Graphene Oxide-based Hydrogels Research Articles

Study of mechanical property and biocompatibility of graphene oxide/MEO2MA hydrogel scaffold for wound healing application.

Wound healing is a complex biological process crucial for restoring tissue integrity and preventing infections. The development of advanced materials that facilitate and expedite the wound-healing process has been a focal point in biomedical research. In this study, we aimed to enhance the wound-healing potential of hydrogel scaffolds by incorporating graphene oxide and poly (ethylene glycol) methyl ether methacrylate (MEO2MA). Various masses of graphene oxide were added to MEO2MA hydrogels via free radical polymerisation. Comprehensive characterizations, encompassing mechanical properties, and biocompatibility assays, were conducted to evaluate the hydrogels' suitability for wound healing. In vitro experiments demonstrated that the graphene oxide-based hydrogels exhibited a proper swelling degree and tensile strength, responding effectively to moisture conditions and adhesiveness for wound healing. Notably, the tensile strength significantly increased to 626 kPa in the graphene oxide hydrogels. Biocompatibility assessments revealed that the graphene oxide/MEO2MA hydrogels were non-toxic to human dermal fibroblast cell growth, with no significant difference in cell viability observed in the graphene oxide/MEO2MA hydrogel (H-HG) group. In a rat skin experiment, the wound-healing rate of the hydrogel incorporating graphene oxide surpassed that of the pristine hydrogel after a 15-day treatment, achieving over 95% wound closure in the H-HG group. The histopathological analysis further supported the efficacy of the H-HG hydrogel dressing in promoting more effective tissue regeneration. These results collectively highlight the potential of the graphene oxide/MEO2MA hydrogel scaffold as a promising dressing for medical applications.

Preparation of quaternized N-halamine modified graphene oxide based antibacterial hydrogel and wound healing of bacterial infection

In clinical practice, the wound on the surface of the skin is prone to bacterial infection, for which healing of infected wounds has always been a tremendous challenge for clinics and research institutions. We developed a multifunctional bactericidal, recyclable, and slow-release graphene oxide-based hydrogel for bacterial wound healing and real-time monitoring of bacterial infection in this study. At the same time, the material has a sensing function, which can be used in the connection between the injured skin and the continuous detection equipment. QNGH (quaternarized N-halamine-grafted GO hydrogel) is manufactured by hydrogen bonding between quaternized N-halamine-modified graphene oxide and polyvinyl alcohol (PVA). The results show that in the mouse model of full-thickness skin repair, the hydrogel can continuously release germicidal ions and recyclability, promoting wound healing and contraction. Further, the graphene oxide-based hydrogel has excellent strain sensing performance. It detects the bending and stretching movements of different parts of the human body quickly, stably, and sensitively to show an excellent real-time monitoring performance of human motion. The sensing function of the hydrogel further broadens its application field. Therefore, this hydrogel material is expected to be a candidate material for sensing devices at the wound.

Double-crosslinked reduced graphene oxide-based hydrogel actuator system with fast electro-responsive deformation and enhanced mechanical properties

Recently, soft actuators made of electroactive materials that show fast environmental response, large deformation, and can mimic multifunctional actuation of living creatures have attracted considerable attention for a variety of applications including wearable electronics, microrobotic devices, and intelligent artificial muscles. In this study, we designed an electro-responsive hydrogel actuator system with high stretchability, good self-recovery, and fast electro-responsive actuation. We prepared a hydrogel with double network structure consisting of partially reduced graphene oxide (CRGO) with carboxylic groups, poly (acrylic acid) (PA), and Fe3+ ions. The partially reduced CRGO shows excellent dispersibility and stability in an aqueous solution. The CRGO-embedded PA/CRGO/Fe hydrogels synthesized by varying the content of CRGO, FeCl3·6H2O, and crosslinker exhibited more than 75% gel fraction and a relatively high equilibrium water content (EWC) of 80.0–95.0%. Particularly, PA/CRGO/Fe hydrogels with a dual crosslinked network structure showed high stretchability of more than 1,200% and excellent self-healing properties. The electro-responsive actuation of PA/CRGO/Fe hydrogel can be precisely controlled by varying the content of CRGO, electric field strength, and concentration of the electrolyte solution. By controlling these influencing factors, PA/CRGO/Fe hydrogels exhibited rapid bending actuation of more than 100° within 1 min under an electric field. In vitro cytotoxicity results showed a relatively high cell viability of more than 97%, indicating that the prepared PA/CRGO/Fe hydrogels had no significant cytotoxicity. Therefore, these PA/CRGO/Fe hydrogels could be a promising material for electro-responsive soft robot applications.

