Publications by authors named "Andrews Nirmala Grace"

23 Publications

  • Page 1 of 1

NH-MIL-125(Ti) doped CdS/Graphene composite as electro and photo catalyst in basic medium under light irradiation.

Environ Res 2021 09 20;200:111719. Epub 2021 Jul 20.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, Tamil Nadu, India. Electronic address:

The development of active electrocatalysts and photocatalysts for hydrogen evolution reaction (HER) and for environmental remediation is a huge challenge. Research is still underway on the development of low-cost catalytic materials with appreciable efficiency for HER. In the present study, a composite of metal organic framework (MOF) with CdS and graphene (NH-MIL-125(Ti)/CdS-graphene) composites were developed with different loadings of graphene material via solvothermal technique. Further the electrocatalytic activity of the synthesized catalysts were investigated for HER and photocatalytic degradation of dye. Results show that the synthesized catalyst with a less amount of graphene was more active. HER results showed a less Tafel slope of 70.8 and 61.9 mVdec with 15.6 mA/cm and 15.46 mA/cm current densities under light on and off conditions. Further the dye degradation activity of the synthesized catalysts was tested with Rhodamine B dye and results showed that the catalyst showed excellent activity for low weight loading of graphene with a degradation efficiency of 95 % and followed pseudo first order kinetic model. Overall results showed that the synthesized composites are promising for HER and photocatalytic applications.
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http://dx.doi.org/10.1016/j.envres.2021.111719DOI Listing
September 2021

Au integrated 2D ZnO heterostructures as robust visible light photocatalysts.

Chemosphere 2021 Oct 28;280:130594. Epub 2021 Apr 28.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India.

Integration of semiconducting nanostructures with noble metal nanoparticles are turning highly desirable for cost efficient energy and environmental related applications. From this viewpoint, we report on a facile aqueous synthesis of polymer capped gold (Au) nanoparticles on free standing 2D layered structures of zinc oxide (ZnO) to result with ZnO/Au nanocomposites. Concentration of Au nanoparticles were observed to promote the preferential growth of ZnO along the (002) wurtzite plane. The ZnO/Au structures and their morphological dissemination was noted to be of few. This flake like structure was also noted to be greatly influenced by the concentration of Au in the colloidal blend. Optical band edge transformations noted in the absorption spectra across the lower wavelength region and the shift in surface plasmon resonance (SPR) towards the red region of the visible spectrum signify the improved absorptivity of the heterostructures along the visible spectrum. These heterostructures exhibited remarkable visible light driven photocatalytic activity (99% efficiency) on par with pristine ZnO. The findings also attest this new class of composite structures to open up new openings in diversified solar energy conversion related functions.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130594DOI Listing
October 2021

Multi-walled carbon nanotube-based nanobiosensor for the detection of cadmium in water.

Environ Res 2021 06 17;197:111148. Epub 2021 Apr 17.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, India. Electronic address:

Industrial and agricultural processes have led to the prevalence of cadmium in the ecosystem. A successive build-up of cadmium in food and drinking water can result in inadvertent consumption of hazardous concentrations. Such environmental contamination of cadmium can pose a substantial threat to human and animal life. In humans, it is known to cause hypertension, cardiovascular diseases, DNA lesions, inhibition of DNA repair protein or disturb the functioning of lung, liver, prostate and kidney. The development of a reliable method for Cd (II) ions detection would reduce the exposure and complement existing conventional methods. In this study, a DNA based electrochemical method is employed for the detection of Cd (II) ions using ethyl green (EG) and multi-walled carbon nanotube (MWCNT). Glassy carbon electrode (GCE)/MWCNT forms the working electrode for differential pulse voltammetry (DPV) analysis for the detection of Cd (II) ions. The dsDNA is immobilized onto the working electrode. The indicator dye EG, preferably binds to ssDNA and its reduction peak current is noticeably less in the presence of dsDNA. The Cd (II) ions after interacting with dsDNA, unwinds the dsDNA to ssDNA, upon which the EG molecules bind to ssDNAs, giving a higher reduction peak current. The difference in the reduction peak currents in the presence and absence of Cd (II) ions is proportional to its concentration. The linear detection range achieved in this method is 2 nM-10.0 nM with a sensitivity of around 5 nA nM and the limit of detection is 2 nM, which is less than the permissible limit of WHO for human exposure. This study considerably broadens the possible application of multi-walled carbon nanotube modified electrodes as biosensors and holds prospects for the detection of other heavy metals in environmental samples.
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http://dx.doi.org/10.1016/j.envres.2021.111148DOI Listing
June 2021

Construction of magnetically recoverable ZnS-WO-CoFeO nanohybrid enriched photocatalyst for the degradation of MB dye under visible light irradiation.

