Assembling of gold nanorods on P(NIPAM–AAPBA) microgels: a large shift in the plasmon band and colorimetric glucose sensing
Assembling of gold nanorods on P(NIPAM–AAPBA) microgels: a large shift in the plasmon band and colorimetric glucose sensing
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DOI：
10.1039/c2ra20466e
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发表时间：
2012-05
期刊：
影响因子：
3.9
通讯作者：
Yapeng Zhang;Kun Liu;Ying Guan;Yongjun Zhang
中科院分区：
文献类型：
--
作者：
Yapeng Zhang;Kun Liu;Ying Guan;Yongjun Zhang
胺修饰金纳米棒（GNR）通过静电相互作用组装在聚n -异丙基丙烯酰胺-co-3-丙烯酰胺苯硼酸（P(NIPAM-AAPBA)）微凝胶表面。研究了pH和GNR/微凝胶比对自组装的影响。结果表明，在较高的pH下，微凝胶颗粒的表面电荷密度随着pH的增加而增加，GNR的表面覆盖率随着GNR/微凝胶比的增加而增加。在pH为8.5和9.0的条件下制备了高GNR/微凝胶比的杂交微凝胶。加热后，这些杂化微凝胶在其等离子体带中表现出超过100 nm的红移，这比文献报道的要大得多。同时，微凝胶分散体的颜色由蓝色逐渐变为灰色。杂化微凝胶可以认为具有核/壳状结构，无论是在完全膨胀状态还是完全坍塌状态下，杂化微凝胶的半径增加与gnr的直径相当。杂化微凝胶的热相变开始于与裸微凝胶相同的温度，但结束于更高的温度。相变变宽是由于非热敏GNR壳层对堆芯溶胀的限制。同样，葡萄糖引起的肿胀也被延缓，导致葡萄糖敏感性降低。葡萄糖引起的膨胀还会导致等离子体带的蓝移和样品的颜色变化。这种新型混合微凝胶可以作为温度和葡萄糖的双比色传感器。
Amine modified gold nanorods (GNR) were assembled onto the surface of poly(N-isopropylacrylamide-co-3-acrylamidophenylboronic acid) (P(NIPAM–AAPBA)) microgel particles via electrostatic interactions. The effects of pH and GNR/microgel ratio on the self-assembly were studied. It was revealed that GNRs can be sequestered more effectively at a higher pH because the surface charge density of the microgel particles increases with increasing pH. In addition, the surface coverage of the GNRs increases with increasing GNR/microgel ratio. Based on these observations hybrid microgels were prepared at pH 8.5 and 9.0 using a high GNR/microgel ratio. Upon heating these hybrid microgels exhibit a redshift of over 100 nm in their plasmon band, which is much larger than those reported in the literature. At the same time, the color of the microgel dispersion gradually changes from blue to grey. The hybrid microgel can be regarded to have a core/shell-like structure, as the radius increase of the hybrid microgel, either at a fully swollen state or a fully collapsed state, is comparable to the diameter of the GNRs. The thermal phase transition of the hybrid microgel starts at the same temperature as that of the bare microgel, but ends at a much higher temperature. The widened phase transition is attributed to the restriction of the non-thermosensitive GNR shell on the deswelling of the core. Similarly glucose-induced swelling is also retarded, resulting in a reduced glucose-sensitivity. The glucose-induced swelling also results in the blueshift of the plasmon band and color change of the sample. The new hybrid microgel can be used as a dual colorimetric sensor for temperature and glucose.