Hairpin DNA (hpDNA) loops were used for the first time as molecular binding elements in gas analysis. The hpDNA loops sequences of unpaired bases were studied in-silico to evaluate the binding versus four chemical classes (alcohols, aldehydes, esters and ketones) of volatile organic compounds (VOCs). The virtual binding score trend was correlated to the oligonucleotide size and increased of about 25% from tetramer to hexamer. Two tetramer and pentamer and three hexamer loops were selected to test the recognition ability of the DNA motif. The selection was carried out trying to maximize differences among chemical classes in order to evaluate the ability of the sensors to work as an array. All oligonucleotides showed similar trends with best binding scores for alcohols followed by esters, aldehydes and ketones. The seven ssDNA loops (CCAG, TTCT, CCCGA, TAAGT, ATAATC, CATGTC and CTGCAA) were then extended with the same double helix stem of four base pair DNA (GAAG to 5′ end and CTTC to 3′ end) and covalently bound to gold nanoparticles (AuNPs) using a thiol spacer attached to 5′ end of the hpDNA. HpDNA-AuNPs were deposited onto 20 MHz quartz crystal microbalances (QCMs) to form the gas piezoelectric sensors. An estimation of relative binding affinities was obtained using different amounts of eight VOCs (ethanol, 3-methylbutan-1-ol, 1-pentanol, octanal, nonanal, ethyl acetate, ethyl octanoate, and butane-2,3-dione) representative of the four chemical classes. In agreement with the predicted simulation, hexamer DNA loops improved by two orders of magnitude the binding affinity highlighting the key role of the hpDNA loop size. Using the sensors as an array a clear discrimination of VOCs on the basis of molecular weight and functional groups was achieved, analyzing the experimental with principal components analysis (PCA) demonstrating that HpDNA is a promising molecular binding element for analysis of VOCs.

发夹DNA（hpDNA）环首次用作气体分析中的分子结合元素。在计算机上研究了未配对碱基的hpDNA环序列，以评估其与挥发性有机化合物（VOC）的四种化学类别（醇，醛，酯和酮）的结合。虚拟结合得分趋势与寡核苷酸的大小相关，并且从四聚体到六聚体增加了约25％。选择两个四聚体和五聚体以及三个六聚体环以测试DNA基序的识别能力。进行选择的目的是使化学类别之间的差异最大化，以便评估传感器作为阵列工作的能力。所有寡核苷酸均显示出相似的趋势，其中醇类的结合得分最高，其次是酯，醛和酮。七个ssDNA环（CCAG，TTCT，然后将CCCGA，TAAGT，ATAATC，CATGTC和CTGCAA）用四个碱基对DNA的相同双螺旋茎（GAAG延伸至5'端，CTTC延伸至3'端）延伸，并使用硫醇间隔子与金纳米颗粒（AuNPs）共价结合连接到hpDNA的5'末端。将HpDNA-AuNPs沉积到20 MHz石英晶体微天平（QCM）上，以形成气体压电传感器。使用不同量的以下8种VOC表示相对结合亲和力的估计值：乙醇，3-甲基丁-1-醇，1-戊醇，辛醛，壬醛，乙酸乙酯，辛酸乙酯和2,3-丁二烷四个化学类别。与预测的模拟结果一致，六聚体DNA环的结合亲和力提高了两个数量级，突出了hpDNA环大小的关键作用。