TY - JOUR
T1 - Effects of DNA probe and target flexibility on the performance of a "signal-on" electrochemical DNA sensor
AU - Wu, Yao
AU - Lai, Rebecca Y.
PY - 2014/9/2
Y1 - 2014/9/2
N2 - We report the effect of the length and identity of a nontarget binding spacer in both the probe and target sequences on the overall performance of a folding-based electrochemical DNA sensor. Six near-identical DNA probes were used in this study; the main differences between these probes are the length (6, 10, or 14 bases) and identity (thymine (T) or adenine (A)) of the spacer connecting the two target binding domains. Despite the differences, the signaling mechanism of these sensors remains essentially the same. The methylene blue (MB)-modified probe assumes a linear unstructured conformation in the absence of the target; upon hybridization to the target, the probe adopts a "close" conformation, resulting in an increase in the MB current. Among the six sensors, the T14 and A14 sensors showed the largest signal increase upon target hybridization, highlighting the significance of probe flexibility on sensor performance. In addition to the target without a midsequence spacer, 12 other targets, each with a different oligo-T or oligo-A spacer, were used to elucidate the effect of target flexibility on the sensors' signaling capacity. For all six sensors, hybridization to targets with a 2- or 3-base spacer resulted in the largest signal increase. Higher signal enhancement was also observed with targets with an oligo-A spacer. For this sensor design, addition of a long nontarget binding spacer to the probe sequence is advantageous, as it provides flexibility for optimal target capture. The length of the spacer in the target sequence, however, should be adequately long to enable efficient hybridization yet does not introduce undesirable electrostatic and crowding effects.
AB - We report the effect of the length and identity of a nontarget binding spacer in both the probe and target sequences on the overall performance of a folding-based electrochemical DNA sensor. Six near-identical DNA probes were used in this study; the main differences between these probes are the length (6, 10, or 14 bases) and identity (thymine (T) or adenine (A)) of the spacer connecting the two target binding domains. Despite the differences, the signaling mechanism of these sensors remains essentially the same. The methylene blue (MB)-modified probe assumes a linear unstructured conformation in the absence of the target; upon hybridization to the target, the probe adopts a "close" conformation, resulting in an increase in the MB current. Among the six sensors, the T14 and A14 sensors showed the largest signal increase upon target hybridization, highlighting the significance of probe flexibility on sensor performance. In addition to the target without a midsequence spacer, 12 other targets, each with a different oligo-T or oligo-A spacer, were used to elucidate the effect of target flexibility on the sensors' signaling capacity. For all six sensors, hybridization to targets with a 2- or 3-base spacer resulted in the largest signal increase. Higher signal enhancement was also observed with targets with an oligo-A spacer. For this sensor design, addition of a long nontarget binding spacer to the probe sequence is advantageous, as it provides flexibility for optimal target capture. The length of the spacer in the target sequence, however, should be adequately long to enable efficient hybridization yet does not introduce undesirable electrostatic and crowding effects.
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U2 - 10.1021/ac5027226
DO - 10.1021/ac5027226
M3 - Article
C2 - 25110351
AN - SCOPUS:84906874821
SN - 0003-2700
VL - 86
SP - 8888
EP - 8895
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 17
ER -