Enhanced Photodegradation of Organic Pollutants by Carbon Quantum Dot (CQD) Deposited Fe₃O₄@mTiO₂ Nano-Pom-Pom Balls

Highly water dispersible, superparamagnetic carbon quantum dot (CQD) deposited Fe₃O₄@mTiO₂ pom-pom balls have been prepared by a simple hydrothermal method. The effective deposition of carbon dots expands the light absorption of mTiO₂ from the UV to visible region. The results of photocurrent measurement reveal that an optimum deposition of C-dot at 20 wt % significantly increases the photocurrent density. High surface area and extended conjugation of carbon dots enhance the adsorption of organic pollutants. The active species generated in the photocatalytic system were also detected through trapping of radicals and holes in the presence of various scavengers. In a comparison with a conventional photocatalyst such as Degussa P25, the developed heterojunction shows much higher degradation efficiency for ciprofloxacin, methylene blue, quinalphos, and 4-nitrophenol under visible light. The light upconversion properties of uniformly deposited carbon quantum dots could be a reason for higher visible light catalytic activity of the synthesized magnetically recoverable hybrid photocatalyst

Design of Fe₃O₄@SiO₂@Carbon Quantum Dot Based Nanostructure for Fluorescence Sensing, Magnetic Separation, and Live Cell Imaging of Fluoride Ion

A robust reusable fluoride sensor comprised 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 (Fe₃O₄@SiO₂–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 (<i>R</i>² = 0.992) was found to be 1–20 μM with a minimum detection limit of 0.06 μM. Excellent magnetic property and 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. Because of high sensitivity, reusability, effectivity, and biocompatibility, it exhibits great promise as a fluorescent probe for intracellular detection of fluoride

Design of Fe₃O₄@SiO₂@Carbon Quantum Dot Based Nanostructure for Fluorescence Sensing, Magnetic Separation, and Live Cell Imaging of Fluoride Ion

A robust reusable fluoride sensor comprised 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 (Fe₃O₄@SiO₂–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 (<i>R</i>² = 0.992) was found to be 1–20 μM with a minimum detection limit of 0.06 μM. Excellent magnetic property and 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. Because of high sensitivity, reusability, effectivity, and biocompatibility, it exhibits great promise as a fluorescent probe for intracellular detection of fluoride

Magnetic Mesoporous Silica Gated with Doped Carbon Dot for Site-Specific Drug Delivery, Fluorescence, and MR Imaging

Construction of a theranostic agent which integrates multiple modalities with different functions into one entity is challenging from a molecular design and synthesis perspective. In this context, the present paper reports the fabrication of a novel type of multifunctional hybrid nanoparticle composed of magnetic gadolinium oxide–iron oxide core, mesoporous silica shell gated with boronic acid functionalized highly luminescent carbon quantum dot (BNSCQD). The porous silica shell acts as an excellent reservoir for anticancer drug 5-fluorouracil, whereas the BNSCQD cap impressively controls the drug transport under simulated intracellular environment. Furthermore, recognition and fluorescence turn on response of BNSCQD toward cell surface glycan sialyl Lewis^a (SL^a) enables targeted drug release and excellent fluorescence imaging of SL^a overexpressed HePG2 cancer cells. The <i>r</i>₁ and <i>r</i>₂ relaxivities of the material are found to be 10 and 165 mM^–1 s^–1 which is comparable to commercially available magnetic resonance imaging contrast agents. Benefiting from the combined advantages of dual stimuli-responsive drug release, excellent optical imaging, and MR imaging, this novel construct can be a promising theranostic material

Highly Hydrophilic Luminescent Magnetic Mesoporous Carbon Nanospheres for Controlled Release of Anticancer Drug and Multimodal Imaging

Judicious combination of fluorescence and magnetic properties along with ample drug loading capacity and control release property remains a key challenge in the design of nanotheranostic agents. This paper reports the synthesis of highly hydrophilic optically traceable mesoporous carbon nanospheres which can sustain payloads of the anticancer drug doxorubicin and T2 contrast agent such as cobalt ferrite nanoparticles. The luminescent magnetic hybrid system has been prepared on a mesoporous silica template using a resorcinol-formaldehyde precursor. The mesoporous matrix shows controlled release of the aromatic drug doxorubicin due to disruption of supramolecular π–π interaction at acidic pH. The particles show MR contrast behavior by affecting the proton relaxation with transverse relaxivity (<i>r</i>₂) 380 mM^–1 S^–1. The multicolored emission and upconversion luminescence property of our sample are advantageous in bioimaging. In vitro cell experiments shows that the hybrid nanoparticles are endocyted by the tumor cells through passive targeting. The pH-responsive release of doxorubicin presents chemotherapeutic inhibition of cell growth through induction of apoptosis