In vitro investigation of electrophoretically deposited bioactive hydroxyapatite/chitosan coatings reinforced by graphene

&#x110,o&#x161,i&#x107,, Marija,Eraković,, Sanja,Janković,, Ana,Vuka&#x161,inovi&#x107,-Sekuli&#x107,, Maja,Mati&#x107,, Ivana Z.,Stojanovi&#x107,, Jovica,Rhee, Kyong Yop,Mi&#x161,ković Elsevier 2017 Journal of industrial and engineering chemistry Vol.47 No.-

<P><B>Abstract</B></P> <P>Graphene (Gr) and natural polymer chitosan (CS) were introduced to hydroxyapatite (HAP) to produce a three-component composite coating, which was fabricated by cathodic electrophoretic deposition on Ti substrates in an ethanol suspension. These HAP/CS/Gr coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements and found that the graphene into HAP/CS composites significantly improves their morphology, thermal stability, and bioactivity. Both HAP/CS and HAP/CS/Gr composite coatings are classified as non-cytotoxic when tested against healthy peripheral blood mononuclear cells (PBMC), while antibacterial activity against <I>Staphylococcus aureus</I> and <I>Escherichia coli</I> could not be verified.</P>

Graphene-based antibacterial composite coatings electrodeposited on titanium for biomedical applications

Janković,, Ana,Eraković,, Sanja,Vuka&#x161,inovi&#x107,-Sekuli&#x107,, Maja,Mi&#x161,ković,-Stanković,, Vesna,Park, Soo Jin,Rhee, Kyong Yop Elsevier 2015 Progress in organic coatings Vol.83 No.-

<P><B>Abstract</B></P> <P>The graphene based silver/hydroxyapatite/graphene (Ag/HAP/Gr) composite coatings were produced by electrophoretic deposition (EPD) on titanium to assemble porous bioactive homogenous coatings, with improved corrosion stability in simulated body fluid (SBF). Novel composite coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron analysis (XPS) and electrochemical impedance spectroscopy (EIS). The improved properties of graphene based coatings in respect to the graphene-free coatings, as a consequence of toughening action of graphene, were demonstrated: reduced surface cracks, better mechanical resistance (hardness and elastic modulus increased by 10%) and enhanced thermal stability, while the Ca/P ratio was closer to the stoichiometric value. The bioactivity of Ag/HAP/Gr composite coatings was proved by a newly formed apatite layer in SBF with enhanced corrosion stability, while antibacterial activity against <I>Staphylococcus aureus</I> and <I>Escherichia coli</I> and noncytotoxicity against healthy peripheral blood mononuclear cells (PBMC) indicate the high potential for biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel graphene based composite coating on titanium obtained by electrophoretic deposition. </LI> <LI> Homogenous, non-toxic Ag/HAP/Gr coating with improved mechanical properties. </LI> <LI> New apatite layer formation in SBF has proved the coating bioactivity. </LI> <LI> Diminished bacterial growth of <I>S. aureus</I> and <I>E. coli</I> after only 3h of exposure. </LI> </UL> </P>

Silver/poly(vinyl alcohol)/chitosan/graphene hydrogels – Synthesis, biological and physicochemical properties and silver release kinetics

Ne&#x161,ovi&#x107,, Katarina,Janković,, Ana,Koji&#x107,, Vesna,Vuka&#x161,inovi&#x107,-Sekuli&#x107,, Maja,Peri&#x107,-Gruji&#x107,, Aleksandra,Rhee, Kyong Yop,Mi&#x161,ković,-Stankovi Elsevier 2018 Composites. Part B, Engineering Vol.154 No.-

<P><B>Abstract</B></P> <P>This study presents the synthesis of novel silver/poly(vinyl alcohol)/chitosan/graphene (Ag/PVA/CHI/Gr) nanocomposite hydrogels by <I>in situ</I> electrochemical reduction of silver ions in the hydrogel matrix and their thorough characterization by UV–visible and Raman spectroscopies, field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and silver release measurements. The influence of chitosan content on the incorporation and stabilization of silver nanoparticles (AgNPs) was investigated, and we found that hydrogels with higher chitosan content contain higher amounts of AgNPs. In addition, the cytotoxicity and antibacterial activity of Ag/PVA/CHI/Gr nanocomposite hydrogels were evaluated. Based on <I>in vitro</I> investigations, the obtained materials exhibit diffusion-controlled release profiles over 28 days, strong antibacterial activity against <I>Staphylococcus aureus</I> and <I>Escherichia coli</I> bacterial strains, and no cytotoxicity toward human and mice fibroblast cell lines.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>In situ</I> electrochemical synthesis of silver nanoparticles in PVA/CHI/Gr hydrogels. </LI> <LI> Effect of chitosan concentration on the amount of embedded silver nanoparticles. </LI> <LI> Effect of chitosan concentration on the silver release kinetics. </LI> <LI> Strong antibacterial activity against <I>S. aureus</I> and <I>E. coli</I>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

