Biosensing: The best alternative for conventional methods in detection of Alzheimer's disease biomarkers.

Conceivably the imperative reason for the absence of appropriate treatment for Alzheimer's disease (AD) is the late onset of clinical symptoms followed by late treatment. Specific biomarkers play a vital role in this area. The amyloid-beta peptide, tau protein and micRNA, are the most important biomarker associated in AD. There are many routine methods for identifying these biomarkers which molecular based methods with a high accuracy and sensitivity have been considered. These methods have some limitations such as; false positive and negative results, problem on the interpretation, complexity and time-consuming, high cost instruments and etc. To overcome these limitations, bioassays were developed extensively. There exist a multitude of possible applications for Alzheimer's disease biomarkers by using biosensors. This review mainly focuses on major biomarkers in Alzheimer's disease, routine and old methods in identifying biomarkers of AD and their advantages and limitation, and biosensors to the identification of amyloid beta, tau protein and micRNAs biomarkers. Furthermore, evaluation the strengths and weaknesses of the developed bioassays and introduce leading challenges are considered in this review.