Colorimetric Detection of Mutant β-Amyloid(1–40) Membrane-Active Aggregation with Biosensing Vesicles

Abstract

Alzheimer’s disease (AD) is a protein misfolding disease commonly characterized by neuritic amyloid plaques and proteinaceous fibrillar aggregate deposits composed of β-amyloid (Aβ) aggregates. The dynamic aggregation of Aβ forms toxic, nanoscale aggregate species which proceed from oligomers to fibrils. Currently, there is need for rapid and direct detection of Aβ peptide aggregation and interaction with lipid membranes, as detecting an interaction with various lipid environments will provide insights to better understand how interactions may modulate membrane function on cellular surfaces, leading to the progression of AD. The goal of this study was to utilize a colorimetric, biomimetic, vesicle-binding assay as a biosensor to detect and investigate the occurrence of neurodegenerative disease-associated protein aggregation and interaction with lipid membranes. Lipid/polydiacetylene (PDA) vesicles were exposed to monomeric preparations of Wild Type Aβ(1–40) or point mutations in Aβ with amino acid substitutions that are commonly associated with familial AD (E22G Arctic, E22Q Dutch, A21G Flemish, D23N Iowa, and E22K Italian). We investigated how these substitutions affect Aβ(1–40) aggregation and interaction with lipid vesicles designed to mimic biological membranes. Time-resolved colorimetric measurements were obtained and reveal that exposure to lipid/PDA vesicle biosensors results in the direct detection of mutant Aβ(1–40) peptide–lipid interaction events. Aβ(1–40) peptide aggregate membrane activity varies among Aβ peptide variants and lipid composition. In addition, we used atomic force microscopy and Thioflavin T fluorescence assays to distinguish the stages of Aβ(1–40) aggregate formation, morphology, and membrane activity. These studies provide a simple means of aggregate detection and insight into the role of cellular surfaces in the mechanism of AD aggregation.

Biofunctionalized Graphene Quantum Dots Based Fluorescent Biosensor toward Efficient Detection of Small Cell Lung Cancer

“…Figure a shows the PL response of the anti-NSE/amine-N-GQDs@AuNPs nanocomplex for the different NSE antigen concentrations (0.1 pg mL –1 to 1000 ng mL –1 ). Fluorescence intensity of anti-NSE/amine-N-GQDs conjugate was found to recover linearly with increasing NSE antigen concentration (Figure b) and can be described by the eq : The PL intensity recovery can be attributed to the formation of immunocomplex arising due to the specific interaction of NSE antigen with anti-NSE antibody, which increases the distance between anti-NSE/amine-N-GQDs donor and AuNPs quencher resulting in the obstruction of the energy transfer process and hence gradual recovery of fluorescence. , Further, the limit of detection (LOD) was found to be 0.09 pg mL –1 calculated using the eq : where σ is the standard deviation, and S is the sensitivity of the fluorescent biosensor calculated using the slope of the calibration curve.…”

“…The PL intensity recovery can be attributed to the formation of immunocomplex arising due to the specific interaction of NSE antigen with anti-NSE antibody, which increases the distance between anti-NSE/amine-N-GQDs donor and AuNPs quencher resulting in the obstruction of the energy transfer process and hence gradual recovery of fluorescence. 48,49 Further, the limit of detection (LOD) was found to be 0.09 pg mL −1 calculated using the eq 6:…”

Consequence of Dementia and Cognitive Impairment by Primary Nucleation Pathway

“…It is at these interfaces that they start to self-assemble and the relative affinities of the various protein species (monomeric vs. oligomeric) for the interface and the extent to which the interfacially-associated monomer lowers the free energy barrier for nucleation determine how quickly primary heterogeneous nucleation can begin. Recent studies have shown that certain amyloidogenic IDPs, including tau, TDP-43, and -synuclein, can phase-separate from the aqueous solution, producing protein droplets, both in vitro and in vivo [76][77][78]. In such an environment, amyloid aggregation is a highly favorable process.…”

The Role of Amyloid β‐Biomembrane Interactions in the Pathogenesis of Alzheimer's Disease: Insights from Liposomes as Membrane Models

“…Recently, Dorsey and coworkers (2019) [22] also studied the interaction of Aβ 1–42 in the presence of various lipids. Three biomimetic systems composed of polydiacetylene (PDA) and BTLE (neutral extract), 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC) (zwitterionic phospholipid) or 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphoglycerol (DMPG) (anionic phospholipid) were used for this purpose.…”