Green emitting carbon dots for sensitive fluorometric determination of cartap based on its aggregation effect on gold nanoparticles

Amphi-Luminescent MoS2 nanostructure for photocatalytic splitting of water and removal of Methylene Blue

Chemical dyes used in the textile industries are one of the major pollutants in water. Methylene blue (MB) is a commonly seen dye that creates hazardous health problems. In this article the photocatalytic degradation of MB by the nanocatalyst MoS2 (Nano-MoS2) and carbon dot (C Dots) incorporated MoS2 (Nano-CD-MoS2) is reported. The photocatalytic degradation of MB is analyzed based on the electron-hole recombination rate of the catalyst. Photoluminescence emission exhibited by the catalyst is used as a key indicator to probe the electron-hole recombination rate. Nano-MoS2 was synthesized hydrothermally at 180 0C for 8 h from ammonium tetra thiomolybdate (ATTM). C Dot was prepared following a green root from ash guard extract which later mixed with Nano-MoS2 and kept in an autoclave at a temperature 140 °C for 4 h to get Nano-CD-MoS2. The photoluminescence (PL) and photocatalytic behavior of Nano-MoS2 and Nano-CD-MoS2 and their application for water splitting and water purification are reported. The incorporation of graphene and artificial C Dot into MoS2 nanostructures are reported to increase the conductivity and active edge sites of MoS2 that enhances the photocatalytic action. Since green C Dots are eco-friendly and easily synthesizable than artificial C Dots, as a novel study, this article investigated the influence of green C Dots on the PL and photocatalytic performance of nanosized MoS2. Nano-MoS2 and Nano-CD-MoS2 exhibited both upconversion and downconversion PL; accordingly the nanostructures were termed as amphi-luminescent. The amphi-luminescence property widens the photon absorption range and hence enhances the catalytic degradation of dyes. Nano-MoS2 which exhibited lesser intensity of amphi-luminescence emission compared to Nano-CD-MoS2 showed better results in degradation of MB. C Dots may bind with the valence band electrons of MoS2, resulting in the reduction of dangling bonds. Dangling bonds can trap photo-induced excitons to hinder the rate of electron-hole recombination. So, fast electron-hole recombination occurs in Nano-CD-MoS2 than Nano-MoS2. Fast electron-hole recombination supports radiative electron-hole recombination while suppresses the non-radiative energy transfer of electrons and causes high PL intensity. However, according to the energy level diagram, Nano-MoS2 with minimal electron-hole recombination rate is more favorable for O2/O2-,.OH/ OH- and.OH/H2O reactions that facilitate MB degradation. Photocatalytic activity of catalysts were confirmed by measuring the photocurrent from a simple custom-made two-electrode water photolysis cell where the nanocatalysts were dispersed in electrolyte. Lead and steel rods were used as electrodes. Multimeter was used to measure current. Nano-MoS2 exhibited better performance with a maximum photocurrent of 141 µA. Influence of green C Dots in energy levels, PL and photocatalysis of MoS2 and mechanisms of PL and degradation of MB are thoroughly investigated in this article.

A Dual-Mode Detection Sensor Based on Nitrogen-Doped Carbon Dots for Visual Detection of Fe(III) and Ascorbic Acid via a Smartphone

Accurately and promptly detecting Fe3+ and ascorbic acid (AA) is a crucial objective. In this study, nitrogen-doped carbon dots (N-CDs) were synthesized using a one-step hydrothermal synthesis method with 6,9-diamino-2-ethoxyacridine lactate as the precursor. The introduction of Fe3+ and AA resulted in both fluorescence (FL) quenching and enhancement of the synthesized N-CDs. The fluorescent response of the N-CDs probe to Fe3+ was observed in the concentration range of 5-20 µM and 25-50 µM, with a limit of detection (LOD) of 290 nM. Remarkably, the fluorescence of the N-CDs was recovered upon the addition of AA to the N-CDs-Fe3+ system. Using the "off-on" fluorescent N-CDs probe, a linear range of 40-90 µM was achieved with an LOD of 0.69 µM. Additionally, the feasibility of employing a smartphone equipped with an RGB Color Picker was demonstrated for the analysis of Fe3+ and AA concentrations, providing a novel visual detection method. Furthermore, the application of N-CDs in solution demonstrated considerable potential for visually detecting Fe3+ and AA. The proposed dual-mode detection sensor was found to be simple, efficient, and stable, enabling the successful determination of Fe3+ and AA in practical samples with satisfactory results.

