Decorated Graphene Oxide Nanosheets Research Articles

Magnetic graphene oxide functionalized alginate-g-poly(2-hydroxypropylmethacrylamide) nanoplatform for near-infrared light/pH/magnetic field-sensitive drug release and chemo/phototherapy

Multifunctional nanoplatforms developed from natural polymers and graphene oxide (GO) with enhanced biological/physicochemical features have recently attracted attention in the biomedical field. Herein, a new multifunctional near-infrared (NIR) light-, pH- and magnetic field-sensitive hybrid nanoplatform (mGO@AL-g-PHPM@ICG/EP) is developed by combining iron oxide decorated graphene oxide nanosheets (mGO) and poly(2-hydroxypropylmethacrylamide) grafted alginate (AL-g-PHPM) copolymer loaded with indocyanine green (ICG) and etoposide (EP) for chemo/phototherapy. The functional groups, specific crystal structure, size, morphology, and thermal stability of the nanoplatform were fully characterized by XRD, UV, FTIR, AFM/TEM/FE-SEM, VSM, DSC/TG, and BET analyses. In this platform, the mGO and ICG, as phototherapeutic agents, demonstrate excellent thermal effects and singlet oxygen production under NIR-light (808 nm) irradiation. The XRD and DSC analysis confirmed the amorphous state of the ICG/EP in the nanoparticles. In vitro photothermal tests proved that the mGO@AL-g-PHPM@ICG/EP nanoparticles had outstanding light stability and photothermal conversion ability. The in vitro release profiles presented NIR light-, pH- and magnetic field-controlled EP/ICG release behaviors. In vitro experiments demonstrated the excellent antitumor activity of the mGO@AL-g-PHPM@ICG/EP against H1299 tumor cells under NIR laser. Benefiting from its low-cost, facile preparation, and good dual-modal therapy, the mGO@AL-g-PHPM@ICG/EP nanoplatform holds great promise in multi-stimuli-sensitive drug delivery and chemo/phototherapy.

Design of quetiapine fumarate loaded polyethylene glycol decorated graphene oxide nanosheets: Invitro-exvivo characterization

Quetiapine Fumarate (QF) is an atypical antipsychotic with poor oral bioavailability (9%) due to its low permeability and pH-dependent solubility. Therefore, this study aims to design QF-loaded polyethylene glycol (PEG) functionalized graphene oxide nanosheets (GON) for nasal delivery of QF. In brief, GO was synthesized using a modified Hummers process, followed by ultra-sonication to produce GON. Subsequently, PEG-functionalized GON was prepared using carbodiimide chemistry (PEG-GON). QF was then decorated onto the cage of PEG-GON using the π-π stacking phenomenon (QF@PEG-GON). The QF@PEG-GON nanocomposite underwent several spectral characterizations, in vitro drug release, mucoadhesion study, ex vivo diffusion study, etc. The surface morphology of QF@PEG-GON nanocomposite validates the cracked nature of the nanocomposite, whereas the diffractograms and thermogram of nanocomposite confirm the conversion of QF into an amorphous form with uniform distribution in PEG-GON. Moreover, an ex vivo study of PEG-GON demonstrates superior mucoadhesion capacity due to its surface functional groups and hydrophilicity. The percent drug loading content and percent entrapment efficiency of the nanocomposite were found to be 9.2±0.62% and 92.3±1.02%, respectively. The developed nanocomposite exhibited 43.82±1.65% drug release within 24h, with the Korsemeyer-Peppas model providing the best-fit release kinetics (R2: 0.8614). Here, the interlayer spacing of PEG-GON prevented prompt diffusion of the buffer, leading to a delayed release pattern. In conclusion, the anticipated QF@PEG-GON nanocomposite shows promise as a nanocarrier platform for nasal delivery of QF.

