Gold and colloidal gold surface influence on dna conformational change

DNA conformational changes caused by gold and colloidal gold surface have been studied by surface enhanced infrared spectroscopy (SEIRA), spectroscopy of plasmon resonance (SPR), atomic force microscopy (AFM) and principal component analysis. Experimental data have shown that DNA conformation is slightly influenced by gold surface, while it is strongly altered by colloidal gold. Spectroscopic features of DNA-colloidal gold system have shown that the intensity of the asymmetric PO₂– band at 1240 cm⁻¹ decreases by two times, and that of symmetric band at 1090 cm⁻¹ decreases by 2.4 times whereas the halfwidth of phosphate bands increases by 35–40 cm⁻¹; a frequency shift of asymmetric band position from 1240 to 1246 cm⁻¹ and a symmetric band from 1090 to 1106 cm⁻¹ has been observed. It was shown that intensity variation and shift of DNA base vibrations together with the broadening of OH, NH, and CH stretching vibrations occur due to DNA conformational changes and the redistribution of the H-bonding network. A supposition about DNA condensation by colloidal gold was made. SEIRA and AFM data have showed major DNA structural changes occurred on gold colloidal particles. It was found that all the spectral features are more prominent for DNA–colloidal gold system deposited on gold substrate than on CaF₂ substrate

Digital aroma technology for chemical sensing: temporal chemical images of complex mixtures

The reliability of Electronic nose applications is mainly based on the sensitivity, repeatability and discernment properties of the sensors composing the array. Due to nature of the chosen sensitive layers, the sensors are particularly suitable to classify environments in which compounds with various chemical functionality play a key role. This article is focusing on the novel strategy aimed at the improving the quality and quantity of chemical information from the sensing instruments based on incorporation kinetic aspects of the array response for perfect formation and improved discrimination of chemical images of the probes. We describe a procedure for reducing both time response and number of elements of gas sensor arrays based on principal component analysis (PCA). Thus, digital aroma technology may be used not only as background for formation of chemical images using intelligent sensor massifs but as well as effective experimental tools for characterization and selection coatings with desired chemical functionality by using time-resolved pattern recognition

Surface enhanced infrared absorption of nucleic acids on gold substrate

Data on surface enhanced infrared absorption (SEIRA) of nucleic acids deposited on the metal surface have been obtained in the experiment in FTIR reflectance mode. As metal surface, we used Au of 200-500 Е thickness on glass substrate. Roughness of Au was about 50 Е. In our experimental conditions, the enhancement factor of SEIRA was 3 to 5. We obtained different enhancement factors for different vibrations of nucleic acids. Application of this method to tumour nucleic acid gave a possibility to reveal some structural peculiarities of their sugar-phosphate backbone and those after application of anti-cancer drugs