Graphene Oxide-Poly(ethylene glycol) methyl ether methacrylate Nanocomposite Hydrogels

Polyethylene glycol embedded reduced graphene oxide supramolecular assemblies for enhanced room-temperature gas sensors

Herein, we present the gas-dependent electrical properties of a reduced graphene oxide nanocomposite. The reduced graphene oxide (rGO) was synthesized by reducing GO with sodium borohydride (NaBH4). As-synthesized rGO was dispersed in DI water containing 1, 2, 3, 4, and 5 wt% polyethylene glycol (PEG) to prepare PEG-rGO supramolecular assemblies. The successful preparation of supramolecular assemblies was verified by their characterization using XRD, FESEM, EDS, TEM, FTIR, and Raman spectroscopy. At room temperature, the gas-dependent electrical properties of these supramolecular assemblies were investigated. The results showed that sensors composed of PEG-rGO supramolecular assemblies performed better against benzene and methanol at 3% and 4% PEG, respectively. However, high selectivity and a wide range of activation energies (∼1.64-1.91 eV) were observed for H2 gas for 4% PEG-modified supramolecular assemblies. The PEG-rGO supramolecular assemblies may be an excellent candidate for constructing ultrahigh-performance gas sensors for a variety of applications due to their high sensitivity and selectivity.

The advance anticancer role of polymeric core-shell ZnO nanoparticles containing oxaliplatin in colorectal cancer

We evaluated the activity of core-shell ZnO nanoparticles (ZnO-NPs@polymer shell) containing Oxaliplatin via polymerization through in vitro studies and in vivo mouse models of colorectal cancer. ZnO NPs were synthesized in situ when the polymerization step was completed by co-precipitation. Gadolinium coordinated-ZnONPs@polymer shell (ZnO-Gd NPs@polymer shell) was synthesized by exploiting Gd's oxophilicity (III). The biophysical properties of the NPs were studied using powder X-ray diffraction (PXRD), Fourier transforms infrared spectroscopy, Ultraviolet-visible spectroscopy (UV-Vis), field emission electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy, dynamic light scattering, and z-potential. (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) was used to determine the antiproliferative activity of ZnO-Gd-OXA. Moreover, a xenograft mouse model of colon cancer was exerted to survey its antitumor activity and effect on tumor growth. In the following, the model was also evaluated by histological staining (H-E; Hematoxylin & Eosin and trichrome staining) and gene expression analyses through the application of RT-PCR/ELISA, which included biochemical evaluation (MDA, thiols, SOD, CAT). The formation of ZnO NPs, which contained a crystallite size of 16.8 nm, was confirmed by the outcomes of the PXRD analysis. The Plate-like morphology and presence of Pt were obtained in EDX outcomes. TEM analysis displayed the attained ZnO NPs in a spherical shape and a diameter of 33 ± 8.5 nm, while the hydrodynamic sizes indicated that the particles were highly aggregated. The biological results demonstrated that ZnO-Gd-OXA inhibited tumor growth by inducing reactive oxygen species and inhibiting fibrosis, warranting further research on this novel colorectal cancer treatment agent.

The Use of Graphene and Its Derivatives for the Development of Polymer Matrix Composites by Stereolithographic 3D Printing

Significant advances in graphene-based materials have facilitated the development of various composites structures in a diverse range of industry sectors. At present, the preparation of graphene-added materials is mainly developed through traditional methods. However, in recent years, additive manufacturing emerged as a promising approach that enables the printing of complex objects in a layer-by-layer fashion, without the need for moulds or machining equipment. This paper reviews the most recent reports on graphene-based photopolymerizable resins developed for stereolithography (SLA), with particular consideration for medical applications. The characteristics of the SLA technology, the most suitable raw materials and formulations and the properties of final 3D products are described. Throughout, a specific focus is placed on the mechanical properties and biocompatibility of the final 3D-printed object. Finally, remaining challenges and future directions are also discussed.

