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Umesh Chandra Garnaik,1 Anshuman Chandra,1 Vijay Kumar Goel,1 Balázs Gulyás,2 Parasuraman Padmanabhan,2 Shilpi Agarwal1 1School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India; 2Cognitive Neuroimaging Centre, Nanyang Technological University (NTU), Singapore, SingaporeCorrespondence: Shilpi Agarwal, Optics and Photonics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi, 110067, India, Email shilpiagarwal@mail.jnu.ac.in Parasuraman Padmanabhan, Cognitive Neuroimaging Centre, Nanyang Technological University (NTU), Singapore, 636921, Singapore, Email ppadmanabhan@ntu.edu.sgPurpose: Development of SERS-based Raman nanoprobes can detect the misfolding of Amyloid beta (Aβ) 42 peptides, making them a viable diagnostic technique for Alzheimer’s disease (AD). The detection and imaging of amyloid peptides and fibrils are expected to help in the early identification of AD.Methods: Here, we propose a fast, easy-to-use, and simple scheme based on the selective adsorption of Aβ 42 molecules on SERS active gold nanoprobe (RB-AuNPs) of diameter 29 ± 3 nm for Detection of Alzheimer’s Disease Biomarkers. Binding with the peptides results in a spectrum shift, which correlates with the target peptide. We also demonstrated the possibility of using silver nanoparticles (AgNPs) as precursors for the preparation of a SERS active nanoprobe with carbocyanine (CC) dye and AgNPs known as silver nanoprobe (CC-AgNPs) of diameter 25 ± 4 nm.Results: RB-AuNPs probe binding with the peptides results in a spectrum shift, which correlates with the target peptide. Arginine peak appears after the conjugation confirms the binding of Aβ 42 with the nanoprobe. Tyrosine peaks appear after conjugated Aβ 42 with CC-AgNPs providing binding of the peptide with the probe. The nanoprobe produced a strong, stable SERS signal. Further molecular docking was utilized to analyse the interaction and propose a structural hypothesis for the process of binding the nanoprobe to Aβ 42 and Tau protein.Conclusion: This peptide–probe interaction provides a general enhancement factor and the molecular structure of the misfolded peptides. Secondary structural information may be obtained at the molecular level for specific residues owing to isotope shifts in the Raman spectra. Conjugation of the nanoprobe with Aβ 42 selectively detected AD in bodily fluids. The proposed nanoprobes can be easily applied to the detection of Aβ plaques in blood, saliva, and sweat samples.Keywords: Alzheimer’s disease, nanoparticles, amyloid beta, surface enhanced Raman spectroscopy |
