Magnetic Carbon Dots Research Articles

Speedy synthesis of magnetite/carbon dots for efficient chromium removal and reduction: a combined experimental and DFT approach

Abstract Magnetic carbon dots (Fe3O4/N–CQDs) was prepared by and eco-friendly and one-step microwave method using sugarcane bagasse (SB) as a starting material, and applied to remove ad reduce Cr(VI) in wastewater. The magnetization process was performed by a novel microwave method instead of the long time conventional co-precipitation method. The prepared Fe3O4/N–CQDs showed high saturated magnetization (Ms ~ 38.047 emu/g). When neat N–CQDs and Fe3O4/N–CQDs were applied to adsorb Cr(VI), the R% was slightly higher in the case of Fe3O4/N–CQDs (93.86%) compared to N–CQDs (91.73%). Moreover, the reduction rate of Cr(VI) by Fe3O4/N–CQDs was higher than the N–CQDs. The study confirmed the presence of magnetic iron oxide (Fe-O) in the N–CQDs at 655 cm−1 using FTIR spectroscopy. Interestingly, XRD analysis revealed peaks indicative of elemental iron (Fe(0)) alongside the iron oxide. Furthermore, TGA/DTG analysis showed a significantly higher weight residue (∑RW) for Fe3O4/N–CQDs compared to N–CQDs alone, suggesting enhanced thermal stability due to the Fe3O4 component. This stability is further supported by higher activation energy (∑A) and pre-exponential factor (∑s) obtained for Fe3O4/N–CQDs compared to N–CQDs. The prepared Fe3O4/N–CQDs showed higher fluorescence compared to the N–CQDs, which make them suitable as a chemosensor for the future work. In addition, DFT calculations confirmed the high stability of the Fe3O4/N–CQDs compared to N–CQDs. Graphical Abstract

Heteroatom-doped magneto-fluorescent carbon dots, a potent agent for multimodal imaging

A simple, one-pot and green method is reported for hydrothermal synthesis of highly fluorescent and magnetic carbon dots (CDs) by using D-glucose, as the carbon source. CDs were fully characterized by the UV-Vis and fluorescence spectroscopy, DLS, FTIR, TEM, EDS, XRD, and VSM. The nitrogen doping of different diamines significantly improved the fluorescence quantum yield (QY) of CDs with the maximum effect obtained by using m-phenylenediamine (mPDA). Temperature and reaction time also affected the QY of CDs with the best results obtained at 150 °C for 3 h. The heteroatom doping by innovative use of different metal sulfates including FeSO4, MnSO4, CuSO4, MgSO4, and ZnSO4, further improved the optical properties of CDs. Interestingly, the magnetic and multicolor CDs with high colloidal stability and QYs of 17.7, 16.5, and 53.9% at 460, 490, and 515 nm, respectively, were synthesized by using 0.1 M of glucose, mPDA and MnSO4. The resulted Mn-, S-, N-doped CDs represented rapid uptake and high-quality fluorescence imaging of the human fibroblast and umbilical vein endothelial cells in vitro, without significant toxicity. The CDs also displayed high r1 relaxivity of 32.3 mM− 1 s− 1 and were used for high-contrast MR and fluorescence imaging of mouse tumor models, in vivo.

Synthesis and characterization of magnetic carbon dots (CDs)-based hybrid material as an adsorbent for the removal of organic dye from water

In recent years, the rapid advancement of materials science and the desire for new functions has led to an enormous demand for novel materials, which could be used in various applications. As a result, hybrid materials have gained the interest of the scientific community due to the infinite combinations of individual components, which could lead to materials with unique properties. In this study, a carbon dots (CDs)-CuFe2O4 nanohybrid material was successfully prepared through a solvothermal process and utilized as an adsorbent for the removal of Congo Red (CR) dye from aqueous environment. The nanohybrid material combines interactive surface functional groups due to CDs and high magnetic saturation due to CuFe2O4 nanoparticles, resulting in enhanced selectivity towards CR dye and easy separation after utilization with an external magnet. The as-prepared material was characterized by various techniques, including XRD, micro-Raman, FT-IR, HR-TEM/EDS, N2 porosimetry, and SQUID. Finally, its capability in the removal efficiency of CR dye was investigated at different initial CR concentrations, contact times and pH values via UV–Vis spectroscopy.

Bifunctional magnetic carbon dots for the rapid fluorescent detection and the efficient adsorptive removal of copper ion

Developing a bifunctional material capable of both sensing and removing heavy metal ions is crucial but remains a significant challenge. Herein, magnetic carbon dots (M/CDs) were developed using ferroferric oxide (Fe3O4) and riboflavin (C17H20N4O6). M/CDs with optimal fluorescence properties were obtained under the specific preparation conditions of a molar ratio of riboflavin / Fe3O4 of 6:5, at a temperature of 200 °C and following a reaction time of 24 h. The structure of M/CDs was characterized using TEM, XRD, FTIR and VSM, which exhibited the prepared M/CDs contained high-affinity groups (–CN, C=O) and excellent magnetic separation properties (83.87 emu/g), offering selective detection and higher separation capacity for copper ion (Cu2+). The fluorescence intensity of the M/CDs progressively decreased with increasing concentrations of Cu2+, and the calculated detection limit was determined to be 0.096 mg/L, which was below the permissible limit. Moreover, the M/CDs demonstrated a removal efficiency of 89 % for 5 mg/L of Cu2+ across a broad pH range. The adsorption data were well described by the pseudo-second-order kinetic and Freundlich isotherm models. Notably, the reusability could be achieved by recycling at least five turns by using an external magnet. All of these indicate magnetic carbon dots hold great promise for simultaneous detection and removal of Cu2+, offering a feasible solution for assessing water quality and treating wastewater.

Strategy for establishing sensitive fluorescent sensor toward p-nitrophenol integrating magnetic molecularly imprinted materials and carbon dots

In this work, a sensitive fluorescent sensor toward p-nitrophenol (4-NP) integrating magnetic molecularly imprinted materials and carbon dots (CDs) was proposed. Magnetic material and CDs derived from K3 [Fe(CN)6] and glucose were simultaneously obtained through simple one-step hydrothermal process. Introducing of molecularly imprinted materials based magnetic solid phase extraction (MSPE) endowed the constructed fluorescent sensor with higher sensitivity and selectivity. The significant factors affecting the sensitivity of the sensor toward 4-NP were optimized. Good linearity was obtained between fluorescent intensity of CDs and different concentration of 4-NP from 0.08 to 62.5 μg L−1. The sensitivity of constructed sensor was very low with detection limit of 0.02 μg L−1. Reliable applicability was also proved by the well-pleasing recoveries of 94.2–97.8% with different spiked concentrations of 4-NP in real environmental waters.

Colorimetric aptasensor based on peroxidase-mimetic metal-organic framework nanoparticles and magnetic carbon dots for visual detection of Staphylococcus aureus.

A colorimetric aptasensor based on the dual recognition of magnetic carbon dots (M-CDs) and copper-based metal-organic frameworks (Cu-MOFs) was constructed for the visual detection of Staphylococcus aureus (S. aureus). Aptamer-modified Cu-MOFs could specifically identify target bacteria and exhibited peroxidase-like activity by catalyzing the colorimetric reaction of the 3,3',5,5'-tetramethylbenzidine-H2O2 (TMB-H2O2) system. M-CDs electrostatically attracted bacteria because of their strong positive electrical properties and offered better capturing performance compared with magnetic beads owing to their smaller size. Visual detection of the target was achieved using the color change of the reaction catalyzed by the resuspension of the sandwich-structured complex. The bacteria were sensitively detected with a limit of detection (LOD) of 1 CFU mL-1 using the peroxidase catalytic activity of Cu-MOFs. Non-target bacteria produced negative results, demonstrating the excellent selectivity of the proposed aptasensor. The strategy showed good recovery in real sample detection, showing great potential for visual monitoring of pathogenic bacteria, and could provide a reference for further development of novel sensing platforms for bacterial detection.

