Recyclable Magnetic Fluorescent Fe₃O₄@SiO₂ Core–Shell Nanoparticles Decorated with Carbon Dots for Fluoride Ion Removal

Abstract

Tremendous efforts have been dedicated to developing fluorescent probes with biocompatible and cyclic features. Challenges remain in terms of high toxicity, poor dispersity in aqueous solution, low efficiency, and high detection limit problems. Inspired by the low biotoxicity and high quantum yield of amine-modified carbon dots (NCDs) as well as the reversible binding between metal ions (Mn+ ions) and carbon dots, a fluorescent quenching receptor is created based on the mechanism of nonradiative electron transfer from NCDs to Mn+ ions. This fluorescent quenching receptor is coordinated on a mesoporous superparamagnetic Fe3O4@mSiO2 nanoparticle, which forms a probe structure of Fe3O4@mSiO2-SiCDs@DTPA-Mn+/NCDs. NCDs detach from metal ions and recover their fluorescence when the probe is placed in the environment to be detected. The concentration of fluoride ions (F– ions) in the environment could be determined by the fluorescence intensity of the detached NCDs. This novel nanoscale probe has recyclable performance and can be reused at least 6 times. The minimum detection limit is down to 65 nM with a wide linear response range of 1 to 25 μM. The ion removal capacity could be up to 21.4 mg/g. This nanoscale fluorescent probe can be used for sufficiently high-response F– ion detection and removal of the platform.

Recyclable Flower-like Fe3O4@SiO2@NiO Nanoparticles for Rhodamine B Adsorption and Photocatalytic Degradation

“…The Fe 3 O 4 @SiO 2 MNPs were fabricated using the modified Stöber method . To ensure that the Fe 3 O 4 MNPs did not oxidize during heating when fabricating the SiO 2 shell, N 2 was used as a protective gas at the initial stage.…”

“…The Fe 3 O 4 @SiO 2 MNPs were fabricated using the modified Stober method. 57 To ensure that the Fe 3 O 4 MNPs did not oxidize during heating when fabricating the SiO 2 shell, N 2 was used as a protective gas at the initial stage. For the SiO 2 coating process, a mixture of 50 mg of Fe 3 O 4 MNPs, 6 mL of DI water, and 40 mL of ethanol was uniformly dispersed via ultrasonication and transferred into a 250 mL three-neck round-bottom flask in a water bath under mechanical stirring at 55 °C.…”

Carbon dot composites for bioapplications: a review

“…Depending on the nature of the inorganic molecules, the nonmetallic inorganics–CD composites can be prepared via physical mixing, hydrothermal treatment, 132,133 the sol–gel method and microwave irradiation. 134–137…”

“…For instance, in Yan and co-workers’ study, glyoxylic acid-modified CDs (GA-CDs) were used as a FRET ratiometric fluorescent probe for the detection of Cu 2+ in aqueous solution. 388 Similarly, Chen et al also applied cyclam-functionalized CDs as a FRET nanoprobe for the detection of Cu 2+ and S. 2–389 In addition to the above examples, the detection of other important metal ions such as Ag + , Cu 2+ , Cr 6+ , and Pb 2+ has also been successfully realized with CD composite-based sensing platforms. 390–401…”

Theoretical investigations on modeling blood flow through vessel for understanding effectiveness of magnetic nanocarrier drug delivery systems

“…Recently, bio-compatible magnetic nanocarriers have attracted much attention due to their superior properties in cancer treatment (5)(6)(7). The motion of these particles in the blood circulating system can be monitored and controlled using magnetic field such as external permanent magnet (8,9).…”