Ultrasensitive Ratiometric Fluorescence Bioassay for Accurate Detection of Covid-19-Specific Nucleocapsid Protein in Clinical Serum Samples Using Modified Cleavable Mesoporous SiO2 Satellite-Enriched Carbon Dots

Due to the presence of various autofluorescent compounds in biological samples like serum and the photobleaching of organic fluorophores, fluorescence sensing has limited practical applicability. This study describes the development of an improved ratiometric fluorescence assay to determine the nucleocapsid protein (N protein), one of the most conserved biomarkers of Covid-19 in spiked and serum samples using highly stable buffer-based near IR-dual emission carbon dots (CDs) encapsulated into the cavities of cleavable silica nanocapsule (SNCs) nanocomposite. The cavities of cleavable silica nanocapsules (SNCs) and the formed core-shell CDs@ SNCs were used as a superior reservoir of fluorescent markers produced by cohydrolyzing tetraethyl orthosilicate and diiminosilane linker, which held hundreds of CDs in silica shell frameworks. The SiO2 nanocomposite was modified with an N protein antibody that specifically paired to the receptor binding region of the Cov-19 spike protein subunit. CDs were taken out of SNCs by NaBH4 reduction, and the released CDs exhibited dual emission at 475 and 675 nm when excited at 400 nm. Ratiometric detection is completed over a binding-induced, concentration-dependent immuno-affinity of the N protein that drives the fluorescence quenching phenomenon between the CDs as fluorophore and the AuNPs as quencher. As the N protein concentration increased, the intensity of the red emission (675 nm) dropped, whereas the intensity of the green emission (475 nm) already remained constant, which is due to sandwich immunoassays of CDs around AuNPs. Using the exceptional fluorescent characteristics of CDs and the high selectivity of nanocomposite functionalized with N-protein antibody, the developed assay efficiently eliminates the autofluorescence background interference of serum samples. The fluorescence ratio (I475/I675) provides a limit of detection of 2 pg mL-1 over a linear range of 0.01 to 5 ng mL-1 and exhibits an amplified sensitivity of 54 times compared to conventional immunoassay using CDs as fluorescent labels. With one-step signal amplification and requiring small sample quantities (only 20 μL), this sensing platform can be effectively used for the accurate detection of N protein, and no cross-reactivity is detected in the presence of different interfering agents.

High-precision luminescent covalent organic frameworks with sp2-carbon connection for visual detecting of nereistoxin-related insecticide

A new strategy for nereistoxin-related insecticide, cartap, detection in foodstuff and the environment is of great importance due to its poisoning of human beings through direct exposure or via biomagnification. Herein, a highly planar conjugated sp² carbon-connected COF (F-C_sp²-TT) was synthesized via Knoevenagel condensation reaction followed by the post-modification to develop a new platform for cartap visual detection in agricultural and food samples. The synergistic effect of highly planar conjugation and dense functional groups in the opened framework endowed F-C_sp²-TT with a high-precision luminescence sensing performance. Meanwhile, the exquisitely designed F-C_sp²-TT presented robust chemical stability, radiation stability, and good reproducibility. Benefiting from these advantages, high-precision luminescent F-C_sp²-TT achieves a low detection limit of 0.51 μg/L to cartap over the range of 1-300 μg/L (R²=0.9938), and the recoveries percentage in food products was calculated as 95.90%- 119.3%. More significantly, the smartphone-based high-precision platform by F-C_sp²-TT was established and successfully applied to portable monitoring of cartap and water content. Therefore, our work revealed the enormous potential of C_sp²-connected COF, which opened a new situation for insecticide detection.

Bifunctional M13 Phage as Enzyme Container for the Reinforced Colorimetric-Photothermal Dual-Modal Sensing of Ochratoxin A

"Point of care" (POC) methods without expensive instruments and special technicians are greatly needed for high-throughput analysis of mycotoxins. In comparison, the most widely used screening method of the conventional enzyme-linked immunosorbent assay (ELISA) confronts low sensitivity and harmful competing antigens. Herein, we develop a plasmonic-photothermal ELISA that allows precise readout by color-temperature dual-modal signals based on enzymatic reaction-induced AuNP aggregation for highly sensitive detection of ochratoxin A (OTA). The bifunctional M13 phage carrying OTA that mimics the mimotope on the end of p3 proteins and abundant biotin molecules on the major p8 proteins is adopted as an eco-friendly competing antigen and enzyme container for amplifying the signal intensity. Under optimal conditions, both colorimetric and photothermal signals enable good dynamic linearity for quantitative OTA detection with the limits of detection at 12.1 and 8.6 pg mL-1, respectively. Additionally, the proposed ELISA was adapted to visual determination with a cutoff limit of 78 pg mL-1 according to a vivid color change from deep blue to red. The recoveries of OTA-spiked corn samples indicate the high accuracy and robustness of the proposed method. In conclusion, our proposed strategy provides a promising method for eco-friendly and sensitive POC screening of OTA. Moreover, it can be easily applied to other analytes by changing the involved specific mimotope sequence.

