Detection of a Biomarker for Alzheimer's Disease from Synthetic and Clinical Samples Using a Nanoscale Optical Biosensor

Abstract

A nanoscale optical biosensor based on localized surface plasmon resonance (LSPR) spectroscopy has been developed to monitor the interaction between the antigen, amyloid-beta derived diffusible ligands (ADDLs), and specific anti-ADDL antibodies. Using the sandwich assay format, this nanosensor provides quantitative binding information for both antigen and second antibody detection that permits the determination of ADDL concentration and offers the unique analysis of the aggregation mechanisms of this putative Alzheimer's disease pathogen at physiologically relevant monomer concentrations. Monitoring the LSPR-induced shifts from both ADDLs and a second polyclonal anti-ADDL antibody as a function of ADDL concentration reveals two ADDL epitopes that have binding constants to the specific anti-ADDL antibodies of 7.3 x 10(12) M(-1) and 9.5 x 10(8) M(-1). The analysis of human brain extract and cerebrospinal fluid samples from control and Alzheimer's disease patients reveals that the LSPR nanosensor provides new information relevant to the understanding and possible diagnosis of Alzheimer's disease.

Localized Surface Plasmon Resonance Nanosensor: A High-Resolution Distance-Dependence Study Using Atomic Layer Deposition

“…These measurements reveal that the Al 2 O 3 deposits on the LSPR Ag surface in a layer-bylayer fashion and the initial nucleation may proceed via the thermal decomposition of trimethylaluminum (TMA) on Ag. 4 OH in order to create a hydrophilic surface on the substrate to facilitate self-assembly of the nanosphere masks. Finally, the substrates were rinsed and stored in water for future use.…”

Accurate Elemental Analysis of Metal‐Containing Polymer Latexes Using ICP‐Optical Emission Spectrometry

“…The evolution of nanotechnology and its promises for technological advance has led to a tremendous interest in colloidal sciences as colloidal or nanoparticles are highly promising candidates for a rich variety of applications, including fields as diverse as catalysis, [1,2] colorants, [3] photonics, [4,5] modern lithographic techniques, [6][7][8][9] as well as biomedical approaches to diagnostics, [10,11] and therapy. [12,13] While some of these applications only require plain inorganic or polymeric nanoparticles, e.g., catalysis, lithography, or the formation of photonic crystals, an increasing number of applications make use of functional nanocomposite particles.…”

Synthesis of gold-poly (dimethylsiloxane) nanocomposite through a polymer-mediated silver/gold galvanic replacement reaction

“…Synthesis of various noble metal nanostructures has been an active area for decades, because of their interesting properties and their importance to a variety of applications such as photonics, SERS, optoelectronics, catalysis and chemical & biological sensing [1][2][3][4]. By controlling the size, shape, and composition (in the case of bimetallic nanoparticles), their properties can be tailored.…”

“…This reaction is based on the reduction potential difference between silver and gold (AuCl 4 -/Au is 0.99V, which is higher than Ag + /Ag = 0.8V) that allows the oxidation of Ag nanostructures by the solution of the gold salt. The gold that results in the replacement reaction grows on the silver template adopting its morphology and forms a thin shell around it.…”

“…This intriguing result suggests that silver nanoparticles, if formed in the process, are transformed immediately to gold by a galvanic replacement reaction. Preliminary spectral results have shown that, when a Ag-PDMS composite film is incubated in a HAuCl 4 solution, Ag will be gradually replaced by gold, the reaction proceeding through several intermediate states. The aim of this work is to investigate in depth the Ag/Au galvanic replacement reaction at the PDMS/aqueous solution interface and to obtain further insights about the mechanisms responsible for the morphological and spectral changes involved in this process.…”