NiO Nanoparticle-decorated graphene oxide nanosheets modified glassy carbon electrode for sensitive electrochemical detection of pethidine

Pethidine (PTD), a synthetic opioid prescribed frequently as a painkiller, was included in the WADA list of prohibited substances in sports. The purpose of this study is to investigate the electrochemical determination of PTD using a modified glassy carbon electrode decorated with NiO nanoparticles and decorated graphene oxide nanosheets (NiO-GO/GCE). NiO-GO nanocomposite was created using a straightforward chemical reduction technique. SEM, TEM, and XRD analysis of the structure and morphology pointed to the NiO-GO nanocomposite's effective production. Results showed that NiO-GO/GCE responded to PTD determination in a sensitive, focused, and stable manner with a relatively low detection limit value (3.8 ng/mL) and a wide linear range (0–500 μg/mL) compared to other PTD sensors. Results on the appropriateness and validation of the NiO-GO/GCE for determining PTD content in clinical and human fluid samples illustrated good recoveries between 90.00 % and 99.66 % with a relative standard deviation less than 5.41 %, which were acceptable and corroborated the appropriateness and validation of the NiO-GO/GCE results for PTD sensor in urine samples from healthy athlete volunteers.

Design and synthesis of imino alcohol decorated graphene oxide nanosheets as an electrode material for sensor applications

Among all the two-dimensional carbon-based nanomaterials, Graphene oxide (GO) has been extensively explored for the covalently conjugation on their surface. In this work, we report the covalent functionalization of diethanolamine on the GO basal planes and thereby the enhancement of interlayer d-spacing from 9.4 Å to 11.2 Å was observed. No significant peak was observed for the formation of reduced graphene oxide and their corresponding 2D peaks, which confirms the intercalation leads to the decoration of enriched oxygen atoms on the surface of GO. The functionalization was performed on the surface through the epoxide ring-opening and thereby leads to the formation alcoholamine moieties. The covalent intercalation was confirmed by XRD, FT-IR, XPS and the surface morphology was analyzed by SEM, and AFM Images. The calculated number of layers were in good agreement in both theoretical and experimental results. As the intercalated GO nanosheets result with iminoalcohol moieties on the basal plane, it could be used for the sensing of metals in the biological fluids.

Three-dimensional porous spherical TiO2–Bi2WO6 decorated graphene oxide nanosheets photocatalyst with excellent visible light catalytic degradation of ethylene

Porous spherical graphene oxide/TiO2–Bi2WO6 (GTB) composite photocatalysts with different graphene oxide (GO) additions (0, 0.5, 1, 1.5, 2 wt%) are synthesized using hydrothermal and surface-deposition methods. The crystal phase composition, morphology, chemical composition, specific surface area and photoluminescence ability of the catalyst were characterized, and their photodegradation performance was evaluated. The results showed that the catalytic effect of TiO2–Bi2WO6 was significantly improved by appropriate GO addition. The 1.5% GTB provided the best synergistic effect of ethylene photocatalytic degradation, and the reaction rate constant, K′, values was 1.25 × 10−3 min−1 which is 15 times that of TiO2, two times that of Bi2WO6, and 1.25 times that of TB microspheres. This was mainly due to the formation of a ternary heterojunction between GO, TiO2 and Bi2WO6 through the interfacial interaction, which increased the specific surface area, reduced the bandgap, enhanced the utilization of visible light and inhibited the recombination of photogenerated electron–hole pairs, thus showing higher visible photocatalytic activity. GTB photocatalyst also had good stability and reusability.

Chloramine-T/N-Bromosuccinimide/FeCl3/KIO3 Decorated Graphene Oxide Nanosheets and Their Antibacterial Activity.

In this work, we report the synthesis of graphene oxide nanosheets (GO NS) using four different oxidants, namely, chloramine-T (CAT), FeCl3, N-bromosuccinimide (NBS), and KIO3. Fourier transform infrared spectroscopy (FTIR) was used to characterize the functional groups present in the synthesized GO. The microstructure analysis was performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate the morphology of GO. High-resolution transmission electron microscopy (HRTEM) studies demonstrated the nanostructure and crystalline phases of GO. The antibacterial activity of the prepared GO NS was investigated against pure cultures of Pseudomonas pneumonia and Staphylococcus aureus. The synthesized GO NS with CAT-GO (C-GO) exhibited very good antibacterial activity towards pathogens.

Red phosphorus decorated graphene oxide nanosheets: label-free DNA detection.

