Stability of plasma amyloid‐β 1‐40, amyloid‐β 1‐42 and total Tau protein over repeated freeze/thaw cycles

Abstract Background Blood biomarkers of Alzheimer’s disease (AD) attract much attention researchers recently. In clinical studies, repeated freeze/thaw cycles often occur and may influence the stability biomarkers. This study is to investigate amyloid‐β 1‐40 (Aβ ), 1‐42 ) total Tau protein (T‐Tau) in plasma over cycles. Method Plasma samples from healthy control (HC, n = 3), AD patients (AD, 3) Parkinson’s (PD, were collected by standardized procedure, immediately frozen at ‐80 °C. Samples underwent 5 (‐80°C/room temperature) The concentrations Aβ , T‐Tau monitored during tests using immunomagnetic reduction (IMR) assay. relative percentage (%) after every cycle was calculated for each biomarker. Result A tendency decrease averaged percentages through freeze thaw (100 97.37%), 95.56%) 96.42%) found. However, decreases are less than 5%. For all three biomarkers, no statistical significance found between levels fresh that experiencing five (p > 0.1). Conclusion 1‐40, stable measured with IMR.