A Novel Serum‐Based Diagnosis of Alzheimer's Disease Using an Advanced Phage‐Based Biochip

55 million people worldwide suffer from Alzheimer's disease (AD). A definitive diagnosis of AD is made postmortem after a neuropathological examination of the brain. There is an urgent need for an innovative, noninvasive methodology that allows for an early and reliable diagnosis. Several engineered phages that recognized Aβ‐autoantibodies present in the sera of AD patients are previously identified. Here, novel phages are tested for their ability to accurately discriminate AD sera using immunophage‐polymerase chain reaction in a miniatured biochip. It is found that five of the six phages analyzed discriminate between healthy controls and AD patients. Further, by combining the response of two phages, non‐AD and severe AD cases are identified with 100% accuracy and mild‐to‐moderate cases with 90% accuracy. While the number of cases used here are relatively small and can be confirmed in larger cohorts, this first‐of‐a‐kind system represents an innovative methodology with the potential of having a major impact in the AD field: from a clinical perspective, it can aid physicians in making an accurate AD diagnosis; from a research perspective, it can be used as a surrogate for AD clinical trials.