Quenching-recovery fluorescent biosensor for DNA detection based on mercaptopropionic acid-capped cadmium telluride quantum dots aggregation
Ali A. Ensafi, Parisa Nasr-Esfahani, B. Rezaei
A new, label-free, highly sensitive, and selective fluorescent ‘‘quenching-recovery’’ model for the detection of DNA was developed through mercaptopropionic acid (MPA)- capped cadmium telluride (CT) quantum dots (QDs) aggregation. At first, imipramine hydrochloride (IMP) effectively quenched the fluorescence of MPA-CT QDs due to their aggregation, in the ‘‘quenching’’ mode. Then, with the addition of DNA, the binding reaction of IMP to DNA was happened and the fluorescence intensity of MPA-CT QDs was raised, in the following ‘‘recovery’’ mode. Several parameters affect the sensitivity of the method were optimized. Under the optimal conditions, the linear dependence of the fluorescence signal and the concentration of DNA was in the range of 23.0 pmol L–1 – 10.8 nmol L–1, with a detection limit of 7.0 pmol L–1. This analytical fluorescent reversible ‘‘quenching-recovery’’ sensor offered a method for the detection of DNA with excellent sensitivity and selectivity.
Keywords: Mercaptopropionic acid; Capped cadmium telluride quantum dots; Imipramine hydrochloride; Deoxyribonucleic acid; Quenching-recovery fluorescent biosensor.