Determination of surface properties and Gutmann’s Lewis acidity–basicity parameters of thiourea and melamine polymerized graphitic carbon nitride sheets by inverse gas chromatography

Sreekanth, T.V.M.,Basivi, Praveen Kumar,Nagajyothi, P.C.,Dillip, G.R.,Shim, J.,Ko, T.J.,Yoo, K. Elsevier 2018 Journal of chromatography Vol.1580 No.-

<P><B>Abstract</B></P> <P>Melamine and thiourea-derived graphitic carbon nitrides (M-GCN/T-GCN) were synthesized and characterized. The surface properties were investigated using inverse gas chromatography (IGC) and compared. Net retention volumes of M-GCN and T-GCN were measured with <I>n</I>-alkanes (C<SUB>5</SUB>–C<SUB>10</SUB>) and polar probes. The London dispersive surface free energies ( γ s d ), calculated using Schultz and Dorris–Gray methods, decreased linearly with increasing temperature. The specific components of the enthalpy and entropy of adsorption for the polar probes were obtained using the Schultz, Dong, and Sawyer–Brookman methods. The Gutmann’s Lewis acid–base parameters, <I>K<SUB>a</SUB> </I> and <I>K<SUB>b</SUB> </I>, were determined using the surface free energy ( Δ G a S ) via these methods. The surface character ‘<I>S’</I> values (<I>K<SUB>b</SUB> </I>/<I>K<SUB>a</SUB> </I>) of M-GCN and T-GCN using the respective methods are 4.04, 3.78, and 5.08 and 4.11, 5.27, and 2.86. Hence, the surfaces contain more basic than acidic sites and could interact strongly with acidic media. Thus, IGC elucidates the surface charges of the GCN matrix resulting from surface chemical modification.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphitic carbon nitride was synthesized using two precursors, melamine and thiourea. </LI> <LI> Physicochemical properties were confirmed by XRD, XPS and BET. </LI> <LI> Inverse gas chromatography was employed to understand surface free energy of GCN. </LI> <LI> The London dispersive parameters were determined by Schultz/Dorris–Gray methods. </LI> <LI> The Lewis acid–base parameters, showing the more basic character of GCN. </LI> </UL> </P>

Enhanced photocatalytic activity of Ag/g-C₃N₄ composite

Nagajyothi, P.C.,Pandurangan, M.,Vattikuti, S.V.P.,Tettey, C.O.,Sreekanth, T.V.M.,Shim, J. Elsevier Science B.V 2017 Separation and purification technology Vol.188 No.-

Silver-graphite carbon nitride (Ag/g-C<SUB>3</SUB>N<SUB>4</SUB>) was designed and synthesized through a simple green chemical route. The photocatalyst was comprehensively characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM), and X -ray photoelectron spectroscopy (XPS). The HR-TEM results indicate that the synthesized Ag spherical-like nanoparticles were randomly loaded on the surface of graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4)</SUB>. In addition, the Ag/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites exhibited 2.5 times higher photocatalytic activity than pristine g-C<SUB>3</SUB>N<SUB>4</SUB> for the degradation of malachite green (MG) dye under UV irradiation.

Differential sensitivity of Madin-Darby canine kidney (MDCK) cells to epinephrine

Muthuraman, P.,Nagajyothi, P. C.,Chandrasekaran, M.,Enkhtaivan, G.,Venkitasamy, B.,Kim, D. H.,Cho, M.,Shim, J. Springer Science + Business Media 2016 The journal of nutrition, health & aging Vol.20 No.5

<P>Catecholamines regulate a variety of cellular functions in the mammalian kidney. The present study was aimed to investigate the differential sensitivity of Madin-Darby Kidney Cells (MDCK cells) to epinephrine in a dose-dependent manner. The loss of adhesion and altered cell shape were observed in MDCK cells. The presence of apoptosis and necrosis were studied by the fluorescence microscope and Confocal Laser Scanning Microscope (CLSM). Scanning Electron Microscope (SEM) analysis showed several surface microvilli, and cells were rounded having ruffled and crenated surface. Agarose gel electrophoresis study showed the presence of smearing, which further confirms the occurrence of necrosis. The fluorescence staining study showed the increased reactive oxygen species (ROS) level. Up-regulation of p53, bax, and caspase 3 mRNA expressions was evidenced by quantitative PCR (qPCR). Caspase 3 activity was also increased in epinephrine treated cells. Our experimental results do not imply that the epinephrine should not be used in the clinical treatments. However, our results add a research note of caution on the possible cytotoxic effect of maximal doses of epinephrine over a prolonged time.</P>

Green synthesis, characterization and anticancer activity of yttrium oxide nanoparticles

