Photoluminescence of CdTe nanocrystals modulated by methylene blue and DNA. A label-free luminescent signaling nanohybrid platform

Abstract

A nanohybrid consisting of water-soluble thioglycolic acid (TGA)-capped CdTe nanocrystals (NCs) and methylene blue (MB) was designed as a label-free luminescent signaling platform for DNA. This sensing system was identified to operate under the photoinduced electron transfer (PET) mechanism in which MB is the electron acceptor and the binding site for the designated target molecule DNA. We showed that MB bound with TGA-capped CdTe NCs via strong electrostatic interactions resulted in an efficient quenching of the photoluminescence (PL) of NCs. Steady-state and time-resolved PL, and electron paramagnetic resonance (EPR) experiments established the quenching pathway of PET from the conduction band (CB) of NCs to the ground state of MB. In the presence of the target molecule DNA, the MB-quenched PL of NCs could be reversibly restored by double-stranded DNA as the PET pathway is blocked when MB is taken away from the NCs surface due to its intercalation into, and electrostatic interaction with, DNA. The platform was successfully applied for sensing DNA and signaling DNA hybridization by switching the PET process. Such a nanohybrid represents a robust PET luminescent nanosensor that is, in principle, applicable for other species by employing suitable electron acceptors as binding sites.

Hydride Generation for Headspace Solid-Phase Extraction with CdTe Quantum Dots Immobilized on Paper for Sensitive Visual Detection of Selenium

“…A triexponential luminescence decay ( Figure S2) and a decrease of luminescence lifetime with increasing Se(IV) were observed ( Table S1), indicating that the mechanism involved in the luminescence quenching is dynamic, and this agrees with previous works. 22,47 On the basis of the above discussions and the previous works, 22,45 we assumed that the binding between Cd in Cd−thiol complex and Se in H 2 Se on the surface of CdTe QDs might cause the increase of surface defects thus facilitate the nonradiative e − /h + recombination in the QD surface, which would eventually result in the fluorescence quenching of the CdTe QDs. Effect of HG Conditions.…”

A Carbon Dots-based Fluorescence Turn-on Method for DNA Determination

“…Under the experimental conditions, MB adsorbed on the surface of CDots, and quenched the fluorescence from CDots. DNA could bind with MB 17,25 and released MB from the surfaces of CDots. As a result, the fluorescence from CDots was restored.…”

“…This is due to the fact that the binding between MB and ds-DNA is stronger than that between MB and ss-DNA. MB binds with ds-DNA via both an electrostatic interaction and intercalation, 17,25 while MB binds with ss-DNA via only an electrostatic interaction. 17 Thus, ds-DNA removed MB from CDots more efficiently than ss-DNA, and hence ds-DNA restored CDots fluorescence more efficiently than ss-DNA.…”

“…3 The superior optical properties show that CDots have potential applications for bioimaging 5,[12][13][14][15][16] and sensing fields. Quantum dots have been widely applied for DNA, [17][18][19] vitamin, 20 carbohydrate, 21,22 protein, 23 and drug 24 detection. However, to the best of our knowledge, fluorescent CDots have never been applied to DNA detection.…”

Interaction Mode Between Methylene Blue-Pr(III) Complex and Herring-Sperm DNA

“…1), as a coplanar polycyclic aromatic basic dye with good spectral properties, has been studied widely for anticancer, antitoxic, and antibacterial property. [4][5][6][7] Many drugs have been used in modern clinical practice that are from the side chain of MB-obtained structural transformation, such as antihistamine, stability class medicine, and antidepressants. [8] Rare earth metals have better physiological activities, and their toxicities are decreased after coordinating with a ligand.…”