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金属纳米材料是指纳米量级(10-9 m)的超微颗粒构成的金属固体物质[1]。纳米颗粒一般为球形或类球形,也有棒状结构,这主要是由于合成方法不同而导致纳米颗粒的形态不同。早在公元前四、五世纪就有对于胶体金的使用的记载。目前对于胶体金的报道主要是关于其在催化工艺和生物大分子中的电子转移中的应用以及利用细胞的内吞作用传输物质等方面[2-3]。金纳米颗粒(gold nanoparticles,GNPs)因其独特的光学、电学和磁学特性以及很好的生物相容性,已广泛用于生物传感器、分子和细胞成像、癌症的诊断和光热治疗以及药物的传输等研究中[4-13]。由于GNPs具有较强的表面等离子共振(surface plasmon resonance,SPR)的特性,使其有可能成为癌细胞成像中的新型造影剂。更重要的是,SPR随着颗粒尺寸的变化而变化,从而使GNPs具有特异性。例如,通过改变金纳米结构的尺寸和形状可以将SPR吸收带从可见光区域移至近红外区域,从而可用于体内成像和治疗。同时,2004年,美国科学家发现了GNPs的放射增敏作用[14]。与传统的块状金相比,GNPs具有更大的光电吸收截面及更强的光吸收和光散射能力,因此,GNPs有望作为一种新型的放射治疗增敏剂。总之,目前对于GNPs的研究越来越热,其制备及应用等方面的研究已成为近年来材料科学界研究的前沿课题。
合成GNPs的方法因原理不同而有所不同。较早合成GNPs的方法是由Turkevich等[15]在1951年提出的。虽然GNPs具有很好的表面化学和光学特性,但是其在高盐和某些生物分子(核酸、蛋白质等)存在的情况下易发生聚集和团聚,而改变表面化学特性是改善分散性和稳定性的关键和常用方法。巯基-聚乙二醇(sulfhydryl-polyethylene glycol,SH-PEG)中富含巯基和羟基,通过这两个基团和GNPs表面的强结合力将PEG与GNPs结合起来,从而提高GNPs的稳定性[16-17]。本研究通过SH-PEG修饰GNPs的表面,从而改进了GNPs的表面化学特性,制备得到了分散性较好的SH-PEG包裹的GNPs(即PEG-GNPs),这些结果对于进一步的放射增敏的研究非常重要。
巯基-聚乙二醇修饰的不同尺寸金纳米颗粒的制备和光学特性
The fabrication and option characteristics of polyethylene glycol-coated gold nanoparticles with differe
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摘要:
目的 利用氯金酸和不同的还原剂(如柠檬酸三钠和硼氢化钠)制备不同尺寸的金纳米颗粒(GNPs),同时制备巯基-聚乙二醇(SH-PEG)修饰的PEG-GNPs。 方法 将氯金酸溶液加热至沸腾,之后加入不同量的柠檬酸三钠或硼氢化钠溶液,搅拌30 min即可制备不同尺寸的GNPs。之后加入一定量的SH-PEG,搅拌1 h,即可制备PEG-GNPs。利用紫外可见分光光度计和透射电子显微镜来观察GNPs和PEG-GNPs的光学特性和尺寸。 结果 利用1%的柠檬酸三钠溶液可以制备10、25、45 nm的GNPs,而用0.11%的硼氢化钠溶液可以制备5 nm的GNPs。通过加入一定量的SH-PEG,可以制备PEG-GNPs。将不同尺寸的GNPs和PEG-GNPs的紫外可见吸收谱相比,发现随着GNPs尺寸的增加,表面等离子共振峰会向长波长方向移动。 结论 通过调节氯金酸与柠檬酸三钠或硼氢化钠的比例,可以制备不同尺寸的GNPs。同时,颗粒尺寸越大,表面等离子共振峰红移的现象越明显。 Abstract:Objective To synthesize gold nanoparticles (GNPs) and polyethylene glycol-coated GNPs(PEG-GNPs)modified by sulfhydryl-polyethylene glycol(SH-PEG), chloroauric acid and different reductant agent, such as trisodium citrate and sodium borohydride were used. Methods Chloroauric acid solution was brought to a boil, and then different volume of trisodium citrate solution or sodium borohydride solution was added to the boiling solution. Then the mixture was boiled for a further 30 minutes. Subsequently some SH-PEG was mixed with the GNPs and stirred for 1 hour to fabricate the PEG-GNPs. The optical characteristic and size of GNPs and PEG-GNPs were observed by UV-Vis spectrophotometer and transmission electron microscopic respectively. Results 10, 25, and 45 nm GNPs were fabricated using 1% trisodium citrate, while the 5 nm GNPs were synthesized using 0.11% sodium borohydride. Meanwhile, SH-PEG was added to the GNPs and obtained the PEG-GNPs. Furthermore, when compared with the GNPs with different size, it can be found that the surface plasmon resonance (SPR) of GNPs have shift to long wavelength region with increasing particles size. The same phenomenon also can be found in the PEG-GNPs with different size. Conclusions The size of GNPs can be modulated by controlling the ratio between chloroauric acid and trisodium citrate or sodium borohydride. Meanwhile, the larger the size of GNPs is, the more significant of the shifting to the long wavelength of SPR is. -
Key words:
- Nanostructures /
- Gold /
- Polyethylene glycols /
- Microscopy /
- electron /
- transmission
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