A straightforward synthetic strategy is developed in this study to synthesize highly fluorescent red phosphorus on nitrogen-doped reduced graphene oxide (f-RP@N-rGO) nanosheets in an aqueous medium; this is used as a novel detection platform for the label-free real-time sensing of nucleic acids with low background noise and a high signal-to-noise ratio.

Polyethylene glycol (PEG) decorated graphene oxide nanosheets for controlled release curcumin delivery

Nowadays, the use of nanostructures in various medical and biological fields such as drug delivery in cancer treatment is increasing. Among the nanostructures, graphene oxide (GO) is an excellent candidate for drug delivery application because of its unique properties. For more stability, GO can bind with various polymers by its carboxyl, hydroxyl and epoxy functional groups. In this study, firstly GO synthesized by the improved Hummers chemical method and then polyethylene glycol polymer was conjugated to it by using EDC/NHS catalyst. Finally, curcumin (Cur) as anti-cancer drug has been loaded onto the PEGylated graphene oxide (GO-PEG). Next, curcumin loaded onto PEGylated graphene oxide (GO-PEG-Cur) were evaluated by using ultraviolet, Fourier transform infrared spectroscopy, differential scanning calorimeter, atomic microscopic force and dynamic light scattering. The amount of loaded drug was calculated about 4.5% with the help of the standard curcumin curve and UV/Vis spectrometer. Also, the result of release shows that maximum drug release rate for this nanocarrier in pH 5.5 and 7.4 was measured 50% and 60%, respectively, after 96 hours. The results showed that the zeta-potential analysis of GO-PEG-Cur was about -13.9 mV that expresses a negative surface charge for produced nanocarrier.

CuO/WO3 nanoparticles decorated graphene oxide nanosheets with enhanced peroxidase-like activity for electrochemical cancer cell detection and targeted therapeutics

The novel method was developed for electrochemical cancer cell detection using CuO/WO3 nanoparticle decorated graphene oxide nanosheet (CuO/WO3-GO) with enhanced peroxidase like-activity, based on catalytic reaction of H2O2 with o-Phenylenediamine (OPD). The prepared nanocomposite conjugated with folic acid (FA), as a cancer cell-targeting ligand, and a miniaturized electrochemical cell for cancer cell detection was designed. In this strategy OPD could oxidize in the presence of H2O2 on the surface of working electrode, which produced an electrochemical signal. However, the redox response signal changed by interaction of cells with FA/CuO/WO3-GO. During interaction between cells and CuO/WO3-GO, some amount of H2O2–OPD system participated in chemical reaction and removed from the electrode, resulting in a decrease in the response signal. As a consequence, cancer cells detected in wide detection range of 50 to 105 cells/mL and a detection limit of 18 cells/mL. Furthermore, the nanocomposite shows therapeutic cancer treatment through superior peroxidase activity. This work unveils an effective method for simple, sensitive and selective monitoring of cancer cells and also has the potential for efficient cancer therapy, which will open an avenue of nanozymes toward biological applications.

Carbon dots decorated graphene oxide nanosheets prepared by a novel technique with enhanced nonlinear optical properties

We report a novel technique to synthesize fluorescent carbon dots decorated graphene oxide (CDs-GO) sheets by microwave irradiation using citric acid as the precursor and ethylenediamine as the passivation agent. The samples are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and ultra violet-visible spectroscopy (UV-Vis). Fluorescence studies reveal strong excitation wavelength dependent fluorescence behaviour for these nanocomposites dispersed in water. Third order nonlinear optical properties of these composites are studied using Z scan technique with Q-switched nanosecond pulsed Nd: YAG laser and the measured highest nonlinear optical susceptibility is 4.624x10-10esu. The optical limiting studies of these nanocomposites yield a lower limiting threshold of 104MW/cm2 enabling them as a strong candidate for optical limiting applications.

Plasmonic carbon nanohybrids for repetitive and highly localized photothermal cancer therapy.