Chemosphere 2021 Jun 19;273:129687. Epub 2021 Jan 19.

Department of Physics, Vellore Institute of Technology (Amaravati Campus), Amaravati, 522501, Guntur, Andhra Pradesh, India.

Easily recyclable photocatalysts have received considerable attention for their practical application, in order to address the wastewater treatments. Here, we report efficient and magnetically recyclable ZnS-WO-CoFeO nanohybrid prepared through wet impregnation method. The photophysical and optical properties of as-prepared photocatalysts was investigated by different spectroscopic techniques. The photocatalytic activity of as synthesized samples were assessed by the photodegradation of methylene blue (MB) dye under visible light irradiation. Amongst, ZnS-WO-CoFeO nanohybrid exhibit higher photodegradation activity than the other bare and hybrid samples. The enhanced light absorption and lower emission intensity provide the improved photocatalytic activity of ZnS-WO-CoFeO nanohybrid. The ZnS-WO-CoFeO nanohybrid exhibit excellent photostability after four consecutive cycles. The ferromagnetic behavior of the hybrid sample using easily recover from the dye solution using an external bar magnet.
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http://dx.doi.org/10.1016/j.chemosphere.2021.129687DOI Listing
June 2021

Double transition metal MXene (TiTaC) 2D materials as anodes for Li-ion batteries.

Sci Rep 2021 Jan 12;11(1):688. Epub 2021 Jan 12.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, Tamil Nadu, 632 014, India.

A bi-metallic titanium-tantalum carbide MXene, TiTaC is successfully prepared via etching of Al atoms from parent TiTaAlC MAX phase for the first time. X-ray diffractometer and Raman spectroscopic analysis proved the crystalline phase evolution from the MAX phase to the lamellar MXene arrangements. Also, the X-ray photoelectron spectroscopy (XPS) study confirmed that the synthesized MXene is free from Al after hydro fluoric acid (HF) etching process as well as partial oxidation of Ti and Ta. Moreover, the FE-SEM and TEM characterizations demonstrate the exfoliation process tailored by the TiTaC MXene after the Al atoms from its corresponding MAX TiTaAlC phase, promoting its structural delamination with an expanded interlayer d-spacing, which can allow an effective reversible Li-ion storage. The lamellar TiTaC MXene demonstrated a reversible specific discharge capacity of 459 mAhg at an applied C-rate of 0.5 °C with a capacity retention of 97% over 200 cycles. An excellent electrochemical redox performance is attributed to the formation of a stable, promising bi-metallic MXene material, which stores Li-ions on the surface of its layers. Furthermore, the TiTaC MXene anode demonstrate a high rate capability as a result of its good electron and Li-ion transport, suggesting that it is a promising candidate as Li-ion anode material.
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http://dx.doi.org/10.1038/s41598-020-79991-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7804453PMC
January 2021

Synthesis and characterisation of starch/agar nanocomposite films for food packaging application.

IET Nanobiotechnol 2020 Dec;14(9):809-814

Centre for Nanotechnology Research, VIT University, Vellore, Tamilnadu 632014, India.

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8-15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram-negative Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.
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http://dx.doi.org/10.1049/iet-nbt.2020.0100DOI Listing
December 2020

Honokiol-camptothecin loaded graphene oxide nanoparticle towards combinatorial anti-cancer drug delivery.

IET Nanobiotechnol 2020 Dec;14(9):796-802

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, TN 632 014, India.

