SERS based optical sensor to detect prion protein in neurodegenerate living cells

The prion proteins and their interaction with copper ion represent a suitable marker in neurodegenerative disorders. A SERS based optical sensor has been developed in order to detect and quantify the prion proteins (PrPC) onto the cell membrane using the higher binding affinity of such proteins for copper ions. A combined method of hydrothermal “green” synthesis and thermal treatment allows us to obtain impurity-free surfaces for SERS measurement, suitable for cell growth. The plasmon absorption of the gold nanostructures was monitored by UV–vis spectrometry. The most significant red shift in the longitudinal plasmon resonance absorption of gold nanostructures was maximized in order to achieve the highest electromagnetic enhancement in Raman measurements. Our SERS based optical sensor has been used to detect and quantify the PrPC–Cu2+ interaction in vitro as a function of copper concentration and time in a rat neuroblastoma cell line (B104) and in three other cell models (SH-SY5Y, GN11, HeLa), expressing PrPC at different levels. The proposed methodology can be engineered in order to obtain an extremely fast and low-cost diagnostic tool to evaluate the subject's proneness to incur neurodegenerative processes.