▎ 摘　　要

Alzheimer's disease (AD), and its consequent effect primarily clinical dementia, Parkinson's disease dementia, etc. currently bring potential avenues for diagnosis centered on identification of beta-amyloid1-42 (A beta 1-42). Unfortunately, techniques engaged in AD core biomarker (A beta 1-42) detection are majorly suffering from poor sensitivity and selectivity. Thus, we fabricated graphene oxide (GO) surface decorated chitosan (CS) mediated layer-by-layer (LbL) assembly based surface plasmon resonance (SPR) biosensor for highly sensitive and selective recognition of A beta 1-42. Briefly, silver nanoparticles (AgNPs) and GO synthesis were achieved through a greener approach. LbL assembly was designed using CS and polystyrene sulphonate (PSS) on surface of AgNPs (AgNPsCS-PSS-CS) and then antibodies of A beta (anti-A beta) were fixed on LbL assembly (AgNPs-CS-PSS-CS@anti-A beta). Herein, amine functionality of CS offers a plethora of sites for anti-A beta antibody immobilization that gives specific direction, high selectivity, and an adequate amount of antibody immobilization. For fabrication, synthesized GO was immobilized on an amine-modified gold-coated sensor chip via carbodiimide chemistry followed by AgNPsCS-PSS-CS@anti-A beta immobilization on an activated GO surface. Inimitable features of LbL assembly showed improved selectivity towards A beta peptide whereas utilization of affinity biotransducer with a combination of plasmonic and non-plasmonic nanomaterial improved sensitivity and selectivity. Consequently, linearity range and limit of detection (LOD) of A beta 1-42 antigens were found to be 2 fg/mL to 400 ng/mL and 1.21 fg/mL, respectively. Moreover, analysis of A beta 1-42 in AD-induced rats confirmed the real-time-applicability of the designed SPR biosensor. Hence, GO surface decorated AgNPs-CS-PSS-CS@anti-A beta mediated SPR biosensor would provide a novel approach for exceptionally sensitive and selective A beta detection.