Honokiol (HK) is a natural product isolated from the bark, cones, seeds and leaves of plants belonging to the genus Magnolia. It possesses anti-cancer activity which can efficiently impede the growth and bring about apoptosis of a diversity of cancer cells. The major concerns of using HK are its poor solubility and lack of targeted drug delivery. In this study, a combinatorial drug is prepared by combining HK and camptothecin (CPT). Both CPT and HK belong to the genus and induce apoptosis by cell cycle arrest at the S-phase and G1 phase, respectively. The combinatorial drug thus synthesised was loaded onto a chitosan functionalised graphene oxide nanoparticles, predecorated with folic acid for site-specific drug delivery. The CPT drug-loaded nanocarrier was characterised by X-ray diffractometer, scanning electron microscope, transmission electron microscope, UV-vis spectroscopy and fluorescence spectroscopy, atomic force microscopy. The antioxidant properties, haemolytic activity and anti-inflammatory activities were analysed. The cellular toxicity was analysed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT assay) and Sulforhodamine B (SRB) assay against breast cancer (MCF-7) cell lines.
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http://dx.doi.org/10.1049/iet-nbt.2020.0103DOI Listing
December 2020

Leaf Extract Mediated Synthesis of Zinc Oxide Nanoparticles: Assessment of Antimicrobial and Anticancer Activity.

Molecules 2020 Oct 23;25(21). Epub 2020 Oct 23.

Henan Province Engineering Research Center for Biomass Value-added Products, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China.

In this work, we present an ecofriendly, non-hazardous, green synthesis of zinc oxide nanoparticles (ZnO NPs) by leaf extract of (). Total phenolic content, total flavonoid and total protein contents of were determined. Further, synthesized ZnO NPs was characterized by UV-visible spectroscopy (UV-vis), X-ray diffractometer (XRD), Fourier transform infra-red (FTIR) Spectra, transmission electron microscope (TEM), and Dynamic light scattering (DLS) analysis. UV-vis shows peak at 375 nm which is unique to ZnO NPs. XRD analysis demonstrates the hexagonal phase structures of ZnO NPs. FTIR spectra demonstrates the molecules and bondings associated with the synthesized ZnO NPs and assures the role of phytochemical compounds of in reduction and capping of ZnO NPs. TEM image exhibits that the prepared ZnO NPs is hexagonal shaped and in size ranged between 16 to 38 nm which is confirmed by DLS. Thermo-gravimetric analysis (TGA) was performed to determine the thermal stability of biosynthesized nanoparticles during calcination. The prepared ZnO NPs showed significant antibacterial potentiality against Gram-positive (S. aureus) and Gram-negative (, , and ) pathogenic bacteria and SEM image shows the generalized mechanism of action in bacterial cell after NPs internalization. In addition, NPs are also found to be effective against the studied cancer cell lines for which cytotoxicity was assessed using MTT assay and results demonstrate highest growth of inhibition at the concentration of 100 µg/mL with IC value at 7.07 µg/mL for HeLa and 6.30 µg/mL for DU145 cell lines, in contrast to positive control ( leaf extract) with IC of 22.30 µg/mL on HeLa cells and 15.72 µg/mL on DU145 cells. Also, DAPI staining was performed in order to determine the effect on nuclear material due to ZnO NPs treatment in the studied cell lines taking leaf extract as positive control and untreated negative control for comparison. Cell migration assay was evaluated to determine the direct influence of NPs on metastasis that is potential suppression capacity of NPs to tumor cell migration. Outcome of the synthesized ZnO NPs using shows antimicrobial activity against studied microbes, also cytotoxicity, apoptotic mediated DNA damage and antiproliferative potentiality in the studied carcinoma cells and hence, can be further used in biomedical, pharmaceutical and food processing industries as an effective antimicrobial and anti-cancerous agent.
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http://dx.doi.org/10.3390/molecules25214896DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660202PMC
October 2020

In-situ development of metal organic frameworks assisted ZnMgAl layered triple hydroxide 2D/2D hybrid as an efficient photocatalyst for organic dye degradation.

Chemosphere 2021 May 14;270:128616. Epub 2020 Oct 14.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, Tamilnadu, India.

