Zhiliang Jiang

Resonance scattering detection of trace microalbumin using immunonanogold probe as the catalyst of Fehling reagent-glucose reaction.

A novel and sensitive resonance scattering (RS) spectral immunoassay for the determination of microalbumin (Malb) was developed, based on the catalytic effect of immunonanogold (ING) probe on Fehling reagent-glucose reaction, and resonance scattering effect of Cu(2)O particles. Nanogold particles in size of 10nm were used to label goat anti-human microalbumin (GMalb) to obtain an ING probe (AuGMalb) for Malb. The probe produced unspecific aggregation in pH 5.0 citric acid-Na(2)HPO(4) buffer solutions. Upon addition of Malb, the dispersed ING complex formed. The ING complex in supernatant was obtained by centrifuging and was used as catalyst for the reaction between Fehling reagent and glucose to form the Cu(2)O particles to amplify the resonance scattering signal at 610 nm. With addition of Malb, the ING complex in the supernatant increased and the RS intensity at 610 nm (I(610 nm)) enhanced linearly. The enhanced intensity DeltaI(610 nm) was proportional to the Malb concentration in the range of 0.014-0.43 ng ml(-1), with a detection limit of 7.2 pg ml(-1). The proposed method was applied to detect Malb in human urine sample with satisfactory results.

A highly sensitive resonance scattering spectral assay for IgG using Fehling reagent–glucose–immunonanogold reaction

Nanogold exhibits strong catalytic effect on the slow reaction between glucose and Fehling reagent at 70 degrees C. The production of Cu(2)O particles have two stronger resonance scattering (RS) peaks at 390 nm and 505 nm. The catalytic effect of nanogold-labeled goat anti-human IgG (AuIgG) on the reaction was investigated with the RS technique. Coupled the immunoreaction and the immunonanogold catalytic reaction and centrifugal technique, a highly sensitive and selective RS method was developed for the detection of immunoglobulin G (IgG) as a model. With the concentration of IgG increased, the RS intensity at 505 nm decreased. The decreased intensity at 505 nm DeltaI(505)(nm) was proportional to IgG concentration in the range of 0.13-53.3 ng mL(-1), with a detection limit of 0.04 ng mL(-1) IgG. This new immunonanogold-catalytic Cu(2)O-particle RS bioassay was applied to the determination of IgG in serum sample, with high sensitivity, good selectivity, and low cost.