Highly photoluminescent carbon dots with a PL quantum yield of 26% have been prepared in one step by hydrothermal treatment of orange juice. Due to high photostability and low toxicity these carbon dots are demonstrated as excellent probes in cellular imaging.
A nitrogen and sulphur co-doped carbon dot (NSCD) based highly selective photoluminescent probe for mercury detection has been designed. The NSCDs with a PL quantum yield of 69% are easily prepared from a single polymeric molecular precursor. The turn on-off fluorescence change upon mercury addition is attributed to the nonradiative electron transfer from the excited state to the d-orbital of the metal ion. The soft-soft acid-base interaction between the sulphur part of the NSCD and Hg(2+) makes the fluorescence probe more specific and selective towards Hg(2+) in contrast to other metal ions. The limit of detection of mercury ions is found to be 0.05 nM. Due to their high photostability, low toxicity and low detection limit, these carbon dots are demonstrated to be excellent probes for the detection of Hg(2+) in the living cell.
Graphical abstractA water dispersible magnetic nanoparticle and carbon quantum dot based sensor has been designed by a simple technique. The nanosensor is highly selective and sensitive towards fluoride ion in aqueous solution and intracellular environment.ABSTRACT:A robust reusable fluoride sensor comprising of a receptor in charge of the chemical recognition and a fluorophore responsible for signal recognition has been designed.Highly fluorescent carbon quantum dot (CD) and magnetically separable nickel ethylenediaminetetraacetic acid (EDTA) complex bound-silica coated magnetite nanoparticle (Fe 3 O 4 @SiO 2 -EDTA-Ni) have been used as fluorophore and fluoride ion receptor respectively.The assay is based on the exchange reaction between the CD and F -, which persuades the binding of fluoride to magnetic receptor. This method is highly sensitive, fast and selective for fluoride ion in aqueous solution. The linear response range of fluoride (R 2 = 0.992) was found to be 1 to 20 µM with a minimum detection limit of 0.06 µM. Excellent magnetic property as well as superparamagnetic nature of the receptor are advantageous for the removal and well quantification of fluoride ion. The practical utility of the method is well tested with tap water.Due to high sensitivity, reusability, effectivity and biocompatibility, it exhibits great promise as a fluorescent probe for intracellular detection of fluoride.
The synthesis of a novel and specific nanoplatform for anticancer drug delivery, fluorescence imaging and contrast agent in magnetic resonance imaging has been described.
In this paper fluorescent magnetic Fe(3)O(4)@m-SiO(2)@YPO(4):Tb(3+) particles with a size of 52 nm have been prepared and characterized. The surface of the nanoparticles was modified with β-cyclodextrin and folic acid using glutathione as a linker. The hydrophobic anticancer drug 5-fluorouracil (5-FU) was successfully loaded on the fluorescent magnetic nanoparticles via formation of the 5-FU-CD inclusion complex. The overall size of the drug conjugate is 71 nm and the particles are highly stable in an aqueous medium without any deterioration of HD size. The drug conjugate favors more release at lower pH owing to instability of the 5-FU-CD inclusion complex. These results demonstrate that the developed multifunctional nanocomposite can be potentially used in magnetically guided delivery of 5-FU.
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