Antimicrobial Bamboo Materials Functionalized with ZnO and Graphene Oxide Nanocomposites.
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ABSTRACT:
SUBMITTER: Zhang J
PROVIDER: S-EPMC5503375 | biostudies-other | 2017 Feb
REPOSITORIES: biostudies-other
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Project description:Graphene oxide (GO) holds high promise for diagnostic and therapeutic applications in nanomedicine but reportedly displays immunotoxicity, underlining the need for developing functionalized GO with improved biocompatibility. Here, we study the adverse effects of GO and amino-functionalized GO (GONH2) during Caenorhabditis elegans development and ageing upon acute or chronic exposure. Chronic GO treatment throughout the C. elegans development causes decreased fecundity and a reduction of animal size, while acute treatment does not lead to any measurable physiological decline. However, RNA-Seq data reveal that acute GO exposure induces innate immune gene expression. The p38 MAP kinase, PMK-1, which is a well-established master regulator of innate immunity, protects C. elegans from chronic GO toxicity, as pmk-1 mutants show reduced tissue-functionality and facultative vivipary. In a direct comparison, GONH2 exposure does not cause detrimental effects in the wild type or in pmk-1 mutants, and the innate immune response is considerably less pronounced. Our work establishes the enhanced biocompatibility of amino-functionalized GO in a whole-organism, emphasizing its potential as biomedical nanomaterial.
2022-05-10 | GSE131070 | GEO
Project description:In the present manuscript, we reported the effective synthesis of 1,3-bis(2'-benzimidazolyl)-5-aminobenzene-grafted graphene oxide, followed by reduction, affording covalently linked benzimidazole-containing chemically modified reduced graphene oxide. The prepared material was further coated with polyaniline via in situ polymerization. The prepared material was successfully characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRPD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermo-gravimetric analysis (TGA); subsequently, it was subjected to electrochemical analysis using a three-electrode system in dilute acid solutions as electrolytes in terms of cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance studies. The polyaniline-coated binary composite materials revealed maximum specific capacitance of 823 F g-1 at 0.2 A g-1 current density, whereas the value for the chemically modified reduced graphene oxide was 477 F g-1. The CV curves denoted the pseudocapacitive nature of the electrode materials. The values for the retention of specific capacitance for the electrode materials were 77.5% and 87.9% up to 5000 charge-discharge cycles.
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Project description:The reduced graphene oxide/iron oxide (rGO/Fe2O3) and reduced graphene oxide/cobalt oxide (rGO/Co3O4) composite anodes have been successfully prepared through a simple and scalable ball-milling synthesis. The substantial interaction of Fe2O3 and Co3O4 with the rGO matrix strengthens the electronic conductivity and limits the volume variation during cycling in the rGO/Fe2O3 and rGO/Co3O4 composites because reduced graphene oxide (rGO) helps the metal oxides (MOs) to attain a more efficient diffusion of Li-ions and leads to high specific capacities. As anode materials for LIBs, the rGO/Fe2O3 and rGO/Co3O4 composites demonstrate overall superb electrochemical properties, especially rGO/Fe2O3T-5 and rGO/Co3O4T-5, showcasing higher reversible capacities of 1021 and 773 mAhg-1 after 100 cycles at 100 mAg-1, accompanied by the significant rate performance. Because of their superior electrochemical efficiency, high capacity and low cost, the rGO/Fe2O3 and rGO/Co3O4 composites made by ball milling could be outstanding anode materials for LIBs. Due to the excellent electrochemical performance, the rGO/Fe2O3 and rGO/Co3O4 composites prepared via ball milling could be promising anode materials with a high capacity and low cost for LIBs. The findings may provide shed some light on how other metal oxides wrapped by rGO can be prepared for future applications.
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Project description:(1) Background: Graphene oxide is a new carbon-based material that contains functional groups (carboxyl, hydroxyl, carbonyl, epoxy) and therefore can be easily functionalized with organic compounds of interest, yielding hybrid materials with important properties and applications. (2) Methods: Graphene oxide has been obtained by a modified Hummers method and activated by thionyl chloride in order to be covalently functionalized with amines. Thus obtained hybrid materials were characterized by infrared and Raman spectroscopy, elemental analysis and scanning electron microscopy and then tested for their antimicrobial and anti-biofilm activity. (3) Results: Eight amines of interest were used to functionalize grapheme oxide and the materials thus obtained were tested against Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacterial strainsin plankonic and biofilm growth state. Both amines, as well as the functionalized materials, exhibited anti-microbial features. Three to five functionalized graphene oxide materials exhibited improved inhibitory activity against planktonic strains as compared with the respective amines. In exchange, the amines alone proved generally more efficient against biofilm-embedded cells. (4) Conclusions: Such hybrid materials may have a wide range of potential use in biomedical applications.
