Statistically quantified measurement of an Alzheimer's marker by surface-enhanced Raman scattering

Fibrillar forms of the Amyloid- (A) protein have been implicated in the early stages of Alzheimer's disease (AD), however there are no standardised assays for soluble A oligomer biomarkers that provide the best indication of the disease progression [1,2]. As a step towards a fast and label-free method for testing different AD biomarkers, we have combined laser nano-textured substrates with a SERS mapping technique and validated it using soluble A-40 oligomers [3-5]. The nano-textured SERS substrates provide fast (&5min), label-free spectra associated with soluble A-40 oligomers down to a concentration of 10 nM. Statistical analysis of the spectral intensities mapped over the substrate surface shows a quantitative correlation with the oligomer concentration.