Metal organic framework (MOF) supported layered triple hydroxide (LTH) 2D/2D hybrid material was prepared by a simple hydrothermal method. The photophysical properties of the prepared samples were investigated through a set of analytical methods such as X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscope, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and mapping. The photocatalytic degradation activity of as prepared 2D/2D MOF-5/LTH hybrid sample was investigated against methylene blue (MB) dye under the UV-visible light irradiation. The degradation efficiency of the MOF-5/LTH hybrid sample was twice a time greater than that of pristine MOF-5, particularly degradation efficiency of the MOF-5, LTH and MOF-5/LTH hybrid samples are 43.3, 57.7 and 98.1% respectively. The Pseudo first order rate and the reusing investigation was further used to study the catalytic activity and stability of the as-synthesized 2D/2D photocatalyst. The observed improvement in the photocatalytic activity of the hybrid samples were owed to enhance visible light absorption, efficient separation and transportation of photoinduced electrons and holes.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128616DOI Listing
May 2021

Investigation on Electroreduction of CO to Formic Acid Using Cu(BTC) Metal-Organic Framework (Cu-MOF) and Graphene Oxide.

ACS Omega 2020 Sep 14;5(37):23919-23930. Epub 2020 Sep 14.

Climate Change Technology Research Division, Korea Institute of Energy Research, 102 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea.

A recent class of porous materials, viz., metal-organic frameworks (MOFs), finds applications in several areas. In this work, Cu-based MOFs (Cu-benzene-1,3,5-tricarboxylic acid) along with graphene oxide, viz., Cu-MOF/GO, are synthesized and used further for reducing CO electrochemically. The reduction was accomplished in various supporting electrolytes, viz., KHCO/HO, tetrabutylammonium bromide (TBAB)/dimethylformamide (DMF), KBr/CHOH, CHCOOK/CHOH, TBAB/CHOH, and tetrabutylammonium perchlorate (TBAP)/CHOH to know their effect on product formation. The electrode fabricated with the synthesized material was used for testing the electroreduction of CO at various polarization potentials. The electrochemical reduction of CO is carried out via the polarization technique within the experimented potential regime vs saturated calomel electrode (SCE). Ion chromatography was employed for the analysis of the produced products in the electrolyte, and the results showed that HCOOH was the main product formed through reduction. The highest concentrations of HCOOH formed for different electrolytes are 0.1404 mM (-0.1 V), 66.57 mM (-0.6 V), 0.2690 mM (-0.5 V), 0.2390 mM (-0.5 V), 0.7784 mM (-0.4 V), and 0.3050 mM (-0.45 V) in various supporting electrolyte systems, viz., KHCO/HO, TBAB/DMF, KBr/CHOH, CHCOOK/CHOH, TBAB/CHOH, and TBAP/CHOH, respectively. The developed catalyst accomplished a significant efficiency in the conversion and reduction of CO. A high faradic efficiency of 58% was obtained with 0.1 M TBAB/DMF electrolyte, whereas for Cu-MOF alone, the efficiency was 38%. Thus, the work is carried out using a cost-effective catalyst for the conversion of CO to formic acid than using the commercial electrodes. The synergistic effect of GO sheets at 3 wt % concentration and CuOH interaction leads to the formation of formic acid in various electrolytes.
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http://dx.doi.org/10.1021/acsomega.0c03170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7513332PMC
September 2020

Highly Porous MIL-100(Fe) for the Hydrogen Evolution Reaction (HER) in Acidic and Basic Media.

ACS Omega 2020 Aug 21;5(30):18941-18949. Epub 2020 Jul 21.

Centre for Nanotechnology Research, VIT University, Vellore 632014, India.

The present study reports the synthesis of a porous Fe-based MOF named MIL-100(Fe) by a modified hydrothermal method without the HF process. The synthesis gave a high surface area with the specific surface area calculated to be 2551 m g and a pore volume of 1.407 cm g with an average pore size of 1.103 nm. The synthesized electrocatalyst having a high surface area is demonstrated as an excellent electrocatalyst for the hydrogen evolution reaction investigated in both acidic and alkaline media. As desired, the electrochemical results showed low Tafel slopes (53.59 and 56.65 mV dec), high exchange current densities (76.44 and 72.75 mA cm), low overpotentials (148.29 and 150.57 mV), and long-term stability in both media, respectively. The high activity is ascribed to the large surface area of the synthesized Fe-based metal-organic framework with porous nature.
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http://dx.doi.org/10.1021/acsomega.0c02171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7408201PMC
August 2020

New Method for the Synthesis of 2D Vanadium Nitride (MXene) and Its Application as a Supercapacitor Electrode.

