P. Divya

Bio: P. Divya is an academic researcher from University of Madras. The author has contributed to research in topics: Hydrogen bond & Nanorod. The author has an hindex of 3, co-authored 3 publications receiving 38 citations.

L-Alanine capping of ZnO nanorods: increased carrier concentration in ZnO/CuI heterojunction diode

Abstract: ZnO nanorods were capped with a simple amino acid, viz., L-alanine to increase the carrier concentration and improve the performance of ZnO/CuI heterojunction diodes. The effect of L-alanine capping on the morphology, structural, optical, electrochemical and electrical properties of ZnO nanorods had been studied in detail. The stable structure with two equally strong Zn–O coordinate bonds predicted by density functional theory was in agreement with the experimental results of FTIR spectroscopy. Due to the presence of electron-releasing (+I effect) moieties in L-Alanine, the carrier concentration of capped ZnO nanorods was two orders of magnitude higher and the ZnO/CuI heterojunction device showed more than a two-fold increase in the photovoltaic power conversion efficiency.

Structural Stability in Dimer and Tetramer Clusters of l-Alanine in the Gas Phase and the Feasibility of Peptide Bond Formation

Abstract: Stability in low-energy structures of the dimer and tetramer clusters of l-alanine in the gas phase is studied by accurate quantum chemical computations at the DLPNO2013-CCSD(T) level. It is found that the dispersion interaction energies in the dimer (-0.3 to -0.6 kcal/mol) and in the tetramer (-1.3 to -2.5 kcal/mol) have a small role in the stability of the clusters as compared to the hydrogen bond (HB) energies -4.1 to -14.2 and -32.2 to -40.1 kcal/mol, respectively. The HB energy in the alanine cluster is obtained from the binding energy (BE) of DLPNO2013-CCSD(T)//B2PLYP/def2-TZVP by subtracting the dispersion interaction energy. Local HB energies deduced from the dimer structures are found to be suitable to estimate total HB energies in similar environments. The BEs of OH···NH and OH···OC bonds are -9.5 and -7.1 kcal/mol, respectively. This suggests that the higher clusters are formed through OH···NH bonds as they confer more stability. Analysis of bonding in the tetramer shows that the low-energy tetramer and higher clusters are formed through the OH···NH mode of hydrogen bonding, unlike the dimer which is formed through the OH···OC bond. Feasibility of the amino acid cluster to function as a precursor for polypeptide formation is examined because the orientation of the OH···NH mode of hydrogen bonding is suitable for chemical condensation. The propensity of forming coiled structures in higher clusters and thus in the polypeptides is examined based on the conformational stability in the tetramer of alanine.

Synthesis and characterization of NADH model compound modified β-cyclodextrin and its role as an energy donor in FRET

Abstract: β -Cyclodextrin is chemically modified to selectively introduce an acridinedione moiety on the primary face. The synthesis involves the substitution of one of the primary hydroxyl groups of β -cyclodextrin by a tosyl group which facilitates the introduction of an ethylene diamine modification which is finally condensed to a tetraketone. The acridinedione modified β -cyclodextrin thus obtained was fully characterized by IR, NMR and Mass spectrometry. The photophysical properties of the compound were also analyzed. The potential of the modified β -cyclodextrin to act as an energy donor in FRET was investigated with a suitable acceptor.

Hydrogen bonding interactions on molecular properties of pesticidal compound 4-nitrophthalic acid: experimental density functional theory computations, electron localized function, localized orbital locator analysis and molecular docking scrutiny

