Liu Shaopu, Yang Zhuo, Liu Zhongfang, Kong Ling
School of Chemistry and Chemical Engineering, Southwest China University, Beibei, Chongqing, People's Republic of China.
Anal Biochem. 2006 Jun 1;353(1):108-16. doi: 10.1016/j.ab.2006.03.012. Epub 2006 Mar 27.
Gold nanoparticles with a 12-nm diameter were used as probes for the determination of proteins by resonance Rayleigh-scattering techniques. In weak acidic solution, large amounts of citrate anions will self-assemble on the surface of positively charged gold nanoparticles to form supermolecular compounds with negative charges. Below the isoelectric point, proteins with positive charges such as human serum albumin (HSA), bovine serum albumin (BSA), and ovalbumin (Ova) can bind gold nanoparticles to form larger volume products (the diameter of the binding product of gold nanoparticles with HSA is 23 nm.) through electrostatic force, hydrogen bonds, and hydrophobic effects, which can result in a red shift of the maximum absorption wavelength, the remarkable enhancement of the resonance Rayleigh-scattering intensity (RRS), and the appearance of the RRS spectra. At the same time, the second-order-scattering (SOS) and frequency-doubling-scattering (FDS) intensities are also enhanced. The binding products of gold nanoparticles with different proteins have similar spectral characteristics and the maximum wavelengths are located near 303 nm for RRS, 540 nm for SOS, and 390 for FDS, respectively. The scattering enhancement (DeltaI) is directly proportional to the concentration of proteins. Among them, the RRS method has the highest sensitivity and the detection limits are 0.38 ng/ml for HSA, 0.45 ng/ml for BSA, and 0.56 ng/ml for Ova, separately. The methods have good selectivity. A new RRS method for the determination of trace proteins using a gold nanoparticle probe has been developed. Because gold nanoparticle probes do not need to be modified chemically in advance, the method is very simple and fast.
直径为12纳米的金纳米颗粒被用作通过共振瑞利散射技术测定蛋白质的探针。在弱酸性溶液中，大量柠檬酸根阴离子会在带正电荷的金纳米颗粒表面自组装，形成带负电荷的超分子化合物。在等电点以下，带正电荷的蛋白质，如人血清白蛋白（HSA）、牛血清白蛋白（BSA）和卵清蛋白（Ova），可以通过静电力、氢键和疏水作用与金纳米颗粒结合，形成更大体积的产物（金纳米颗粒与HSA的结合产物直径为23纳米），这会导致最大吸收波长红移、共振瑞利散射强度（RRS）显著增强以及RRS光谱出现。同时，二级散射（SOS）和倍频散射（FDS）强度也会增强。金纳米颗粒与不同蛋白质的结合产物具有相似的光谱特征，RRS的最大波长分别位于303纳米附近，SOS为540纳米，FDS为390纳米。散射增强（ΔI）与蛋白质浓度成正比。其中，RRS法灵敏度最高，HSA、BSA和Ova的检测限分别为0.38纳克/毫升、0.45纳克/毫升和0.56纳克/毫升。这些方法具有良好的选择性。开发了一种使用金纳米颗粒探针测定痕量蛋白质的新型RRS方法。由于金纳米颗粒探针无需预先进行化学修饰，该方法非常简单快速。
