Vibrational spectroscopic analysis of critical micelle concentration in sodium decanoate solutions.

The presented study is devoted to the investigation of the micellization-induced liquid-liquid fluctuations in sodium decanoate (NaD) aqueous solutions, based on the vibrational spectroscopic study of NaD and the determination of critical micelle concentration (CMC) of this system. At the same time, we focused on monitoring the effect of the addition of decanol to this system and changing its basic parameters from the point of view of CMC. CMC is an important parameter from a practical point of view and a characteristic feature of each micelle-forming compound. Upon analyzing the spectroscopic data we focus our attention mainly on the intensity and band position variations of both the symmetrical and antisymmetrical vibrational modes of CH2 groups situated in the high-frequency part of the spectrum. The study used normal (non-enhanced) Raman spectroscopy with excitation wavelength 785 nm, surface-enhanced Raman spectroscopy (SERS) on large-scaled gold-coated SERS-active substrates and infrared spectral measurements. The results of spectroscopic measurements were supported by tensiometry and potentiometry.

Glucan particles as suitable carriers for the natural anti-inflammatory compounds curcumin and diplacone - Evaluation in an ex vivo model.

Natural compounds offer a wide spectrum of potential active substances, but often they have a poor bioavailability. To increase the bioavailability and bioactivity of the natural anti-inflammatory molecules curcumin and diplacone, we used glucan particles (GPs), hollow shells from Saccharomyces cerevisiae composed mainly of ß-1,3-d-glucan. Their indigestibility and relative stability in the gut combined with their immunomodulatory effects makes them promising carriers for such compounds. This study aimed to determine how curcumin and diplacone, either alone or incorporated in GPs, affect the immunomodulatory activity of the latter by assessing the respiratory burst response and the secretion of pro-inflammatory cytokines by primary porcine innate immune cells. Incorporating curcumin and diplacone into GPs by controlled evaporation of the organic solvent substantially reduced the respiratory burst response mediated by GPs. Incorporated curcumin in GPs also reduced GPs mediated secretion of IL-1ß and TNF-α by innate immune cells. The obtained results indicate a potentially beneficial effect of the incorporation of curcumin or diplacone into GPs against inflammation.

Vibrational spectroscopic study of selected alkaloids with therapeutic effects.

Nowadays, scientists from various fields of chemistry, biochemistry or biology are interested in trace detection of different natural or synthetic substances such as alkaloids which can either positively or negatively affect human physical and mental health. Linked with that, growing interest in broad applications of advanced vibrational spectroscopic techniques encourage higher demands in this rapidly developing field. This study is focused on a detailed description of infrared and Raman spectra of two natural alkaloids (namely galantamine and buprenorphine) and study of their optical response in the vicinity of gold and silver nanostructured surface. The interpretation of individual bands was supported by DFT calculations. Both alkaloids were also studied using surface-enhanced Raman scattering technique aiming at a comparison with non-enhanced vibrational data construction of concentration-dependent series and determination of their limit of detection. From SERS spectral series the regression models were developed to predict alkaloids concentration in the range of 10-3-10-7 mol/l, in the case of buprenorphine adsorbed on Ag substrate we were able to broaden this range down to 10-9 mol/l.

Detection and identification of medically important alkaloids using the surface-enhanced Raman scattering spectroscopy.

Currently, trace detection of drugs, medicinal products, psychoactive substances, poisons and other natural or synthetic compounds in the human body has become one of the most important areas of interest in medicine, toxicology and forensic research. Due to the rapid development of nanotechnology, applications in forensic and biological sciences, food industry and art preservation there is an increasing interest in surface-enhanced Raman scattering (SERS) spectroscopy as a technique capable of low detection limits in the analysis of small amounts of studied analytes. In this study, different excitation wavelengths (785 nm and 1064 nm) were used to find the appropriate experimental conditions for the detection and identification of medically significant alkaloids - atropine and pergolide - by means of surface-enhanced Raman scattering spectroscopy. SERS spectra of selected alkaloids were measured in the concentration range 10-3-10-9 mol∙L-1 using large-scaled platinum substrates coated with electrochemically prepared gold or silver SERS-active layers. Identification was based on the assignment of surface-enhanced characteristic vibrational bands using theoretical (DFT) calculations and comparing them with normal (non-enhanced) Raman spectra of pure compounds. All sets of spectral data were subjected to multivariate statistical approach (partial least squares regression) aiming at prediction of alkaloids concentration in developed models and its comparison with experimental results.

The use of infrared spectroscopic techniques to characterize nanomaterials and nanostructures: A review.

Recent advances in nanotechnology have opened a lot of new possibilities for nanomaterials application in wide variety of industrial, pharmaceutical, medicinal and environmental applications. This review aims to description of various Fourier Transform Infrared (FTIR)-based spectroscopic techniques suitable to characterize (i) different types of nanomaterials and (ii) various macroscopic samples at their nanoscale. In the introductory section, nanomaterials are classified according to their crucial properties, i.e. chemical composition, size and surface morphology. Application of traditional FTIR techniques, such as Attenuated Total Reflection (ATR), Diffuse Reflection (DRIFT) and infrared micro (spectro)scopy, for characterization of nanomaterials and nanostructures is compared with novel optical nanoscopic techniques derived from scanning probe microscopy which enable to overcome the diffraction limit and to characterize nanomaterials at molecular scale.

In situ SERS spectroelectrochemical analysis of antioxidants deposited on copper substrates: what is the effect of applied potential on sorption behavior?

The detection of p-coumaric acid and ferulic acid using a combined in situ electrochemical and surface-enhanced Raman scattering spectroscopic technique in specially made electrode cell is described. New in situ spectroelectrochemical cell was designed as the three-electrode arrangement connected via positioning device to fiber-optic probe of Raman spectrometer Dimension P2 (excitation wavelength 785 nm). In situ SERS spectra of p-coumaric acid and ferulic acid were recorded at varying applied negative potentials to copper substrates. The spectral intensities and shapes of bands as well as spatial orientation of molecules on the surface depend significantly on varying values of the applied electrode potential. The change of electrode potential influences analyte adsorption/desorption behavior on the surface of copper substrates, affecting the reversibility of the whole process and overall spectral enhancement level. Principal component analysis is used to distinguish several stages of spectral variations on potential changes.

Polytetrafluorethylene-Au as a substrate for surface-enhanced Raman spectroscopy.

This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS) applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE) foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD) from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.