Machine-Learning Assisted Handwriting Recognition Using Graphene Oxide-Based Hydrogel.

Machine-learning assisted handwriting recognition is crucial for development of next-generation biometric technologies. However, most of the currently reported handwriting recognition systems are lacking in flexible sensing and machine learning capabilities, both of which are essential for implementation of intelligent systems. Herein, assisted by machine learning, we develop a new handwriting recognition system, which can be applied as both a recognizer for written texts and an encryptor for confidential information. This flexible and intelligent handwriting recognition system combines a printed circuit board with graphene oxide-based hydrogel sensors. It offers fast response and good sensitivity and allows high-precision recognition of handwritten content from a single letter to words and signatures. By analyzing 690 acquired handwritten signatures obtained from seven participants, we successfully demonstrate a fast recognition time (less than 1 s) and a high recognition rate (∼91.30%). Our developed handwriting recognition system has great potential in advanced human-machine interactions, wearable communication devices, soft robotics manipulators, and augmented virtual reality.

Evaluation of the Adsorption Efficiency of Graphene Oxide Hydrogels in Wastewater Dye Removal: Application of Principal Component Analysis.

Industrial dye wastewater is one of the major water pollution problems. Adsorbent materials are promising strategies for the removal of water dye contaminants. Herein, we provide a statistical and artificial intelligence study to evaluate the adsorption efficiency of graphene oxide-based hydrogels in wastewater dye removal by applying Principal Component Analysis (PCA). This study aims to assess the adsorption quality of 35 different hydrogels. We adopted different approaches and showed the pros and cons of each one of them. PCA showed that alginate graphene oxide-based hydrogel (without polyvinyl alcohol) had better tolerance in a basic medium and provided higher adsorption capacity. Polyvinyl alcohol sulfonated graphene oxide-based hydrogels are suitable when higher adsorbent doses are required. In conclusion, PCA represents a robust way to delineate factors affecting hydrogel selection for pollutant removal from aqueous solutions.

Application of Graphene Oxide-Based Hydrogels in Bone Tissue Engineering.

As an important derivative of graphene-based materials, graphene oxide (GO) not only plays an important role not only in optoelectronics and sensing but also in biology due to its unique mechanical, electronic, and optical properties. This article reviews the application of GO-based hydrogels in bone tissue engineering. Whether it is a hydrogel synthesized with natural polymer compounds, synthetic polymer chemicals, bioceramics, bioactive factors, or other materials, the addition of GO can significantly improve various properties of the hydrogel. We also introduce some high-performance GO-based hydrogels in this paper, proposing some insights into materials that may be applied to bone tissue engineering in the future.

Double-Crosslinked Reduced Graphene Oxide-Based Hydrogel Actuator System with Fast Electro-Responsive Deformation and Excellent Mechanical Properties

Double-Crosslinked Reduced Graphene Oxide-Based Hydrogel Actuator System with Fast Electro-Responsive Deformation and Excellent Mechanical Properties

Withdrawal Notice: Application of Graphene Oxide-Based Hydrogels in Bone Tissue Engineering

It is a condition of publication that manuscripts submitted to this journal have not been published and will not be simultaneously submitted or published elsewhere. Furthermore, any data, illustration, structure or table that has been published elsewhere must be reported, and copyright permission for reproduction must be obtained. Plagiarism is strictly forbidden, and by submitting the article for publication the authors agree that the publishers have the legal right to take appropriate action against the authors, if plagiarism or fabricated information is discovered. By submitting a manuscript the authors agree that the copyright of their article is transferred to the publishers if and when the article is accepted for publication.

