Enhanced Mechanical, Thermal, and Biological Properties of Polymethyl Methacrylate–Zinc Oxide/Graphene Oxide Nanocomposites for Wound‐Healing Applications

ABSTRACTWe successfully prepared poly(methyl methacrylate) (PMMA)–graphene oxide (GO) and PMMA–GO–zinc oxide (ZnO) nanocomposites and characterized them using different techniques. The adsorption performances of the as‐prepared composites were investigated for crystal violet (CV) dye removal. The contact time as a main factor affecting the adsorption process by adsorbents was studied. Because the adsorption capacity value for CV was found to show no extensive changes after 35 min, 35 min was selected as the best contact time for our system. The adsorption results revealed that the best capacity of CV adsorption onto the PMMA–GO and PMMA–GO–ZnO nanocomposites occurred at pH 12 and 298 K. The respective entropies (−0.208 and −0.168 kJ mol−1 K−1) and enthalpies (−72.86 kJ/mol, and −55.54 kJ/mol) for PMMA–GO and PMMA–GO–ZnO and Gibbs energy revealed that the process of adsorption was exothermic. In addition, the Elovich, pseudo‐first‐order, intraparticle diffusion, and pseudo‐second‐order (four types) models were applied to our kinetic study. Our results indicate that CV adsorption onto PMMA–GO and PMMA–GO–ZnO was good with the pseudo‐second‐order (type 1) and pseudo‐first‐order models because of the low χ2 value and the high correlation coefficient value. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47495.

The study investigates the effects of graphene oxide/zinc oxide (GO‐ZnO) nanohybrids, combined with Mentha longifolia essential oil, on the mechanical, UV resistance, antibacterial, and rheological properties of polylactic acid (PLA). GO‐ZnO nanohybrids were prepared at ZnO‐to‐GO ratios of 1:1 and 2:1 and incorporated into PLA at various concentrations. The addition of GO‐ZnO significantly enhanced the tensile strength and modulus of PLA composites due to strong interactions between PLA and the functionalized nanohybrids. Hydrolytic degradation tests revealed accelerated PLA degradation with GO‐ZnO, attributed to the catalytic effects of ZnO. Rheological analysis showed reduced elasticity with higher nanohybrid content, attributed to thermal degradation. UV absorption tests demonstrated improved UV protection with GO‐ZnO and essential oil. Antibacterial tests indicated higher inhibition percentages against E. coli and Listeria , highlighting a synergistic antibacterial effect of the hybrid system. These findings suggest PLA/GO‐ZnO/oil composites are promising candidates for antibacterial packaging applications. Highlights PLA hydrolytic degradation enhanced by GO‐ZnO nanohybrids, M. longifolia oil. GO‐ZnO and M. longifolia oil catalyze PLA thermal degradation during scission. PBS mechanical properties improved via GO‐ZnO interaction with PLA and oil. GO‐ZnO and M. longifolia oil provide synergistic antibacterial effects in PLA. Thermal degradation of PLA with GO‐ZnO and oil analyzed through rheology.

New materials with good antibacterial activity and less toxicity to other species have attracted numerous research interests. Modified Hummers method was used for preparing graphene oxide (GO). Zinc oxide/graphene oxide (ZnO/GO) nanocomposites were synthesized with three different ratios (0.5:1, 1:1, and 2:1) by solution precipitation method. The ZnO/GO nanocomposites were characterized by Fourier transform infrared spectroscopy, X–ray diffraction, Raman spectroscopy, Brunauer–Emmett–Tellerspecific surface area, and transmission electron microscopy image. The characterization results showed that ZnO nanoparticles with a mean size of 12–18 nm were randomly decorated on the surfaces and edges of GO sheets. ZnO/GO 1:1 with a high specific surface area of 65 m2/g was obtained. The antibacterial activity of ZnO, GO, and ZnO/GO was tested against Gram negative bacteria escherichia coli (E. coli) and Gram positive bacteria staphylococcus aureus (S. aureus) using well diffusion method. The test results confirmed that antibacterial activity of ZnO/GO was higher than that of GO and ZnO. Additionally, the ZnO/GO with the ratio of 1:1 is the strongest activity and more active against S. aureus than against E. coli and minimal inhibitory concentration (MIC) value of ZnO/GO 1:1 is 80 µg/mL for S. aureus and 160 µg/mL for E. coli. This novel nanocomposite could be used as a potential material for antimicrobial application.

