Laser-based double beam absorption detection for aggregation immunoassays using gold nanoparticles

Abstract

A laser-based double beam absorption detection system for aggregation immunoassays has been developed. The assay was based on the aggregation of gold nanoparticles that are coated with protein antigens in the presence of their corresponding antibodies. The aggregation of the gold nanoparticles results in an absorption change that is monitored at 635 nm using the double beam spectrometer. The noise level of the spectrometer is 1×10 -6 arbitrary units. This corresponds to a tenfold improvement in comparison to commercial absorption detectors and is comparable with previously reported more complicated laser-based absorption spectrometers. The dye Nile-Blue-A was used to test the analytical performance of the system. A limit of detection of 3×10 -8 M Nile-Blue-A was observed. The relative standard deviation between consecutive measurements was lower than 1.5%. The system is suitable for field applications of aggregation-based immunoassays.

Integrated Nanoparticle–Biomolecule Hybrid Systems: Synthesis, Properties, and Applications

“…A laserbased double-beam absorption detection system for aggregation immunoassays has been developed. [133,134] The assay was based on the aggregation of gold NPs, which were coated with protein antigens, in the presence of the corresponding antibodies. The aggregation of the gold NPs resulted in a change in the absorption bands which enabled the assay to be monitored at 635 nm with a detection limit for an antibody of 3 10 À8 m. A rapid immunoassay for the detection of an analyte within complex biological media without any sample preparation was demonstrated with gold nanoshells, namely, layered dielectric-metal NPs, whose optical resonance is a function of the relative size of their constituent layers.…”

Integrierte Hybridsysteme aus Nanopartikeln und Biomolekülen: Synthese, Eigenschaften und Anwendungen

“…Basierend auf der Aggregation von Nanopartikeln durch Antigen‐Antikörper‐Wechselwirkung in Lösung wurden Immunassays mit optischer Detektion entwickelt, z. B. ein lasergestütztes Doppelstrahlsystem zur Absorptionsmessung 133. 134 Der Assay basiert auf der Aggregation von Gold‐Nanopartikeln, die mit Proteinantigenen beschichtet waren, durch die zugehörigen Antikörper.…”

High power Bragg reflection waveguide diode lasers with twin near-circular emission spots

“…The double well-correlated laser beams can be used as signal and reference beams respectively in order to eliminate the noise in high sensitivity measurements [5]. Some approaches have been proposed to split an incident beam into two beams, including diffraction grating, nondegenerate optical parametric oscillator [8], external feedback [9] etc.…”

“…High power diode laser with ultra-stable twin beams output is very attractive as a light source for a wide variety of applications such as the high speed laser scanning [1,2], high precision laser detection [3][4][5] and high quality laser processing [6,7]. The double well-correlated laser beams can be used as signal and reference beams respectively in order to eliminate the noise in high sensitivity measurements [5].…”