Novel synthesis of fibronectin derived photoluminescent carbon dots for bioimaging applications

Fibronectin (FN) derived from human plasma has been used for the first time as the carbon precursor in the top-down, microwave-assisted hydrothermal synthesis of nitrogen doped carbon dots (CDs). FN is a large glycoprotein primarily known for its roles in cell adhesion and cell growth. Due to these properties FN can be over expressed in the extracellular matrix (ECM) of some cancers allowing FN to be used as an indicator for the detection of cancerous cells over non-cancerous cells. These FN derived CDs display violet photoluminescence with UV excitation and appear to possess similar functional groups on their surface to their carbon precursor (-COOH and -NH2). This is believed to be due to the self-passivation of the CDs' nitrogen-containing surface functional groups during the heating process. These CDs were then used to stain MCF-7 and MDA-231 breast cancer cells and were observed to interact primarily with the cell membrane rather than intercalating into the cell like the many other types of CDs. This led to the hypothesis that the CDs are selectively binding to the FN overexpressed within the cancer cells' ECM via amide linkages. This is in agreement with the EDX and FTIR spectra of the FN CDs which indicate the presence of -COOH and nitrogen containing surface groups like -NH3. The inherent selectivity of the CDs combined with their ability to photoluminesce enables their use as a fluorophore for bioimaging applications.

Silver Nanoparticle-Functionalised Nitrogen-Doped Carbon Quantum Dots for the Highly Efficient Determination of Uric Acid

The fabrication of efficient fluorescent probes that possess an excellent sensitivity and selectivity for uric acid is highly desirable and challenging. In this study, composites of silver nanoparticles (AgNPs) wrapped with nitrogen-doped carbon quantum dots (N-CQDs) were synthesised utilising N-CQDs as the reducing and stabilising agents in a single reaction with AgNO₃. The morphology and structure, absorption properties, functional groups, and fluorescence properties were characterised by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, fluorescence spectroscopy, and X-ray diffraction spectroscopy. In addition, we developed a novel method based on AgNPs/N-CQDs for the detection of uric acid using the enzymatic reaction of uric acid oxidase. The fluorescence enhancement of the AgNPs/N-CQDs composite was linear (R² = 0.9971) in the range of 2.0–60 μmol/L, and gave a detection limit of 0.53 μmol/L. Trace uric acid was successfully determined in real serum samples from the serum of 10 healthy candidates and 10 gout patients, and the results were consistent with those recorded by Qianxinan Prefecture People’s Hospital. These results indicate that the developed AgNP/N-CQD system can provide a universal platform for detecting the multispecies ratio fluorescence of H₂O₂ generation in other biological systems.

Ultrahigh sensitivity nitrogen-doping carbon nanotubes-based metamaterial-free flexible terahertz sensing platform for insecticides detection

With the rapid advances in terahertz (THz) spectroscopy, metamaterial-free THz sensors have been of importance due to efficient cost, high sensitivity and overcoming the limited tunability of the optical constants of metals. Here, a metamaterial-free and flexible THz sensor based on nitrogen-doping carbon nanotubes (N-CNTs) coupled with signal-enhancing Au NPs was proposed for detecting nereistoxin-related insecticides (NRIs). Sensitivity and selectivity for NRIs detection have been realized over the range of 3.3-100 μg/L with good linear fitting (R² ≥ 0.9003) and LOD was 1.33 μg/L. Accuracy was validated by the recovery rates of 105.87-109.75% of NRI in spiked food-matrix sample. These results indicated the developed signal-enhancing THz method, validated by LC-MS/MS, exhibited high sensitivity and simplicity detection, which has noteworthy potential for applications in food safety and environment monitoring.

