Understanding the Adsorption of Proteins on Gold-Nanoantennas towards New Medical Diagnostics

Proteins are essential biomolecules for living organism to regulate cellular growth and their sustainability in the crowded biological environments. Evolving proteins need to be correctly folded to embrace their appropriate structure to maintain proper functionality. Failure to do so or due to accumulation of misfolded proteins may contribute to the development of many neurodegenerative diseases like amyloidosis, diabetes and Alzheimer’s. Therefore, understating the specific adsorption behavior of proteins on gold nanoantennas is crucial towards the development of advanced biocompatible devices for improved medical diagnosis. Metallic-nanoantennas are subwavelength structures that interact with light and confine the optical intensity within a tiny volume. This research identifies the specific deposition nature of selective proteins on gold-nanoantenna surfaces using high resolution imaging tool - atomic force microscope (AFM) together with their molecular vibrational detection with FTIR spectroscopy. The specific nanoantennas are asymmetric-split ring resonators (A SRRs) based on a circular geometry and are fabricated using electron-beam lithography. The plasmonic resonance of A-SRRs were tuned to match the vibrational resonance of proteins molecules in the mid-infrared region, thereby enhancing the sensitivity of detection down to nanogram (10-9) per millilitre range. For higher concentrations - accumulated selective deposition of proteins were imaged on the functionalised nanoantenna surfaces and are shown in Figure 1. The specific nature of folded proteins may be significant because folded proteins are associated with the development of degenerative diseases, such as Alzheimer’s - but further experiments are required to draw firmer conclusions. The outcomes from this research will benefit significantly to the wider audience in understanding and development of new medical diagnostic devices with a faster response and enhanced sensitivity