Novel Graphene Oxide Nanohybrid Doped Methacrylic Acid Hydrogels for Enhanced Swelling Capability and Cationic Adsorbability

Abstract

Novel versatile hydrogels were designed and composited based on covalent bond and noncovalent bond self-assembly of poly(methacrylic acid) (PMAA) networks and nanohybrids doped with graphene oxide (GO). The structures and properties of the neat PMAA and the prepared PMAA/GO hydrogels were characterized and analyzed in detail, using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, swelling and cationic absorption, etc. The swelling results showed that the water penetration follows the non-Fick transport mechanism based on swelling kinetics and diffusion theory. The swelling capacity of PMAA and composited PMAA/GO hydrogels toward pH, Na+, Ga2+, and Fe3+ was investigated; the swelling ratio was tunable between 4.44 and 36.44. Taking methylene blue as an example, the adsorption capacity of PMAA/GO hydrogels was studied. Nanohybrid doped GO not only self-associated with PMAA via noncovalent bonding interactions and had a tunable swelling ratio, but also interacted with water molecules via electrostatic repulsion, offering a pH response of both the network and dye absorption. Increases in pH caused a rise in equilibrium swelling ratios and reduced the cumulative cationic dye removal.

Gelatin-Graphene Oxide Nanocomposite Hydrogels for Kluyveromyces lactis Encapsulation: Potential Applications in Probiotics and Bioreactor Packings

“…This deficient swelling level can be explained by the absence of interactions with free ions, which, in turn, leads to facile dissolution [86]. Compared with hydrogels without GO, the presence of the nanomaterial leads to superior swelling capacity, possibly due to the prevalence of heavily cross-linked patches where very stable covalent bonds provide resilience to the increased tension induced by the incorporated water molecules, which, in turn, penetrate the matrix easily by the higher permeability resulting from a larger pore size distribution [61,76]. This notion is further supported by the high correlation observed between low crosslinking levels (0.0 mg/mL GO) and reduced swelling degrees and pore sizes.…”

“…In this regard, a much better alternative to graphene for preparing mixtures in aqueous media (which is the case for most biological and biomedical applications) is graphene oxide (GO) [59]. This nanomaterial is obtained from graphene by chemical oxidation of natural graphite [61]. Additionally, it has been reported to exhibit high loading capacity of drug-like molecules, large surface area, negative electric charge, and the presence of surface functional groups such as hydroxyl, epoxy, carbonyl, and carboxylic [62], which might enhance colloidal stability [63] and enable different bioconjugation routes to other nanomaterials, polymers and drugs [64].…”

Novel Developments on Stimuli-Responsive Probiotic Encapsulates: From Smart Hydrogels to Nanostructured Platforms

“…Remarkably, novel developments in the fabrication of nanocarbon-based materials (e.g., reduced graphene oxide, graphene quantum dots, graphene nanoribbons), silicabased nanocarriers, and inorganic nanoparticles have enabled the fabrication of emerging nanocomposites with improved mechanical strengths, high drug loading, and reduced toxicity [144,158,159]. These features have been reported to not only favor the controlled release of on-cargo molecules but also increase the survival of encapsulated living organisms (e.g., probiotics and mammalian cells) [160,161].…”

“…Similarly, clay mineral silicates have gained popularity given their unique cationic exchange properties that can be exploited to fabricate water barriers due to hydrogen bonding [162,163]. Kim and colleagues reported superior shape integrity for bentonite/alginate-based encapsulates during gastric fluid exposure and appropriate disintegration in the intestinal area upon oral administration in mice [158]. Relevant nanocomposites for probiotic encapsulation are listed in Table 4.…”