Following the Chemical Immobilization of Membrane Proteins on Plasmonic Nanoantennas Using Infrared Spectroscopy

Abstract

Plasmonic nanoantennas are promising sensing platforms for detecting chemical and biological molecules in the infrared region. However, integrating fragile biological molecules such as proteins on plasmonic nanoantennas is an essential requirement in the detection procedure. It is crucial to preserve the structural integrity and functionality of proteins while attaching them. In this study, we attached lactose permease, a large membrane protein, onto plasmonic nanoantennas by means of the nickel-nitrile triacetic acid immobilization technique. We followed the individual steps of the immobilization procedure for different lengths of the nanoantennas. The impact of varying the length of the nanoantennas on the shape of the vibrational signal of the chemical layers and on the protein spectrum was studied. We showed that these large proteins are successfully attached onto the nanoantennas, while the chemical spectra of the immobilization monolayers show a shape deformation which is an effect of the coupling between the vibrational mode and the plasmonic resonance.

Plasmonic Resonant Nanoantennas Induce Changes in the Shape and the Intensity of Infrared Spectra of Phospholipids

“…A modification of the profile of the vibrational signals of CH 2 , C=O, and PO 2 − , functional groups of the lipid was observed on the nanoantennas. This observation seems to be linked to the plasmonic resonance effect of the respective nanoantennas, as experimentally and theoretically shown [ 3 , 9 ]. The understanding of this phenomenon is crucial for the future application of nanoantennas as a tool in analytical sciences.…”

“…The plasmonic response critically depended on both, the rod length and radius. When the vibrational frequency of the molecules in the vicinity of the hot spots matches the plasmonic resonant frequency, a coupling between the two modes occurs resulting in an increase in the amplitude of the molecular vibrational signal [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Theoretical studies predict an influence of the resonance of the nanostructure on the spectral properties of the studied molecules [ 9 ].…”

Study of Membrane Protein Monolayers Using Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS): Critical Dependence of Nanostructured Gold Surface Morphology

“…52 Once the protein is adsorbed onto the surface of the AuNPs, they can alter the size, aggregation state, and interfacial properties of the nanomaterial. 53 It is noted that structures with a highly defined shape, including nanoarrays and nanoantenna's lead to a significantly higher enhancement, [54][55][56] however the creation of these surfaces is much more laborious.…”

Towards multi-molecular surface-enhanced infrared absorption using metal plasmonics

“…An immobilization protocol has also been developed to study large transport proteins with SEIRA, which should enable analysis of a wider range of biochemical processes. 90…”