Diterpenoic acids analysis using a coupled TLC-surface-enhanced Raman spectroscopy system

Hyphenation of thin layer chromatography (TLC) with surface-based spectral methods requires a homogeneous surface for direct and quantitative analysis on the chromatographic plate after separation. Since most chromatographic materials do not produce strong background signals in Raman spectroscopy (RS) or surface-enhanced RS (SERS), we tested the suitability of two different chromatographic substrates and one interface for coupling SERS with TLC. This was carried out by using a chromatographic thin layer, specially produced for RS measurements, and a monolithic silica thin layer. A typical TLC plate with a modified aluminium backplate foil on one side was used as an interface. Three biologically active diterpenes, namely gibberellic acid (GA), abietic acid (AA) and kaurenoic acid (KA), were used as test analytes. Stock solutions were applied directly onto the surface, followed by the addition of silver colloid and measurements were taken by SERS. The strongest signal (excitation at 514.5 nm) was obtained for GA using a Raman treated thin layer where the enhancement factor value was determined to be 1

SALIVARY EXOSOME PROTEOME AS A NEW TOOL FOR THE DIAGNOSIS OF ORAL DISEASES

Introduction, aim: Exosomes generated by the endosomal pathway are released by the exocytosis into the extracellular space, including saliva. They contain nucleic acids, proteins and lipids that are transported to different parts of the body. They participate in intercellular communication, whether they support or disrupt various physiological processes. The aim of this work was to verify the efficiency of the ultracentrifugation method of isolation of exosomes from saliva, to exctract and identify proteins contained therein, with an emphasis on exosomal proteins related to diseases of the oral cavity or systemic diseases with manifestations in the oral cavity. Methods: Exosomes were isolated from full unstimulated human saliva by repeated centrifugation steps with washing in phosphate buffer followed by methanol/chloroform protein precipitation. Proteins were identified by a bottom-up approach using mass spectrometry with pre-separation by liquid chromatography. Results: The identified proteins were classified according to protein classes, molecular functions and biological processes. The most identified proteins were of the protein classes: cytoskeletal proteins, defense/immune proteins and structural proteins and proteins responsible for catalytic activity and structural molecular activity. Conclusions: Proteins have been classified into groups based on their molecular function and biological processes in which they participate in the human body. Some proteins/family of proteins have been identified that may be of interest in investigating the etiology of some oral diseases e.g. annexin A1, zymogen granular protein 16 homologue B, mucin-5B, Ig lambda-3 chain C region, Ig kappa chain C region, Ig alpha-2 chain C region and Ig alpha-1 chain C region

Surface enhanced Raman spectroscopy on silver-nanoparticle-coated carbon-nanotube networks fabricated by electrophoretic deposition

In this study, the efficiency of silver nanoparticle (AgNP) decorated carbon nanotube (CNT) based porous substrates has been investigated for surface-enhanced Raman spectroscopy (SERS) applications. The fabrication of uniform thin coatings of carbon nanotubes is accomplished by Electrophoretic Deposition (EPD) on organosilane functionalized silicon substrates. The deposition process exemplifies a fast, reproducible and single-step room temperature coating strategy to fabricate horizontally aligned porous CNT network. Surfactant stabilized AgNPs were deposited on the CNT networks by immersion coating. The acquired Raman spectra of Rhodamine6G (R6G) analyte examined on the fabricated Ag-CNT-Si substrates exhibited enhanced signal intensity values when compared to SERS-active planar AgNP-Si substrates. An overall enhancement factor of ~;109 was achieved for the tested analyte which enables pushing the limit of detection to 1 × 10-12 M (1 pM). The enhancement can be attributed to the large surface area offered by the AgNP-CNT porous network, which is expected to increase the number of effective hot spots for the SERS effect. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht