Research Publications (Applied Sciences)
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Item Biosynthesis of ZnO nanoparticles using Jacaranda mimosifolia flowers extract: Synergistic antibacterial activity and molecular simulated facet specific adsorption studies(Elsevier, 2016) Sharma, Deepali; Sabela, Myalowenkosi Innocent; Kanchi, Suvardhan; Mdluli, Phumlani Selby; Singh, Gulshan; Stenström, Thor-Axel; Bisetty, KrishnaThe naturally occurring biomolecules present in the plant extracts have been identified to play an active role in the single step formation of nanoparticles with varied morphologies and sizes which is greener and environmen-tally benign. In the present work, spherical zinc oxide nanoparticles (ZnO NPs) of 2–4 nm size were synthesized using aqueous extract of fallen Jacaranda mimosifolia flowers (JMFs), treated as waste. The microwave assisted synthesis was completed successfully within 5 min. Thereafter, phase identification, morphology and optical band gap of the synthesized ZnO NPs were done using X-ray diffraction (XRD), high resolution transmission elec-tron microscopy (HRTEM) and UV–Visible spectroscopy techniques. The composition of JMFs extract was ana-lyzed by gas chromatography–mass spectrometry (GC–MS) and the ZnO NPs confirmation was further explored with fourier transform infrared spectroscopy (FTIR). The GC–MS results confirmed the presence of oleic acid which has high propensity of acting as a reducing and capping agent. The UV–Visible data suggested an optical band gap of 4.03 eV for ZnO NPs indicating their small size due to quantum confinement. Further, facet specific adsorption of oleic acid on the surface of ZnO NPs was studied computationally to find out the im-pact of biomolecules in defining the shape and size of NPs. The viability of gram negative Escherichia coli and gram positive Enterococcus faecium bacteria was found to be 48% and 43%, respectively at high concentration of NPs.Item Analytical evaluation of steviol glycosides by capillary electrophoresis supported with molecular docking studies(Iranian Chemical Society, 2014-05-05) Ayyappa, Bathinapatla; Kanchi, Suvardhan; Singh, Parvesh; Dovey, Martin; Sabela, Myalowenkosi Innocent; Bisetty, KrishnaThis paper reports on a newly developed elec-trokinetic chromatographic method for the simultaneous separation and determination of steviol glycosides in real stevia samples by capillary electrophoresis and supported by molecular docking studies. Our results obtained using 30-mM heptakis-(2,3,6-tri-o-methyl betacyclodextrin) as a separating agent, suggest that at optimum experimental conditions the detection limits of 2.017 9 10-5 and 7.386 9 10-5 M and relative standard deviations (n = 5) of 1.10 and 1.17 were obtained for rebaudioside-A and stevioside, respectively. In addition, the molecular docking studies explained to a certain extent why the separation was successful. The calculated binding free energy results for the rebaudioside-A and stevioside complexes formed with the separating agent showed that although both ligands penetrated deeply into the hydrophobic cavity of the sep-arating agent, the presence of additional hydrogen bonding in the case of stevioside is probably responsible for its stronger binding affinity than that of rebaudioside-A.Item A Box-Behnken Design and Response Surface Approach for the Simultaneous Determination of Chromium (III) and (VI) Using Catalytic Differential Pulse Polarography(ESG, 2004-09-29) Sabela, Myalowenkosi Innocent; Kanchi, Suvardhan; Ayyappa, Bathinapatla; Bisetty, KrishnaThe present paper describes an optimized Box-Behnken design using a catalytic-differential pulse polarograhic technique for the simultaneous determination of chromium (III) and (VI) in wastewater samples using ammonium piperidine dithiocarbamate as a complexing agent. The optimization strategy was carried out using a two level full factorial design. The results of the experimental design were based on an analysis of variance and demonstrated that only the pH, concentrations of the buffer and the complexing agent were statistically significant throughout the experiment. The optimal values for the three variables were 8.0, 0.2 mM and 5.0 mM for pH, concentrations of the buffer and the complexing agent respectively. Under optimum experimental conditions the detection limit of the proposed method was found to be 0.0841 µg L-1 while the linear range was 1.0-10.0 and 0.5-25.0 µg L- for chromium (III) and (VI) respectively. The present method was also applied for the simultaneous determination of chromium in the presence