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首页> 外文期刊>Chemistry: A European journal >Controlled synthesis of gold nanostars by using a zwitterionic surfactant
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Controlled synthesis of gold nanostars by using a zwitterionic surfactant

机译：两性离子表面活性剂可控合成金纳米星

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By replacing cetyltrimethylammonium bromide (CTAB) with the zwitterionic lauryl sulfobetaine (LSB) surfactant in the classical seed-growth synthesis, monocrystalline gold nanostars (m-NS) and pentatwinned gold asymmetric nanostars (a-NS) were obtained instead of nanorods. The main product under all synthetic conditions was a-NS, which have branches with high aspect ratios (AR), thus leading to LSPR absorptions in the 750-1150 nm range. The percentage of m-NS versus a-NS, the aspect ratio of the a-NS branches, and consequently the position of their LSPR absorption can be finely tuned simply by regulating the concentration of reductant, the concentration of surfactant, or the concentration of the "catalytic" Ag ~+ cation. The m-NS have instead shorter and larger branches, the AR of which is poorly influenced by synthetic conditions and displays an LSPR positioned around 700 nm. A growth mechanism that involves the direct contact of the sulfate moiety of LSB on the surface of the nano-object is proposed, thereby implying preferential coating of the {111} Au faces with weak interactions. Consistent with this, we also observed the straightforward complete displacement of the LSB surfactant from the surface of the nanostars. This was obtained by the simple addition of thiols in aqueous solution to yield extremely stable coated a-NS and m-NS that are resistant to highly acidic, basic, and in similar to in vivo conditions. Stargazing: Laurylsulfobetaine (LSB), a zwitterionic surfactant, was introduced into the seed-growth approach for the synthesis of gold nano-objects. Nanostars were obtained. The aspect ratio of their branches could be easily tuned by multiple synthetic parameters, which finely regulated the localized surface plasmon resonance absorption in the near-IR region (see figure). Removal of LSB led to stable nanostars under all conditions.
机译：在经典的种子生长合成中，通过用两性离子月桂基磺基甜菜碱（LSB）表面活性剂代替十六烷基三甲基溴化铵（CTAB），获得了单晶金纳米星（m-NS）和五键缠绕的金不对称纳米星（a-NS）而不是纳米棒。在所有合成条件下，主要产物均为a-NS，其分支具有高长宽比（AR），因此导致LSPR吸收在750-1150 nm范围内。 m-NS相对于a-NS的百分比，a-NS分支的长径比以及因此LSPR吸收的位置可以通过调节还原剂的浓度，表面活性剂的浓度或H-NS的浓度进行微调。 “催化” Ag〜+阳离子。相反，m-NS具有较短和较大的分支，其AR受合成条件的影响很小，并且显示LSPR位于700 nm附近。提出了涉及LSB的硫酸盐部分在纳米物体表面上直接接触的生长机理，从而暗示了具有弱相互作用的{111} Au表面的优先涂层。与此相一致，我们还观察到LSB表面活性剂直接从纳米星表面完全置换。这是通过在水溶液中简单添加硫醇以得到极其稳定的包被的a-NS和m-NS而获得的，这些a-NS和m-NS对高酸，碱性和体内条件都具有抵抗力。观星：两性离子表面活性剂Laurylsulfobetaine（LSB）被引入到种子生长方法中，用于合成金纳米物体。获得了纳米星。可以通过多个合成参数轻松调节其分支的长宽比，这些参数可以精细调节近红外区域中的局部表面等离子体共振吸收（见图）。去除LSB可以在所有条件下产生稳定的纳米星。

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