BackgroundEnhancing the antibacterial properties of polymethyl methacrylate (PMMA) dental resins is crucial in preventing secondary infections following dental procedures. Despite the necessity for such improvement, a universally applicable method for augmenting the antibacterial properties of PMMA without compromising its mechanical properties and cytotoxicity remains elusive. Consequently, this study aims to address the aforementioned challenges by developing and implementing a composite material known as zinc oxide/graphene oxide (ZnO/GO) nanocomposites, to modify the PMMA.MethodsZnO/GO nanocomposites were successfully synthesized by a one-step procedure and fully characterized by TEM, EDS, FTIR and XRD. Then the physical and mechanical properties of PMMA modified by ZnO/GO nanocomposites were evaluated through water absorption and solubility test, contact angle test, three-point bending tests, and compression test. Furthermore, the biological properties of the modified PMMA were evaluated by direct microscopic colony count method, crystal violet staining and CCK-8.ResultsThe results revealed that ZnO/GO nanocomposites were successfully constructed. When the concentration of nanocomposites in PMMA was 0.2 wt. %, the flexural strength of the resin was increased by 23.4%, the compressive strength was increased by 31.1%, and the number of bacterial colonies was reduced by 60.33%. Meanwhile, It was found that the aging of the resin did not affect its antibacterial properties, and CCK-8 revealed that the modified PMMA had no cytotoxicity.ConclusionZnO/GO nanocomposites effectively improved the antibacterial properties of PMMA. Moreover, the mechanical properties of the resin were improved by adding ZnO/GO nanocomposites at a lower range of concentrations.

Formation of poly(methyl methacrylate)-ZnO nanoparticle quantum dot composites by dispersion polymerization in supercritical CO2

The present study is an attempt to improve thermal, mechanical and electrical properties of poly (methyl methacrylate) (PMMA). For this purpose, vinyltriethoxysilane (VTES) was grafted covalently on the surface of graphene oxide (GO). This VTES functionalized graphene oxide (VGO) was dispersed in the PMMA matrix using the solution casting method. The morphology of the resultant PMMA/VGO nanocomposites was analyzed by SEM indicating well-dispersed VGO in the PMMA matrix. Thermal stability, tensile strength and thermal conductivity increased by 90%, 91% and 75%, respectively, whereas volume electrical resistivity and surface electrical resistivity reduced to 9.45 × 105 Ω/cm and 5.45 × 107 Ω/cm2, respectively.

This paper reports on preparing two types of graphene oxide‐zinc oxide (GO‐ZnO) nano‐hybrids and their effect on the performance of polybutylene succinate (PBS) matrix. This view synthesized GO, ZnO, and GO‐ZnO nano‐hybrids at 1:1 and 1:2 weight ratios. Subsequently, various spectroscopy and microscopy analyses (FTIR, UV, Raman, AFM, and TEM) were employed to characterize the structure of synthesized nanomaterials. The obtained results revealed that the hybridization was successfully occurred and microstructure of two types of prepared nano‐hybrids are basically different depending on the preparation procedure. Following this, PBS nanocomposites with 0.5, 1, and 1.5 wt% of GO‐ZnO nano‐hybrids (NPs) were produced via the solvent‐blending method. The mechanical, microstructural, rheological, biodegradability and UV‐shielding properties of the fabricated films were then investigated. Mechanical properties showed that addition of 0.5 wt% ZnO‐GO nanohybrids improved elongation at break from 21.6% to 28.7% and increased tensile strength by 20%. However, rheological assessments showed a one‐order‐of‐magnitude decrease in viscosity with the addition of only 0.5 wt%. In degradation analysis, 100 percent of mass loss was observed during 5 weeks for PBS with 1.5 wt% of GO‐ZnO. PBS/GO‐ZnO nanocomposites indicated tailored mechanical properties, biodegradability, suggesting a promising potential in packaging applications. Highlights GO‐ZnO nanohybrids were successfully synthesized. Incorporating GO‐ZnO into PBS improved its hydrolytic degradation The thermal decomposition of PBS was accelerated by the addition of GO‐ZnO. Adding GO‐ZnO nanohybrids to PBS resulted in a drop in viscosity. Nanohybrids with higher ZnO content exhibited greater hydrolytic and thermal degradation.