3D Printing of Covalent Functionalized Graphene Oxide Nanocomposite via Stereolithography

A major challenge for many industries wanting to adopt 3D printing technologies for rapid prototyping, customized parts, and low-volume manufacturing depends on the availability and functionality of the input materials to suit specific requirements. A well-studied nanofiller because of its distinct properties and wide range of applications, graphene oxide (GO) proves to be a good choice in the development of new materials. However, as a filler in a polymer matrix, GO has its own unique set of problems enough to make certain constraints in achieving an optimum reinforcement in the targeted polymer matrix. The need for a matrix-filler interaction is critical because reinforcement occurs only when the external load applied to the material can be successfully transmitted from the matrix to the filler, which will only happen if the interfacial adhesion between the matrix and the filler is strong. This study demonstrates the synthesis of the covalently linked GO-methacrylate (MA) nanocomposite materials through 3D printing via stereolithography (SL). Spectral analysis using Fourier-transform infrared confirms the successful functionalization of GO and ascertains the presence of the functionalized GO (fGO) in the 3D-printed nanocomposite specimens. Likewise, further validation using thermogravimetric analysis and differential scanning calorimetry also affirms the formation of fGO for use as a functional filler, activating a stronger interfacial bonding with the MA polymer. Excellent attributes of GO will become futile because of premature fracturing of the material simply because of an oversight to consider robustness during the early stages of design. Hence, different mechanical and thermal properties of the new 3D-printed MA-fGO nanocomposite material are characterized and presented in the discussion. This work demonstrates the first successful 3D printing of the functionalized GO nanocomposite via SL, forming a complex structure with consistently high fidelity and enhanced material properties with potential for various industrial applications.

pH and thermal dual-responsive poly(NIPAM-co-GMA)-coated magnetic nanoparticles via surface-initiated RAFT polymerization for controlled drug delivery

Herein, a novel type of multifunctional magnetic nanoparticles with dual thermal and pH-responsive behavior was fabricated as the carrier for delivery of doxorubicin (DOX). Fe₃O₄@SiO₂ magnetic nanoparticles, were grafted with polymer brushes consisting of poly (NIPAM-co-GMA) (PNG) chains via surface initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. The polymer brushes were then modified with hydrazine groups as DOX binding sites. The prepared multifunctional magnetic nanoparticles were characterized by FT-IR, ¹H NMR, XPS, TGA, DLS, VSM, GPC, TEM, and XRD analysis. The in vitro drug release of the multifunctional magnetic nanoparticles was examined at 37 °C (above LCST) and 25 °C (below LCST) in different pH media and exhibited excellent pH- and thermo-sensitive behavior. The results show that the Fe₃O₄@SiO₂@PNG-Hy fabricated via SI-RAFT polymerization is a viable candidate material for tumor treatment studies.

Tuning Physical Crosslinks in Hybrid Hydrogels for Network Structure Analysis and Mechanical Reinforcement

Hydrogels with high mechanical strength are needed for a variety of industrial applications. Here, a series of hydrogels was prepared by introducing hybrid particles as hydrophobic association points to toughen the hydrogels. These toughened hydrogels were able to transfer an external mechanical force via the reorganization of the crosslinking networks. They exhibited an extraordinary mechanical performance, which was the result of the coordination between hydrophobic segments and hybrid particles. Herein, the connection between the dissipated energy of the inner distribution structure (on a small scale) and the mechanical properties (on a large scale) was conducted. Specifically, we inspected hydrogels of latex particles (LPs) with different chain lengths (C4, C12, C18) and studied their inner structural parameters, namely, the relationship between the density and molecular weight of crosslinking points to the mechanical strength and energy dissipation. Favorable traits of the hydrogels included compact internal structures that were basically free from defects and external structures with puncture resistance, high toughness, etc. Based on the experimental results that agreed with the theoretical results, this study provides a profound understanding of the internal structure of hydrogels, and it offers a new idea for the design of high-strength hybrid hydrogels.

High-Strength Stereolithographic 3D Printed Nanocomposites: Graphene Oxide Metastability

The weak thermomechanical properties of commercial 3D printing plastics have limited the technology's application mainly to rapid prototyping. In this report, we demonstrate a simple approach that takes advantage of the metastable, temperature-dependent structure of graphene oxide (GO) to enhance the mechanical properties of conventional 3D-printed resins produced by stereolithography (SLA). A commercially available SLA resin was reinforced with minimal amounts of GO nanofillers and thermally annealed at 50 and 100 °C for 12 h. Tensile tests revealed increasing strength and modulus at an annealing temperature of 100 °C, with the highest tensile strength increase recorded at 673.6% (for 1 wt % GO). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) also showed increasing thermal stability with increasing annealing temperature. The drastic enhancement in mechanical properties, which is seen to this degree in 3D-printed samples reported in literature, is attributed to the metastable structure of GO, polymer-nanofiller cross-linking via acid-catalyzed esterification, and removal of intercalated water, thus improving filler-matrix interaction as evidenced by spectroscopy and microscopy analyses.