Fluorescent Quantum Dots Research Articles

Chemo-Triggered luminescence of sulfur nanoparticles for highly secure information storage

Most of the information storage technologies that rely solely on the luminous signals of specific materials may be cracked and forged. It is always a technical challenge that special “keys” are used to trigger luminescent material for encryption. In this paper, green fluorescent quantum dots (green SQDs) were synthesized by utilizing the corrosion and encapsulation functions of polyethyleneimine (PEI). Green SQDs transform into blue SQDs under the stimulation of H2O2. Stimulus-responsive characterization of green SQDs was used for highly secure message encryption. This work provides a promising application in the field of high-security information storage for chem-triggered luminescent materials.

The Green Synthesis of Carbon Quantum Dots through One-step Hydrothermal Approach by Orange Juice for Rapid, and Accurate Detection of Dopamine.

In the current study, the fluorescent Carbon quantum dots (CDs) were synthesized through one-step hydrothermal approach by orange juice without any additional agents. The as-prepared green-CDs (GCDs) were quasi-spherical shape ranged from 2 to 8nm with an average diameter of 5nm, and emitted bright blue fluorescent (FL) under ultraviolet light irradiation (Uv). Different detailed analyses proved that the as-prepared GCDs had good morphologies, various functional groups, high water solubility, great optical features, and excellent stability towards diverse environmental conditions. The results indicated that the as-prepared GCDs can detect different concentrations of dopamine from 1 to 100 µM based on the quenching of their native fluorescent. Furthermore, the good linear relationship was obtained for dopamine in the broad range of concentrations from 1 to 100 µM with the limit of detection (LOD) of 0.81 µM. In addition, the as-prepared GCDs can be applied as a fluorescent probe for detection of dopamine in the different real samples.

Dual‐emission ratiometric fluorescence sensors based on silica, molecularly imprinted polymers and carbon quantum dots for high‐sensitivity and high‐selectivity detection of sulfadiazine

AbstractIn this work, a dual‐emission ratiometric fluorescence sensor was prepared and used for the detection of sulfadiazine (SDZ) drug. The hydrothermal method was used to synthesize carbon quantum dots (CQD) (fluorescence response signal) and sulfhydryl‐modified cadmium telluride quantum dots (fluorescence reference signal), and a molecularly imprinted polymer was subsequently synthesized. After eluting the template molecule SDZ, the blot recognition site remains on the surface of the imprinted polymer. During the process of detection, due to electron transfer between SDZ and CQDs, holes of stimulated electrons are filled. This leads to fluorescence quenching at around 430 nm, which greatly improves sensor selection performance. Compared with traditional single‐emission fluorescence sensors, ratiometric fluorescence sensors have a wider linear range and higher detection accuracy. Under the optimal conditions, the sensor exhibited excellent performance in terms of low detection limit (4.2 nmol L−1) and satisfactory linear range (2–20 μmol L−1). This intelligent response change mode also provides prospect for detection of other sulfonamide antibiotics and offers a reference to signal transform for other molecular imprinting technologies. © 2023 Society of Industrial Chemistry.

H2O2-responsive dual-peak ratiometric NIR-II fluorescent probe for in situ hepatic oxidative stress level monitoring

Timely detection of hepatic oxidative stress is effective in preventing the onset and progression of liver disease. However, real-time and dynamic monitoring of oxidative stress in vivo remains challenging. Herein, we report a H2O2-responsive dual-peak ratiometric NIR-II fluorescent probe (Er@Ag2S:Pb), made by combining H2O2-responsive fluorescent Pb-doped Ag2S quantum dots (Ag2S:Pb QDs) with a fluorescence-stabilized reference substrate NaYF4:Yb/Er @NaYF4. By monitoring the change in emitted I1550/I1220 intensities the probe can be used to sense and quantify H2O2 concentrations ranging from 5 to 100 μM with excellent specificity. Experimental studies using mice models have shown that this probe can be used to monitor of hepatic H2O2-related oxidative stress in real time and non-invasively. Thus, the developed probe provides a powerful ratiometric NIR-II fluorescence imaging tool for timely monitoring of oxidative stress in vivo.

Multi-signal aptasensor for thrombin detection based on catalytically active gold nanoparticles and fluorescent silicon quantum dots.