Remarkable performance of GO/ZnO nanocomposites under optimized parameters for remediation of Cd (II) from water

At present, petrochemical-based plastics are commonly used in many industries. Yet, environmental concerns over these materials have led to the search for biodegradable alternatives in several industries including packaging. In this regard, the renewable resource-based polymer, poly (lactic acid) (PLA), holds a greater demand due to its unique properties (such as biodegradability and biocompatibility). Despite the merits of PLA, limitations in mechanical, thermal and gas barrier properties have restricted the usage of PLA in a wider range of applications in the packaging industry. Therefore, it has become a necessity to reinforce PLA to overcome these drawbacks. The main objective of this research is to investigate the feasibility of halloysite nanotubes (HNTs) as a nanofiller to reinforce PLA. PLA/HNTs nanocomposite films were prepared using the solution casting method by varying the HNTs loading (from 2.5 – 10 (w/w %)). Evaluation of the physico-chemical properties of the films revealed that the mechanical and thermal properties of PLA films were enhanced with the addition of HNTs. The interfacial interaction was further investigated with Fourier transform infrared (FTIR) spectroscopy and the end-hydroxyl groups of PLA were found to chemically interact with outer surface siloxane groups of HNTs. Furthermore, a comparison study was conducted to investigate the influence of the nanocomposite processing methods, namely melt compounding and solution casting, on the thermo-mechanical properties of PLA/HNTs nanocomposite films. Moreover, the ductility of PLA/HNTs films was improved by incorporating a plasticiser, poly (ethylene) glycol (PEG), while the dispersion of HNTs in PLA at high filler loadings was further improved by modifying the outer surface of HNTs with a silane modifier, γ-aminopropyltriethoxysilane (APTES). In addition, after evaluating the effect of three different types of HNTs (which are structurally different) on the tensile properties, this study suggests the best type of HNTs that can be incorporated into the PLA matrix in order to obtain the optimum tensile properties. In this dissertation, an alternative finite element (FE) approach to accurately predict the elastic modulus of polymer/HNTs nanocomposites is proposed. A real-structure-based 3-D computational model with randomly oriented HNTs was developed and compared with the conventional, idealized modelling approach. The developed idealized model consists of nanotubes with fixed aspect ratio and the proposed alternative real-structure-based model takes the experimentally observed variations in HNTs sizes, impurities and aspect ratios into account. According to the parametric studies, a unit cell model with cylindrical reinforcements (representing HNTs) and at least 30 inclusions gave promising results, provided the model included actual information about HNT's size ranges and aspect ratios. Numerical studies were validated with experimental findings and the developed real-structure-based model gave more accurate results than idealized and analytical models. Furthermore, the reinforcing mechanism was carefully studied in terms of the stress distribution. As the final stage of this research, the PLA/HNTs nanocomposite films were further developed for better end user application by creating high performance, multifunctional, active packaging films. ZnO nanoparticles have been successfully investigated to remarkably enhance the antimicrobial properties of poly (lactic acid) (PLA) composite films for active packaging, where they can enhance the shelf life of goods, but the addition of ZnO into PLA decreases its thermo-mechanical properties. In this study, ZnO nanoparticles were deposited on the outer and inner surfaces of halloysite nanotubes (HNTs) using a novel solvothermal method and these ZnO deposited HNTs (ZnO-HNTs) were incorporated into the PLA matrix as a reinforcing filler. PLA nanocomposite films with ZnO had inferior mechanical properties compared to PLA films with ZnO-HNTs which showed significant improvements, with an increase in the tensile strength and modulus by 33% and 74%, respectively, with the addition of 5 (w/w %). Antimicrobial tests revealed that ZnO-HNTs can act as a promising antimicrobial agent against bacteria such as Escherichia coli and Staphylococcus aureus where the bacteria count reduced by more than 99%.