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Project description:Graphene oxide (GO) has emerged as an ideal filler to reinforce polymeric matrices owing to its large specific surface area, transparency, flexibility, and very high mechanical strength. Nonetheless, functionalization is required to improve its solubility in common solvents and expand its practical uses. In this work, hexamethylene diisocyanate (HDI)-functionalized GO (HDI-GO) has been used as filler of a conductive polymer matrix, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The nanocomposites have been prepared via a simple solution casting method, and have been characterized by scanning electron microscopy (SEM), UV⁻Vis and Raman spectroscopies, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile tests, and four-point probe measurements to get information about how the HDI-GO functionalization degree (FD) and the HDI-GO concentration in the nanocomposite influence the final properties. SEM analysis showed a very homogenous dispersion of the HDI-GO nanosheets with the highest FD within the matrix, and the Raman spectra revealed the existence of very strong HDI-GO-PEDOT:PSS interactions. A gradual improvement in thermal stability was found with increasing HDI-GO concentration, with only a small loss in transparency. A reduction in the sheet resistance of PEDOT:PSS was found at low HDI-GO contents, whilst increasing moderately at the highest loading tested. The nanocomposites showed a good combination of stiffness, strength, ductility, and toughness. The optimum balance of properties was attained for samples incorporating 2 and 5 wt % HDI-GO with the highest FD. These solution-processed nanocomposites show considerably improved performance compared to conventional PEDOT:PSS nanocomposites filled with raw GO, and are highly suitable for applications in various fields, including flexible electronics, thermoelectric devices, and solar energy applications.
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Project description:Infectious microbial diseases can easily be transferred from person to person in the air or via high contact surfaces. As a result, researchers must aspire to create materials that can be implemented in surface contact applications to disrupt pathogen growth and transmission. This study examines the antimicrobial properties of polyacrylonitrile (PAN) nanofibers coated with silver nanoparticles (AgNPs) and silver(I,III) oxide. PAN was homogenized with varied weight concentrations of silver nitrate (AgNO3) in N,N-dimethylformamide solution, a common organic solvent that serves as both an electrospinning solvent and as a reducing agent that forms AgNPs. The subsequent colloids were electrospun into nanofibers, which were then characterized via various analysis techniques, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, dynamic light scattering, and X-ray photoelectron spectroscopy. A total of 10 microbes, including 7 strains of Gram-positive bacteria, 2 strains of Gram-negative bacteria, and Candida albicans, were incubated with cutouts of various PAN-AgNP nanocomposites using disk diffusion methods to test for the nanocomposites' antimicrobial efficiency. We report that our electrospun PAN-AgNP nanocomposites contain 100% AgO, a rare, mixed oxidation state of silver(I,III) oxide that is a better sterilizing agent than conventional nanosilver. PAN-AgNP nanocomposites also retain a certain degree of antimicrobial longevity; samples stored for approximately 90 days demonstrate a similar antimicrobial activity against Escherichia coli (E. coli) and Lactobacillus crispatus (L. crispatus) when compared to their newly electrospun counterparts. Moreover, our results indicate that PAN-AgNP nanocomposites successfully display antimicrobial activity against various bacteria and fungi strains regardless of their resistance to conventional antibiotics. Our study demonstrates that PAN-AgNP nanocomposites, a novel polymer material with long-term universal antimicrobial stability, can potentially be applied as a universal antimicrobial on surfaces at risk of contracting microbial infections and alleviate issues related to antibiotic overuse and microbial mutability.
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Project description:High-density polyethylene (HDPE)-based and ultra-high molecular weight polyethylene (UHMWPE)-based composites with carbonaceous reinforcements are being widely investigated for biomedical applications. The enhancement of material properties critically depends on the nature, amount and compatibility of the reinforcement with the polymeric matrix. To this end, this study demonstrates the efficacy of a 'dual' hybrid approach of incorporating modified inorganic nanofiller into an optimized polyethylene blend. In particular, a unique synthesis strategy was adopted to design a covalently bonded maleated polyethylene (mPE) grafted modified graphene oxide (mGO) hybrid nanocomposite. In this scheme, polyethyleneimine (PEI) was initially attached onto GO to synthesize amine functionalized GO (GO-PEI). This is followed by mPE grafting, resulting in mGO. Melt-extrusion together with injection moulding of a polymer mix (60% HDPE-40% UHMWPE) with different proportions (less than or equal to 3 wt%) of surface functionalized GO was conducted to develop nanocomposites of different sizes and shapes. When compared with unreinforced PE blend, the nanocomposites with 1 wt% mGO exhibited an increase in ultimate tensile strength by 120% (up to 65 MPa) and elastic modulus by 40% (up to 908 MPa). The uniform dispersion of modified GO nanofillers, confirmed using X-ray micro-computed tomography and transmission electron microscopy, facilitated effective interfacial adhesion and compatibility with the hybrid polymer matrix. The variation in mechanical properties with GO/mGO addition to PE blend was critically discussed in reference to the structural modification of GO, crystallinity and nature of dispersion of fillers. Importantly, the nanocomposites support the attachment and proliferation of C2C12 murine myoblast cells over 3 days in culture in a statistically insignificant manner with respect to polymer blends without any nanofiller. Taken together, the experimental results suggest that HDPE/UHMWPE/mGO is a promising biomaterial for bone tissue engineering applications.
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Project description:Hollow ZnO microspheres were successfully synthesized by a hydrothermal method and then functionalized with graphene oxide (GO) flakes, previously obtained through electrochemical oxidation. Their photocatalytic activity toward the photodegradation of salicylic acid under UV light irradiation was evaluated by UV-Vis spectroscopy. Unfunctionalized microspheres and ZnO functionalized with chemically oxidized graphene were also studied as comparative terms. The hybrid materials of ZnO with both electrochemical and chemical GO gave a similar photodegradation yield of ∼28% against 18% of the non-functionalized microspheres. The similar degradation yields and rate constants obtained with the two GO synthetic methods indicate that electrochemical oxidation of GO represents an eco-friendly option over traditional methods for photocatalytic degradation systems.
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Project description:The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process.
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