Non-invasive screening for early Alzheimer's disease diagnosis by a sensitively immunomagnetic biosensor.

Amyloid-beta peptide 1-42 (Aβ42) is considered as a reliable biomarker for the early diagnosis of Alzheimer's disease (AD). Thus, it is urgent to develop a simple and efficient method for the detection of Aβ42. In this work, a reusable biosensor based on magnetic nitrogen-doped graphene (MNG) modified Au electrode for the detection of Aβ42 has been developed. The antibodies of Aβ 1-28 (Aβab) are used as the specific biorecognition element for Aβ42 that were conjugated on the surface of MNG. In the presence of magnetic nanoparticles on MNG, the electrode coating material, the biosensor can be quickly constructed, without requiring an electrode drying process, which reduce the analysis time and is convenient for proceeding to detection. The reusable biosensor with good reproducibility and stability was linear within the range from 5 pg mL(-1) to 800 pg mL(-1), covering the cut-off level of Aβ42 and a detection limit of 5 pg mL(-1) had been achieved. Furthermore, the fabricated biosensor for Aβ42 detection not only improves the detection performance but also reduces the cost and shortens the response time, demonstrating its potential in diagnosing applications.