Integrating metallic and non-metallic platform for cancer nanomedicine is a challenging task and bringing together multi-functionality of two interfaces is a major hurdle for biomaterial design. Herein, NIR light responsive advanced hybrid plasmonic carbon nanomaterials are synthesized, and their properties toward repetitive and highly localized photothermal cancer therapy are well understood. Graphene oxide nanosheets having thickness of ∼2 nm are synthesized using modified Hummers' method, thereafter functionalized with biodegradable NIR light responsive gold deposited plasmonic polylactic-co-glycolic acid nanoshells (AuPLGA NS, tuned at 808 nm) and NIR dye (IR780) to examine their repetitive and localized therapeutic efficacy as well resulting side effects to nearby healthy cells. It is observed that AuPLGA NS decorated graphene oxide nanosheets (GO-AuPLGA) and IR780 loaded graphene oxide nanosheets (GO-IR780) are capable in standalone complete photothermal ablation of cancer cells within 4 min. of 808 nm NIR laser irradiation and also without the aid of any anticancer drugs. However, GO-AuPLGA having the potential for repetitive photothermal treatment of a big tumor, ablate the cancer cells in highly localized fashion, without having side effects on neighboring healthy cells.

Hydrophilic ZIF-8 decorated GO nanosheets improve biocompatibility and separation performance of polyethersulfone hollow fiber membranes: A potential membrane material for bioartificial liver application

The hydrophobic nature of zeolitic imidazole framework-8 (ZIF-8) nanoparticles restricts their use as additives in hollow fiber membranes (HFMs) for biomedical applications. In this study, hydrophilic ZIF-8 decorated graphene oxide nanosheets (ZGs) were synthesized and used as additives (0–1 wt%) in polyethersulfone (P) HFMs with the aim of improving the biocompatibility and separation performance so as to make the ZGP HFMs suitable for bioartificial liver (BAL) application. Elemental mapping and Fourier transform infrared studies confirmed the efficacious incorporation of ZG nanohybrids in the ZGP HFMs, which resulted in their improved hydrophilicity. The remarkably improved biocompatibility was experimentally demonstrated for the ZGP HFMs, which also were antioxidative and hemocompatible. There was a significantly high attachment and proliferation of HepG2 cells on these HFMs, and they showed remarkably high urea synthesis and albumin secretion. Further, the ZGP HFMs showed high ultrafiltration coefficient (392.2 ± 26.5 mL/h/m2/mm Hg), high flux recovery ratio (84.3%), low flux reduction (15.7%), and desirable molecular weight cutoff (125–135 kDa). Thus, these results experimentally demonstrated that the hydrophilic ZG nanohybrids improve the desirable properties of ZGP HFMs making them a potential biocompatible material for biomedical applications including BAL application.

Bimetallic Oxide Nanoflowers Decorated Graphene Oxide Nanosheets as Novel Nanohybrids for 4-Nitrophenol Removal at Room Temperature

Bimetallic Oxide Nanoflowers Decorated Graphene Oxide Nanosheets as Novel Nanohybrids for 4-Nitrophenol Removal at Room Temperature

Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor

In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu2O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu2O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu2O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers.

Exfoliated Pd decorated graphene oxide nanosheets (PdNP–GO/P123): Non-toxic, ligandless and recyclable in greener Hiyama cross-coupling reaction

Graphene oxide nanosheets were applied as a support for Pd nanoparticles in Hiyama reaction of various aryl halides and triethoxyphenylsilane to generate biaryl derivatives in aqueous conditions. Addition of surfactant during the catalysis caused a significant increase in yields of products through well-exfoliation of PdNP–GO. Among various studied surfactants, P123 showed superior activity rather to other surfactants, SDS and CTAB. This heterogeneous catalytic system has attained the advantages of being non-toxic, available, recyclable, ligand-free, and compatible to reaction medium.