UiO-67 decorated on porous carbon derived from Ce-MOF for the enrichment and fluorescence determination of glyphosate

A nanocomposite was prepared by loading UiO-67 nanoparticles onto porous carbon materials derived from Ce-MOF (Ce-PC) for fluorescence detection of glyphosate. The probe (UiO-67/Ce-PC) exhibits fluorescence emission at 414 nm as the response signal under excitation at 310 nm. The fluorescence enhancement mode of UiO-67 reduces the background interference, and the introduction of Ce-PC provide hierarchical nanostructure and large specific surface area that can increase the contact availability and improve the pre-enrichment effect, ensuring UiO-67/Ce-PC with superior sensitivity. The abundant metal hydroxyl group (M-O-H) of UiO-67/Ce-PC could recognize phosphoryl groups (-PO₃H₂) of glyphosate through ligand exchange, which synergizes with H-bonding interaction and electrostatic attraction to exhibit specificity toward glyphosate. The competitive coordination effects weaken the ligand-to-metal charge transfer (LMCT) and consequently induce the fluorescence recovery. The calibration plot of the fluorescence enhancement response of UiO-67/Ce-PC towards glyphosate was recorded in the range 0.02-30 μg mL^-1 with a low limit of detection (LOD) of 0.0062 μg mL^-1, which is superior to the pure UiO-67. In addition, the sensor exhibited high selectivity and satisfactory accuracy and precision with recoveries of 92.1-105.6% and RSDs below 3.4%. This work not only presents a feasible sensor for sensitive and selective determination of glyphosate from cereal samples, but also provides a promising strategy for the design of MOF-based nanocomposites to achieve trace detection of various pollutants.

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.

An ionic liquid-assisted quantum dot-grafted covalent organic framework-based multi-dimensional sensing array for discrimination of insecticides using principal component analysis and clustered heat map

A robust multi-dimensional sensing array based on VBimBF₄B/MAA-anchored quantum dot (QD)-grafted covalent organic frameworks (COFs) [(V-M)/QD-grafted COFs] was established via one-pot strategy. The multi-dimensional sensing array has the outstanding advantages of physicochemical and thermal stability, large specific surface area, and regular pore structures. The assistance of ionic liquid VBimBF₄B enhanced the transduction efficiency, and the synergistic effect of COFs enhanced detection efficiency. The improved multi-dimensional sensing array by COFs and ionic liquid VBimBF₄B served to identify seven insecticides by non-specific interactions via hydrogen bonding, and the differences in the kinetics of the binding to the insecticides resulted in variation of the three-output channel (fluorescence, phosphorescence, and light scattering) signals, thus generating a distinct optical fingerprint. The unique fingerprint patterns of seven kinds of common insecticides at 200 μg L^-1 were successfully discriminated using principal component analysis and clustered heat map analysis. The multi-dimensional sensing array showed a response to seven insecticides based on three spectral channels over the range of 0.001-0.4 μg mL^-1 with a limit of detection of 1.08-18.68 μg L^-1. The spiked recovery of tap water was 79.86-134.22%, with RSD ranging from 0.89-14.9%. This study broadens the applications of sensing arrays technology and provides a promising building block for insecticide determination.

A new method for cartap detection with high sensitivity and selectivity based on the inner filter effect between GSH-Cu NCs and Au NPs

Herein, a novel and sensitive fluorescence method for cartap determination is established on the basis of the inner filter effect (IFE) of gold nanoparticles (Au NPs) on the fluorescence of glutathione protected Cu NCs (GSH-Cu NCs). In the presence of Au NPs, the fluorescence of GSH-Cu NCs was strongly quenched by the IFE because the absorption spectra of Au NPs overlap well with the emission spectra of GSH-Cu NCs. Upon addition of cartap, cartap could induce the aggregation of Au NPs whose absorption spectrum does not overlap with the emission spectrum of GSH-Cu NCs. Then, with the increase in cartap concentration, the IFE-decreased fluorescence was gradually recovered, realizing the fluorescence sensing of cartap. Under optimal conditions, the proposed method has a good linear relationship with cartap concentration in the range of 7-100 nM, and the detection limit is 3.34 nM. In addition, satisfactory results were obtained for cartap analysis using tap water and cabbage as real samples, which demonstrated that the method as-developed would have great practical application prospects.

Recent advances in the construction and analytical applications of carbon dots-based optical nanoassembly

Recently, more and more attention has been focused on the construction and analytical applications of optical nanoassembly through combining carbon dots (CDs) with various other functional nanomaterials. The rational design and manufacture of CDs-based optical nanoassembly will be critical to meeting the needs of analytical science. The last decade has witnessed the immense potential of CDs-based optical nanoassembly in multiple sensing applications owing to their controlled optical properties, adjustable surface chemistry and microscopic morphology. This feature article collects the recent advances in the research and development of CDs-based optical nanoassembly and their applications in analytical sensors, aiming to provide vital insights and suggestions to inspire their broad sensing applications.

