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

预计到2050年，全球阿尔茨海默病(AD)患者的数量将增加到1.52亿人。AD被列为全球第五大死因。目前，可用的治疗方法仅用于缓解症状。在AD生物标志物中，淀粉样β蛋白(Abeta)是检测AD最有前景的标志物。目前的检测方法(如酶联免疫吸附试验)存在交叉反应和缺乏特异性抗体的遗传性问题。因此，需要取得突破，以明确检测低浓度的Abeta1-40肽，以便早期预防/治疗AD。本项目旨在开发一种高灵敏度、无抗体、低成本的比色方法来检测Abeta1-40，基于金纳米颗粒(AuNPs)-Abeta-金属离子夹心装置。金属离子用于提高Abeta1-40的检测下限(纳摩尔水平)。将试验几种功能化的AuNPs和金属离子(例如镍)，并将使用最佳组合(基于灵敏度和重现性)来开发比色分析。利用UV-Vis、纳米Zetasizer、HR-ESI-MS、XPS、透射电子显微镜和电位法对Au-NPs-Aβ-金属夹心结合物的有效性进行了分析。这种低成本的生物传感器将构成AD早期检测的一步改变，作为一种更好的替代ELISA。此外，绿色化学原理还将应用于功能化金纳米颗粒的合成和膦配体的合成路线。

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.