Nicolae Leopold

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We report a fast, one-step, facile, and green preparation method that yields very stable and biocompatible silver colloids that are highly active as surface-enhanced Raman spectroscopy (SERS) platforms that has a possible application in biomedicine. Reduction of silver nitrate has been carried out using polyethylene glycol (PEG) which acts as both reducing(More)
We report a new strategy for on-line monitoring of chemical reactions in ultrasonically levitated, nanoliter-sized droplets by Raman spectroscopy. A flow-through microdispenser connected to an automated flow injection system was used to dose picoliter droplets into the node of an ultrasonic trap. Taking advantage of the flow-through characteristics of the(More)
Monosodium glutamate (MSG), a common flavor enhancer, is detected in aqueous solutions by Raman and surface-enhanced Raman (SERS) spectroscopies at the micromolar level. The presence of different species, such as protonated and unprotonated MSG, is demonstrated by concentration and pH dependent Raman and SERS experiments. In particular, the symmetric(More)
Raman and IR spectra of betulinic acid (BA) (3beta-hydroxy-20(19) lupaen-28 oic acid) and of the natural birch bark have been successfully recorded and discussed. A high selectivity of the Raman technique was remarked for evidencing the betulin in the birch bark. Surface enhanced Raman spectrum (SERS) of BA on colloidal silver has been obtained. The(More)
We studied the physico-chemical properties (size, shape, zeta-potential), cellular internalization and toxicity of gold nanoparticles (NPs) stabilized with the most abundant mammalian protein, collagen. The properties of these gold NPs were compared to the same sized gold NPs coated with synthetic poly(isobutylene-alt-maleic anhydride) (PMA). Intracellular(More)
In this work the surface-enhanced Raman scattering (SERS) spectra of five genomic DNAs from non-cryopreserved control tomato plants (Lycopersicon esculentum Mill. cultivars Siriana, Darsirius, Kristin, Pontica and Capriciu) respectively, have been analyzed in the wavenumber range 400-1800 cm(-1). Structural changes induced in genomic DNAs upon(More)
2,2,5,5-Tetramethyl-3-pyrrolin-1-yloxy-3-carboxamide (tempyo) labeled bovine serum albumin and cytochrome c at different pH values were prepared and investigated using Raman-resonance Raman (RR) spectroscopy and surface enhanced Raman scattering (SERS) spectroscopy. The Raman spectra of tempyo labeled proteins in the pH 6.7-11 range were compared to those(More)
Absorption spectra of PTCDI (3,4,9,10-perylene-tetracarboxylic-diimide) have been investigated in chloroform, N,N'-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). While no signature of assembled PTCDI molecules is observed in chloroform solution, distinct bands assigned to their aggregation have been identified in DMF and DMSO solutions. PTCDI(More)
The present study reports findings regarding the contrast between H2S interaction with bovine hemoglobin (Hb) and horse heart myoglobin (Mb), in terms of binding and dissociation kinetics, affinities, and mechanism. At pH9.5, oxidation of ferric-sulfide adducts in presence of no free sulfide, using hexachloroiridate as oxidant is examined using stopped-flow(More)
Potential energy curves along the inter-planar coordinates have been calculated for the dimers of two perylene derivatives (PTCDI and PTCDA) by using MP2 and dispersion corrected DFT (DFT-D) methods with B3LYP, B97 and PBE0 density functionals. The performance of dispersion-correcting potentials (DCPs) for describing intermolecular van der Waals(More)