ACS Omega 2020 Jul 13;5(29):17983-17992. Epub 2020 Jul 13.

Centre for Nanotechnology Research, Vellore Institute of Technology (VIT), Vellore 632014, Tamil Nadu, India.

MXenes are the class of two-dimensional transition metal carbides and nitrides that exhibit unique properties and are used in a multitude of applications such as biosensors, water purification, electromagnetic interference shielding, electrocatalysis, supercapacitors, and so forth. Carbide-based MXenes are being widely explored, whereas investigations on nitride-based ones are seldom. Among the nitride-based MXenes obtained from their MAX phases, only TiN and TiN are reported so far. Herein, we report a novel synthesis of VNT (T is the surface termination) obtained by the selective removal of "Al" from VAlN by immersing powders of VAlN in the LiF-HCl mixture (salt-acid etching) followed by sonication to obtain VNT (T = -F, -O) MXene which is then delaminated using the dimethyl sulfoxide solvent. The VNT MXene is characterized by X-ray diffraction studies, field emission scanning electron microscope imaging, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope imaging. Supercapacitor electrodes are prepared using VNT MXenes and their electrochemical performances are examined by cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. The VNT MXene electrode exhibits a specific capacitance of 112.8 F/g at a current density of 1.85 mA/cm with an energy and power density of 15.66 W h/kg and 3748.4 W/kg, respectively, in 3.5 M KOH aqueous electrolyte. The electrode exhibits an excellent capacitance retention of 96% even after 10,000 charge/discharge cycles. An asymmetric supercapacitor fabricated with VNT as a negative electrode and MnO nanowalls as a positive electrode helps obtain a cell voltage of 1.8 V in aqueous KOH electrolyte.
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http://dx.doi.org/10.1021/acsomega.0c01215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391371PMC
July 2020

Reversible, stable Li-ion storage in 2 D single crystal orthorhombic α-MoO anodes.

J Colloid Interface Sci 2020 Apr 28;565:197-204. Epub 2019 Dec 28.

Centre for Nanotechnology Research, VIT University, Vellore 632 014, Tamil Nadu, India. Electronic address:

Engineering two dimensional (2D) materials at atomic level is a key factor to achieve enhanced electrochemical Li-ion storage properties. This work demonstrates that single crystals of orthorhombic α-MoO phase can preferentially grow with a 2D nanoarchitecture via a ball-milling process, followed by heat treatment at elevated temperature. Detailed FE-SEM and TEM micrographs proved the 2D architecture of α-MoO nanoparticles and Raman spectroscopy evidenced the active vibration modes that correspond to the orthorhombic α-MoO phase. Single crystalline MoO belts depicted high intensity of (0 2 0) and (0 4 0) indexed planes indicating a preferential arrangement. As Li-ion host anode, the 2D α-MoO nanostructure delivered high reversible specific discharge capacity of ~540 mA h g at 0.2 C-rate with 99.9% coulombic efficiency as well as 63% capacity retention after 200 charge-discharge cycles. An excellent reversible Li-ion storage performance (high capacity, longer cycle life and good rate capability) was attributed to the 2D α-MoO arrangement consists of MoO octahedron by corner sharing chains.
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http://dx.doi.org/10.1016/j.jcis.2019.12.113DOI Listing
April 2020

Natural biomass derived hard carbon and activated carbons as electrochemical supercapacitor electrodes.

Sci Rep 2019 11 8;9(1):16315. Epub 2019 Nov 8.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, Tamil Nadu, India.