MOFs-induced high-amphiphilicity in hierarchical 3D reduced graphene oxide-based hydrogel

Micro-nano surface with high-amphiphilic structures possesses fascinating physical properties and promising applications in many areas. Herein, we reported a three dimensional (3D) porous hierarchical architecture with internal crosslinked network structures constructed from metal-organic frameworks (MOFs) and graphene oxide (GO) through a facile self-assembly hydrothermal method. In contrast to conventional 3D graphene hydrogel with strongly hydrophobic structures, the resulting composite exhibited high-amphiphilic features with both highly hydrophilic and oleophilic ability, which could absorb water and oils simultaneously, owing to the synergistic effect between MOFs and reduced graphene oxide. MOFs acted as a dopant and intercalated between reduced graphene oxide layers, which could largely increase the specific surface areas of graphene hydrogels (GH) and artistically adjust the surface structures of pristine GH as well. Accordingly, the 3D porous hierarchical MIL-101-GH materials showed great absorption capacity for oil and water. The advantages of this high amphiphilic properties were proved by constructing a biphasic catalytic system with the introduction of molecular sieve into the 3D MIL-101-GH hybrid. As a result, the designing functionalized foam exhibited good catalytic performance in heterogeneous catalysis for epoxidation of olefins without addition of co-solvents.

Graphene oxide-based hydrogels as a nanocarrier for anticancer drug delivery

Graphene oxide (GO) possesses excellent mechanical strength, biocompatibility, colloidal stability, large surface area and high adsorption capability. It has driven to cancer nanotechnology to defeat cancer therapy obstacles, via integration into three-dimensional (3D) hydrogel network with biocompatible polymers as nanocomposites carrier, and controllable release of anticancer drugs. Specifically, the surface of GO affords π-π stacking and hydrophilic interactions with anticancer drugs. Additionally, modification of GO with various polymers such as natural and synthetic polymers enhances its biodegradability, drug loading, and target delivery. In this review, GO based hydrogels research accomplishments are reviewed on the aspects of crosslinking strategies, preparation methods, the model drug, polymer conjugation and modification with targeting ligands. Moreover, swelling kinetics, drug release profile and biological activity in vivo and in vitro are discussed. The biocompatibility of GO based hydrogels is also discussed from the perspective of its nano-bio interfaces. Apart from that, the clinical potential of GO based hydrogels and its major challenges are addressed in detail. Finally, this review concludes with a summary and invigorating future perspectives of GO based hydrogels for anticancer drug delivery. It is anticipated that this review can stimulate a new research gateway to facilitate the development of anticancer drug delivery by harnessing the unique properties of GO based hydrogels, such as large surface area, chemical purity, high loading capacity of drug, chemical stability, and the nature of lipophilic for cell membrane penetration.

Self-assembled three-dimensional reduced graphene oxide-based hydrogel for highly efficient and facile removal of pharmaceutical compounds from aqueous solution

Herein, self-assembled three-dimensional reduced graphene oxide (RGO)-based hydrogels were synthesized and characterized in detail. A thorough investigation on the uptake of three widely used pharmaceutical drugs, viz. Naproxen (NPX), Ibuprofen (IBP) and Diclofenac (DFC) was carried out from aqueous solutions. To ensure the sustainability of developed hydrogel assembly, practically important parameters such as desorption, recyclability and applicability to real samples were also evaluated. Using the developed 3D hydrogels as adsorptive platforms, excellent decontamination for the above mentioned persistent pharmaceutical drugs was achieved in acidic pH with a removal efficiency in the range of 70–80%. These hydrogels showed fast adsorption kinetics and experimental findings were fitted to different kinetic models, such as pseudo-first order, pseudo-second order, intra-particle and the Elovich models in an attempt to better understand the adsorption kinetics. Furthermore, equilibrium adsorption data was fitted to the Langmuir and Freundlich models, where relatively higher R2 values obtained in case of former one suggested that monolayer adsorption played an important part in drug uptake. Thermodynamic aspects were also studied and negative ΔG0 values obtained indicated the spontaneous nature of adsorption process. The study was also extended to check practical utility of as-prepared hydrogels by spiking real aqueous samples with drug solution, where high % recoveries obtained for NPX, IBP and DFC were of particular importance with regard to prospective application in wastewater treatment systems. We advocate RGO-based hydrogels as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in wastewater purification.