Advanced ZnO–graphene oxide nanohybrid and its photocatalytic Applications

Hydrophilic fouling-resistant GO-ZnO/PES membranes for wastewater reclamation

UV–Visible silicon detectors with zinc oxide nanoparticles acting as wavelength shifters

Bio-inks consisting of pectin (Pec), carboxymethyl cellulose (CMC), and ZnO nanoparticles (ZnO) were used to prepare films by solution casting and 3D-printing methods. Field emission scanning electron microscopy (FE-SEM) was conducted to observe that the surface of samples made by 3D bioprinter was denser and more compact than the solution cast samples. In addition, Pec/CMC/ZnO made by 3D-bioprinter (Pec/CMC/ZnO-3D) revealed enhanced water vapor barrier, hydrophobicity, and mechanical properties. Pec/CMC/ZnO-3D also showed strong antimicrobial activity within 12 h against S. aureus and E. coli O157: H7 bacterial strains compared to the solution cast films. Further, the nanocomposite bio-inks used for 3D printing did not show cytotoxicity towards normal human dermal fibroblast (NDFB) cells but enhanced the fibroblast proliferation with increasing exposure concentration of the sample. The study provided two important inferences. Firstly, the 3D bioprinting method can be an alternative, better, and more practical method for fabricating biopolymer film instead of solution casting, which is the main finding of this work defining its novelty. Secondly, the Pec/CMC/ZnO can potentially be used as 3D bio-inks to fabricate functional films or scaffolds and biomedical applications.

In this study, poly(methyl methacrylate)/titanium dioxide (PMMA/TiO2) nanocomposite films (NFs) were prepared by a solution casting method and afterward irradiated with gamma (γ)-rays at different doses. The structural and optical properties of the PMMA/TiO2NFs before and afterγ-irradiation at different doses were analyzed by X-ray diffraction (XRD) and ultraviolet-visible (UV-vis) spectroscopy, respectively. In addition, the impact ofγ-dose on the wetting properties of PMMA/TiO2was determined by measuring the water contact angle. The XRD patterns illustrated new sharp peaks after the incorporation of TiO2nanoparticles (NPs) into the PMMA matrix, which could be due to the interaction of TiO2with PMMA owing to the change in the crystallographic organization. Moreover, the degree of the disorder increases with increasingγ-dose. Optical property studies revealed that the optical gap-band energy of the PMMA/TiO2dropped to 3.92 eV at the highestγ-dose compared with pure PMMA, which was estimated to be 4.5 eV. A remarkable increase in the number of carbon atoms per cluster was observed with increasingγ-dose. The water contact angle was decreased with increasingγ-dose. The decrease in water contact angle is due to the formation of an oxidized layer and/or carbonaceous clusters on the surface of theγ-irradiated nanocomposite films. Therefore, it can be concluded that PMMA/TiO2NFs with controlled optical gap-band energy and controlled water contact angle can be prepared by theγ-irradiation technique to be used for the fabrication of optoelectronic products.

Anchorage of the femoral head prosthesis to the shaft of the femur.