A multi-signal aptasensor for thrombin determination isproposed based on catalytically active gold nanoparticles (AuNPs) and fluorescent silicon quantum dots (SiQDs). Yellow 4-Nitrophenol (4-NP) could be converted to colorless 4-Aminophenol (4-AP) by catalytically active aptamer-modified AuNPs (S1-AuNPs). The SiQDs emitted strong blue fluorescence at 455nm at the excitation wavelength of 367nm. When thrombin was absent, S1-AuNPs could catalytically reduce yellow 4-NP to colorless 4-AP. When thrombin was added, the aptamer could be transformed into a G-quadruplex structure, which masked the surface-active catalytic sites of AuNPs and restrained the reduction of 4-NP. Thus, the fluorescence of SiQDs was greatly quenched by 4-NP through the inner filter effect (IFE), and the solution color remained yellow. As the concentration of thrombin increased, the catalytic activity of S1-AuNPs decreased. The concentration of 4-NP that was converted to 4-AP declined and the unconverted 4-NP increased. In this process, the absorption peak of 4-NP at 400nm increased while the fluorescence emission of SiQDs at 455nm decreased. The linear ranges of the fluorometric and colorimetric aptasensor were 0.5-30nM and 0.3-30nM, respectively. The limits of detection (LOD) for the two modes were 0.15nM and 0.13nM. Furthermore, a portable sensing platform was constructed by combining the smartphone-based device with the software ImageJ for the determination of thrombin. With the advantages of cost-effectiveness, simplicity of operation and broad applicability, this aptasensor provided a new perspective for on-site determinationof thrombin in the clinical field.

Microwave-Prepared Quantum Dots and Their Potential Applications as Adsorbents and Chemosensors.

A combination of different eco-friendly materials prepared promising fluorescent quantum dots (QDs) through the one-step process using the microwave heating of urea with cellulose, chitosan, and biochar. Characterizations of the prepared QDs, including the investigation of their structure by infrared spectroscopy, Raman analysis, X-ray diffraction, thermal gravimetric analysis, morphology, and optical properties, were performed. The results showed that QDs possess a small size, high UV absorption, and excitation wavelength-dependent fluorescence. The prepared QDs were also tested for metal ions removal from aqueous solutions. The adsorption at different contact times was investigated to optimize the adsorption efficiency of the prepared QDs. All QDs were found to be an ideal sorbent for Cr(II), Cu(II), Mn(II), and Pb(II). From the data, Cr(II) was more highly adsorbed than other metal ions. The results of the kinetic investigation showed that the pseudo-second-order kinetic model fit the adsorption process effectively. In addition, the fluorescence spectra of QDs were changed after the adsorption of metal ions; hence, the prepared QDs could be utilized in environmental sectors such as wastewater pollution detection, adsorption, and chemical sensing applications.

A fluorescent system based on graphene quantum dots-capped magnetic hydroxyapatite-MIL-100 metal-organic frameworks for pH-sensitive and controlled release of DOX

Since metal-organic frameworks (MOFs) have shown great potential as emerging candidates in biomedical applications, it is worthwhile to construct an MOF-based drug delivery system. Hence, in this work, magnetic hydroxyapatite-MIL-100 metal-organic frameworks (SiO2@Fe3O4-HA-MIL-100) with antioxidant properties were synthesized as a novel drug delivery system through in-situ self-assembly of MIL-100 MOFs around pre-synthesized magnetic hydroxyapatite nanoparticles. Then, SiO2@Fe3O4-HA-MIL-100 nanocomposites were capped with fluorescent graphene quantum dots (SiO2@Fe3O4-HA-MIL-100-GQDs) for loading and delivering of doxorubicin (DOX). The SiO2@Fe3O4-HA-MIL-100, GQDs, and SiO2@Fe3O4-HA-MIL-100-GQDs encapsulation efficiency was 80.2, 42.2, and 95.8 %, respectively. The in vitro DOX release amount after 72 h from SiO2@Fe3O4-HA-MIL-100, GQDs, and SiO2@Fe3O4-HA-MIL-100-GQDs at pH 5 was 75.8 %, 86.2 %, and 67.2 %, while at pH 7.4 was 37.3 %, 50.1 %, and 29 %, respectively. These results confirmed a pH-responsive controlled release of DOX from nanocomposites. The release mechanism of DOX from the prepared nanocomposites was also well fitted to the Korsmeyer-Peppas kinetic, Fickian diffusion, and diffusion-controlled release. In addition, the MTT assays of nanocomposites against MCF-7 breast cancer cell lines clearly illustrated that the prepared nanocomposites had no significant cytotoxicity, while DOX-loaded nanocomposites had notable toxicity to MCF-7 cells. The IC50 values of DOX, SiO2@Fe3O4-HA-MIL-100-DOX, GQDs-DOX, and SiO2@Fe3O4-HA-MIL-100-GQDs-DOX against MCF-7 cells calculated at about 4.2 μg/mL, 1.8 μg/mL, 3 μg/mL, and 1.2 μg/mL, respectively. The DPPH test results also showed that the nanocomposites have excellent antioxidant activity. In addition, the in vitro hemolysis results displayed neglectable hemolysis activity (lower than 5 %) of SiO2@Fe3O4-HA-MIL-100-GQDs even at a high dose. Therefore, these new drug delivery systems can be used safely as potential drug carriers in targeted cancer therapy.

