Is the Use of Surface-Enhanced Infrared Spectroscopy Justified in the Selection of Peptide Fragments That Play a Role in Substrate-Receptor Interactions? Adsorption of Amino Acids and Neurotransmitters on Colloidal Ag and Au Nanoparticles.

E Proniewicz,E Iłowska,A Ta̧Ta,A Prahl

doi:10.1021/acs.jpcb.1c00546

Abstract

This paper describes an application of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and surface-enhanced infrared spectroscopy (SEIRA) to characterize the selective adsorption of four peptides present in body fluids such as neuromedin B (NMB), bombesin (BN), neurotensin (NT), and bradykinin (BK), which are known as markers for various human carcinomas. To perform a reliable analysis of the SERIA spectra of these peptides, curve fitting of these spectra in the spectral region above 1500 cm–1 and SEIRA measurements of sulfur-containing and aromatic amino acids were performed. On the basis of the analyses of the spectral profiles, specific conclusions were drawn regarding specific molecule–metal interactions and changes in the interaction during the substrate change from the surface of silver nanoparticles (AgNPs) to gold nanoparticles (AuNPs).

Highlights

Vibrational spectroscopy is a widely used, reliable, and powerful method for studying conformational changes and molecular interactions and for unambiguously identifying and characterizing a variety of molecules by their vibrational fingerprint
Neuromedin B (NMB), BN, NT, and BK are important neurotransmitters found in body fluids and are known as tumor growth factors
We present SEIRA results for the above neurotransmitters immobilized on the surface of readily available and homogeneous, in terms of shape and diameter, Ag and Au nanoparticles, which may bring us closer to the more frequent and routine application of SEIRA

Summary

Introduction

Vibrational spectroscopy (infrared absorption and Raman) is a widely used, reliable, and powerful method for studying conformational changes and molecular interactions and for unambiguously identifying and characterizing a variety of molecules by their vibrational fingerprint. In conventional form, it does not provide sufficient sensitivity for trace concentrations and thin molecular layers (usually a few pmol/cm2), since most (bio)organic molecules absorb radiation in the mid-infrared range (2.5−25 μm) relatively poorly and do not scatter electromagnetic radiation effectively. This leads to a limitation of the application range of vibrational spectroscopy based on the detection of chemical traces (food safety, detection of hazardous substances, or biosensors). Later reports showed the possibility of using other metals,[7−14] semiconductors,[15] and polar dielectric nanostructures.[16]

Methods

Results

Conclusion