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1.
Chem Commun (Camb) ; 57(68): 8445-8448, 2021 Sep 04.
Article in English | MEDLINE | ID: mdl-34341805

ABSTRACT

Here, we report the preparation and characterization of stable AgIn5Te8 (AITe) nanocrystals (NCs) and their respective AITe-ZnS and AITe-ZnSe alloys. A green route of synthesis is described by using an aqueous electrochemical method in a cavity cell. The elemental ratio modulation of the NCs was investigated to determine the ideal improvement of the structural and electronic properties. The AITe NCs presented an emission band at 889 nm and hypsochromic shifts when coated with ZnS and ZnSe seeds. Photothermal analyses point to theranostic applications.

2.
Colloids Surf B Biointerfaces ; 187: 110672, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31796242

ABSTRACT

Mosquito-borne arboviruses compromise human health worldwide. Due to resistance to chemical insecticides, natural compounds have been studied to combat mosquitoes. Previous works have demonstrated a larvicidal activity of the water-soluble Moringa oleifera lectin (WSMoL) against Aedes aegypti, suggesting a mechanism of action based on the interaction between lectin and chitin present in the larvae's peritrophic matrix. In this work, it was investigated the WSMoL activity against Aedes aegypti larvae, by using luminescent bioconjugates of WSMoL conjugated to l-glutathione capped CdTe quantum dots. The conjugation was confirmed by ITC experiments, presenting high enthalpy associated to hydrogen bond interactions between nanoparticles and lectins. The bioconjugate luminescence stability was evaluated by the quantum yield (QY) at different pHs, ionic strengths and heat treatment time. The best parameters reached were pH 7.0, absence of electrolytes and heat treatment, giving QY = 4.4 %. The larvae were exposed to the bioconjugates and analyzed by confocal and fluorescence microscopy. CdTe-WSMol were detected along the entire midgut tract, suggesting a strong interaction with peritrophic matrix and lumen of the Aedes aegypti.


Subject(s)
Cadmium Compounds/chemistry , Glutathione/chemistry , Larva/drug effects , Lectins/chemistry , Moringa oleifera/chemistry , Quantum Dots/chemistry , Tellurium/chemistry , Aedes/drug effects , Animals , Biomarkers/analysis , Hot Temperature , Hydrogen Bonding , Hydrogen-Ion Concentration , Luminescence , Microscopy, Electron, Transmission , Microscopy, Fluorescence , Quantum Dots/ultrastructure , X-Ray Diffraction
3.
Talanta ; 144: 986-91, 2015 Nov 01.
Article in English | MEDLINE | ID: mdl-26452917

ABSTRACT

The fluorescence quenching of TGA-CdSe quantum dots (QDs) was used for Cr(3+) quantification in vitamin supplements. The QD was electrochemically synthesized, demonstrating high reproducibility with control of particle size, thus making it a clean method, without the presence of reducing agents. Under ideal conditions, with the fluorescence band at 551 nm (excitation 365 nm), the maximum fluorescence quenching was observed at pH 4.0, with a time of 200 s for each data acquisition. Under optimum experimental conditions, linear quenching was observed for Cr(3+) in the range of 25.0-325.0 ng L(-1) (R=0.9996, n=6), a limit of detection of 5.67 ng L(-1), and relative standard deviation of 4.43% (n=10). The recovery test for Cr(3+) quantification in vitamin supplements presented results from 82% to 98%. These Cr(3+) determination results were compared to the same vitamin supplement sample using flame atomic absortion spectrometry (FAAS) method, and no significant differences were observed at 95% confidence level.


Subject(s)
Cadmium Compounds/chemistry , Chromium/analysis , Dietary Supplements/analysis , Quantum Dots/chemistry , Selenium Compounds/chemistry , Thioglycolates/chemistry , Vitamins/analysis , Chromium/chemistry , Electrochemical Techniques , Fluorescent Dyes/chemistry
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