Biologically synthesized ZnS Quantum Dots as fluorescent probes for Lead (II) Sensing.
Luminescence. 2020 Jun 08;:
Authors: Jacob JM, Rajan R, Kurup GG
The manuscript presents a robust strategy for the selective Pb (II) sensing based on the fluorescence turn-off mechanism by ZnS QDs biosynthesized using Aspergillus sp. The biogenic nano-probe displayed remarkable sensing efficiency in presence of Pb ions in concentration ranges from 5-100 μM with limits of detection of around 2.45 μM. Performance optimization studies revealed that the maximum fluorescence quenching efficiency was obtained in presence of [ZnS NPs] at 4 mg/mL, alkaline pH of 10 recorded under stable ambient temperature for approximately 5 min quenching process. Advanced morphological analysis indicated that the biosensing mechanism is essentially a surface based phenomenon in which the Pb ions in very close proximity of the QDs form stable ground state Pb-ZnS complexes, resulting in a quenched fluorescence of the QDs. Simultaneously, a larger fraction of Pb ions interact via collisions with the excited ZnS QDs and result in an effective energy transfer from the excited QD to the Pb ions thereby resulting in an obvious decrease in the QD fluorescence. These insights were well supported by theoretical analysis using Stern-Volmer and sphere of action models.
PMID: 32510819 [PubMed – as supplied by publisher]