<i>In situ</i> electrochemical synthesis of silver-doped poly(vinyl alcohol)/graphene composite hydrogels and their physico-chemical and thermal properties

Abudabbus, Mohamed M.,Jevremovi&#x107,, Ivana,Ne&#x161,ovi&#x107,, Katarina,Peri&#x107,-Gruji&#x107,, Aleksandra,Rhee, Kyong Yop,Mi&#x161,ković,-Stanković,, Vesna Elsevier 2018 Composites Part B, Engineering Vol.140 No.-

<P><B>Abstract</B></P> <P>This paper presents silver/poly(vinyl alcohol) (Ag/PVA) and silver/poly(vinyl alcohol)/graphene (Ag/PVA/Gr) composites prepared by the immobilization of silver nanoparticles (AgNPs) in PVA and PVA/Gr hydrogel discs previously cross linked by the freezing/thawing method. The AgNPs inside the hydrogel matrices were synthesized following an innovative <I>in situ</I> method of electrochemical reduction of Ag<SUP>+</SUP> ions within PVA and PVA/Gr hydrogel discs. In addition, the novel materials introduced here were characterized by UV–visible spectroscopy, cyclic voltammetry, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, silver release measurements, and thermogravimetric analysis. The effective immobilization of the AgNPs inside the PVA and PVA/Gr hydrogel networks was achieved by their bonding with the exposed hydroxyl groups in PVA. Also, the incorporation of graphene into the PVA matrix and the bonding between PVA molecules and incorporated graphene sheets improves thermal stability of Ag/PVA/Gr and prevents aggregation and growth of AgNPs as observed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel biomedical silver/(polyvinyl alcohol) and silver/(polyvinyl alcohol)/graphene hydrogels. </LI> <LI> <I>In situ</I> electrochemical synthesis of silver nanoparticles in hidrogel polymer matrix. </LI> <LI> Cyclic voltammetric investigation of silver nanoparticles (AgNPs) oxidation/reduction mechanism. </LI> <LI> Silver release kinetics show prolonged stability and good immobilization of AgNPs. </LI> <LI> Potential for application as wound dressings. </LI> </UL> </P>

Investigation of corrosion behaviour of carbon nanotubes coated basalt fabric as a reinforcement material

Mittal, Garima,Ne&#x161,ovi&#x107,, Katarina,Rhee, Kyong Yop,Mi&#x161,ković,-Stanković,, Vesna Elsevier 2019 Composites Part B, Engineering Vol.178 No.-

<P><B>Abstract</B></P> <P>In this study, the corrosion behaviour of carbon nanotubes (CNTs) coated basalt fibre (BF) (BFCNTs) obtained by chemical vapour deposition (CVD), was studied. During CVD, the CNTs were grown on BF, (a) at different growth temperatures and (b) for different growth times. The physicochemical measurements were performed using X-ray diffraction, Raman spectroscopy, and field-emission scanning electron microscopy. The corrosion performances were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic sweep (PDS), linear polarization resistance (LPR) and weight loss measurements. The BFCNT prepared at 650 °C for 120 min exhibited the best corrosion stability during the prolonged exposure to 0.1 M NaCl electrolyte. The outcomes of this study would be useful in designing the carbon nanotubes coated basalt fibre with the best corrosion resistance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CNTs coated basalt fibres were obtained using chemical vapour deposition. </LI> <LI> CNTs were grown at different growth temperatures and for different growth times. </LI> <LI> BFCNTs prepared for longer growth time showed better CNT formation on BF. </LI> <LI> Better CNT formation on BF improved the corrosion stability of the BFCNTs composite. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Comprehensive electrochemical study on corrosion performance of graphene coatings deposited by chemical vapour deposition at atmospheric pressure on platinum-coated molybdenum foil

Naghdi, Samira,Ne&#x161,ovi&#x107,, Katarina,Mi&#x161,ković,-Stanković,, Vesna,Rhee, Kyong Yop Pergamon Press 2018 Corrosion science Vol.130 No.-

