Single-platform, Attomolar Detection of Multiple Biomarkers by a Flexible SERS Sensor.

Early detection of Alzheimer's disease (AD) is critical for better healthcare management. Herein, we demonstrate a Surface Enhanced Raman Spectroscopy (SERS) active sensor for highly sensitive and selective detection of β-Amyloid Peptide (Aβ1-42 ), a biomarker of Alzheimer's disease. Polyacrylonitrile (PAN) nanofiber mats, containing purine-based ligand (L; 0 mg (P1 ), 50 mg (P2 ), and 100 mg (P3 )) were prepared by electrospinning followed by functionalization with silver nanoparticles (AgNPs). The fabricated SERS sensors were employed for the detection of Rhodamine 6G (Rh-6G) dye for optimization and the highest sensitivity was achieved on P3 /AgNPs SERS sensor. The P3 /AgNPs sensor was chosen for the detection of Aβ1-42 and human Insulin (HI). The limit of detection (LoD) was found to be 76×10-18 M and 26×10-18 M for Aβ1-42 and HI, respectively. The sensitivity achieved is one order improved for Aβ1-42 and four orders for HI when compared with reported values. Also, demonstrated the selectivity of the P3 /AgNPs sensor by testing a simulated cerebrospinal fluid (CSF) and achieved easily identifiable peaks of Aβ1-42 among the noise of HI and bovine serum albumin should be written before the acronym of BSA. This approach could be extended to develop ultra-sensitive flexible SERS sensors for the facile detection of multiple biomarkers on a single platform with excellent sensitivity, selectivity and stability.