Park Ki Soo, Oh Seung Soo, Soh H Tom, Park Hyun Gyu
Department of Chemical and Biomolecular Engineering (BK 21+ Program), KAIST, Daejeon 305-701, Republic of Korea.
Nanoscale. 2014 Sep 7;6(17):9977-82. doi: 10.1039/c4nr00625a.
A novel, label-free, fluorescence based sensor for theophylline has been developed. In the new sensor system, an abasic site-incorporated duplex DNA probe serves as both a pocket for recognition of theophylline and a template for the preparation of fluorescent silver nanoclusters. The strategy relies on theophylline-controlled formation of fluorescent silver nanoclusters from abasic site-incorporated duplex DNA. When theophylline is not present, silver ions interact with the cytosine groups opposite to the abasic site in duplex DNA. This interaction leads to efficient formation of intensely red fluorescent silver nanoclusters. In contrast, when theophylline is bound at the abasic site through pseudo base-pairing with appropriately positioned cytosines, silver ion binding to the cytosine nucleobase is prevented. Consequently, fluorescent silver nanoclusters are not formed causing a significant reduction of the fluorescence signal. By employing this new sensor, theophylline can be highly selectively detected at a concentration as low as 1.8 μM. Finally, the diagnostic capability and practical application of this sensor were demonstrated by its use in detecting theophylline in human blood serum.
一种新型的、无标记的、基于荧光的茶碱传感器已被开发出来。在新的传感器系统中，一个含有无碱基位点的双链DNA探针既作为识别茶碱的口袋，又作为制备荧光银纳米簇的模板。该策略依赖于由含有无碱基位点的双链DNA在茶碱控制下形成荧光银纳米簇。当不存在茶碱时，银离子与双链DNA中与无碱基位点相对的胞嘧啶基团相互作用。这种相互作用导致高效形成强烈红色荧光的银纳米簇。相反，当茶碱通过与适当定位的胞嘧啶进行假碱基配对而结合在无碱基位点时，银离子与胞嘧啶核碱基的结合被阻止。因此，不会形成荧光银纳米簇，导致荧光信号显著降低。通过使用这种新型传感器，可以在低至1.8 μM的浓度下高度选择性地检测茶碱。最后，通过在人血清中检测茶碱，证明了该传感器的诊断能力和实际应用。
