micron-Sized Water Droplets from Viscous Oils.

Efficient micron-sized droplet separation materials have become a new demand for environmental protection and economic development. However, existing separation methods are difficult to be effectively used for micron-sized water droplets surrounded by viscous oil, and common materials have difficulty maintaining hydrophilicity underoil. Here, inspired by the microstructure of tree xylem, we report a cellulose-polyurethane sponge (CP-Sponge) with wood-like pores and underoil superhydrophilicity using directional freeze-casting. The CP-Sponge has an excellent selective water absorption capacity underoil and compression resilience. This preparation strategy can flexibly control the sponge's dimensional morphology. The designed cylindrical CP-Sponge can be easily installed in the silicone tube of a peristaltic pump. During pump operation, with a simple absorption, compression, and recovery process, the CP-Sponge continuously and effectively removes micron-sized water from crude oil and lubricating oil, reducing residual water in the oil to less than 2 ppm. The absorption-saturated sponge can be dried to continue recycling. Eco-friendly, recyclable, and sustainable artificial porous sponges provide new ideas and inspiration for the practical application of deep dehydration of viscous oils.

Bletilla striata polysaccharide modified collagen fiber composite sponge with rapid hemostasis function

Emergencies often result in uncontrollable bleeding, which is thought to be the leading cause of death at the scene of the injured. Among various hemostasis scenarios, collagen fiber (CF) is gradually replacing traditional hemostatic materials due to its superior properties and ease of sourcing from animals. Herein, we use CF and the natural herbaceous Bletilla striata as raw materials to prepare a collagen fiber-oxidized Bletilla striata composite hemostatic sponge (CFOB). During the cross-linking process, the triple helix structure of collagen stays intact, and its porous three-dimensional network structure brings excellent bulkiness and water absorption properties. Experiments show that the optimal amount of sponge CFOB-10, namely oxidized Bletilla striata polysaccharide 0.5 mg/mL and CF 5 mg/mL, only needed 25 ± 4.06 s for hemostasis time in the rat liver hemorrhage model. In addition, CFOB meets the safety performance requirements of cytotoxicity classification standard 0. Therefore, the optimal amount of CFOB is an excellent new hemostatic material with application potential.Graphical

Novel superabsorbent polymer composites based on α-cellulose and modified zeolite: synthesis, characterization, water absorbency and water retention capacity

Most superabsorbent polymers (SAPs) are prepared based on synthetic polymers (from petroleum resources), making them costly, nondegradable, and not ecofriendly. To overcome these drawbacks, biodegradable and renewable natural materials are proposed as additions into SAPs. In this article, a new SAP composite was synthesized by using AA, AM, α-cellulose, and modified zeolite (MZE). The prepared SAP composites were analysed by FTIR spectroscopy, XRD, SEM and TGA. Then, their water absorbency and water retention capacity results were evaluated. AA and AM were successfully grafted to the α-cellulose chains, and MZE was uniformly dispersed in the SAP composite matrix as an inorganic filler, which endowed the SAP composites with a more undulant and coarser surface along with more abundant hydrophilic groups. In contrast with poly(AA-co-AM), the water absorbency of the prepared SAP composites increased by 93.88% in distilled water and 89.58% in 0.9 wt.% NaCl solution. Additionally, the water retention time of these SAP composites was 11.2 h when evaluated at 50 °C, which was a 71.79% increase. Moreover, both the Tonset and Tpeak of the prepared SAP composites slightly increased compared with those of α-cellulose-poly(AA-co-AM), showing that the introduction of MZE could slightly improve the thermal stability of the SAP composites. These novel SAP composites with their excellent water absorbency and retention capacity could be applied to the agricultural and horticultural fields as water-keeping materials.

A multifunctional 3D dressing unit based on the core-shell hydrogel microfiber for diabetic foot wound healing.

The healing mechanism of diabetic foot wounds is very complicated, and it is difficult for a single-function medical dressing to achieve good therapeutic effects. We propose a simple coaxial biological 3D printing technology, which uses one-step 3D deposition to continuously produce multifunctional medical dressings on the basis of core-shell hydrogel fibers. These dressings have good biocompatibility, controlled drug-release performance, excellent water absorption and retention, and antibacterial and anti-inflammatory functions. In vivo experiments with type 2 diabetic rats were performed over a 14-day period to compare the performance of the multifunctional 3D dressing with a gauze control; the multifunctional 3D dressing reduced inflammation, effectively increased the post-healing thickness of granulation tissue, and promoted the formation of blood vessels, hair follicles, and highly oriented collagen fiber networks. Therefore, the proposed multifunctional dressing is expected to be suitable for clinical applications for healing diabetic foot wounds.