Construction of specific molecularly imprinted electrochemical probe utilizing magnetic carbon dots for effective measurement of bisphenol AP in plastic products

A creative electrochemical probe utilizing molecularly imprinted modified magnetic carbon dots was designed and fabricated. Carbon dots are a new kind of green, pollution-free, cheap and easy to obtain nanomaterials. The combination of Fe3O4 and carbon dots improved the defect of ferric oxide being easy to aggregate, and their co-modification significantly enhanced the electrochemical activity of the electrode. Cyclic voltammetry and differential pulse voltammetry were executed to evaluate the electrochemical behavior of the co-modified electrode surface and performance of the probe. The constructed probe exhibited excellent selectivity and sensitivity for determining bisphenol AP in plastic products. The introduction of molecularly imprinted polymers endowed the sensor excellent selectivity, ensuring specific recognition of bisphenol AP. The fabricated sensor demonstrated a good two-stage linear range of 0.07–0.3 μM and 0.3–10 μM, and the detection limit was 0.027 μM. The constructed probe was validated to detect bisphenol AP in self-heating hot pot, instant noodle bucket and disposable plastic cup, and satisfactory results were achieved. These results indicated that the fabricated sensor was a cheap, rapid, and selective sensing-platform for detecting bisphenol AP, and could be employed as a reliable routine tool.

Advances in Magnetic Carbon Dots: A Theranostics Platform for Fluorescence/Magnetic Resonance Bimodal Imaging and Therapy for Tumors.

Theranostics technology that combines tumor diagnosis or monitoring with therapy is an important direction for the future development of tumor treatment. It takes advantage of efficiently observing tumor tissues, monitoring tumor treatment in real time, and significantly improving the cure efficiency. Magnetic carbon dots (CDs) are of wide interest as molecular imaging probes, drug carriers, photosensitizers, and radiosensitizers in the integration of tumor fluorescence/magnetic resonance bimodal diagnosis and treatment because of their small size, good optical stability, magnetic relaxation rate, and biocompatibility. This review first analyzes and compares the synthesis methods and physicochemical properties of magnetic CDs in recent years and then concludes their mechanism in tumor fluorescence/magnetic resonance bimodal imaging and therapy in details. Subsequently, the research progress of their application in tumor theranostics are summarized. Finally, the problems and challenges of magnetic CDs for development at this stage are prospected. This review provides new ideas for their controlled synthesis and application in efficient and precise therapy for tumors.

Biogenic synthesis of Allium cepa derived magnetic carbon dots for enhanced photocatalytic degradation of methylene blue and rhodamine B dyes

Biogenic synthesis of Allium cepa derived magnetic carbon dots for enhanced photocatalytic degradation of methylene blue and rhodamine B dyes

Ultrasound-assisted adsorption approach for desulfurization of n-heptane using nitrogen-doped magnetic carbon dot nanocomposite

Desulfurization is an important process that not only affects the quality and performances of fuels but also is of great importance from environmental aspects. In this research, nitrogen-doped magnetic carbon dots nanocomposite was synthesized and characterized, and it's potential in adsorptive removal of thiophenes (i.e., thiophene, benzothiophene, and dibenzothiophene) from n-heptane (i.e., as model fuel) was investigated. After optimization of adsorption process, the removal efficiency was obtained above 95% for all of studied thiophenes. Besides that, it was concluded that using ultrasound during the adsorption process could enhance the maximum adsorption capacity. Langmuir model was able to appropriately describe the adsorption isotherm data, where the maximum equilibrium adsorption capacities for thiophene, benzothiophene and dibenzothiophene were obtained as 90.22, 96.51 and 100.38 mgg−1, respectively. The analysis of kinetic data also revealed that all thiophenes were being adsorbed following Pseudo-second-order model. To regenerate the adsorbent, the desorption process was also investigated using different solvents under different conditions, methanol was found as effective solvent for regeneration. The proposed adsorbent was used successfully for the removal of pollutants in a gasoline sample.

Two strategies for rapid and sensitive detection of procalcitonin using carbon dots-encapsulated nanocapsule and magnetic carbon dots as coupled labels

