Alloyed AuFeZnSe quantum dots@gold nanorod nanocomposite as an ultrasensitive and selective plasmon-amplified fluorescence OFF-ON aptasensor for arsenic (III)

According to documented reports, more than 200 million people across the globe are exposed arsenic (As) contamination at levels above World Health Organization (WHO) guideline limit of 10 μg/L. In this work, a novel fluorescence OFF-ON ultrasensitive aptasensor was developed for As (III). To construct aptasensor, AuFeZnSe alloyed quantum dots (QDs) were newly synthesized and surface-coated with amphiphilic polymers (Amp-P) render QDs biocompatible stable. Thereafter, cationic gold nanorods (AuNRs) electrostatically bonded Amp-P-QDs form an Amp-P-QDs-AuNR nanocomposite which switched OFF bound QDs. Thiolated anti-As (III) DNA aptamer (Apt) thereafter assembled on surface Amp-P-Apt-QDs-AuNR probe. The affinity binding interaction between targeted concentration Apt, triggered localized plasmon resonance (LSPR) from AuNRs amplify intensity signal, thereby switching ON Amp-P-QDs. Comparison Amp-P-Apt-QDs probes, showed that presence AuNR enhanced by as much 230%, representing ∼20-fold increase over probe without AuNRs. Under optimum conditions, selectively quantitatively detected ultra-high sensitivity. linear range 0.01–100 μg/L, while obtained detection 0.01 μg/L (69.12 pM) 1000 times lower WHO recommended limit. We successfully applied detect in environmental biological samples analytical recoveries ∼93 105%.