A simple resonance Rayleigh scattering method for determination of trace CA125 using immuno-AuRu nanoalloy as probe via ultrasonic irradiation

Abstract

AuRu nanoalloy (GR) with Au/Ru molar ratio of 32/1 was prepared by the sodium borohydride reduction method. It was used to label the CA125 antibody (Ab) to obtain an immunonanoprobe (GRAb) for cancer antigen 125 (CA125). In pH 7.0 citric acid–Na2HPO4 buffer solution and irradiation of ultrasound, the probes were aggregated nonspecifically to big clusters that showed a strong resonance Rayleigh scattering (RRS) peak at 278nm. Upon addition of CA125, GRAb reacted specifically with CA125 to form dispersive immunocomplexes of CA125–GRAb in the solution and this process enhanced by the ultrasonic cavitation effect, which led to the RRS intensity decreased greatly. The decreased RRS intensity was linear to the concentration of CA125 in the range of 1.3–80U/mL, with a detection limit of 0.6U/mL. The proposed method was applied to detect CA125 in real sample, with satisfactory results.