Procalcitonin (PCT) is a crucial biomarker for diagnosing bacterial infections in clinical settings. Here, a biosensing system utilizing a fluorescence amplification system of nanocapsules and magnetic carbon dots was developed. The system incorporated two PCT sensing strategies: highly sensitive immunomagnetic separation and rapid homogeneous immunoassay. In these strategies, nanocapsules modified with antibodies function as immunosensors and energy transmitters, while magnetic carbon dots modified with antibodies serve as capture probes and immunosensors. The immunomagnetic separation analysis strategy utilized immunonanocapsules as sensors and immunomagnetic carbon dots as capture probes. This strategy demonstrated the capability to achieve ultrasensitive trace detection of PCT within the range of 1–1000 pg/mL, following normal immunoreactivity and magnetic separation. The limit of detection to 0.3 pg/mL (serum) and 0.33 pg/mL (plasma). Via the fluorescence resonance energy transfer principle, the homogeneous immunoassay strategy used immunonanocapsules as energy transmitters and immunomagnetic carbon dots as sensors. This enabled direct and rapid detection of PCT in a wide range of 0–100 ng/mL in diluted serum, with a limit of detection of 0.41 ng/mL. Both strategies demonstrated high recoveries (93.5%-104.6% and 98.4%-103.8%) and exhibited reliability in achieving accurate quantitative PCT detection. Such a novel analytical approach to PCT may broaden the potential uses of carbon dots-based immunofluorescent sensing. Furthermore, it was direct implications for ultrasensitive and rapid point-of-care detection of various serum biomarkers in clinical settings.

Sensitive measurement of silver ions in environmental water samples integrating magnetic ion-imprinted solid phase extraction and carbon dot fluorescent sensor

Increasing use of silver in various fields has caused Ag+ pollution in water environment, taking great threats to people's health. As a consequence, establishing rapid and reliable methods for sensitive determination of Ag+ is of great significance. Fluorescent (FL) sensors based on carbon dots (CDs), an excellent carbonaceous nanomaterial with strong and stable fluorescence, have absorbed extensive attentions in analysis of pollutants due to its advantages of carbon sources being readily available, low cost, easy operation and fast response. Moreover, ion-imprinting is a better way to increase the selectivity of the proposed method. Present work described an effective method for the sensitive measurement of silver ion in water samples in combination with magnetic ion-imprinted solid phase extraction and CDs based fluorescent sensor, which took full advantages of easy separation and high enrichment of magnetic solid phase extraction, high selectivity of ion-imprinting technology, and sensitivity and rapid response of fluorescent sensor from CDs. Sulfur-doped CDs derived from dithizone and magnetic ion-imprinted nanomaterial were prepared, and characterized with Fourier transform infrared spectroscopy and transmission electron microscope, etc. Magnetic Ag+ imprinted nanomaterial based solid phase extraction was employed for separating and enriching Ag+ from water samples. The significant parameters were optimized in detail. Under the optimal conditions, the proposed method provided good linearity in the range of 0.01–0.4 µmol/L and low detection limit of 3 nmol/L. The reliability of the proposed method was validated with real water samples, and the results demonstrated that the proposed method was simple, robust, selective and sensitive detection tool for Ag+ in real water samples.

Controllable synthesis of bifunctional magnetic carbon dots for rapid fluorescent detection and reversible removal of Hg2+

Mercury is one of the most toxic heavy metals, whose identification and separation are crucial for environmental remediation. Till now, it remains a significant challenge upon simultaneous detection and removal of Hg2+. Herein, bifunctional probe magnetic carbon dots were synthesized and optimized via systematic structure manipulation of the carbon and iron precursors towards fluorescence, Hg2+ adsorption and magnetic separation. The probe exhibited blue emission at 440 nm with high quantum yield of 55 % and a high paramagnetism with the saturation magnetization value of 22.70 emu/g. Furthermore, the fluorescent detection of Hg2+ with limit of 5.40 nM and high selectivity were achieved through surface structure manipulation with moderate -NH2, -SH and Fe contents. As a result, the magnetic removal of Hg2+ was consecutively effectuated with high removal efficiency of 98.30 %. The detection and recovery of Hg2+ in real samples were further verified and demonstrated the excellent environmental tolerance of probe. The reusability was viable with recycling at least three turns by external magnet. This work not only provides a promising approach for simultaneous detection and removal of heavy metal pollution, but also provides an excellent example as a versatile platform for multifunction integration via the structure manipulation for other applications.