With every moving day, the aspect that is going to be the most important for modern science and technology is the means to supply sufficient energy for all the scientific applications. As the resource of fossil fuel is draining out fast, an alternative is always required to satisfy the needs of the future world. Limited resources also force to innovate something that can utilise the resource more efficiently. This work is based on a simple synthesis route of biomass derived hard carbon and to exploring the possibility of using it as electrochemical supercapacitors. A cheap, eco-friendly and easily synthesized carbon material is utilized as electrode for electrochemical energy-storage. Four different hard carbons were synthesized from KOH activated banana stem (KHC), phosphoric acid treated banana stem derived carbons (PHC), corn-cob derived hard carbon (CHC) and potato starch derived hard carbons (SHC) and tested as supercapacitor electrodes. KOH-activated hard carbon has provided 479.23 F/g specific capacitance as calculated from its cycle voltammograms. A detailed analysis is done to correlate the results obtained with the material property. Overall, this work provides an in depth analysis of the science behind the components of an electrochemical energy-storage system as well as why the different characterization techniques are required to assess the quality and reliability of the material for electrochemical supercapacitor applications.
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http://dx.doi.org/10.1038/s41598-019-52006-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6841744PMC
November 2019

Pt-free, low-cost and efficient counter electrode with carbon wrapped VO(M) nanofiber for dye-sensitized solar cells.

Sci Rep 2019 Mar 26;9(1):5177. Epub 2019 Mar 26.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India.

The present study reports the use of one-dimensional carbon wrapped VO(M) nanofiber (VO(M)/C) as a cost-effective counter electrode for dye-sensitized solar cells (DSSCs); where M denotes monoclinic crystal system. Uniform short length nanofiber was synthesised by a sol-gel based simple and versatile electrospinning and post carbonization technique. The investigation of nanostructure and morphological analysis were performed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscope (TEM) with EDAX. The electrochemical response was comprehensively characterized by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization. The electrochemical analysis of the VO(M)/C nanofiber counter electrode exhibits significant electrocatalytic activity towards the reduction of triiodide and low charge transfer resistance at the electrode-electrolyte interface. The DSSCs fabricated with carbon-wrapped VO(M) nanofiber CE showed high power conversion efficiency of 6.53% under standard test condition of simulated 1SUN illumination at AM1.5 G, which was comparable to the 7.39% observed for conventional thermally decomposed Pt CE based DSSC under same test conditions. This result encourages the next step of modification and use of low-cost VO(M) as an alternate counter electrode for DSSCs to achieve a substantial efficiency for future energy demand.
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http://dx.doi.org/10.1038/s41598-019-41693-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6435790PMC
March 2019

Natural polymer functionalized graphene oxide for co-delivery of anticancer drugs: In-vitro and in-vivo.

Int J Biol Macromol 2018 Jul 27;113:515-525. Epub 2018 Feb 27.

Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore 632 014, Tamil Nadu, India. Electronic address:

The present study focuses on the development of a chitosan functionalized nanobiocomposite for the co-delivery of two anti-cancer drugs camptothecin (CPT) and 3,3'‑Diindolylmethane (DIM). The difference in the mechanism of action of the two drugs makes them a promising candidate to produce a synergistic effect against breast cancer. Herein a nanobiocomposite was developed by functionalizing a natural polymer chitosan to graphene oxide nanoparticles and decorated with folic acid. The nanobiocomposite thus synthesized was loaded with camptothecin and 3,3'‑Diindolylmethane and characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy (UV) and atomic force microscopy (AFM).Biocompatibility was assayed by hemolysis and anti-inflammatory assay. The cellular toxicity was measured by 3‑(4,5‑Dimethylthiazol‑2‑yl)‑2,5‑Diphenyltetrazolium Bromide (MTT), Sulforhodamine B (SRB) and cell death assay against MCF-7 cell lines. Further in vivo studies were carried out to analyze the biodistribution of the drug, blood biochemical analysis and bioavailability of the drug. The data revealed a significant increase in anticancer activity after co-loading of CPT and DIM to the nanocarrier. Also in-vivo studies revealed that DIM successfully masked the toxic effects produced by CPT.
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http://dx.doi.org/10.1016/j.ijbiomac.2018.02.153DOI Listing
July 2018

Mono- and dinuclear Cu complexes of the benzyldipicolylamine (BDPA) ligand: crystal structure, synthesis and characterization.

