Chip-Based Chiral 3D Metamaterial with Functional Core-Shell Architecture for Femtomolar Biodetection

Abstract

Advanced sensing tools capable to detect extremely low concentrations of circulating biomarkers can open unexplored routes towards early diagnostics of diseases and their progression monitoring. Plasmonic sensors are an emerging technology enabling different optical effects that can be used as molecular tracking solutions. Here we demonstrate the sensing capabilities of a chip-based metamaterial, combining the 3D chiral geometry with an optically functional core-shell architecture. The sensor can be easily handled and exhibits reliability and stability during the whole functionalization and analytical procedure thanks to the on-chip format. The system shows a linear shift of circular dichroism spectrum upon interaction with different concentrations of TAR DNA-binding protein TDP-43, a clinically relevant biomarker for neurodegenerative disease screening. The measurements were performed in spiked solution as well as in human serum, with concentrations from 1pM down to 10fM, a range not accessible with commonly used immunological assays and that can thus open new perspectives for disease knowledge and early diagnostics.

Trends of Biosensing: Plasmonics through Miniaturization and Quantum Sensing

“…Surfaces with chiral properties are a specific type of metasurface, and since chirality is a crucial aspect of the molecular domain, these highly functional surfaces play a crucial role in biosensing; DNA, proteins, and numerous synthetic pharmaceutical compounds used in therapy, all contain chirality. The integration of a functional core-shell nanoarchitecture in a fluid chip enabled the achievement of picomolar sensitivity, which is relevant for the study of neurodegenerative diseases [58] . The proposed configuration exhibits significant flexibility by using a conformal coating with a polymer shell that modifies the near-and far-field optical response of the chiral metamaterial as a result of energy transfer between the polarization charges of the dielectric shell and a free electron of the plasmonic core.…”