Electrochemical aptamer-based nanobiosensors for diagnosing Alzheimer's disease: A review.

Diagnosis and prognosis of Alzheimer's disease by electrochemical nanoaptasensors have recently received abundant attention. In this review, all recent nanomaterial-based electrochemical aptasensors developed to diagnose or prognosis Alzheimer's disease have been collected, categorized, and reviewed. Analytes in these aptasensors were specific biomarkers, including amyloid-β (Aβ) and tau protein, as well as other nonspecific markers (microRNAs (miRNAs), dopamine, thrombin, adenosine triphosphate (ATP), interleukin-6, α-1 antitrypsin, α-synuclein, target DNA (tDNA), and glycated albumin). The synthesis methods of the applied nanomaterials, characterization, and applications have also been considered here. Gold nanostructures were the most nanomaterials applied in the structure of considered aptasensors. The use of the most optimal nanomaterials in the structure of these diagnostic tools has been dependent on various parameters, the most important of which are the type of signal transducer and the functional group related to the biorecognition element. In general, the choice of nanomaterials in these biosensors depends on interactions between nanomaterials and other molecules or environments. Indeed, with the assistance of nanomaterials, more expansive active surfaces have been created in the interactions of aptasensors components that have played a very positive and efficient role in amplifying the output signals and increasing the analytical/diagnostic sensitivity. The diagnostic mechanisms and the interaction between the various components of aptasensors and the nanomaterials' position were also considered. The main achievements were classification, analysis, and scheming of the elements and techniques used, the possibility of comparing detection range, and the limit of detection (LOD).