Molecular Biomarkers for Early Detection of Alzheimer’s Disease and the Complementary Role of Engineered Nanomaterials: A Systematic Review

Alzheimer’s disease (AD) instantly requires affordable diagnostic tools for targeting the responsible molecular biomarkers. In this review, we briefly discussed the overview of the AD population, performance of different analytical techniques and nanoparticles/composites, molecular biomarkers, and the interest of countries towards the detection of AD biomarkers during 2012–2025. The desired result was attained by lateral flow assay, surface-enhanced Raman scattering, and colorimetric sensor techniques with nanoparticles of magnetic, gold, and carbon-containing silver, and iridium oxide nanoparticles, upon biomarkers of dopamine, amyloid beta41, and Apolipoprotein E, individually. Additionally, the outstanding performance of nanoparticles including gold nanoparticles, carbon-containing nanoparticles, and manganese dioxide with their particle size of 5.7 nm, 35 nm, 37.3 nm, 120 nm, and 220 nm, respectively, has been discussed. Moreover, the percentages of AD-related biomarkers including amyloid beta42 having research articles of 21.2%, amyloid beta1-42 12.1%, amyloid beta oligomer 12.1%, phosphorylated Tau detection 12.1%, amyloid beta1-40 9.09%, Dopamine 9.09%, amyloid beta40 9.17%, apolipoprotein 6.06%, etc., have also been included. Additionally, LOD comparison with respect to applied analytical techniques, investigated through a timeline and electrochemical sensor, was found most suitable. Finally, a portable molecular diagnostic device to combine amyloid beta1-42, amyloid beta1-40, and phosphorylated Tau detection in non-invasive bodily fluid was proposed for the future and clinical diagnosis.