Micro- and Nanoscale Spectroscopic Investigations of Threonine Influence on the Corrosion Process of the Modified Fe Surface by Cu Nanoparticles

Abstract

The work presents a comprehensive vibrational analysis of the process of adsorption of threonine (Thr) onto an Fe surface with deposited Cu nanoparticles (NPs) (of about 4–5 nm in size) in a corrosive environment. The application of surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRA) provides the opportunity for detailed description of adsorption geometry of amino acid onto a metal surface. The combination of conventional infrared spectroscopy (IR) with atomic force microscopy (AFM) resulted in a nano-SEIRA technique which made it possible to provide a precise description of adsorbate binding to the metal surface. The studies presented confirmed that there is a very good correlation between the spectra recorded by the SERS, SEIRA, and nano-SEIRA techniques. Threonine significantly influenced the process of corrosion of the investigated surface due to the existing strong interaction between the protonated amine and carboxylate groups and the CuNPs deposited onto the Fe surface. In addition, the application of two polarization modulations (s and p) in nano-SEIRA allows subtle changes to be observed in the molecule geometry upon adsorption, with the carboxylate group of Thr being almost horizontally oriented onto the metal surface; whereas the amine group that contains nitrogen is oriented perpendicular to this surface.

Spectroscopic Investigations of 316L Stainless Steel under Simulated Inflammatory Conditions for Implant Applications: The Effect of Tryptophan as Corrosion Inhibitor/Hydrophobicity Marker

“…The proposed band assignments were based on many theoretical and experimental data from the literature on the molecular structure of Trp and Trp derivatives obtained under various conditions [42,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]. As mentioned in our previous paper [28], the preparation of samples for experiments may affect the information obtained from spectral patterns (i.e., the state of the sample condition, pH of the surrounding environment). Therefore, the same sample preparation procedure was applied in all experiments.…”

“…The surface-enhanced effects are governed mainly by surface-enhanced Raman (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRA). These techniques, as it was reported in our previous paper [28], are a promising tool for studying the conformational changes of potential inhibitors upon corrosion/inhibition process(es). Although the enhancement factor for SEIRA (up to 10 3 ) is smaller than for SERS (usually up to 10 6 ), the cross-section for infrared absorption is several times higher than the Raman cross-section [40,41].…”

“…Amino acids have previously been used to improve the corrosion resistance of different materials-such as copper, mild steel, and stainless steel [20,[27][28][29][30][31][32][33]. Moretti and Guidi [31] obtained a good inhibition efficiency of Trp in a short time of exposition and at the highest concentration (0.01 M) for copper corrosion under acidic conditions.…”

“…The most frequently used methods to investigate the inhibition process of amino acids are electrochemical, and less frequently, spectroscopic methods [13,34,35]. Vibrational spectroscopy is a powerful tool to monitor the corrosion and inhibition processes [28,34]. Raman and Fourier-transform infrared spectroscopic methods are usually quick, nondestructive, and do not require complicated sample preparation to obtain chemical complex information about the investigated sample.…”

Quantitative and qualitative analyses of drug adsorption on silver nanoparticle monolayers: QCM, SERS, and TEIRA nanospectroscopy studies

“…Previously published results prove that the surface-enhanced technique combining AFM with IR spectroscopy, namely AFM-SEIRA, enables the detailed characterization of how molecules adsorb on the MeNP monolayers. [25][26][27][28] In these studies, TEIRA nanospectroscopy was used to characterize the molecular structure of erlotinib, a drug approved for non-small cell lung cancer (NSCLC) therapy, immobilized on the monolayers formed from silver nanoparticles prepared using hydroxylamine hydrochloride (HH). It is well known that the suspensions of AgNPs prepared with the use of HH are particularly attractive for spectroscopic techniques.…”