Determination of Trace Water Using Fluorescence Probes Based on Nitrogen‐Doped Carbon Quantum Dot Fluorescence Senors (Y‐CDs and R‐CDs)

AbstractIn this work, we reported two nitrogen doped carbon quantum dot fluorescence sensors (Y‐CDs and R‐CDs) with good stability and luminescence efficiency, which can be quickly, sensitively and low‐cost for the determination of trace water content in organic solvents. Using o‐phenylenediamine and p‐phenylenediamine as nitrogen sources and terephthalic acid as carbon sources, the preparation was carried out through simple solvothermal synthesis and heteroatom doping. The luminescence characteristics and interaction mechanism with the target were discussed. The results indicate that the two carbon dots can effectively quench the water content in acetone, ethanol, and DMF, as well as physical interactions such as hydrogen bonding and dynamic quenching, which are the reasons for the observed quenching effect. Based on this, a new method for determining water content in organic solvents using carbon quantum dot fluorescence probes has been established. The linear relationship between the fluorescence quenching efficiency F0/F of two carbon quantum dots and the water content in different organic solvents was studied. The detection limits (LOD) of water in acetone, ethanol and N,N‐dimethylformamide (DMF) were 0.17 %, 2.35 %, 0.26 %, respectively, determined by Y‐CDs. The LOQ of acetone, ethanol, and DMF were 0.554 %, 7.83 %, 0.855 %, respectively. The LOD of water in acetone, ethanol and DMF determined by R‐CDs were 0.056 %, 0.69 %, 0.27 % and the LOQ was 0.187 %, 2.290 %, 0.909 %, respectively. Good recovery rates and precision were achieved in practical applications.

Full-Wood Utilization Strategy toward a Directional Luminescent Solar Concentrator.

Luminescent solar concentrators (LSCs) have proven to be highly effective in enhancing the conversion efficiency of photovoltaic (PV) cells. However, the traditional LSCs always suffer from self-absorption and escape the losses of luminescence. To these challenges, this study presents an ingenious all-wood-based LSC (W-LSC) with directional light-concentrating capabilities. By converting lignin into fluorescent carbon quantum dots (CQDs) and integrating them into transparent cellulose channels in delignified wood, we achieved efficient directional luminescence transmission in the W-LSC is achieved. The synthesized lignin-based CQDs (L-CQDs) exhibited a large Stokes shift (0.63 eV) and a bright yellow emission (540 nm). The prepared W-LSC possessed an external optical efficiency (ηopt) along the longitudinal (L) direction of 4.60% under a low irradiation intensity (40 mW·cm-2). Besides, contributed to the low thermal conductivity (0.300 W·m-1·K-1) of wood, the W-LSC maintained an ηopt of 4.03% at a temperature of 65 °C. Furthermore, the W-LSC demonstrated high tensile strength (424 MPa) and light transmission (85%). By leveraging the advantages of wood, this approach provides a different solution for enhancing solar energy utilization and advancing sustainable building.

Facile Preparation of a Low-Cost Liquid Interlayer Material with Intelligent UV-NIR-Shielding Function for Smart Windows.

