Novel “turn off-on” sensors for highly selective and sensitive detection of spermine based on heparin-quenching of fluorescence CdTe quantum dots-coated amphiphilic thiophene copolymers

Abstract

Novel “turn off-on” optosensors based on amphiphilic thiophene copolymers coated CdTe quantum dots (P1QDs and P2QDs) were developed for the dual detection of heparin and spermine. The emission of the P1QDs and P2QDs is found to be quenched in the presence of heparin by electron transfer mechanism through electrostatic and hydrogen bonding interactions. Upon the addition of spermine, heparin has been removed from the surface of P1QDs and P2QDs due to the strong electrostatic interactions between spermine and heparin, which showed significant fluorescence recovery of the sensors. Under optimum conditions, both P1QDs and P2QDs sensors displayed excellent limits of detection for heparin of 1.59nmolL−1 (R2=0.9955) and 0.88nmolL−1 (R2=0.9908) with linear ranges of 1–11μmolL−1 and 1–10μmolL−1, respectively. P1QDs and P2QDs also showed remarkable limits of detection for spermine of 2.90nmolL−1 (R2=0.9957) and 1.66nmolL−1 (R2=0.9928) with linear ranges of 0.05–15μmolL−1 and 1–12μmolL−1, respectively. The P1QDs and P2QDs sensors show a high selectivity to heparin and spermine over common interfering substances and ions. In addition, the proposed method was successfully utilized in serum samples, which could facilitate the further heparin and spermine biochemical and biomedical research.