Tip-enhanced Raman spectroscopy of bradykinin and its B₂receptor antagonists adsorbed onto colloidal suspended Ag nanowires

Abstract

The tip-enhanced Raman scattering (TERS) spectra of bradykinin (BK) and its potent B2 BK receptor antagonists, [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK and [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK, approximately with a size of about 40 nm, adsorbed onto colloidal suspended Ag nanowires with diameter in the range of 350-500 nm and length of 2-50 μm were recorded. The metal surface plasmon resonance and morphology of the Ag nanowires were studied by ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). Briefly, it was shown that two C-terminal amino acids of BK and [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK are involved in the interaction with the colloidal suspended Ag nanowire surface, whereas three last amino acids of the [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK sequence attached the Ag surface. Thus, BK adsorbs on the colloidal suspended Ag nanowires mainly through the Phe(5/8) ring (tilted orientation) and the one oxygen atom of the carboxylate group and the H2N-C-NH-CH2- fragment of Arg(9). In the case of [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK, the Thi(8) ring (through the lone electron pair on the sulfur atom) and the both oxygen atoms of the carboxylate group and the amine group of Arg(9) mainly participated in the interaction with the Ag nanowire surface. For [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK, the d-Phe(7) ring, the Pip(8) ring, and the Arg(9) side-chain assisted in the peptide interaction with the Ag surface. The obtained results emphasize the importance of the C-terminal part of these peptides in the adsorption process onto the colloidal suspended Ag nanowires.

Effects of wavelength, fluence, and dose on fragmentation pathways and photoproduct ion yield in 213 nm and 266 nm ultraviolet photodissociation experiments

“…The increased PY at 213 nm compared to 266 nm is in accordance with the increased extinction coefficient of bradykinin in aqueous solution at 213 nm compared to 266 nm. 38 In addition to y - and b -type ions, an increased number of a -, c -, and z -ions as well as the unique ( a + 2) + and ( y -2) + ions are detected in 213 nm UVPD experiments of [M + 2H] 2+ . In recent studies, Dugourd and coworkers described the formation of ( a + 2) + and ( y -2) + peptide ions in 213 nm UVPD experiments.…”

Tip‐Enhanced Raman Spectroscopy: A Tool for Nanoscale Chemical and Structural Characterization of Biomolecules

“…The detection of gold NPs functionalized with peptides showing distinct binding affinity with integrin membrane receptors on healthy and cancer cells was also achieved . A TERS study of the adsorption process of bradykinin (an endogenous hormone peptide potentially implicated in many diseases and suggested as an important target for cancer growth) onto silver colloidal NPs and nanowires also revealed the roles of Phe and Arg amino acid residues in the silver–bradykinin interaction …”

“…Vibrational marker bands for sugar can be found in the literature . Additional studies were finally performed on proteins bound to metal NPs . Biotin‐labeled gold NPs bound to a streptavidin‐functionalized glass slides were imaged through TERS by following spectral features of these two proteins, and the specific chemical adsorption of antibody‐conjugated NPs on intact cellular membranes was subsequently investigated .…”

Application of Alanine Scanning to Determination of Amino Acids Essential for Peptide Adsorption at the Solid/Solution Interface and Binding to the Receptor: Surface-Enhanced Raman/Infrared Spectroscopy versus Bioactivity Assays

“…In recent years, our research has aimed to demonstrate that SERS and now SEIRA can be used as potential tools to predict the biochemical activity of some neuropeptides. 6 , 18 , 19 In other words, we seek to show that SERS/SEIRA techniques can be useful to identify the most important amino acid residues involved in substrate–receptor interactions in systems where biological studies are difficult or do not lead to the unequivocal identification of the molecular fragments responsible for the biological activity of the peptide.…”