  Highly sensitive and selective label free devices for real-time
identification of specific biomarkers are expected to significantly impact the
biosensing field. The ability of plasmonic systems to confine the light in
nanometer volume and to manipulate it by tuning the size, shape and material
features of the nanostructures, makes these systems promising candidates for
biomedical devices. In this work we demonstrate the engineered sensing
capabilities of a compact array of 3D metal dielectric core-shell chiral
metamaterial. The intrinsic chirality of the nano-helices makes the system
circular polarization dependent and unaffected by the background interferences,
allowing to work even in complex environment. The core-shell architecture
enhances the sensing properties of the chiral metamaterial on both in the far
and near field, offering also a large surface to molecular immobilization. With
our system we recorded sensitivity of about 800nm/RIU and FOM= 1276 RIU-1. The
sensing abilities of the system is demonstrated with the detection of the of
the TAR DNA-binding protein 43 (TDP-43) , a critical biomarker for the
screening of neurodegenerative diseases. In particular, the sensor was tested
in different environments, such as human serum, with concentrations ranging
from 1pM down to 10fM, opening new perspectives for novel diagnostic tools.
