Design and preparation of quantum dots fluorescent probes for in situ identification of Microthrix parvicella in bulking sludge

Abstract

A series of quantum dots (QDs) fluorescent probes for the in situ identification of Microthrix parvicella (M. parvicella) in bulking sludge were designed and prepared. In the preparation of CdTe/CdS QDs, the 11-mercaptoundecanoic acid (11-acid) and 16-mercaptohexadecanoic acid (16-acid) were used as the stabilizer. The prepared QDs probes were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM), and the results showed that the CdTe/CdS QDs formed a core-shell structure and the long carbon chain was successfully grafted onto its surface. And the three QDs probes had different crystallinity and particle size, which was due to the inhibition effect of long carbon chain. The optical properties test results showed that although the formed core-shell structure and long carbon chain affected the fluorescent intensity, adsorption, and emission spectra of the QDs probes, the probes B and C had a large stokes-shift of 82 and 101 nm, which was a benefit for their fluorescent labeling property. In the fluorescent identification of M. parvicella, the probes B and C effectively adsorbed onto the surface of M. parvicella through a hydrophobic bond, and then identified M. parvicella by their unique fluorescence. In addition, it was found that a better hydrophobic property resulted in better identification efficiency.

The effects of QD stabilizer structures on pH dependence, fluorescence characteristics, and QD sizes

“…NaHTe solution was prepared according to a reported method [21][22][23][24][25]. Simply, tellurium powder (0.5 mmol) and 1.5 mmol of NaBH 4 were loaded into a three-necked flask and 5 mL deionized water added.…”

Antimicrobial and Antioxidant Activity of the Biologically Synthesized Tellurium Nanorods; A Preliminary In vitro Study

“…Reviewing the literature, it was found that the toxicity of the tellurite occurs via the two probable mechanisms: i) replacing the sulfur group in a number of amino acids and as a result creating non-functional proteins and ii) severely oxidizing the glutathione reservoir of the cells, which lead to the generation of excessive amounts of reactive Shakibaie M et al oxygen species (ROS) disrupting cell macromolecules involved in metabolic pathways (5,6). Recently, tellurium has been applied in the development of novel materials such as fl uorescent CdTe quantum dots (7,8) and diff erent telluride nanostructures (9), tellurium containing nanoparticles (NPs) (10), and tellurium nanotubes (11), which may fi nd potential applications in the electronics and medicine as a new fi eld of nanotechnology approaches.…”

Design Mechanism and Property of the Novel Fluorescent Probes for the Identification of Microthrix Parvicella In Situ

“…The process is in accordance with M. parvicella transport of fatty acids reported by McIlroy [ 20 ]. According to Fei [ 32 ], the quantum dots probe can only identify M. parvicella filaments protruding from the flocs and free ones in the activated sludge, but it cannot label M. parvicella inside the flocs. The quantum dots probe is nano level in size, and bigger than the fluorescent molecule probes, which makes it difficult for the quantum dots probe to penetrate the sludge flocs which are composed of bacterial aggregation.…”