High-performance interlayer materials have garnered considerable interest owing to their low manufacturing costs and applicability in smart windows. In this study, a novel smart-window interlayer material capable of selective shielding against both near-infrared (NIR) and ultraviolet (UV) radiation is developed based on the light transmittance control mechanism. An excellent thermoresponsive liquid, denoted as CDs@TRL (viz., carbon quantum dots at thermal-responsive liquid), is synthesized by compositing biomass-based fluorescent carbon quantum dots (CDs) and poly(N-isopropylacrylamide) (pNIPAM) at natural ambient temperature and in an aqueous phase. Due to the characteristics of CDs and synergistic effect of hydrogen bonds, CDs@TRL exhibits a high specific heat capacity (4.41 kJ kg-1 K-1), large thermal storage capacity (264.6 kJ kg-1), and better UV-NIR-blocking properties, compared to pure pNIPAM, as well as improves the sensitivity of thermal response. When injected into a window as a liquid interlayer, CDs@TRL can intelligently adjust the light transmittance according to ambient light intensity to achieve an intelligent response. The shielding rate of a 10 mm-thick CDs@TRL composite liquid against UV radiation (200-400 nm) was more than 95% in an overcast environment with insufficient light and close to 100% in a well-lighted environment. In addition, CDs@TRL is a cost-effective material that can be prepared from a wide range of raw material sources using a simple preparation process and exhibits excellent mobility and recyclability. Because of these features, it is considered to be a promising candidate for developing energy-saving and climate-adapted smart windows.

Photoluminescence enhancement of aluminum ion intercalated MoS2 quantum dots

Low photoluminescence (PL) quantum yield of molybdenum disulfide (MoS2) quantum dots (QDs) has limited practical application as potential fluorescent materials. Here, we report the intercalation of aluminum ion (Al3+) to enhance the PL of MoS2 QDs and the underlying mechanism. With detailed characterization and exciton dynamics study, we suggest that additional surface states including new emission centers have been effectively introduced to MoS2 QDs by the Al3+ intercalation. The synergy of new radiative pathway for exciton recombination and the passivation of non-radiative surface traps is responsible for the enhanced fluorescence of MoS2 QDs. Our findings demonstrate an efficient strategy to improve the optical properties of MoS2 QDs and are important for understanding the regulation effect of surface states on the emission of two dimensional sulfide QDs.

One-step assembly of TA-FeIII supramolecular shell on AgNPs surface for regulating fluorescence intensity of quantum dots

During surface-enhanced fluorescence processes, the spatial spacing layer on the surface of noble metals plays an important role in regulating the fluorescence intensity. We propose a method for regulating fluorescence intensity using the AgNPs@TA-FeIII composite nanostructured materials as the substrate and using characteristic fluorescence of graphene quantum dots as the detection signal. Tannins-FeIII (TA-FeIII) nanofilms were prepared with a one-step assembly method, which is simple, fast, green, and safe. This work is expected to help the application of polyphenol metal nanofilm technology in the field of surface enhanced fluorescence (SEF).

Organic acid-induced triple fluorescent emission carbon quantum dots identification of distilled liquor.

An acid-sensitive carbon dot fluorescence sensing array was investigated for the differentiated recognition of distilled spirits. Due to the electrostatic interactions between CDs and organic acids, organic acids affect the protonation and fluorescence properties of CDs, which in turn modify the CDs triple fluorescence emission. The regular linear variation of the fluorescence sensor was found under acidic conditions (3.0<pH<6.2). A comprehensive study of acids with selectivity, different concentrations (0.1mM, 1mM, 10mM, 40mM), different types (8 species) and mixed acids (formic acid and acetic acid), and good quantification capability for acetic acid (0.01-1mM). Demonstrating good recognition ability of the sensor array for complex analyte. On this basis, the fluorescence sensor array was applied to the classification and recognition of liquors. LDA has realized the identification of 16 kinds of Baijiu and 21 kinds of distilled liquors with an accuracy of 100%.

Dual-mode immunochromatographic assay based on dendritic gold nanoparticles with superior fluorescence quenching for ultrasensitive detection of E. coli O157:H7.

We presented a colorimetric/fluorescent dual-mode immunochromatographic assay (ICA) for the sensitive detection of Escherichia coli O157:H7. The use of polydopamine (PDA)-modified gold nanoparticles (AuNPs) with broadband absorption allowed for excellent colorimetry signals for the ICA detection. Moreover, the absorption spectrum of PDA-AuNPs significantly overlaps with the excitation and emission spectra of ZnCdSe/ZnS quantum dots (QDs), resulting in effective quenching of the QDs fluorescence due to the inner filter effect. The fluorescence intensity changes induced by PDA-AuNPs were utilized for the sensitive detection of E. coli O157:H7, achieving a detection limit of 9.06×101 CFU/mL, which was 46-fold lower than that of traditional AuNPs-based immunoassay. The proposed immunosensor exhibited the recovery rate between 80.12% and 114.69% in detecting actual samples, indicating its reliability and satisfactory accuracy. This study provides insights into dual-mode signal outputs and the ICA development for food safety applications.

