Surface-enhanced vibrational spectroscopy of B vitamins: what is the effect of SERS-active metals used?

Abstract

Surface-enhanced Raman scattering (SERS) spectroscopy and surface-enhanced infrared absorption (SEIRA) spectroscopy are analytical tools suitable for the detection of small amounts of various analytes adsorbed on metal surfaces. During recent years, these two spectroscopic methods have become increasingly important in the investigation of adsorption of biomolecules and pharmaceuticals on nanostructured metal surfaces. In this work, the adsorption of B-group vitamins pyridoxine, nicotinic acid, folic acid and riboflavin at electrochemically prepared gold and silver substrates was investigated using Fourier transform SERS spectroscopy at an excitation wavelength of 1,064 nm. Gold and silver substrates were prepared by cathodic reduction on massive platinum targets. In the case of gold substrates, oxidation-reduction cycles were applied to increase the enhancement factor of the gold surface. The SERS spectra of riboflavin, nicotinic acid, folic acid and pyridoxine adsorbed on silver substrates differ significantly from SERS spectra of these B-group vitamins adsorbed on gold substrates. The analysis of near-infrared-excited SERS spectra reveals that each of B-group vitamin investigated interacts with the gold surface via a different mechanism of adsorption to that with the silver surface. In the case of riboflavin adsorbed on silver substrate, the interpretation of surface-enhanced infrared absorption (SEIRA) spectra was also helpful in investigation of the adsorption mechanism.

Silver‐capped silicon nanopillar platforms for adsorption studies of folic acid using surface enhanced Raman spectroscopy and density functional theory

“…Even though the SERS spectra of FA have been investigated experimentally both on colloids and metallic surfaces, to the best of our knowledge, there are no previous reports of the adsorption studies and computed vibrational frequencies of FA in metallic surfaces nanostructured. The assignment of Raman bands of FA in a previously reported study was incomplete, and a deeper analysis of all vibrational modes of FA is warranted. In the following paragraph, the complete assignment of the Raman bands of FA is presented using both experimental and theoretical spectra (see summarized data in Table ).…”

“…The calculations were carried out using the GAUSSIAN 09 software package. [35] Results and discussion Raman spectra of FA Even though the SERS spectra of FA have been investigated experimentally both on colloids and metallic surfaces, [12,19,20] to the best Figure 2. Density functional theory calculated (blue) and experimental (red) surface enhanced Raman scattering (SERS) spectra of folic acid using silver-capped silicon nanopillar substrates.…”

“…In the study of Zhang et al ., the authors evaluated the adsorption behavior of nicotinic acid on a gold nanowire array using SERS and DFT calculations. The adsorption of biomolecules on SERS substrates increases the Raman scattering intensity by several orders of magnitude, which is important for vibrational studies, analysis, identification and quantification of the target compounds . Jing et al .…”

“…The adsorption of biomolecules on SERS substrates increases the Raman scattering intensity by several orders of magnitude, which is important for vibrational studies, analysis, identification and quantification of the target compounds. [1,19,20] Jing et al [21] studied the adsorption of L-cysteine because of its strong tendency to be adsorbed onto the surfaces of a variety of metals. SERS of adenine-containing micro-RNA chains has been obtained by adsorption on a new silver grass-like nanostructure.…”

Measuring and tracking vitamin B12: A review of current methods with a focus on optical spectroscopy

“…Raman measurements of vitamin B12, therefore, have the potential to yield both useful and innovative results. A strong case can be provided by other vitamins; SERS measurements of vitamin C show a detection behavior that closely matches the performance of HPLC measurements by using a structured silver substrate to enhance the Raman signal (129), and SERS has also been identified as a reliable technique to build up libraries of spectral signature for vitamin (130). Recent approaches such as producing SERS-active biotags for the characterization of biological samples have shown that the intensity of the SERS signal can be as high as that of fluorescencebut with the added advantage of unique identification of the compound (131) which represents an exciting step towards detecting physiologically-relevant concentration of vitamin B12.…”