Label-free Monitoring of Alzheimer's Disease Biomarkers in Cerebrospinal Fluid

This paper reports for the first time the monitoring of two types of promising biomarkers, beta-amyloid (A beta 42) and total tau (T-tau), in both buffer and cerebrospinal fluid from pooled Human donors for Alzheimer's disease (AD) using label-free optical nanosensors. Experiments found that as low as similar to 15.6 pg/ml of A beta 42 in buffer can be readily detected by the sensor with very good specificity. A beta 42 spiked in commercially available cerebrospinal fluid (CSF) has been detected successfully. Based on our measurements, the purchased CSF itself contains A beta 42, whose concentration is estimated to be about 400 pg/ml by our measurements. We also have demonstrated the detection of a mixture of A beta 42 and T tau in CSF successfully, indicating the feasibility of the optical nanosensors to detect these biomarkers in clinic samples.