Effect of colloidal ß-cyclodextrins-Fe3 O4 magnetic nanoparticles on the chemiluminescence enhancement of luminol-Ag(III) complex for rapid and sensitive determination of cysteine in human serum.

ABSTRACT

Colloidals solution of Fe3 O4 magnetic nanoparticles (MNPs), capped with ß-cyclodextrins (ß-CD) as inclusion complexes, were found to enhance the chemiluminescence (CL) intensity of the luminol-diperiodatoargentate(III) (DPA) system. On injection of cysteine into the luminol-DPA-ß-CD-Fe3 O4 MNPs inclusion complexes system, the CL intensity is strongly enhanced. The enhanced CL signal is ascribed to the catalytic effect of Fe3 O4 MNPs capped with ß-CD, which is assumed to stabilize the CL intermediate. Based on these findings, a rapid and sensitive assay was developed for the determination of cysteine in human serum. The effects of analytical variables on the CL signal were studied and optimized. Under the optimum conditions, the CL intensity was directly proportional to the concentration of cysteine in the range 8.0 × 10(-9) -1.0 × 10(-6) mol/L. The detection limit was 2.8 × 10(-9) mol/L (3 S(b) /m) and the relative standard deviation (RSD) for 10 replicate determinations of 1.0 × 10(-7) mol/L cysteine was 3.5%. The proposed method was applied to the sensitive determination of cysteine in human serum samples, and compared with the Ellman method with satisfactory results.