Abstract: Abstract Nitroaromatic compounds are expansively used in the manufacturing of pharmaceuticals, pesticides, plasticizers, azo dyes and explosives. Nitrophenolic compounds can accumulate in the soil as a result of hydrolysis of several insecticides such asparathion, methyl parathion, and fenitrothion which can cause propitious effects to the biological systems. In optimized geometry hyperconjugation of nitro and dicarboxylic acid groups with the ring system increases the electron density of the aromatic system. Electron localized Function and Localized orbital Locator Analysis has value in a region wherein indicates high localization of electrons due to the presence of covalent bond, a lone pair of electrons or a nuclear shell in that region. In Nuclear Magnetic Resonance analysis signals in highly deshielded region clearly indicates the presence of carboxylic carbon in the compound. From vibrational assignments, broadening and red shifting depicts the level of intermolecular hydrogen bonding. In-vitro antimicrobial activity results clearly reveal that in all the four strains, activity increases with increase in compound concentration and the inhibition of the strains also increases. From both molecular docking and In-vitro Antimicrobial Activity the title compound can be certified that it inhibits antimicrobial activity and it is a pesticide.

Effect of Antiepileptic Drugs on Serum Lipid Profile among Children with Epilepsy at a Tertiary Care Hospital, Chennai, India

Abstract: Introduction: An arsenal of Antiepileptic Drugs (AED) is used in the management of childhood seizure disorders. Most of them are taken long-term. These drugs have the potential to cause hyperlipidemia by inducing the P450 enzyme system. The alteration in lipid profile caused by long-term use of antiepileptic drugs in children needs to be studied to reduce the risk of future atherosclerosis. Aim: To analyse the effect of antiepileptic drugs on serum lipid profile in children with epilepsy in a tertiary care. Materials and Methods: This prospective descriptive study was conducted in the Outpatient and Inpatient Wards of the Department of Paediatrics and Neurology, Institute of Child Health and Hospital for Children, Chennai, Tamil Nadu, India, from February 2017 to September 2017. The study involved a total of 155 children, who were on monotherapy antiepileptic drugs for atleast 6 months (33 on phenytoin, 42 on phenobarbitone, 20 on levetiracetam, 20 on carbamazepine, 40 on sodium valproate). A corresponding numbers of children, who attended the General Outpatient Department for acute upper respiratory tract and were otherwise healthy, were included as controls. A blood sample (3 mL) was drawn after an overnight fast for serum glucose, liver enzymes, total cholesterol, High Density Lipoprotein-Cholesterol (HDL-C), Low Density LipoproteinCholesterol (LDL-C), Very Low Density Lipoprotein (VLDL) cholesterol and Triglycerides (TG) measurement. Chi-square test was performed to find out the significance of association and independent t-test was used to compare the mean between various groups. Results: Cytochrome P450 (CYP) enzyme inducers like carbamazepine, phenytoin and phenobarbitone significantly modified serum lipids in epileptic children when compared to healthy controls. In children on long-term phenytoin monotherapy, mean cholesterol levels were significantly higher in the cases compared to controls (156.73±31.93 mg/dL vs 105.03±8.60 mg/dL, p-value <0.0001), significantly elevated triglycerides (123.48±25.99 mg/dL vs 87.88±12.16 mg/dL, p-value <0.0001), and HDL-C level was significantly lower (44.52±10.14 mg/ dL vs 56.73±12.56 mg/dL, p-value <0.0001) than in controls. Phenobarbitone use was associated with significantly higher levels of cholesterol (164.97±34.41 mg/dL vs 107.76±9.28 mg/dL, p-value <0.0001), LDL (155.27±28.55 mg/dL vs 93.36±6.81 mg/ dL, p-value <0.0001), and triglycerides (125.55±42.19 mg/dL vs 86.30±8.12 mg/dL, p-value <0.001) and lower HDL (46.30±9.47 mg/dL vs 57.73±14.41 mg/dL, p-value <0.0001). Levetiracetam was not associated in significant alteration in both liver enzymes and lipid profile (p-value >0.05). Carbamazepine monotherapy was associated with higher levels of cholesterol (180.50±28.06 mg/dL vs 112.15±13.55 mg/dL, p-value <0.0001), LDL (138.85±22.55 mg/dL vs 82.45±12.12 mg/dL, p-value<0.0001) and triglycerides (142.80±9.48 mg/dL vs 85.40±6.29 mg/dL, p-value <0.0001) when compared to healthy controls. There was no alteration in lipid profile in valproate monotherapy. Valproate monotherapy was associated with significant increase in levels of SGOT and SGPT when compared to mean levels (40.35±11.208 (IU/L), and 40.70±8.809 (IU/L), respectively) observed in other AEDs and significant increase in SGPT levels when compared to healthy controls (36.50±10.61(IU/L) in cases vs 40.70±8.81 (IU/L) in controls). Conclusion: Levetiracetam did not produce significant changes in the serum lipid profile and liver enzymes and appears to be safe to use in children for long-term epilepsy management especially in children with baseline deranged lipid profile.