Nagajyothi, P.C.,Pandurangan, M.,Veerappan, M.,Kim, Doo Hwan,Sreekanth, T.V.M.,Shim, Jaesool Elsevier 2018 Materials letters Vol.216 No.-

<P><B>Abstract</B></P> <P>Yttrium oxide nanoparticles (Y<SUB>2</SUB>O<SUB>3</SUB> NPs) are synthesized successfully using <I>Forsythiae fructus</I> aqueous fruit extract. The structrural and morphological properties of Y<SUB>2</SUB>O<SUB>3</SUB> NPs were systematically studied by FTIR, SEM, TEM, XPS and XRD patterns. The results indicate the NPs with flake-like flower morphology. The overall results indicated that the green synthesized Y<SUB>2</SUB>O<SUB>3</SUB> NPs exhibited potent anti-cancer activity against renal carcinoma cells. The synthesis method is inexpensive, eco-friendly, reduced harmful side effects and alternative to physical/chemical methods.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Y<SUB>2</SUB>O<SUB>3</SUB> NPs were synthesized using an aqueous extract of <I>Forsythiae fructus</I> fruits. </LI> <LI> TEM and XRD analysis confirmed that NPs flake-like shape with an size of ∼11 nm. </LI> <LI> NPs were non-toxic to MDCK but highly toxic to Caki-2 cells at high concentration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ultra-sonication-assisted silver nanoparticles using <i>Panax ginseng</i> root extract and their anti-cancer and antiviral activities

Sreekanth, T.V.M.,Nagajyothi, P.C.,Muthuraman, P.,Enkhtaivan, G.,Vattikuti, S.V.P.,Tettey, C.O.,Kim, Doo Hwan,Shim, Jaesool,Yoo, Kisoo Elsevier 2018 Journal of photochemistry and photobiology Biology Vol.188 No.-

<P><B>Abstract</B></P> <P>A simple, inexpensive ultra-sonication method was used to synthesize quasi spherical silver nanoparticles (AgNPs) with an aqueous extract from <I>Panax ginseng</I> roots. This method has the advantages of being completely eco-friendly and allows increased reaction rates, uniform dispersal of the nanoparticles in liquids, and effective breaking of aggregates. Biomolecules present in plant extracts are often used to reduce metal ions to nanoparticles in a single-step green synthesis route. The formation of the AgNPs was characterized using UV–visible (UV–vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy- dispersive X-ray analysis (EDX), Fast Fourier Transform (FFT), and high-resolution transmission electron microscopy (HR-TEM). The formation of AgNPs (456 nm) was confirmed by UV–vis spectroscopy. HR-TEM analysis revealed that most of the AgNPs were quasi spherical with sizes ranging from approximately 5 to 15 nm. The crystalline nature of the AgNPs was confirmed by XRD, and the presence of elemental silver was confirmed by energy-dispersive X -ray analysis. The AgNPs showed dose-dependent cytotoxicity towards HeLa cells in vitro (3.88% at 0.005 M, 5.11% at 0.01 M, 7.52% at 0.015 M, 11.19% at 0.02 M, and 19.45% at 0.025 M) as revealed by sulforhodamine B assay. They were also shown to be virucidal against the influenza A virus (strain A/PR/8). Hence, the present facile, eco-friendly, and efficient method results in the synthesis of AgNPs that can act as an alternative biomaterial for future biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AgNPs synthesized via green route using <I>Panax ginseng</I> root aqueous extract. </LI> <LI> AgNPs were spherical in shape, with a crystallite size of 5 to 15 nm. </LI> <LI> In addition, the green synthesized AgNPs were studied for in-vitro cytotoxic and antiviral activities. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrothermally synthesized Na₂Ti₃O₇ nanotube–V₂O₅ heterostructures with improved visible photocatalytic degradation and hydrogen evolution - Its photocorrosion suppression

Vattikuti, S.V. Prabhakar,Reddy, Police Anil Kumar,NagaJyothi, P.C.,Shim, Jaesool,Byon, Chan Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.740 No.-

