Small-angle X-ray scattering and UV–vis absorption measurements were performed on mixed solutions of gold nanoparticles (AuNPs) and atelocollagen (AC), triple-helical collagen without telopeptide, in acetate buffer at pH 4 under different temperature conditions, i.e., preparation temperature T_prep and measurement temperature T_meas. Due to the significantly higher electron density of gold than that of AC, the structure factor S(q) of AuNPs is readily estimated from the scattering intensities of AuNP-only and mixed solutions. The resulting S(q) profile for the mixed solution indicated significant attractive interactions, especially for the smaller AuNPs. Therefore, the sticky sphere model was applied to analyze S(q) to determine the interaction parameters at different T_prep and T_meas. The attractive interactions between AuNPs were higher at higher T_prep, suggesting that single-chain AC tends to make the interactions between AuNPs more attractive than those for triple-helical AC. Complex formation was also detected by the aggregation-induced surface plasmon absorption shift. More densely packed AuNPs were detected from the absorption spectra for higher AuNP content at which the ζ potential disappeared, while a split absorption band was also found, indicating that not all AuNPs can form a complex with AC at ζ = 0.

中文翻译：

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X 射线散射和吸收光谱研究水介质中金纳米颗粒与胶原的复合形成


在不同温度条件下，对金纳米粒子（AuNPs）和去端肽胶原（AC）（不含端肽的三螺旋胶原蛋白）在醋酸盐缓冲液中的混合溶液进行小角X射线散射和紫外可见吸收测量，即制备温度T _prep和测量温度T _meas 。由于金的电子密度明显高于 AC，因此可以根据纯 AuNP 溶液和混合溶液的散射强度轻松估计 AuNP 的结构因子S ( q )。混合溶液的S ( q ) 分布表明显着的吸引相互作用，特别是对于较小的 AuNP。因此，应用粘性球模型来分析S ( q )以确定不同T _prep和T _meas下的相互作用参数。 AuNPs 之间的相互作用在较高的T _prep下更高，这表明单链 AC 往往使 AuNPs 之间的相互作用比三螺旋 AC 更有吸引力。复合物的形成也通过聚集诱导的表面等离子体吸收位移来检测。当 AuNP 含量较高时，从吸收光谱中检测到更密集的 AuNP，此时 z 电位消失，同时还发现了分裂的吸收带，这表明并非所有 AuNP 都能在 z = 0 时与 AC 形成复合物。