Defocused imaging-based quantification of plasmon-induced distortion of single emitter emission

Optical properties of single emitters can be significantly improved through the interaction with plasmonic structures, leading to enhanced sensing and imaging capabilities. In turn, single emitters can act as sensitive probes of the local electromagnetic field surrounding plasmonic structures, furnishing fundamental insights into their physics and guiding the design of novel plasmonic devices. However, the interaction of emitters in the proximity to a plasmonic nanostructure causes distortion, which hinders precise estimation of position and polarization state and is one of the reasons why detection and quantification of molecular processes yet remain fundamentally challenging in this era of super-resolution. Here, we investigate axially defocused images of a single fluorescent emitter near metallic nanostructure, which encode emitter positions and can be acquired in the far-field with high sensitivity, while analyzing the images with pattern matching algorithm to explore emitter-localized surface plasmon interaction and retrieve information regarding emitter positions. Significant distortion in defocused images of fluorescent beads and quantum dots near nanostructure was observed and analyzed by pattern matching and finite-difference time-domain methods, which revealed that the distortion arises from the emitter interaction with nanostructure. Pattern matching algorithm was also adopted to estimate the lateral positions of a dipole that models an emitter utilizing the distorted defocused images and achieved improvement by more than 3 times over conventional diffraction-limited localization methods. The improvement by defocused imaging is expected to provide a way of enhancing reliability when using plasmonic nanostructure and diversifying strategies for various imaging and sensing modalities.

Green and fast microwave-driven synthesis of fluorescent N,S-carbon dots for determination of two 5-nitroimidazole antimicrobials

A green, fast, and economical technique for the manufacture of N,S-CQDS has been devised based on 3-min microwave irradiation of citric acid and thiosemicarbazide that furnished highly fluorescent quantum dots (λex/em of 360/430 nm) with high water solubility and stability. Transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Zeta potential analysis, Fourier transform infrared, UV-Visible spectroscopy, and fluorescence spectroscopy were used to fully characterize the N,S-CQDS. The obtained N,S-CQDS are spherical shaped with average size of 13.2 ± 4.3 nm and Zeta potential of -32.46 ± 1.55 mv. The effect of UV light and pH on the fluorescence intensity of the synthesized N,S-CQDS were also investigated. The synthesized N,S-CQDS were used as a fluorescent nanoprobe for the determination of two 5-nitroimidazole antimicrobials; secnidazole (SNZ) and tinidazole (TNZ) by fluorescence turn-off via inner filter effect and static quenching mechanisms. This approach demonstrated a linear dependency of the fluorescence signal on the concentration of both drugs over the range of 15-200 μM. The limit of detection and limit of quantification were 2.18 and 6.62 μM, respectively, for SNZ, and 2.29 and 6.96 μM, respectively, for TNZ. The developed method was used to determine both drugs in pharmaceutical dosage forms and human urine samples with % recovery of 100.65 ± 1.35 for SNZ, 98.66 ± 0.47 for TNZ in pharmaceutical dosage forms and 102.24 ± 2.93 for SNZ, 98.2 ± 1.78 for TNZ in case of spiked human urine samples. The approach's selectivity was confirmed for determining both analytes in the presence of various co-existing and co-administered species. The method validity was assessed in accordance with ICH recommendations. Various metrics were used to evaluate the greenness of the proposed probe. The developed probe is environmentally-friendly due to the quick synthesis of luminous N,S-CQDS using affordable and low-energy microwave radiation, and the absence of organic solvents.

