Turkish Journal of Chemistry




A novel "turn off-on" sensor for detection of interaction between DNA and acrylamide (ACR) was developed. In this method, L-cysteine capped Mn-doped ZnS quantum dots (QDs) were used as room temperature phosphorescent probes. In the ``turn-off'' mode, ACR was absorbed onto the surface of QDs via electrostatic interaction, which caused a quenching effect of room-temperature phosphorescence signal by photoinduced electron-transfer mechanism. ACR was removed from the QDs' surface with the addition of DNA. Thus, the phosphorescence emission of QDs was recovered and the system was turned to the ``turn-on'' mode. The quenching mechanism of QDs by ACR was collisional (dynamic) and the quenching constant, binding constant, and binding site number were calculated as 3.2 x 10$^{4\, }$ M$^{-1}$, 2.04 x 10$^{4\, }$ M$^{-1}$, and 1.2, respectively. An absorption spectrometric method was also used to evaluate ACR-DNA interaction and the binding constant (K) was found as 2.4 x 10$^{5\, }$ M$^{-1}$. The developed biosensor is simple, is free of interferences coming from autofluorescence and scattering light, and does not need any derivatization step or sample pretreatment.


Acrylamide, DNA interaction, quantum dots, phosphorescence, photoinduced electron transfer

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