Investigation of Functionalized Surface Charges of Thermoplastic Starch/Zinc Oxide Nanocomposite Films Using Polyaniline: The Potential of Improved Antibacterial Properties.

Abstract: Improving the antibacterial activity of biodegradable materials is crucial for combatting widespread drug-resistant bacteria and plastic pollutants. In this work, we studied polyaniline (PANI)-functionalized zinc oxide nanoparticles (ZnO NPs) to improve surface charges. A PANI-functionalized ZnO NP surface was prepared using a simple impregnation technique. The PANI functionalization of ZnO successfully increased the positive surface charge of the ZnO NPs. In addition, PANI-functionalized ZnO improved mechanical properties and thermal stability. Besides those properties, the water permeability of the bionanocomposite films was decreased due to their increased hydrophobicity. PANI-functionalized ZnO NPs were applied to thermoplastic starch (TPS) films for physical properties and antibacterial studies using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The PANI-functionalized ZnO bionanocomposite films exhibited excellent antibacterial activity for both E. coli (76%) and S. aureus (72%). This result suggests that PANI-functionalized ZnO NPs can improve the antibacterial activity of TPS-based bionanocomposite films.

Polypeptide formation in clusters of β-alanine amino acids by single ion impact.

Abstract: The formation of peptide bonds by energetic processing of amino acids is an important step towards the formation of biologically relevant molecules. As amino acids are present in space, scenarios have been developed to identify the roots of life on Earth, either by processes occurring in outer space or on Earth itself. We study the formation of peptide bonds in single collisions of low-energy He2+ ions (α-particles) with loosely bound clusters of β-alanine molecules at impact energies typical for solar wind. Experimental fragmentation mass spectra produced by collisions are compared with results of molecular dynamics simulations and an exhaustive exploration of potential energy surfaces. We show that peptide bonds are efficiently formed by water molecule emission, leading to the formation of up to tetrapeptide. The present results show that a plausible route to polypeptides formation in space is the collision of energetic ions with small clusters of amino acids. Formation of peptide bonds in cold gas-phase environments might represent a prebiotic synthesis route of polypeptides. Here, the authors show the formation of up to tetra-peptide species in the collision of He2+ ions, with kinetic energies typical for solar wind ions, with cold β-alanine clusters.

Application of green synthesized nanocrystalline CuI in the removal of aqueous Mn(VII) and Cr(VI) ions

Abstract: Purging of heavy metals like chromium and manganese from water using various adsorbents is the need of the hour for our environment. Copper iodide nanoparticle (CuI NP) has garnered a lot of attention due to its singular physical and chemical properties. The present study reports the of use of green synthesized CuI NP using Hibiscus rosa-sinensis L. flower extract which contains the anthocyanin, cyanidin-3-sophoroside (acts as both reducing and capping agents) in the removal of aqueous Cr(VI) and Mn(VII) ions. The synthesized CuI NP was characterized and was found to be nanocrystalline in nature, showing the presence of some surface crystal defects and having a high surface area making it a good adsorbent with adsorption capacities of 169.5 mg/g for Cr(VI) and 200 mg/g for Mn(VII) ions. The kinetics of metal removal was probed. The removal of metals was also probed using Freundlich and Langmuir adsorption models.