Preparation of Graphene Oxide-Based Hydrogels as Efficient Dye Adsorbents for Wastewater Treatment.

Graphene oxide (GO) sheets exhibit superior adsorption capacity for removing organic dye pollutants from an aqueous environment. In this paper, the facile preparation of GO/polyethylenimine (PEI) hydrogels as efficient dye adsorbents has been reported. The GO/PEI hydrogels were achieved through both hydrogen bonding and electrostatic interactions between amine-rich PEI and GO sheets. For both methylene blue (MB) and rhodamine B (RhB), the as-prepared hydrogels exhibit removal rates within about 4 h in accordance with the pseudo-second-order model. The dye adsorption capacity of the hydrogel is mainly attributed to the GO sheets, whereas the PEI was incorporated to facilitate the gelation process of GO sheets. More importantly, the dye-adsorbed hydrogels can be conveniently separated from an aqueous environment, suggesting potential large-scale applications of the GO-based hydrogels for organic dye removal and wastewater treatment.

Simultaneous Sheet Cross-Linking and Deoxygenation in the Graphene Oxide Sol–Gel Transition

The precursor material to graphene aerogels is a hydrogel formed from an aqueous solution of graphene oxide. We investigate the time evolution of the physical and chemical properties of a graphene oxide suspension as it transitions to a hydrogel. Fully formed hydrogels undergo densification during reaction, forming mechanically stable monoliths. We demonstrate that the gelation process removes oxygen functional groups, partially re-forms the sp2 network, and creates bonds between graphene oxide sheets. Furthermore, these changes to the physical and chemical properties occur on exactly the same time scale, suggesting that they have a common origin. This discovery lends greater understanding to the formation of graphene oxide-based hydrogels, which could allow more flexibility and tunability in synthetic methods for graphene-like materials.

A facile one-pot method to two kinds of graphene oxide-based hydrogels with broad-spectrum antimicrobial properties

Abstract Graphene oxide (GO) has immense potential applications in water purification and biomedical field. Recently, three-dimensional GO-based hydrogels have attracted great attention owing to their advantageous properties. However, it is quite difficult to develop highly efficient, low cost, broad spectrum antibacterial materials that can be easily recycled. In this experimental work, we used a facile one-pot method to synthesize two kinds of GO-based hydrogels: benzalkonium bromide/graphene oxide hydrogel (BKB/GOG) and benzalkonium bromide/polydopamine/reduced graphene oxide hydrogel (BKB/PDA/rGOG). The as-prepared three-dimensional hydrogels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The swelling degrees of BKB/GO xerogels and BKB/PDA/GO xerogels with different BKB concentrations were calculated. The maximum value of swelling degree was found to be 95.2 mg/mg. Owing to the synergistic effect of graphene oxide and benzalkonium bromide, the resultant hydrogels exhibited strong antibacterial activities against both Gram-negative and Gram-positive bacteria. The result of bacterial kinetic tests agreed well with that of the qualitative antibacterial experiments. The resultant hydrogels could be easily removed from the solution, which enhanced their potential use in industrial applications. The antibacterial effect of the hydrogel synthesized from benzalkonium chloride (BKC) and graphene oxide was investigated. The findings of this investigation can be beneficial in elucidating the mechanism of synthesis process that involves benzalkonium salts and graphene oxide.

One-pot synthesis of 3-dimensional reduced graphene oxide-based hydrogel as support for microbe immobilization and BOD biosensor preparation

We report a hydrothermal method to prepare reduced graphene oxide (rGO)-based hydrogel (GelrGONR), using neutral red (NR) to mediate the assembly of rGO sheets and tune the pore size of GelrGONR. A series of techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and BET were employed to characterize the physico-chemical properties of GelrGONR. A large pore size of up to 20µm and interconnected porous structure of GelrGONR were obtained. GelrGONR was used as a support for immobilizing microbe (denoted as GelrGONR-M), which showed ~3.3 times more load mass of microbe than commonly used supports (i.e., activated carbon and carbon fiber felt) and 2.5 times higher biodegradation efficiency (BE) than carbon fiber felt. Further use of GelrGONR-M as a biocatalyst for establishing a BOD biosensor exhibits a linear range of 2–64mgOL−1 and a detection limit 0.4mgOL−1 for glucose–glutamic acid (GGA). Moreover, our proposed BOD detection strategy shows a long-term viability over one year and stability up to 2 months with a relative standard deviation of 2.1%. Our results demonstrated the great potential of employing GelrGONR as a microbe-immobilization support for biosensor development.

