Spectral Extinction of Colloidal Gold and Its Biospecific Conjugates

We have prepared gold sols with mean particle diametersd_min the range 4 to 50 nm and measured their extinction spectra and size dependences of the extinction peak position λ_maxand valueE_max. The measured increasing function λ_max(d_m) displays a pronounced bend near the particle diameterd_m∼ 10 nm, where the value of λ_maxsharply decreases with reduction in the particle size. To explain these findings, the extinction spectra of sols with the particle size and axial ratio polydispersity are calculated using Mie's theory, the T-matrix method, and various experimental sets of the bulk gold optical constants modified with regard to size-limiting effects. It is shown that the measured λ_max(d_m) andE_max(d_m) dependences are inconsistent with calculations based on Mie's theory and the bulk gold optical constants. The most generalized model including the size dependence of the imaginary part of the dielectric permeability and the size and shape polydispersity gives good agreement with experimental extinction spectra for 5-, 10-, 24-, and 40-nm sols, as well as with the measured functions λ_max(d_m) andE_max(d_m). Based on electron-microscopic and spectral data, calibration curves are obtained for efficient spectrophotometric control over the particle size and for estimation of the amount of restorer essential for the preparation of particles of a given size. A simplest two-layer spherical model is employed to elucidate the basic changes in sol spectra after conjugation with specific biomacromolecules and to draw some conclusions about the conjugate shell structure.     

On Chiral Space Groups and Chiral Molecules

This note explains the relationship (as well as the absence of a relationship) between chiral space groups and chiral molecules (which have absolute configurations).For a chiral molecule,which must crystallize in a chiral space group,the outcome of the absolute configuration determination must be linked to some other properties of the chiral crystal such as its optical activity for the observation to the relevant.     

Differential Light Scattering Spectroscopy for Studying Biospecific Assembling of Gold Nanoparticles with Protein or Oligonucleotide Probes

A new method is proposed for studying biospecific interactions in systems of conjugates of colloidal gold nanoparticles. The method is based on measuring the differential spectra of light scattered at 90° within wavelength range 350–800 nm. Addition of complementary component to bioconjugate probe results in the nanoparticle aggregation that can be monitored by the light scattering or extinction spectra. To this end, we developed a special attachment to a Specord M-40 spectrophotometer and a corresponding measurement procedure called by us the differential light scattering spectroscopy. The method is compared with the common spectrophotometry as applied to colloidal gold conjugates to various polymers including proteins and oligonucleotides. Our experiments with the gold nanoparticles of different sizes showed a higher potential sensitivity of the suggested method as compared to spectrophotometry. It is expected that the differential light scattering spectroscopy can be used to develop sensitive analytical biospecific test for various biopolymers.     

Polyelectrolyte microcapsules containing molecules of sulfated β-cyclodextrin in the structure of nanosized shell

Alternate adsorption of the molecules of poly(allylamine hydrochloride) (PAA) and sulfated β-cyclodextrin (sulfo-β-CD) is studied by piezoelectric microweighing upon the formation of coatings of nanosized thicknesses by the polyionic assembly procedure. The thickness of planar coatings on the surface of single-crystalline silicon is determined by ellipsometry. The layer-by-layer character of the formation of planar nanosized coating is revealed and assumptions about the structure of the PAA and sulfo-β-CD bilayers are stated. A comparison of the spherical microparticles of polystyrene, as well as manganese and calcium carbonates, demonstrated that it is feasible to use microparticles of calcium carbonate as a template for producing microcapsules. Microcapsules with shells containing five (PAA/sulfo-β-CD) layers are prepared and studied by confocal fluorescent microscopy.     

KLn Dielectronic Recombination Process of B- Through He-like Cu Ions

The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidelberg electron beam ion trap （EBIT）. The theoretical resonant positions agree with the experimental resonant positions to a precision of 0.4%, in comparison with the resonant positions of those highest peaks between theory and experiment. The experimental spectra are then fitted using a formula with the theoretical resonant energies and strengths, the result shows good overall agreement between theory and experiment over a wide electron energy range. The distribution of highly charged states is obtained from the fitting parameters.     

Orientational averaging of integrated cross sections in the discrete dipole method

Using the discrete dipole method, exact and approximate analytical solutions for orientation-averaged cross sections for extinction, absorption, and scattering of light are obtained. The analytical solutions can be applied to the calculation of integrated cross sections of fractal clusters formed by primary particles with different optical properties (soot in air and aqueous suspensions of aggregates of polystyrene, gold, and silver nanoparticles). It is shown that two models of aggregates that differ only in trajectories (ballistic or Brownian) of primary particles and intermediate clusters and in average fractal dimensions give close values of averaged extinction cross sections.     

Synthesis temperature as an instrument for tuning the plasmon resonance of gold nanorods

The one-stage unseeded method of the synthesis of gold nanorods has been employed to systematically study the influence of process temperature on nanorods sizes and plasmon resonance properties. It has been shown for the first time that even slight variations in the temperature have a very strong effect on these characteristics. Analysis of the obtained results has indicated that the observed effect is caused by the influence of temperature on the nucleation rate of the nanoparticles.     

Synthesis,Crystal Structure and Characterization of a Cobalt Coordination Polymer： [Co（bib）（L）]-0.5H2O

The title coordination polymer, [Co（bib）（L）].0.5H2O 1 （bib = 1,1＇-（1,4-butanediyl）bis（imidazole） and L = 4,4＇-oxy（bisbenzoate） has been hydrothermally synthesized and characterized by IR and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group Cc with a = 8.8568（5）, b = 19.936（1）, c = 26.209（2） γ, y = 97.510（1）°, V= 4587.8（5） A3, Z = 8, CoC24H23N4O5.5, Mr = 514.39, Dc = 1.489 g/cm3, F（000） = 2128, μ（MoKa） = 0.795 mm^-1, R = 0.0419 and wR = 0.1002. Compound 1 exhibits a rare two-fold interpenetrating CdSO4 type topology. The O-H...O hydrogen bonds stabilize the structure of 1.     

A Novel 3D Zn-La Heterometallic Coordination Polymer Involving in situ Glycinate Ligand Synthesis

One novel 3D 3d-4f coordination polymer, [LaZn(glc)(ox)2(H2O)2]n (1, glc = glycinate, ox = oxalate), was obtained by the in situ synthesis of glycinate from the reaction of tetrazole-1-acetic acid, sodium oxalate, zinc nitrate and lanthanide oxide in the presence of a trace quantity of nitric acid under hydrothermal conditions. Compound 1 is of monoclinic, space group P21/n with a = 0.99601(9), b = 1.14592(10), c = 1.19107(10) nm and β = 108.7150(10)°. 1 exhibits an unusual 3D heterometallic coordination framework constructed by heterometallic dinuclear LaZn subunits and mixed ox and glc linkers with a uninodal 6-connected vme {33 .43 .58 .6} net.