VG@nAu-based fluorescent biosensor for grading Alzheimer's disease by detecting P-tau181 protein in clinical samples.

Background: Alzheimer's disease (AD) is a neurodegenerative disorder with a very long duration, posing a serious threat to people's life and health. To date, no medicine that can cure or reverse the disease has been developed or reported, so early diagnosis and timely intervention are essential. The concentration of Phosphorylated tau181 (P-tau181) in blood has been approved by FDA as a standard for assisting clinical diagnosis of AD.

Results: In this study, a fluorescence biosensor based on vertical graphene-modified nano-gold film (VG@nAu) was developed for the grading of AD diagnosis by detecting P-tau181 protein in the blood. The VG@nAu substrate that produces hundreds of times IR800 molecular compared with a glass substrate, which is prepared by sputtering nano-gold onto vertical graphene surface. The detection limit of this fluorescence biosensor for P-tau181 is 0.82 pg/mL. The sensor also shows excellent selectivity and stability. Moreover, we analyzed the levels of P-tau181 in 16 clinical samples divided into four groups (HC group, SCD group, MCI group, and AD group) and found significant differences in P-tau181 levels. The grouping result based on the detection results using this biosensor is consistent with the grouping results of the clinical doctors.

Significance: This study achieves ultrasensitive detection of P-tau181 protein by constructing a fluorescent biosensor, which validates the feasibility of the VG@nAu-based fluorescence biosensor for the grading of AD diagnosis. This research provides a promising tool for ultrasensitive detecting biomarkers in clinical samples, indicating significant potential for its use in related diagnosing disease.