Hydrogen bonding donor/acceptor active sites exposed on imide-functionalized carbon dots aid in enhancing arsenic adsorption performance

During the arsenic (As) adsorption process, amino-functionalization has been widely considered as one of the effective adsorbents optimization methods, while this study reveals that imide functional groups also play a non-negligible role. Herein, magnetic carbon dots (CDs) equipped with imide (FeCD-NH) or amino functional groups (FeCD-NH2) were synthesized to deduce the relationship between different configurations of amino-like functional groups and As. The results showed that FeCD-NH exhibited extraordinary As(V) adsorption behavior (with 97.80 % As(V) removal within 5 min), outperformed that equipped with amino functional groups (FeCD-NH2). An array of advanced characterization techniques and density functional theory (DFT) calculation collectively revealed a dual-configuration hydrogen bond synergistic mechanism of FeCD-NH toward As(V). Different from monomorphic hydrogen bond of amino functional group, imide functional group forms abundant adsorption sites through dual-configuration hydrogen bonds to realize the ultrafast adsorption of As(V). In addition, FeCD-NH can remove As(V) from other more complex water matrices to levels below the World Health Organization (WHO) drinking water standards and the Chinese surface water standards. Therefore, this work provides a promising strategy for As decontamination by fine-tune the surface chemistry of adsorbents.

Magneto-Luminescent Nanocomposites Based on Carbon Dots and Ferrite with Potential for Bioapplication.

Multifunctional nanocomposites that combine both magnetic and photoluminescent (PL) properties provide significant advantages for nanomedical applications. In this work, a one-stage synthesis of magneto-luminescent nanocomposites (MLNC) with subsequent stabilization is proposed. Microwave synthesis of magnetic carbon dots (M-CDs) was carried out using precursors of carbon dots and magnetic nanoparticles. The effect of stabilization on the morphological and optical properties of nanocomposites has been evaluated. Both types of nanocomposites demonstrate magnetic and PL properties simultaneously. The resulting MLNCs demonstrated excellent solubility in water, tunable PL with a quantum yield of up to 28%, high photostability, and good cytocompatibility. Meanwhile, confocal fluorescence imaging showed that M-CDs were localized in the cell nuclei. Consequently, the multifunctional nanocomposites M-CDs are promising candidates for bioimaging and therapy.

Novel electrochemical sensor from magnetic carbon dots and cetyltrimethylammonium bromide for sensitive measurement of tetrabromobisphenol A in beverages

Present work depicted a novel electrochemical sensor fabricated with magnetic carbon dots (M-CDs) and cetyltrimethylammonium bromide (CTAB) modified glassy carbon electrode (GCE) for selective measurement of 3,3′,5,5′-tetrabromobisphenol A (TBBPA) in beverages. The M-CDs composite material revealed good electrocatalytic activity, and CTAB has strong hydrophobic interaction which enable it have good enrichment capacity of hydrophobic compounds, and combination of them further enhances the electrochemical signal. Hence CTAB decoration can markedly improve the detection performance of TBBPA. Electrochemical properties of the fabricated sensor was investigated through performing cyclic voltammetry (CV). The morphology and functional groups of the modified materials were examined with transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the synthesized material had a spherical-like structure, good dispersion properties and plenty of functional groups on the surface. The effects of incubation potential, incubation time, pH of electrolyte, and scanning rate on oxidation peak current were investigated. Under optimal conditions, the designed sensor had good linear range of 1 nM–1000 nM, and the detection of limit of the constructed sensor was 0.75 nM. The constructed sensor was utilized to detect TBBPA in vitamin water, scream drink and genki forest, and satisfactory detection performance had been achieved.

Nanocomposite of functionalized halloysite and Ag(0) decorated magnetic carbon dots as a reusable catalyst for reduction of dyes in water

A new magnetic, catalytic nanocomposite of Hal-MT-Cys-Ag/MNCD was fabricated and utilized for catalyzing reductive de-colorization of methyl orange and rhodamin B in aqueous media at room temperature. To prepare this material, Cl-functionalized halloysite nanoclay was successively reacted with melamine and 2,4,6-trichloro-1,3,5-triazine to furnish multi-nitrogen containing ligand on halloysite surface. Then, magnetic carbon dots were crafted through a facile method and decorated with Ag nanoparticles and cysteine to furnish Cys-Ag/MNCD species. The final nanocomposite was obtained via incorporation of this latter species onto functionalized halloysite. This new composite was characterized through the XRD, TEM, BET, FTIR, TGA, EDX, and mapping analyses. The catalytic experiments confirmed that low loadings of the Hal-MT-Cys-Ag/MNCD composite reduction of both dyes were performed in ~1 min. This material could also be readily collected from the reaction media magnetically and displayed excellent recyclability with a slight decrease in its activity of at most ~6% up to 8 cycles. The kinetic and thermodynamic study of de-colorization reactions emphasized high catalytic performances of the synthesized nanocomposite. More precisely, activation energy, enthalpy, and entropy were determined to be 48.15 kJ mol−1, 45.65 kJ mol−1, and -124.61 J mol−1 K−1; respectively for the methyl orange while the corresponding values for the rhodamine B were found to be 11.03 kJ mol−1, 8.53 kJ mol−1, and -249.93 J mol−1. K−1.

