Development of a new sensitive, antibody-free, and low-cost colorimetric assay for early detection of Alzheimer's disease

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The number of Alzheimer's disease (AD) patients worldwide is projected to increase to 152 million by 2050. AD is ranked as the fifth leading cause of death globally. Currently, available treatments are just for mitigating symptoms. Among AD biomarkers, amyloid-beta peptide (Abeta) has shown to be the most promising for the detection of AD. Current detection methods (e.g. ELISA) present inherited issues of cross-reactivity and lack of specific antibodies. Therefore, breakthroughs are required for the unequivocal detection of Abeta1-40 peptides at low concentrations, for early AD prevention/treatment. This project aims to develop a highly-sensitive, antibody-free and low-cost colorimetric method to detect Abeta1-40, based on gold nanoparticles(AuNPs)-Abeta-metal ion sandwich devices. Metal ions are used to improve the Abeta1-40 detection limit (nanoMolar levels). Several functionalised AuNPs and metal ions (e.g. nickel) will be trialled and the best combination (based on sensitivity and reproducibility) will be used to develop the colorimetric assay. The effectivity of AuNPs-Abeta-metal sandwich conjugates will be analysed by UV-Vis, nano-zetasizer, HR-ESI-MS, XPS, TEM and potentiometry. This low-cost biosensor will constitute a step-change in the early detection of AD, as a better alternative to ELISA. Additionally, green chemistry principles will be applied to the syntheses of functionalised gold nanoparticles and phosphonium ligand synthetic route.