<P><B>Abstract</B></P> <P>There is still a need to prepare heterostructure photocatalysts with high activity and recyclability but without using precious metals to reduce the cost of photocatalysts. Thus, a facile and simple method for the synthesis of a Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst via hydrothermal synthesis is reported herein. The chemical composition, morphology, and structural features of the photocatalyst were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N<SUB>2</SUB> adsorption–desorption specific surface area analysis (BET), and diffuse reflectance absorption (DRS) methods. It was observed that the specific surface area of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst increased with the incorporation of V<SUB>2</SUB>O<SUB>5</SUB>. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst was then used for the removal of rhodamine B (RhB) under simulated solar light irradiation. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst revealed excellent photocatalytic activity and photodegradation kinetics as compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. Furthermore, both the photoactivity and long-term stability of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst were superior to those of the pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. The excellent photocatalytic performance of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst can be ascribed to its high specific surface area (283.71 m<SUP>2</SUP>g<SUP>−1</SUP>), mesoporous structure, highly dispersed V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles, and hindrance of electron–hole pair recombination of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> due to the V<SUB>2</SUB>O<SUB>5</SUB> incorporation, which is proven by the photoelectrochemical results, including photocurrent and electron impendence spectroscopy results. In addition, during the study of photocatalytic hydrogen evolution, the hydrogen yield of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite was 1.83 times that of pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>, which also exhibited excellent photocatalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterojunction of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs was developed via hydrothermal method. </LI> <LI> Visible photocatalytic RhB degradation studies were performed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> <LI> Improved degradation efficiency was observed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs when compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs. </LI> <LI> V<SUB>2</SUB>O<SUB>5</SUB> NPs were successfully utilized as cocatalyst for pollutant degradation. </LI> <LI> Charge recombination was diminished in the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs by the addition of V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Determination of Band Alignment in the Synergistic Catalyst of Electronic Structure-Modified Graphitic Carbon Nitride-Integrated Ceria Quantum-Dot Heterojunctions for Rapid Degradation of Organic Pollutants

Sreekanth, T. V. M.,Nagajyothi, P. C.,Dillip, G. R.,Lee, Yong Rok American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.45

<P>We engineered novel heterojunction ceria (CeO<SUB>2</SUB>) QDs decorated on the surfaces of graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) nanosheets by a facile in situ hydrothermal synthetic route. Using core-level/valence-band X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy, and work function measurements of the materials, we constructed the energy band alignment at the heterojunction. The band alignment has a Type-II alignment between organic (g-C<SUB>3</SUB>N<SUB>4</SUB>) and inorganic (CeO<SUB>2</SUB> QDs) semiconductors junction with valence/conduction band offsets (VBO/CBO) of −0.07/–0.31 eV. The calculated band alignment parameters of the heterojunction were compared with the experimental values of g-C<SUB>3</SUB>N<SUB>4</SUB>/CeO<SUB>2</SUB> QD composite and a new energy band diagram was proposed for the electronic structure-modified g-C<SUB>3</SUB>N<SUB>4</SUB>/CeO<SUB>2</SUB> QDs heterojunction. The newly constructed heterojunction is formed by carbon-vacancy-promoted g-C<SUB>3</SUB>N<SUB>4</SUB> coupled to lower defect-mediated (oxygen vacancies) CeO<SUB>2</SUB>, as determined by high-resolution XPS analysis. Moreover, the CeO<SUB>2</SUB> QD distribution on g-C<SUB>3</SUB>N<SUB>4</SUB> sheets using HR-TEM and the lattice parameter variations of g-C<SUB>3</SUB>N<SUB>4</SUB>/CeO<SUB>2</SUB> QDs as compared with those of pristine CeO<SUB>2</SUB> QDs from Rietveld refinement were investigated. To demonstrate the ability of the proposed heterojunction as a catalyst, we tested the catalytic activity of the composite junction for the degradation of Rhodamine B (RhB) in the presence of NaBH<SUB>4</SUB> as an example. The band alignment mechanism is useful for promoting the catalytic activity of the graphitic carbon nitride-based organic semiconductor and will attract researchers’ attention for developing new composite heterojunction catalysts for multifunctional applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2017/jpccck.2017.121.issue-45/acs.jpcc.7b08568/production/images/medium/jp-2017-08568k_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp7b08568'>ACS Electronic Supporting Info</A></P>

Binder-free WS₂/ZrO₂ hybrid as a photocatalyst for organic pollutant degradation under UV/simulated sunlight and tests for H₂ evolution

Vattikuti, S.V. Prabhakar,Devarayapalli, K.C.,Nagajyothi, P.C.,Shim, Jaesool Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.809 No.-