Detection of Subsurface Damage Morphology of Lapped Optical Components by Analysis of the Fluorescence Lifetimes of Quantum Dots

Optical components inevitably suffer subsurface damage (SSD) during grinding and lapping, and this SSD substantially degrades the performance of optical systems. Moreover, given the surface roughness of optical components after grinding or lapping, it is impossible to non-destructively and accurately detect SSD generated by these processes, especially regarding the morphological details of such SSD. Accordingly, a novel method for detecting the morphological details of SSD in lapped optical components via analysis of the fluorescence lifetimes of quantum dots (QDs) is developed. This paper shows that, (1) compared with other methods, this novel method detects more morphological details of SSD in lapped optical components and that this detection is unaffected by the elemental composition/size/fluorescence lifetime of the QDs; (2) SSD detection achieved by analyzing the QD fluorescence lifetime can detect more SSD details on the premise of achieving the detection of SSD distribution and depth; and (3) the SSD in lapped optical components exhibits textural features, and “hole”-type SSD is detected in addition to “solid”-point and strip SSD. These findings will facilitate research on the formation mechanism of SSD, thereby enabling improvements in optical manufacturing techniques.

Conversion of palm oil empty fruit bunches to highly stable and fluorescent graphene oxide quantum dots: An eco-friendly approach

Empty fruit bunches, a byproduct of palm oil mills, are currently underutilized despite their potential as a valuable source of biomass for material development. A novel and sustainable method is proposed in this work to produce graphene oxide quantum dots (GOQDs) using empty fruit bunches (EFB) as a starting material. Carbonization of EFB was conducted in a nitrogen atmosphere furnace at temperatures ranging from 30 to 750 °C with a constant heating rate of 10 °C/min, followed by synthesis of GO from the carbonized cellulose using the modified Hummers' method. Subsequently, hydrothermal treatment was employed to synthesize GOQDs from GO, resulting in highly stable and fluorescent GOQDs with an average diameter size of 6.80 nm. The optical properties of GOQDs were characterized by UV–vis spectroscopy, which exhibited a strong absorption at 230 nm, yellow color under visible light, and blue-green luminescence under a 395 nm UV lamp. FTIR spectra confirmed the existence of hydroxyl, carbonyl, and hydrocarbon groups, which originated from lignocellulosic materials and provided excellent water stability and solubility properties to GOQDs. The current study presents an eco-friendly approach to converting biomass waste into materials with outstanding chemical and physical properties that can be applied in various fields.

Ultrasensitive quantifying copper ions in serum by tapered optical fiber fluorescent sensor based on static quenching effect

As an essential trace element, abnormal levels of copper ions (Cu2+) in body are associated with various disease. Various methods have been developed for Cu2+ sensing, but the construction of portable sensors for online and sensitive detection of Cu2+ in complex samples is still urgent. In this work, a portable and in-situ optical fiber fluorescent sensor was firstly operated by combining tapered optical fiber and fluorescent silicon quantum dots (SiQDs) via hydrogel strategy and used for ultrasensitive detection of Cu2+ in serum. The hydrothermally synthesized SiQDs of blue fluorescence exhibited excellent specificity of response to Cu2+ due to the static quenching effect. Good linear correlations were obtained over Cu2+ concentration from 0.01 to 50 μM. The sensor was successfully used for rapid detection of Cu2+ in serum samples avoiding tedious pretreatment. The sensor provided a portable and effective platform for online and ultrasensitive determination of Cu2+ in complex samples with the detection limit of 3.58 nM, as well as promising for the detection of biomolecule mediated by Cu2+. This method demonstrated superiority in high sensitivity and selectivity, convenient practicability and easy fabrication. It is of significance for the analysis in narrow space, remote sensing and emergency analysis.

Synthesis of Fluorescent Carbon Quantum Dots based on Boletus speciosus and Analysis of Metronidazole

Background: Metronidazole is widely used due to its clinical excellence in treating systemic or local infections caused by anaerobic bacteria. However, it is easily soluble in water, not easy to biodegrade and adsorb and stays for a long time in environments, causing great harm to human health and food safety. Therefore, it is important to choose highly selective and sensitive methods for metronidazole content determination in environments. In this paper, the edible fungus Boletus speciosus was used as the carbon precursor to successfully prepare carbon dots by one-step hydrothermal method, and were used to analyze metronidazole. Methods: Characterization of the prepared carbon dots from B. speciosus (Bs-CDs) were studied by Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-Ray Diffraction. Results: The linear equation was y=0.06231+0.01099x (R2=0.9970) with a metronidazole concentration of 2.5~50 μM, and the detection limit was 71 nM. The fluorescence quenching mechanism of Bs-CDs detecting metronidazole belonged to the internal filtration effect. Bs-CDs were applied to detect metronidazole in actual water samples, presenting good sensitivity and a high recovery rate (97.0~106.0%). Conclusion: This method provides a new idea for the application of carbon dots in metronidazole content detection.