Acta Crystallogr C Struct Chem 2017 Nov 26;73(Pt 11):1024-1029. Epub 2017 Oct 26.

Green Energy Process Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.

The crystal structures of mono- and dinuclear Cu trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate) and BDPA, a water-bound Cu mononuclear complex, aqua(benzyldipicolylamine-κN,N',N'')bis(trifluoromethanesulfonato-κO)copper(II) tetrahydrofuran monosolvate, [Cu(CFSO)(CHN)(HO)]·CHO, (I), and a triflate-bridged Cu dinuclear complex, bis(μ-trifluoromethanesulfonato-κO:O')bis[(benzyldipicolylamine-κN,N',N'')(trifluoromethanesulfonato-κO)copper(II)], [Cu(CFSO)(CHN)], were synthesized. The presence of residual moisture in the reaction medium afforded water-bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single-crystal X-ray structure analysis reveals that the Cu centres adopt slightly distorted octahedral geometries in both complexes. The metal-bound water molecule in (I) is involved in intermolecular O-H...O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C-H...F(triflate) and C-H...O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT-IR and UV-Vis spectroscopy, cyclic voltammetry and elemental analysis.
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http://dx.doi.org/10.1107/S2053229617012785DOI Listing
November 2017

Removal of cationic and anionic heavy metals from water by 1D and 2D-carbon structures decorated with magnetic nanoparticles.

Sci Rep 2017 10 26;7(1):14107. Epub 2017 Oct 26.

Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.

In this study, cobalt ferrites (C) decorated onto 2D material (porous graphene (PG)) and 1D material (carbon nanofibers (CNF)), denoted as PG-C and CNF-C nanocomposites, respectively, were synthesized using solvothermal process. The prepared nanocomposites were studied as magnetic adsorbents for the removal of lead (cationic) and chromium(VI) (anionic) metal ions. The structural and chemical analysis of synthesized nanocomposites was conducted using different characterization techniques including Brunauer-Emmett-Teller (BET) analysis, field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), high resolution-transmission electron microscopy (HR-TEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Batch mode adsorption studies were conducted with the prepared nanocomposites to examine their maximum adsorption potential for lead and chromate ions. Performance parameters (time, pH, adsorbent dosage and initial ion concentrations) effecting the adsorption capacity of the nanocomposites were optimized. Different kinetic and isotherm models were examined to elucidate the adsorption process. Synthesized nanocomposites exhibited significant potential for the studied metal ions that can be further examined at pilot scale for the removal of metal ions from contaminated water.
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http://dx.doi.org/10.1038/s41598-017-14461-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5658355PMC
October 2017

Sequel of MgO nanoparticles in PLACL nanofibers for anti-cancer therapy in synergy with curcumin/β-cyclodextrin.

Mater Sci Eng C Mater Biol Appl 2017 Feb 25;71:620-628. Epub 2016 Oct 25.

Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore, Singapore.

Pharmaceutical industries spend more money in developing new and efficient methods for delivering successful drugs for anticancer therapy. Electrospun nanofibers and nanoparticles loaded with drugs have versatile biomedical applications ranging from wound healing to anticancer therapy. We aimed to attempt for fabricating elastomeric poly (l-lactic acid-co-ε-caprolactone) (PLACL) with Aloe Vera (AV), magnesium oxide (MgO) nanoparticles, curcumin (CUR) and β-cyclodextrin (β-CD) composite nanofibers to control the growth of MCF-7 cells for breast cancer therapy. The study focused on the interaction of MgO nanoparticle with CUR and β-CD inhibiting the proliferation of Michigan Cancer Foundation-7 (MCF-7) breast cancer cells. FESEM micrographs of fabricated electrospun PLACL, PLACL/AV, PLACL/AV/MgO, PLACL/AV/MgO/CUR and PLACL/AV/MgO/β-CD nanofibrous scaffolds achieved bead free, random and uniform nanofibers with fiber diameter in the range of 786±286, 507±171, 334±95, 360±94 and 326±80nm respectively. Proliferation of MCF-7 cells was decreased by 65.92% in PLACL/AV/MgO/CUR with respect to PLACL/AV/MgO nanofibrous scaffolds on day 9. The obtained results proved that 1% CUR interacting with MgO nanoparticles showed higher inhibition of MCF-7 cells among all other nanofibrous scaffolds thus serving as a promising biocomposite material system for the breast cancer therapy.
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http://dx.doi.org/10.1016/j.msec.2016.10.050DOI Listing
February 2017

CO2 absorption and sequestration as various polymorphs of CaCO3 using sterically hindered amine.