Thermostable and Impermeable “Nano-Barrier Walls” Constructed by Poly(lactic acid) Stereocomplex Crystal Decorated Graphene Oxide Nanosheets

In contrast to the relatively clear understanding of epitaxial crystallization induced by one-dimensional nanofillers, the underlying interfacial interactions between polymer crystals and two-dimensional graphene oxide (GO) nanosheets are something of a mystery. Here, the GO-assisted formation of poly(lactic acid) (PLA) stereocomplex crystals (SCs) is disclosed from the quantitative structural analysis to the direct morphological observations at multiscale and the interaction mechanism at the molecular level. It is unexpected to observe that the edges of GO featuring rich grooves and ultralow thickness were ready to induce a layer of ordered lamellae, in clear contrast to the random growth of lamellae on the basal planes. The origin of GO-induced crystallization was appraised from the interaction point of view as indicated by the evident red-shift of a set of functional groups in the Fourier transform infrared spectroscopy spectra. More importantly, the GO nanosheets, albeit presented at an extremely low content (0.05 wt %), decorated by the preferred formation of SCs enabled the simultaneous enhancement of gas barrier properties and resistance to heat distortion. Specifically, the unique combination of greatly improved heat deformation temperature (HDT) and low oxygen permeability coefficient (PO2) for the composite crystallized at 165 °C was demonstrated (146.5 °C and 0.95 × 10–15 cm3 cm cm–2 s–1 Pa–1), outperforming pure PLA with an increment of 75% and a decrease of 77% in HDT and PO2, respectively. The proposed methodology affords elucidation of well-tailored thermal and barrier properties, which may motivate further extension of this rational design to other material combinations.

Cyanobacterium metallothionein decorated graphene oxide nanosheets for highly selective adsorption of ultra-trace cadmium

Graphene oxide (GO) nanosheets were decorated with a cysteine-rich metal-binding protein, cyanobacterium metallothionein (SmtA). The SmtA–GO composites were characterized by means of FT-IR, AFM and TGA, giving rise to a SmtA binding amount of 867 mg g−1. The SmtA–GO composites exhibit ultra-high selectivity toward the adsorption of cadmium, i.e., the tolerant concentrations for the coexisting metal and anionic species were 1–800 000 fold improved after SmtA decoration with respect to bare GO. The SmtA–GO composites were then assembled onto the surface of cytopore microbeads and used for highly selective adsorption and preconcentration of ultra-trace cadmium. In comparison with bare GO (carboxyl-rich GO) loaded cytopore (GO@cytopore), SmtA–GO loaded cytopore (SmtA–GO@cytopore) shows a 3.3-fold improvement over the binding capacity of cadmium, i.e. 7.70 mg g−1 for SmtA–GO@cytopore compared to 2.34 mg g−1 for that by GO@cytopore. A novel procedure for selective cadmium preconcentration was developed using SmtA–GO@cytopore beads as a renewable sorption medium incorporated into a sequential injection lab-on-valve system, with detection by graphite furnace atomic absorption spectrometry (GFAAS). The cadmium retained on the SmtA–GO surface was eluted with a small amount of nitric acid. An enrichment factor of 14.6 and a detection limit of 1.2 ng L−1 were achieved within a linear range of 5–100 ng L−1 by using a sample volume of 1 mL. The procedure was validated by analyzing cadmium in certified reference materials and a series of environmental water samples.

Synthesis of Au nanoparticles decorated graphene oxide nanosheets: Noncovalent functionalization by TWEEN 20 in situ reduction of aqueous chloroaurate ions for hydrazine detection and catalytic reduction of 4-nitrophenol

In this paper, we develop a cost-effective and simple route for the synthesis of Au nanoparticles (AuNPs) decorated graphene oxide (GO) nanosheets using polyoxyethylene sorbitol anhydride monolaurate (TWEEN 20) as a stabilizing agent for GO as well as a reducing and immobilizing agent for AuNPs. The AuNPs assemble on the surface of TWEEN-functionalized GO by the in situ reduction of HAuCl4 aqueous solution. The morphologies of these composites were characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). It is found that the resultant AuNPs decorated GO nanosheets (AuNPs/TWEEN/GO) exhibit remarkable catalytic performance for hydrazine oxidation. This hydrazine sensor has a fast amperometric response time of less than 3s. The linear range is estimated to be from 5μM to 3mM (r=0.999), and the detection limit is estimated to be 78nM at a signal-to-noise ratio of 3. The AuNPs/TWEEN/GO composites also exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the GO supports also enhance the catalytic activity via a synergistic effect.