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Graphene oxides with different surface charges were fabricated from carboxylated graphene oxide by chemical modification with amino- (–NH2), poly-m-aminobenzene sulfonic acid- (–NH2/–SO3H), or methoxyl- (–OCH3) terminated functional groups. The chemically functionalized graphene oxides and the carboxylated graphene oxide were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, UV-Vis spectrometry, ζ potential measurements, field emission scanning electron microscopy, and contact angle analyses. Subsequently, the resulting graphene oxides were used as substrates for culturing primary rat hippocampal neurons to investigate neurite outgrowth and branching. The morphological features of neurons that directly reflect their potential capability in synaptic transmission were characterized. The results demonstrate that the chemical properties of graphene oxide can be systematically modified by attaching different functional groups that confer known characteristics to the substrate. By manipulating the charge carried by the functionalized graphene oxides, the outgrowth and branching of neuronal processes can be controlled. Compared with neutral, zwitterionic, or negatively charged graphene oxides, positively charged graphene oxide was found to be more beneficial for neurite outgrowth and branching. The ability to chemically modify graphene oxide to control neurite outgrowth could be implemented clinically, especially in cases wherein long-term presence of outgrowth modulation is necessary. [ABSTRACT FROM AUTHOR]

We used graphene oxide (GO) and egg albumen (EA) to fabricate bipolar resistance switching devices with indium tin oxide (ITO)/GO/EA/GO/Aluminum (Al) and ITO/EA/Al structures. The experimental results show that these ITO/GO/EA/GO/Al and ITO/EA/Al bio-memristors exhibit rewritable flash memory characteristics. Comparisons of ITO/GO/EA/GO/Al devices with 0.05 ωt %, 0.5 ωt %, and 2 ωt % GO in the GO layers and the ITO/EA/Al device show that the ON/OFF current ratio of these devices increases as the GO concentration decreases. Among these devices, the highest switching current ratio is 1.87 × 103. Moreover, the RESET voltage decreases as the GO concentration decreases, which indicates that GO layers with different GO concentrations can be adopted to adjust the ON/OFF current ratio and the RESET voltage. When the GO concentration is 0.5 ωt %, the device can be switched more than 200 times. The retention times of all the devices are longer than 104 s. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hierarchical structure of CeMOF@GO boosts rapid fluoride adsorption within 25 min. • CeMOF@GO shows high selectivity towards fluoride. • CeMOF@GO exhibits satisfactory solvent stability, adsorption capacity, pH applicability and salt tolerance. • The specific adsorption of fluoride is governed by ligand exchange at metal defects. • CeMOF@GO removes fluoride from diverse complex samples efficiently. The rational design of functional heretrostructures with integrated advantages for the efficient adsorption and removal of fluoride is important for water pollution control. In this study, a cerium metal organic framework-graphene oxide heterostructure composite (CeMOF@GO) is successfully prepared through ultrasonic irradiation and vapor diffusion-assisted interfacial growth. CeMOF@GO with hierarchical structure boosts the mass transport of fluoride with adsorption time reduced to 25 min. By virtue of the specific ligand exchange between adsorbed H 2 O/OH− at metal defect sites and fluoride ions, such unique CeMOF@GO can be utilized for fluoride removal, showing satisfactory adsorption capacity (151.5 mg g−1), excellent specific affinity (with a distribution coefficient of up to 21.865 L g−1), glorious salt tolerance (8.0 mol L−1 of nitrate), wide pH applicability and eminent recycling ability. The practical application of CeMOF@GO is well demonstrated by the selective scavenging of fluoride from diverse environmental water samples. This work is expected to provide a reliable defluorination approach, and bridge the gap between academic MOF-based adsorbent research and practical environmental application. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Graphene oxide-catechol hybrid poly(dimethylsiloxane) (PDMS-GO-DMA) surface was prepared. • PDMS-GO-DMA surface exhibited antibacterial abilities in some degree. • PDMS-GO-DMA surface exhibit favorable biocompatibility properties. Abstract We have prepared the graphene oxide (GO)- a catechol derivative –dopamine methacrylamide monomer (DMA) composite modified poly (dimethylsiloxane) (PDMS) surfaces by π−π stacking of 1-pyrenebutyric acid on the GO and dopamine surface. PDMS substrates were first oxidized by plasma to transform the Si−CH 3 groups on their surfaces into Si−OH groups. Subsequently, aminopropyltriethoxysilane (γ-APS) was immobilized onto the PDMS−OH surface, and 1-pyrenebutyric acid (PA) was then bonded covalently onto the PDMS-γ-APS surfaces by the amidation reaction. Finally, PDMS-GO-DMA surfaces were prepared by modifying GO-DMA composites onto the PDMS-PA surface by π−π stacking between 1-pyrenebutyric acid and GO-DMA. Various characterization techniques, including contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS), were used to ascertain the successful prepared the PDMS-GO-DMA surface. The antibacterial ability of PDMS-GO-DMA surface was investigated by the classic colony and visible spectrophotometry methods. The results showed that PDMS-GO-DMA surface displayed antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria compared with native PDMS surface. Furthermore, we studied the biocompatibility of the PDMS-GO-DMA by culturing the cell lines (HepG2 and A549) on the PDMS-GO-DMA surface which exhibited excellent biocompatibility. Additionally, our results present possible uses for the PDMS–GO-DMA surface as antibacterial functional surfaces in biomedical microdevices applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Graphene oxide-catechol hybrid PLA (PLA-GO-DMA) nanofibers were prepared. • PLA-GO-DMA nanofiber mats exhibited excellent antibacterial abilities. • PLA-GO-DMA nanofiber mats exhibit favorable biocompatibility properties. Abstract The functionalization of electrospun mats with antimicrobial nanomaterials is an attractive strategy when developing functional graphene oxide coating materials to prevent bacterial colonization on surfaces. In this study, we demonstrated a simple approach to produce antimicrobial electrospun mats by dip-coating a polylactic acid (PLA) nanofiber into a graphene oxide-catechol derivative. PLA was first electrospun to yield narrow-diameter polymeric nanofibers. We then modified the graphene oxide (GO) with a catechol derivative – dopamine methacrylamide monomer (DMA) – to synthesize a GO-DMA nanocomposite material which exhibited robust antimicrobial properties. The catechol groups promote the immobilization of graphene oxide onto the PLA nanofibers and possess strong antimicrobial properties. We therefore selected this functional group to modify GO. We dipped the GO-DMA onto the PLA nanofiber to produce the final functionalized electrospun mats. The PLA mats which were functionalized using the GO-DMA nanocomposite (PLA-GO-DMA) displayed antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Furthermore, we studied the biocompatibility of the mats by culturing the cell lines (HepG2, A549, and HUVEC-C) of PLA-GO-DMA among the nanofibers which exhibited excellent biocompatibility. These results collectively demonstrate the potential of PLA-GO-DMA nanofiber mats as antimicrobial biomaterials and provide fundamental information toward the establishment of future biomedical applications. [ABSTRACT FROM AUTHOR]

