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Abstract: Nanogold exhibits strong catalytic effect on the slow reaction between glucose and Fehling reagent at 70°C. The production of Cu2O particles have two stronger resonance scattering (RS) peaks at 390nm and 505nm. 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 505nm decreased. The decreased intensity at 505nm ΔI 505 nm was proportional to IgG concentration in the range of 0.13–53.3ngmL−1, with a detection limit of 0.04ngmL−1 IgG. This new immunonanogold–catalytic Cu2O–particle RS bioassay was applied to the determination of IgG in serum sample, with high sensitivity, good selectivity, and low cost. [Copyright &y& Elsevier]

Abstract: Gold nanoparticles in size of about 10nm was used to label goat anti-human complement 3 (anti-C3) to obtain a sensitive and selective immunoresonance scattering spectral probe for C3. It was based on the immune reaction between labeled anti-C3 and C3 in the pH 5.6 Na2HPO4–citric acid buffer solutions and in presence of polyethylene glycol (PEG). The resonance scattering (RS) intensity at 560nm enhanced greatly with C3. Well linear relationships between the enhanced RS intensity (△I RS) and the C3 concentration in the range of 8.33–200ngml−1 were obtained, with a detection limit of 2.8ngml−1 and the limit of quantification 8.51ngml−1 for C3. The convenient and selective and sensitive assay was applied to quantification of C3 in human sera, with satisfactory results. [Copyright &y& Elsevier]

A new catalytic kinetic method has been proposed for the determination of Se from 8.0×10−9 to 8.0×10−8 M, using the fact that Se(IV) can catalyze the slow reaction between KClO3 and phenylhydrazine sulfate (PH) in 0.1 M H2SO4 solution at 100 °C. The reduction product of ClO3−, Cl−, reacts with Ag+ to form (AgCl)n nanoparticles. The nanoparticles exhibit a maximum resonance scattering spectral peak at 470 nm. The intensity of resonance scattering light at 470 nm is linear with respect to the Se concentration, using the fixed-reaction time procedure. The factors influencing the determination of Se were examined. This catalytic resonance scattering spectral method has been applied to the analysis of Se in real samples, with satisfactory results. [Copyright &y& Elsevier]

Abstract: Gold nanoparticles in diameter of 10nm were used to label rabbit anti-human chorionic gonadotrophin (RhCG) antiserum to obtain a resonance scattering spectral probe (AuRhCG) for human chorionic gonadotrophin (hCG). The immunoreaction between AuRhCG and hCG take place to form hCG–AuRhCG immunocomplex in pH 5.0 citric acid–Na2HPO4 buffer solution. The immunocomplex solutions were centrifuged to obtain the supernatant solution. The AuRhCG in the supernatant solution exhibited strong catalytic effect on the particle reaction between Ag+ and hydroquinone to produce gold–silver composite particles in pH 3.4 citric acid–trisodium citrate buffer solution. There is a stronger resonance scattering (RS) peak at 423nm for the particles. With the addition of hCG, the AuRhCG in the supernatant solution decreased, and the RS intensity at 423nm decreased. The decreased RS intensity ΔI 423nm was proportional to the concentration of hCG in the range of 2.5–208.3mIU/mL with a detection limit of 0.83mIU/mL. This method has been applied to the determination of hCG in urine samples, with satisfactory results. [Copyright &y& Elsevier]

Abstract: A gold-labeled immunoresonance scattering spectral probe for trace prealbumin (PA) was prepared by using gold nanoparticles in size of 9.0nm to label goat anti-human prealbumin polyclonal antibody. The immune reaction between the gold-labeled antibody and prealbumin took place in pH 7.6 Na2HPO4–NaH2PO4 buffer solution. In the presence of polyethylene glycol PEG-10000, the labeled gold nanoparticles were released and aggregated which brought the resonance scattering intensity (I RS) at 580nm to enhance greatly. The ΔI RS is proportional to the prealbumin concentration in the range from 16.67 to 666.67ng/mL, with a detection limit of 4.1ng/mL. This simple, sensitive and selective assay was applied to determination of prealbumin in human plasma, with satisfactory results. [Copyright &y& Elsevier]