Catalytic effect of ReAu nanoalloy on the Te particle reaction and its application to resonance scattering spectral assay of CA125

ABSTRACT ReAu nanoparticles with a molar ratio of 2:8 Re and Te nanoparticles were prepared by NaBH4 reduction. In HCl medium at 65°C, ultratrace Re, Te and ReAu bimetallic nanoparticles strongly catalyzed the slow reaction between Sn(II) and Te(VI) to form Te particles, which exhibited the strongest resonance scattering (RS) peak at 782 nm. As the amount of nanocatalyst increased, the RS intensity at 782 nm (I782 nm) increased linearly, and the increase in intensity ΔI782 nm was linear to the ReAu, Re and Te concentrations in the ranges 0.07–9.0, 0.01–4.5 and 30–1200 nm, respectively. As a model, a ReAu immunonanoprobe catalytic Te–particle resonance scattering spectral (RSS) method was established for detection of CA125, using ReAu nanoparticle labeling CA125 antibody (CA125Ab) to obtain an immunonanoprobe (ReAuCA125Ab) for CA125. In pH 7.6 citric acid–Na2HPO4 buffer solution, ReAuCA125Ab aggregated nonspecifically. Upon addition of CA125, the immunonanoprobe reacted with it to form ReAuCA125Ab–CA125 dispersive immunocomplex in the solution. After the centrifugation, the supernatant containing the immunocomplex was used to catalyze the reaction of Te(VI)–Sn(II) to produce the Te particles that resulted in the I782 nm increasing. The ΔI782 nm was linear to CA125 concentration (CCA125) in the range 0.1–240 mU/mL. The regression equation, correlation coefficient and detection limit were ΔI782 nm = 1.61 CCA125 + 1.5, 0.9978 and 0.02 mU/mL, respectively. The proposed method was applied to detect CA125 in serum samples, with satisfactory results. Copyright © 2010 John Wiley & Sons, Ltd.