Abstract: Hemin aptamer was used to modify gold nanoparticles (AuNPs) to obtain a stable aptamer-nanogold probe (AussDNA).In the condition of pH8.0 Tris-HCl buffer solution containing 50 mmol/L NaCl,the substrate chain of AussDNA was cracked by hemin to produce a short single-stranded DNA (ssDNA) and then further combine with hemin to form a stable hemin-ssDNA conjugate.The AuNPs released from AussDNA would be aggregated in the condition of 50 mmol/L NaCl and exhibited a strong resonance Rayleigh scattering (RRS) peak at 367.6 nm.Under the selected conditions,the increased RRS intensity (ΔI_{367.6 nm}) was linear to hemin concentration in the range of 5～750 nmol/L,with a regression equation of ΔI_{367.6 nm}=2.4C-144.4,coefficient of 0.982 9,and a detection limit of 66 pmol/L.This RRS method was applied to determination of residual hemin in serum samples,with satisfactory results.The remnant AussDNA in the solution exhibited a strong catalytic activity on the Cu₂O particle reaction of Fehling reagent-glucose that can be monitored by RRS technique at 370 nm.When the hemin concentration increased,the AussDNA decreased,the catalysis decreased,and the RRS intensity at 370 nm decreased.The decreased RRS intensity ΔI_{370 nm} was linear to the hemin concentration in the range of 0.25～200 nmol/L,with a regression equation of ΔI_{370 nm}=5.5C+78,coefficient of 0.971 9,and a detection limit of 17 pmol/L.Accordingly,a sensitivity,selectivity,and simplicity new method of resonance Rayleigh scattering spectra to detect hemin using aptamer-modified nanogold as catalyst was established.

Key words: hemin, aptamer, nanogold catalysis, Cu₂O particle, resonance Rayleigh scattering