<P><B>Abstract</B></P> <P>In this work, we present the results of electrochemical, Raman, FE-SEM/EDS, and XPS studies of graphene coatings deposited by chemical vapour deposition at atmospheric pressure on Mo foil and Pt-coated Mo foil as catalysts. The results showed that the graphene coating synthesized on Pt-coated molybdenum foil was bi-layer and had fewer defects, while the graphene coating on Mo foil was few-layer with more defects. The corrosion studies indicated that both graphene coatings on bare Mo and Pt-coated Mo exhibited good protective properties and can act as a barrier against corrosion in 0.1M NaCl.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene chemical vapour deposition (CVD) at atmospheric pressure on molybdenum. </LI> <LI> Platinum thin film on molybdenum provided catalytic effect for CVD of graphene. </LI> <LI> Graphene coating on Pt-coated Mo samples had larger grain size and fewer defects. </LI> <LI> Both graphene coatings on Mo and Pt-coated Mo exhibited corrosion protection. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Chemical vapour deposition at atmospheric pressure of graphene on molybdenum foil: Effect of annealing time on characteristics and corrosion stability of graphene coatings

Naghdi, Samira,Jevremovi&#x107,, Ivana,Mi&#x161,ković,-Stanković,, Vesna,Rhee, Kyong Yop Elsevier 2016 Corrosion science Vol.113 No.-

<P><B>Abstract</B></P> <P>In this work, the effect of pre-annealing of Mo substrate on the quality of graphene layers grown by chemical vapour deposition was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Moreover, different electrochemical techniques were employed to investigate the corrosion stability of the graphene coated Mo in 0.1M NaCl. Longer annealing time resulted in less defective graphene coatings with fewer layers. Graphene coating on the annealed Mo provided better protection against corrosion during the initial exposure times, while after prolonged exposure times, both graphene coatings on annealed and non-annealed Mo exhibited nearly the same corrosion inhibitive properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atmospheric pressure chemical vapor deposition of graphene on molybdenum foils. </LI> <LI> Quality and domain size of graphene layers increased with longer annealing times. </LI> <LI> The number of graphene layers decreased with longer annealing times. </LI> <LI> Graphene coatings on molybdenum foils exhibited corrosion inhibitive properties. </LI> </UL> </P>

Dispersion and damping of the interband π plasmon in graphene grown on Cu(111) foils

Politano, A.,Radovi&#x107,, I.,Borka, D.,Mi&#x161,ković,, Z.L.,Yu, H.K.,Farí,as, D.,Chiarello, G. Elsevier 2017 Carbon Vol.114 No.-

<P><B>Abstract</B></P> <P>By means of angle-resolved electron energy loss spectroscopy, we have measured the interband π plasmon in high-quality graphene grown on peeled-off epitaxial Cu(111) foils. Experimental loss spectra have been reproduced by means of a hydrodynamic model. The dispersion relation of the plasmon frequency shows a nearly-flat dispersion up to a critical wave-vector of 0.3 Å<SUP>−1</SUP>. We propose that the observed behavior could be originated by confinement effects in ripples in the strained graphene sheet. Strain also limits the dispersion at higher momenta, as a consequence of the increased effective mass of charge carriers. The analysis of momentum dependence of the line-width and of the inverse quality factor indicates that damping processes are dominated by decay in electron-hole pairs via indirect interband transitions.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Reinforcements in multi-scale polymer composites: Processing, properties, and applications

Mittal, Garima,Rhee, Kyong Y.,Mi&#x161,ković,-Stanković,, Vesna,Hui, David Elsevier 2018 Composites Part B, Engineering Vol.138 No.-

<P><B>Abstract</B></P> <P>Smart and novel materials require the replacement of conventional composites with superior ones, which requires an advanced class of composites with multi-functionality. Multi-scale composites are advanced composites that are reinforced with nanoscale materials along with macroscale fibers, and these materials have attracted the attention of researchers as well as various industries. Multi-scale composites have potential applications in almost every field due to their remarkable features like extraordinary mechanical, electrical, and optical properties; extremely high aspect ratios of the nanomaterial constituents; and the uniformity, flexibility, and stability of the fibers. To optimize the performance of these kinds of composites, it is crucial to understand the selection of appropriate reinforcements, processing, and utilization of these advanced materials. Most reviews in this area concentrate only on CNTs, while this review considers other nanomaterials too. Additionally, various methods to improve the dispersion of nanomaterials into the matrix are also discussed. Overall, this article focuses on the components of multi-scale composites, key challenges related to their processing, and the multi-functionality of designed multi-scale composites.</P>