Synthesis, surface modification and optical properties of thioglycolic acid-capped ZnS quantum dots for starch recognition at ultralow concentration

Mahnoush Tayebi, Mohammad Tavakkoli Yaraki*, Mahnaz Ahmadieh, Azadeh Mogharei, Mohammadreza Tahriri*, Daryoosh Vashaee, Lobat Tayebi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

In this research, water-soluble thioglycolic acid-capped ZnS quantum dots (QDs) are synthesized by the chemical precipitation method. The prepared QDs are characterized using x-ray diffraction and transmission electron microscopy. Results revealed that ZnS QDs have a 2.73 nm crystallite size, cubic zinc blende structure, and spherical morphology with a diameter less than 10 nm. Photoluminescence (PL) spectroscopy is performed to determine the presence of low concentrations of starch. Four emission peaks are observed at 348 nm, 387 nm, 422 nm, and 486 nm and their intensities are quenched by increasing concentration of starch. PL intensity variations in the studied concentrations range (0–100 ppm) are best described by a Michaelis–Menten model. The Michaelis constant (K m) for immobilized α-amylase in this system is about 101.07 ppm. This implies a great tendency for the enzyme to hydrolyze the starch as substrate. Finally, the limit of detection is found to be about 6.64 ppm.
Original languageEnglish
Pages (from-to)5671-5678
Number of pages8
JournalJournal of Electronic Materials
Volume45
Issue number11
DOIs
Publication statusPublished - Nov 2016
Externally publishedYes

Keywords

  • ZnS QDs
  • starch
  • a-amylase
  • thioglycolic acid
  • photoluminescence
  • concentration

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