Pharmaceuticals and personal care products (PPCPs) are gaining attention due to their persistence in the environment. Therefore, the development of novel adsorbents to remove them is strongly anticipated. In this study, an improved dual ice-template assembly method had been used for the preparation of ZIF-67/QGO/SB-CS aerogel through ZIF-67, benzoquinone-modified graphene oxide (QGO), and sulfobetaine-modified chitosan (SB-CS) for the adsorption and removal of PPCPs in water. We reported for the first time that the chitosan composite aerogel has antifouling, bacterial filtration and oil-water separation abilities with excellent PPCPs adsorption performance and reusable, which would be a viable option for long-lasting adsorbents for PPCPs in water. [Display omitted] [ABSTRACT FROM AUTHOR]

A quaternized poly(dimethylaminoethyl methacrylate) functionalized graphene oxide (GO–QPDMAEMA) was successfully prepared in this study via click chemistry. Alkyne-functionalized graphene oxide (GO–alkyne) was first synthesized through a two-step amidation reaction of GO–COOH. Meanwhile, azide-terminated poly(dimethylaminoethyl methacrylate) (PDMAEMA–N 3 ) was prepared via the atom-transfer radical-polymerization of dimethylaminoethyl methacrylate (DMAEMA). Subsequently, PDMAEMA–N 3 was grafted onto the GO–alkyne through click chemistry to obtain PDMAEMA modified graphene oxide (GO–PDMAEMA). Finally, the tertiary amino groups of GO–PDMAEMA were quaternized by ethyl bromide to provide a quaternized poly(dimethylaminoethyl methacrylate) functionalized graphene oxide (GO–QPDMAEMA). Various characterization techniques, including Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis spectrometry, ζ potential, Raman, contact angle analyses and field emission scanning electron microscope were used to ascertain the successful preparation of the quaternized GO–QPDMAEMA. Furthermore, antibacterial and antifouling activities of GO–QPDMAEMA were investigated via protein adsorption, as well as bacterial and cell adhesion studies. The results suggest that the GO–QPDMAEMA surface exhibited significant antibacterial and antifouling properties, compared with the GO–COOH and GO–PDMAEMA surfaces. [ABSTRACT FROM AUTHOR]

A highly selective and sensitive electrogenerated chemiluminescence (ECL) biosensor for the detection of prostate PC-3 cancer cells was designed using a prostate specific antibody as a capture probe and ruthenium complex-labelled wheat germ agglutinin as a signal probe. The ECL biosensor was fabricated by covalently immobilising the capture probe on a graphene oxide-coated glassy carbon electrode. Target PC-3 cells were selectively captured on the surface of the biosensor, and then, the signal probe was bound with the captured PC-3 cells to form a sandwich. In the presence of tripropylamine, the ECL intensity of the sandwich biosensor was logarithmically directly proportion to the concentration of PC-3 cells over a range from 7.0 × 10 2 to 3.0 × 10 4 cells mL −1 , with a detection limit of 2.6 × 10 2 cells mL −1 . The ECL biosensor was also applied to detect prostate specific antigen with a detection limit of 0.1 ng mL −1 . The high selectivity of the biosensor was demonstrated in comparison with that of a lectin-based biosensor. The strategy developed in this study may be a promising approach and could be extended to the design of ECL biosensors for highly sensitive and selective detection of other cancer-related cells or cancer biomarkers using different probes. [ABSTRACT FROM AUTHOR]