A magnetic thermosensitive fluorescence imprinted polymer for selective detection of bovine hemoglobin

In this paper, a new type of magnetic thermosensitive fluorescence imprinted polymer was prepared for high selective identification of bovine hemoglobin with the magnetic carbon dots as the fluorescence source, poly(n-isopropylamide) and N, N-methylenebis acrylamide as the functional monomers and cross-linker, respectively. The magnetic thermosensitive fluorescence imprinted polymer was characterized by Fourier-transform infrared, fluorescence spectrometer, scanning electron microscope, transmission electron microscope and vibrating sample magnetometer in detail. The fluorescence of the magnetic thermosensitive fluorescence imprinted polymer was quenched linearly with bovine hemoglobin concentration in the range of 0.1- 9.0 μM with the detection limit of 48.0 nM. The imprinting factor was 2.3, which indicated excellent specificity of the magnetic thermosensitive fluorescence imprinted polymer toward bovine hemoglobin. With the advantage of the thermosensitivity, the elution efficiency of bovine hemoglobin could be significantly simplified and enhanced. In addition, the developed method was applied for selective identification of bovine hemoglobin in the real samples with the recoveries of 99.0–104.7%. This proposed protocol provides a feasible and reliable strategy for preparation of the smart imprinted material with multiple stimulation responses.

Colorimetric Immunoassay for the Detection of Staphylococcus aureus by Using Magnetic Carbon Dots and Sliver Nanoclusters as o-Phenylenediamine-Oxidase Mimetics

Staphylococcus aureus (S. aureus) is an important foodborne pathogen that causes food poisoning and severe infections. Herein, we design a novel and sensitive colorimetric immunoassay for the detection of S. aureus based on the formation of a magnetic bead-based sandwich complex and signal amplification via an enzyme mimic. Magnetic nanoparticles decorated with carbon dots offer rapid enrichment and separation of target bacteria in complex matrices. Sliver nanoclusters are used as an artificial enzyme that can oxidize o-phenylenediamine to form a yellow product with a maximum absorption peak at 421 nm. This method can visually detect S. aureus ranging from 10 to 106 cfu mL−1. Its limit of detection reaches down to 4.9 cfu mL−1. By analyzing food samples, the recovery is from 85.6 to 103.7%.

Nitrogen, Cobalt Co-doped Fluorescent Magnetic Carbon Dots as Ratiometric Fluorescent Probes for Cholesterol and Uric Acid in Human Blood Serum.

Detection of cholesterol and uric acid biomarkers is of great importance for clinical diagnosis of several serious diseases correlated with their variations in human blood serum. In this study, a new kind of well selective and highly sensitive ratiometric fluorescent probe for cholesterol and uric acid determination in human blood serum was innovatively developed on the basis of the inner filter effect (IFE) process of nitrogen, cobalt co-doped carbon dots (N,Co-CDs) with 2,3-diaminophenazine (DAP). DAP was the oxidative product during the oxidation reaction between o-phenylenediamine and H2O2. Fluorescent magnetic N,Co-CDs possessing blue emission and magnetic property were prepared through a facile one-pot hydrothermal strategy by using citric acid, diethylenetriamine, and cobalt(II) chloride hexahydrate as precursors. N,Co-CDs exhibited good ferromagnetic property and excellent optical properties even in extremely harsh environmental conditions, implying the huge potential applications of such N,Co-CDs in biological areas. On the basis of the IFE process between N,Co-CDs and DAP, N,Co-CDs were applied to establish ratiometric fluorescent probes for the indirect detection of cholesterol and uric acid that participated in enzyme-catalyzed H2O2-generation reactions. The established IFE-based fluorescent probes exhibited relatively low detection limits of 3.6 nM for cholesterol and 3.4 nM for uric acid, respectively. The fluorescent probe was successfully utilized for the determination of cholesterol and uric acid in human blood serum with satisfying results, which provided an informed perspective on the applications of such doped CDs to explore the specific and sensitive nanoprobe in disease diagnoses and clinical therapy.