Polyvalent gold nanoparticle oligonucleotide conjugates are subject of intense research. Even though 2 nm diameter AuNPs have been previously modified with DNA, little is known about their structure and electrochemical behavior. In this work, we examine the influence of different surface modification strategies on the interplay between the meso-organization and the molecular recognition properties of a 27-mer DNA strand. This DNA strand is functionalized with different sulfur-containing moieties and immobilized on 2 nm gold nanoparticles confined on a nanoporous alumina, working the whole system as an electrode array. Surface coverages were determined by EXAFS and the performance as recognition elements for impedance-based sensors is evaluated. Our results prove that low DNA coverages on the confined nanoparticles prompt to a more sensitive response, showing the relevance in avoiding the DNA strand overcrowding. The system was able to determine a concentration as low as 100 pM of the complementary strand, thus introducing the foundations for the construction of label-free genosensors at the nanometer scale.

多价金纳米颗粒寡核苷酸缀合物是深入研究的主题。即使直径2 nm的AuNPs先前已被DNA修饰，但对其结构和电化学行为知之甚少。在这项工作中，我们研究了不同表面修饰策略对27-mer DNA链的介观组织和分子识别特性之间相互作用的影响。该DNA链用不同的含硫部分进行功能化，并固定在纳米纳米氧化铝上的2 nm金纳米颗粒上，将整个系统用作电极阵列。通过EXAFS确定表面覆盖率，并评估基于阻抗的传感器作为识别元件的性能。我们的结果证明，封闭的纳米颗粒上的低DNA覆盖率提示了更敏感的反应，显示了避免DNA链过度拥挤的相关性。该系统能够确定低至100 pM的互补链浓度，从而为构建纳米级无标记基因传感器奠定了基础。