Development of the Gel -Assisted Transfer Technique

本文研究了水溶性纳米粒子在琼脂糖凝胶表面的二维组装，并首次报道了纳米粒子在固体基质上的凝胶辅助转移（GAT）实验。凝胶上的铺展溶液通过渗透或在约100 ℃后通过蒸发而消失。反应12小时随后将固体基质（HOPG，云母）压在凝胶表面上。在扫描电子显微镜中，发现密集堆积的二氧化硅纳米粒子是由于它们从固体基质上的凝胶表面转移。在这些实施例中，纳米颗粒以单层和多层的形式转移，而没有形成均匀的阵列。通过原子力显微镜（AFM）进一步研究所得表面。在冲洗掉转移的纳米颗粒后，形成了高度约为100 μ m的琼脂糖碎片网络。大量观察到25 nm和50-70 nm的宽度。毫无疑问，琼脂糖的网状结构与纳米颗粒一起转移，表明凝胶的表面层由琼脂糖纤维的网状结构组成，其与通常认为的三维交联结构不同。琼脂糖的表面网络必须通过将二氧化硅颗粒支撑在一起并使它们作为“分子胶”粘附到阴离子云母表面来辅助转移。

We have studied two-dimensional organization of water-solubie nanoparticles by the use of hydrogel surface as substrate, and provide the first experimental report on gel-assisted transfer (GAT) of nanoparticles onto solid substrates.Colloidal dispersions of silica nano-particles (diameter, 100 nm) were spread on agarose gel surface. The spreading solution on the gel disappeared either by penetration or by evaporation after ca. 12 hrs. Solid substrates (HOPG, mica) were subsequently pressed against the gel surface. In scanning electron microscopy, densely packed silica nanoparticles are found due to their transfer from the gel surface on the solid substrates. In these examples, nanoparticles are transferred as monolayers and multilayers, without formation of uniform array.These silica particles transferred on HOPG and mica surfaces were easily removed upon dipping in water (5 ml), as demonstrated by SEM observation. The resultant surface was further investigated by atomic force microscopy (AFM). After rinsing off the transferred nanoparticles, fragmentary network of agarose with heights of ca. 25 nm and widths of 50-70 nm are abundantly observed. Undoubtedly, ultrathin network of agarose is transferred together with nanoparticles, suggesting that the surface layer of gel is comprised of ultrathin networks of agarose fibers that are distinguished from three dimensionally cross linked structures as generally considered. The surface network of agarose must assist the transfer by supporting silica particles together and making them adherent to anionic mica surface as "molecular glue".