A facile one-step approach to functionalized graphene oxide-based hydrogels used as effective adsorbents toward anionic dyes

Abstract Herein, we used a facile method mainly through self-assemble, hydrogen bonding and electrostatic interaction to synthesize poly(diallyldimethylammonium chloride)/graphene oxide (PDDA/GO) hydrogels, which can be easily used as adsorbents to eliminate anionic dyes. The as-prepared PDDA/GO hydrogels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. In order to research the adsorption kinetics for the removal of anion dyes from water pollution, we further investigated that the effect of concentration, temperature, pH, ionic strength or cycle number on the removal process. The results indicated that due to the strong π–π stacking and anion–cation interaction, there were high removal efficiencies for both ponceau S (PS) and trypan blue (TB). The equilibrium time of adsorption is 30 min and 120 min for PS and TB, respectively, at which the solution could be decolorized to nearly colorless. Meanwhile, the adsorption process was more according with the pseudo-second-order model than the pseudo-first-order model. The hydrogels exhibited high removal efficiency for those two anionic dyes after four repeated adsorption and desorption treatments. It was demonstrated that PDDA/GO hydrogels would have great potential as a freestanding and reusable adsorbent for the practical application in water purification.

Reduced graphene oxide-based hydrogels for the efficient capture of dye pollutants from aqueous solutions

Three dimensional (3D) reduced graphene oxide (RGO)-based hydrogels were synthesized by the reduction of graphene oxide using sodium ascorbate. During gelation, mono-, bi-, and trilayer graphene nanosheets self-assemble into a well-defined and interconnected 3D porous network through strong van der Waals and π–π interactions. The 3D RGO-based hydrogels showed a large surface area, and a uniform pore size distribution. The application of the 3D mesoporous material as an adsorbent for the removal of the organic dyes, methylene blue (MB) and rhodamine B (RhB), from aqueous solutions was investigated. The 3D RGO-based hydrogels showed excellent removal capabilities for MB (∼100%) and RhB (∼97%) due to adsorption through strong π–π stacking and anion–cation interactions. Toxicity tests show that the aqueous solutions purified by 3D RGO-based hydrogels are comparable to control experiments conducted using distilled water.

Graphene Oxide-Based Hydrogels to Make Metal Nanoparticle-Containing Reduced Graphene Oxide-Based Functional Hybrid Hydrogels

In this study, stable supramolecular hydrogels have been obtained from the assembly of graphene oxide (GO) in presence of polyamines including tris(aminoethyl)amine, spermine, and spermidine [biologically active molecule]. One of these hydrogels has been well characterized by various techniques including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD) study, and Raman spectroscopy. TEM and AFM studies of one of these hydrogels have revealed the presence of a network structure of cross-linked nanosheets. This suggests the supramolecular assembly of GO in the presence of polyamines using the acid-base type electrostatic interaction. In presence of a mild reducing agent (vitamin C), one of these GO hydrogels has been transformed into a reduced graphene oxide (RGO)-based hydrogel by a simple in situ reduction of GO sheets within the hydrogel matrix. Moreover, noble metal nanoparticle containing RGO based hybrid hydrogels have been obtained using in situ and simultaneous co-reduction of GO and noble metal precursors within the GO gel matrix. The elegance of this method is in situ, "green chemical" and simultaneous reduction of GO and metal salts within the hydrogel matrix to form RGO-based hybrid gel and concomitant stabilization of metal nanoparticles (MNPs) within the gel system. The nascently formed MNPs are homogeneously and uniformly distributed on the surface of the RGO nanosheets within the hybrid gel. Interestingly, this MNP containing RGO-based hybrid hydrogel matrix acts as a potential catalyst for the reduction of aromatic nitro to amino group. The catalyst (hybrid gel matrix) can be separated easily after the reaction and reused several times.