<P><B>Abstract</B></P> <P>Novel photocatalysts based on sunlight-driven active two-dimensional (2D) layered materials have drawn considerable attention because of their structural-to-photoactive properties. In this study, via binder-free electrostatic self-assembly, WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids were synthesized using a two-step hydrothermal process. The catalysts were thoroughly examined using different analysis techniques. The results indicated that in the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids, ZrO<SUB>2</SUB> nanoparticles (NPs) were randomly grafted on the planar surfaces of WS<SUB>2</SUB> nanosheets (the ZrO<SUB>2</SUB> NPs were tightly anchored to the nanosheets). The WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrids could considerably enhance the photocatalytic reactions under ultraviolet (UV) and simulated sunlight irradiation with an increase in the amount of ZrO<SUB>2</SUB> NPs anchored to WS<SUB>2</SUB> nanosheets, which influenced the photodegradation rate of crystal violet (CV) dye and the H<SUB>2</SUB> evolution activity. Notably, the rate of H<SUB>2</SUB> generation via the photolysis of water was 1023.9 μmol g<SUP>−1</SUP> h<SUP>−1</SUP> for the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 catalyst, indicating both the enhanced photocatalytic degradation activity and the H<SUB>2</SUB> advancement performance of the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrid. The photocatalytic H<SUB>2</SUB> advancement rate for the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 catalyst was 5.28 and 1.49 times higher than those for the bare WS<SUB>2</SUB> catalyst under UV and simulated solar illumination, respectively. Additionally, the WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 hybrid exhibited high recyclability owing to the highly hydrophobic nature of the 2D WS<SUB>2</SUB>, which was beneficial for the separation of the hybrid photocatalyst from the CV solution. Finally, the results of a scavenger-trapping experiment indicated that active holes (h<SUP>+</SUP>) were mainly responsible for the photocatalytic reaction, rather than ˙O<SUB>2</SUB> <SUP>−</SUP> and ˙OH<SUP>−</SUP>. Plausible photoreaction mechanisms of photocatalytic degradation and H<SUB>2</SUB> production in aqueous solutions of the WS<SUB>2</SUB>/ZrO<SUB>2</SUB> hybrid were elucidated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 2D/0D-WS<SUB>2</SUB>/ZrO<SUB>2</SUB> heterostructure was synthesized via reducing ethanol approach. </LI> <LI> Improved photocurrent response in WS<SUB>2</SUB>/ZrO<SUB>2</SUB> heterostructure is due to suitable band potential of cocatalyst (ZrO<SUB>2</SUB>). </LI> <LI> The introduction of ZrO<SUB>2</SUB> lead to suppress the electron-hole recombination. </LI> <LI> Strong interaction of WS<SUB>2</SUB>/ZrO<SUB>2</SUB> sheets with organic compounds. </LI> <LI> WS<SUB>2</SUB>/ZrO<SUB>2</SUB>-2 exhibited higher photodegradation and H<SUB>2</SUB> evolution rate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Green synthesis: In-vitro anticancer activity of copper oxide nanoparticles against human cervical carcinoma cells

Nagajyothi, P.C.,Muthuraman, P.,Sreekanth, T.V.M.,Kim, D.H.,Shim, J. Elsevier ; King Saud University 2017 Arabian journal of chemistry Vol.10 No.2

<P>Copper oxide nanoparticles (CuO NPs) were synthesized by a green route using an aqueous black bean extract and characterized by XRD, FT-IR, XPS, Raman spectroscopy, DLS, TEM, SAED, SEM, and EDX. The synthesized CuO NPs were spherical in shape, and the XRD results show the average size of the NPs was similar to 26.6 nm. The cytotoxic effect of the CuO NPs was determined by sulforhodamine-B assay. Mitochondria-derived reactive oxygen species (ROS) were increased and initiated lipid peroxidation of the liposomal membrane, which regulates several signaling pathways and influences the cytokinetic movements of cells. Mitochondrial fragmentation disruption assay confirmed the alteration in the mitochondrial structure after incubation with nanoparticles. In addition, clonogenic assay confirmed the inability of NPs incubated cancer cells to proliferate well. Our experimental results show that the CuO NPs can induce apoptosis and suppress the proliferation of HeLa cells. (C) 2016 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.</P>

Green Synthesis of Iron Oxide Nanoparticles and Their Catalytic and In Vitro Anticancer Activities

Nagajyothi, P. C.,Pandurangan, Muthuraman,Kim, Doo Hwan,Sreekanth, T. V. M.,Shim, Jaesool Springer-Verlag 2017 Journal of cluster science Vol.28 No.1

<P>The green synthesis of nanoparticles is a convenient, inexpensive, rapid and eco-friendly method compared to traditional synthesis methods. We synthesized iron oxide nanoparticles (alpha-Fe2O3 (hematite)) nanoparticles from iron (III) chloride using an aqueous extract of Psoralea corylifolia seeds as a reducing agent. Various characterization methods indicate that nanoparticles were crystalline with an average size of similar to 39 nm. The nanoparticles were assessed for their catalytic activity on methylene blue using a UV-Vis spectrophotometer and showed a rapid reduction within 63 min. The in vitro anticancer activity of the nanoparticles was also determined by Sulforhodamine (SRB) assay, and caspase-3 expression was determined using caspase-3 fluorescence and immunofluorescence assays. The results were suggested the strong cancer cell growth inhibition in a dose-dependent manner.</P>