Plasmonic silvered nanostructures on macroporous silicon decorated with graphene oxide for SERS-spectroscopy.

A method for fabricating surface-enhanced Raman scattering (SERS)-active substrates by immersion deposition of silver on a macroporous silicon (macro-PS) template with pore diameters and depth ranging from 500-1000 nm is developed. The procedure for the formation of nanostructured silver films in the layers of macro-PS was optimized. Silver particles of dimensions in the nano- and submicron-scale were formed on the external surface of the macro-PS immersed in the water-ethanol solution of AgNO3, while the inner pore walls were covered by smaller, 10-30 nm diameter, silver nanoparticles. Upon introducing the hydrofluoric acid to the reaction mixture, the size of nanoparticles grown on the pore walls increased up to 100-150 nm. Such nanostructures were found to yield SERS-signal intensities from CuTMpyP4 analyte molecules of the same order to those obtained from silvered mesoporous silicon reported previously. The tested storage stability for the silvered macro-PS-based samples reached up to 8 months. However, degradation of the SERS intensity under illumination by the laser beam during spectral measurements was observed. To improve the stability of the SERS-signal a hybrid structure involving graphene oxide deposited on the top of analyte molecules adsorbed on the Ag/macro-PS was formed. A systematic observation of the time evolution of the characteristic peak at 1365 cm-1 showed that the addition of the oxidized graphene layer over the analyte results in ∼2 times slower decay of the Raman intensity, indicating that the graphene coating can be used to enhance the stability of the SERS-signal from the CuTMpyP4 molecules.

Surface-enhanced Raman scattering on silvered porous alumina templates: role of multipolar surface plasmon resonant modes.

Nanostructured silver films with different thicknesses were prepared by vapor deposition onto the surface of the anodic aluminum oxide (AAO) template to be used as surface-enhanced Raman scattering (SERS) active substrates. Both the peak position of the surface plasmon resonance (SPR) band and SERS enhancement of silvered AAO samples displayed non-monotonous dependence on Ag layer thickness. Using 441.6 nm excitation and a water-soluble cationic porphyrin, Cu(ii)-tetrakis(4-N-methylpyridyl) (CuTMPyP4), as a SERS-reporting analyte, two maxima of the SERS enhancement were obtained for Ag layers of 15 and 120 nm thickness. Thickness dependencies have been analyzed taking into account the type of SPR modes identified by means of quasicrystalline approximation (QCA) of statistical theory of multiple scattering of waves and multi-Lorentzian deconvolution. The analysis revealed that SERS enhancement is related to the absolute magnitude of the distance between excitation wavelength and spectral position of collective SPR mode. It was shown that matching of excitation wavelength and the most intensive SPR modes with non-radiative decay, generated mainly by coherent interaction of higher-order plasmon resonant modes (quadrupole and octupole), plays a dominate role in SERS performance. Besides, it has been observed that more intense SERS signal can be obtained when the analyte deposited on the Ag/AAO substrate was excited through the AAO template rather than from the silvered side. Our results demonstrate that appropriate excitation geometry and fine-tuning of the optical properties of the Ag/AAO substrate by adjusting the thickness of the Ag layer with respect to particular excitation wavelength can contribute to more effective SERS enhancement.

FTIR spectra and normal-mode analysis of chlorin e(6) and its degradation-induced impurities.

Fourier transform infrared spectra of chlorin e(6) and its trisodium salt are presented. The geometrical structure and frequencies of normal vibrations of both compounds were calculated using density functional method with the PBE exchange-correlation functional. The frequencies were assigned and IR spectra of the studied molecules were interpreted for the first time. Spectral effects of degradation of chlorin e(6) and its trisodium salt upon their storage on the air are analyzed. The possible structures of degraded species are discussed.

[Correction of hemocoagulation disorders in complicated forms of acute cholecystitis]. / Korrektsiia narushenii gemokoaguliatsii pri oslozhnennykh formakh ostrogo kholetsistita.

The comparative analysis of the low-molecular-weight heparin Clexane influence and the unfractionated heparin on the parameters of blood coagulation homeostasis in 70 patients with complicated forms of acute cholecystitis. The tendency for hypercoagulation is observed. Prophylactic use of Clexane in patients with complicated forms of acute cholecystitis, in comparison with unfractionated heparin, is accompanied by the decrease of coagulating potential of blood.

[Rational parenteral feeding in acute pancreatitis]. / Ratsional'noe parenteral'noe pitanie pri ostrom pankreatite.

The efficiency of amino acid drugs Polyamine and Amikin as means of nutrition in treatment of acute pancreatitis are not inferior to the preparation Alvezin "New" (GDR), the degree of nitrogen retention being even superior.

[Amino acid spectrum of the blood during parenteral feeding of patients with acute pancreatitis using polyamine]. / Aminokis'lotnyi spektr krovi pri peranteral'nom pitanii bol'nykh ostrym pankreatitom s primeneniem poliamina.

The investigation of the dynamics of changes of the plasma amino acid spectrum was performed in 58 patients with acute pancreatitis in parenteral feeding with the use of the amino acid preparation Polyamine. The parenteral feeding proved to be effective since by the end of the 5th day of the parenteral feeding the content of plasma amino acids approximated or even was higher than that in practically healthy people.