Langmuir 2013 Dec 6;29(50):15655-63. Epub 2013 Dec 6.

Korea Institute of Energy Research, Daejeon 305-343, Korea.

One aspect of the attempt to restrain global warming is the reduction of the levels of atmospheric CO2 produced by fossil fuel power systems. This study attempted to develop a method that reduces CO2 emissions by investigating the absorption of CO2 into sterically hindered amine 2-amino-2-methyl-1-propanol (AMP), the acceleration of the absorption rate by using the enzyme carbonic anhydrase (CA), and the conversion of the absorption product to stable carbonates. CO2 absorbed by AMP is converted via a zwitterion mechanism to bicarbonate species; the presence of these anions was confirmed with (1)H and (13)C NMR spectral analysis. The catalytic efficiency (kcat/Km), CO2 absorption capacities, and enthalpy changes (ΔHabs) of aqueous AMP in the presence or absence of CA were found to be 2.61 × 10(6) or 1.35 × 10(2) M(-1) s(-1), 0.97 or 0.96 mol/mol, and -69 or -67 kJ/mol, respectively. The carbonation of AMP-absorbed CO2 was performed by using various Ca(2+) sources, viz., CaCl2 (CAC), Ca(OOCCH3)2 (CAA), and Ca(OOCCH2CH3)2 (CAP), to obtain various polymorphs of CaCO3. The yields of CaCO3 from the Ca(2+) sources were found in the order CAP > CAA > CAC as a result of the effects of the corresponding anions. CAC produces pure rhombohedral calcite, and CAA and CAP produce the unusual phase transformation of calcite to spherical vaterite crystals. Thus, AMP in combination with CAA and CAP can be used as a CO2 absorbent and buffering agent for the sequestration of CO2 in porous CaCO3.
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http://dx.doi.org/10.1021/la403671yDOI Listing
December 2013

Carbonic anhydrase promotes the absorption rate of CO2 in post-combustion processes.

J Phys Chem B 2013 May 26;117(18):5683-90. Epub 2013 Apr 26.

Korea Institute of Energy Research, Daejeon, Korea.

The rate of carbon dioxide (CO2) absorption by monoethanol amine (MEA), diethanol amine (DEA), N-methyl-2,2'-iminodiethanol (MDEA), and 2-amino-2-methyl 1-propanol (AMP) solutions was found to be enhanced by the addition of bovine carbonic anhydrase (CA), has been investigated using a vapor-liquid equilibrium (VLE) device. The enthalpy (-ΔHabs) of CO2 absorption and the absorption capacities of aqueous amines were measured in the presence and/or absence of CA enzyme via differential reaction calorimeter (DRC). The reaction temperature (ΔT) under adiabatic conditions was determined based on the DRC analysis. Bicarbonate and carbamate species formation mechanisms were elucidated by (1)H and (13)C NMR spectral analysis. The overall CO2 absorption rate (flux) and rate constant (kapp) followed the order MEA > DEA > AMP > MDEA in the absence or presence of CA. Hydration of CO2 by MDEA in the presence of CA directly produced bicarbonate, whereas AMP produced unstable carbamate intermediate, then underwent hydrolytic reaction and converted to bicarbonate. The MDEA > AMP > DEA > MEA reverse ordering of the enhanced CO2 flux and kapp in the presence of CA was due to bicarbonate formation by the tertiary and sterically hindered amines. Thus, CA increased the rate of CO2 absorption by MDEA by a factor of 3 relative to the rate of absorption by MDEA alone. The thermal effects suggested that CA yielded a higher activity at 40 °C.
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http://dx.doi.org/10.1021/jp401622cDOI Listing
May 2013
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