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 (Aβ42) 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 ∼15.6 pg/ml of Aβ42 in buffer can be readily detected by the sensor with very good specificity. Aβ42 spiked in commercially available cerebrospinal fluid (CSF) has been detected successfully. Based on our measurements, the purchased CSF itself contains Aβ42, whose concentration is estimated to be about 400 pg/ml by our measurements. We also have demonstrated the detection of a mixture of Aβ42 and T-tau in CSF successfully, indicating the feasibility of the optical nanosensors to detect these biomarkers in clinic samples.