以没食子酸为还原剂和稳定剂,用种子生长法制备出粒径均匀、单分散性和稳定性好、近球形的Ag/Au 核壳纳米粒子.高分辨透射电镜(HRTEM)与 X-射线能量色散光谱仪(EDX)测试表明,在Ag/Au摩尔比为1:1.6时,Au已完全包裹在Ag纳米粒子表面时,平均粒径为25 nm.以此摩尔比制备的Ag/Au核壳纳米粒子为探针用共振瑞利散射光谱测定人血清总蛋白,在NaAc-HAc缓冲液(pH 4.4)及0.05 mol/L NaCl介质中,Ag/Au核壳纳米粒子与HSA形成稳定的复合物;Ag/Au-HSA纳米复合物的相对散射强度ΔI390 nm与HSA浓度在0.0011～0.35 mg/L范围内呈线性关系,其回归方程为ΔI390 nm＝-0.54+494.82c(r＝0.9994),检出限为0.36 μg/L.本方法有较好的选择性,可用于人血清蛋白分析,结果与考马斯亮蓝G-250法一致,回收率在98.2%～102.3%之间,相对标准偏差为2.3%.%Nearly spherical Ag/Au core/shell nanoparticles with good monodispersity and stability were synthesized in aqueous solution by seed growth method using gallic acid as reductant and stabilizer. High resolution transmission electron microscopic (HRTEM) image and energy dispersive X-ray spectrometry (EDX) showed complete coating of gold on the surface of Ag nanoparticles and the presence of Au and Ag in individual nanoparticle with the average size of about 25 nm. The Ag/Au core/shell nanoparticles with Au/Ag molar ratio of 1:1.6 were used as probes to determine human serum proteins by resonance Rayleigh scattering (RRS) spectrometry. The results indicated that in pH 4.4 NaAc-HAc buffer solutions and in the presence of NsC1 of 0.05 mol/L, HSA was combined with Ag/Au core/shell nanoparticles to form stable complex. The enhanced resonance scattering intensity at 390 nm (△I390nm) was linear to HSA concentration in the range of 0. 0011-0.35 mg/L, with the regress equation of △I390nm = -0. 54+494. 82C(r＝ 0. 994) and the detection limit of 0.36 μg/L.Co-existing metal ions and amino acids excepting L-cysteine did not interfere with the detection,indicating the assay is of good selectivity. The assay was applied to the detection of total proteins in human serum, with a RSD of 2.3％ and the recovery range of 98.2％ - 102.3％, and the results were in a good agreement with that of Coomassie brilliant blue G-250 assay.
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