Novel “turn off-on” sensors for detection of DNA-acrylamide interaction using ZnS quantum dots as a phosphorescent probe

Abstract

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 phosphorescentprobes. In the “turn-off” mode, ACR was absorbed onto the surface of QDs via electrostatic interaction, which caused aquenching effect of room-temperature phosphorescence signal by photoinduced electron-transfer mechanism. ACR wasremoved from the QDs’ surface with the addition of DNA. Thus, the phosphorescence emission of QDs was recoveredand 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 × 10 4 M −1, 2.04 × 10 4M −1, and 1.2, respectively. An absorption spectrometric method was also used to evaluate ACR-DNA interaction andthe binding constant (K) was found as 2.4 × 10 5 M −1. The developed biosensor is simple, is free of interferences comingfrom autofluorescence and scattering light, and does not need any derivatization step or sample pretreatment.