of some foreign ions with satisfactory analytical responses.Item Polarographic catalytic hydrogen wave technique for the determination of copper(II) in leafy vegetables and biological samples†(ESG, 2013-03-01) Kanchi, Suvardhan; Singh, Parvesh; Sabela, Myalowenkosi Innocent; Naidu, N. Venkatasubba; Bisetty, KrishnaAn economical, novel, eco-friendly and robust method for the quantification of copper(II) in various leafy vegetables, milk and blood samples has been developed using direct current catalytic hydrogen wave (DC-CHW) technique involving the formation of ammonium salts of piperidine/morpholine dithiocarbamates metal complex. Ammonium piperidine/morpholine dithiocarbamates complexed with copper(II) in the presence of NH4Cl-NH4OH medium at pH 6.5±1 produces CHW’s at -0.35±1 V vs SCE. Consequently, various optimal parameters such as preparation medium, effect of pH, ligand concentration, metal ion concentration and indifferent ions effect on peak height were optimized to enhance the sensitivity and selectivity. The novel aspect in the work address the interaction of ammonium piperidine/morpholine dithiocarbamates with copper(II) were confirmed with cyclic voltammetry (CV) and supported by computational calculations using Density Functional Theory (DFT) methods. Furthermore, the student “t”-test and variance ratio “f”-tests indicated no significant difference between the present method and the differential pulse polarographic (DPP) method.Item Evaluation of enantioresolution of (±)-catechin using electrokinetic chromatography and molecular docking(SRP, 2012) Sabela, Myalowenkosi Innocent; Singh, Parvesh; Gumede, Njabulo Joyfull; Bisetty, Krishna; Sagrado, SagradoThis study involves the enantioresolution of (±) catechin with the highly sulphated beta cyclodextrin (HS-β-CD) as a chiral selector using capillary electrophoresis (CE). The purpose of this study was to be tter understand enantioresolution amongst host-guest interactions. Furthermore, molecular docking was carried out to elucidate the mechanism of the enantioselective separations of (±) catechin enantiomers obtained in Electrokinetic chroma tography (EKC). A large difference in the interaction energies observed between the two enantiomers represents significant enantiodifferentiation. Our results also suggest that the host-guest interactions between the phenyl ring of the ligand and the open cavity of the HS-β-CD are due mainly to hydrophobic interactions. Interestingly, the stronger interactions observed with (+)-catechin is consistent with the elution order observed in the CE experiments.Item Preparation, spectrochemical, and computational analysis of L-Carnosine (2-[(3-Aminopropanoyl)amino]-3-(1H-imidazol-5- yl)propanoic Acid) and Its Ruthenium (II) coordination complexes in aqueous solution(MDPI, 2011-12-09) Branham, Michael Lee; Bisetty, Krishna; Sabela, Myalowenkosi Innocent; Govender, Thirumala; Singh, ParveshThis study reports the synthesis and characterization of novel ruthenium (II) complexes with the polydentate dipeptide, L-carnosine (2-[(3-aminopropanoyl)amino]-3-(1H-imidazol-5-yl)propanoic acid). Mixed-ligand complexes with the general composition [MLp(Cl)q(H2O)r]·xH2O (M = Ru(II); L = L-carnosine; p = 3 − q; r = 0–1; and x = 1–3) were prepared by refluxing aqueous solutions of the ligand with equimolar amounts of ruthenium chloride (black-alpha form) at 60 °C for 36 h. Physical properties of the complexes were characterized by elemental analysis, DSC/TGA, and cyclic voltammetry. The molecular structures of the complexes were elucidated using UV-Vis, ATR-IR, and heteronuclear NMR spectroscopy, then confirmed by density function theory (DFT) calculations at the B3LYP/LANL2DZ level. Two-dimensional NMR experiments (1H COSY, 13C gHMBC, and 15N gHMBC) were also conducted for the assignment of chemical shifts and calculation of relative coordination-induced shifts (RCIS) by the complex formed. According to our results, the most probable coordination geometries of ruthenium in these compounds involve nitrogen (N1) from the imidazole ring and an oxygen atom from the carboxylic acid group of the ligand as donor atoms. Additional thermogravimetric and electrochemical data suggest that while the tetrahedral-monomer or octahedral-dimer are both possible structures of the formed complexes, the metal in either structure occurs in the (2+) oxidation state. Resulting RCIS values indicate that the amide-carbonyl, and the amino-terminus of the dipeptide are not involved in chelation and these observations correlate well with theoretical shift predictions by DFT.