A turn-on fluorescent sensor based on carbon dots from Sophora japonica leaves for the detection of glyphosate

Carbon dots (CDs) having low cost and low toxicity and synthesized via a green route were applied to establish a fluorescent nanoprobe for the measurement of glyphosate. The synthesis was realized via a one-pot hydrothermal procedure using Sophora japonica leaves as the carbon source. It was found that electron transfer occurred between Fe3+ and the as-prepared CDs. Therefore, Fe3+ exhibited a specific dynamic-quenching toward CDs. However, the electron transfer process was inhibited by glyphosate. The fluorescence of the quenched CDs/Fe3+ system was recovered by the addition of glyphosate. It resulted from the strong complexation between Fe3+ and the functional groups (like -PO3H2 and -COOH) in the glyphosate molecule. These functional groups captured Fe3+ from the CD/Fe3+ system to reduce the electron transfer. With such a design, the rapid detection of glyphosate could be realized by this turn-on fluorescent sensor based on the CD/Fe3+ system. Under optimal conditions, the CD/Fe3+ system showed a concentration-dependent fluorescent response toward glyphosate in the linear range from 0.1 to 16 ppm. The limit of detection was calculated to be as low as 8.75 ppb (3σ/S). In addition, the successful detection of glyphosate in real samples with satisfactory recoveries exhibited a practical application of the CD/Fe3+ nanoprobe in food safety and environmental monitoring.

A peptide nucleic acid-regulated fluorescence resonance energy transfer DNA assay based on the use of carbon dots and gold nanoparticles

A convenient fluorometric method was developed for specific determination of DNA based on peptide nuclei acid (PNA)-regulated fluorescence resonance energy transfer (FRET) between carbon dots (CDs) and gold nanoparticles (AuNPs). In this system, CDs that display lake blue fluorescence with excitation/emission maxima at 345/445 nm were used as fluorometric reporter, while AuNPs were used as fluorescence nanoquencher. A neutral PNA probe, which is designed to recognize the target DNA, was used as a coagulant to control the dispersion and aggregation of AuNPs. Without DNA, PNA can induce immediate AuNP aggregation, thus leading to the recovery of the FRET-quenched fluorescence emission of CDs. However, the addition of the complementary target DNA can protect AuNPs from being aggregated due to the formation of DNA/PNA complexes, which subsequently produces a high fluorescence quenching efficiency of CDs by dispersed AuNPs. Under optimized conditions, quantitative evaluation of DNA was achieved in a linear range of 5-100 nM with a detection limit of 0.21 nM. This method exhibited an excellent specificity towards fully matched DNA. In addition, the application of this assay for sensitive determination of DNA in cell lysate demonstrates its potential for bioanalysis and biodetection. Graphical abstract A simple fluorometric biosensor for specific detection of DNA was developed based on peptide nuclei acid (PNA)-regulated fluorescence resonance energy transfer (FRET) between carbon dots (CDs) and gold nanoparticles (AuNPs).

An electroanalytical platform for nereistoxin-related insecticide detection based on DNA conformational switching and exonuclease III assisted target recycling

In this work, an electroanalytical platform for nereistoxin (NRT)-related insecticide detection is proposed on the basis of NRT induced DNA conformational switching and exonuclease III (Exo III) assisted target recycling. NRT-related insecticides were first hydrolyzed and converted into NRT with two thiol groups (-SH). Then, a cytosine-Ag+-cytosine (C-Ag+-C) mismatched base pair was adopted to induce a blunt-ended hairpin configuration of HP DNA. In the presence of converted NRT, it could take up Ag+ from HP DNA to change its conformation from a hairpin to single-stranded structure (HP ssDNA). Thereafter, the obtained HP ssDNA was further hybridized with an H1 hairpin probe on the electrode surface to trigger the Exo III cleavage process, releasing HP ssDNA for recycling leaving the G-quadruplex fragment of H1, which was used for hemin/G-quadruplex complex formation. The reversible redox reaction of Fe(iii)/Fe(ii) of hemin gave a remarkable electrochemical response for quantitative determination of the NRT-related insecticides. As an analytical model, a low detection limit of 3.9 ng L-1 and a wide linear range of 0.01-1500 μg L-1 with excellent selectivity were achieved for cartap detection. The proposed method also displayed great applicability for cartap detection in agricultural products.

Switch on fluorescence mode for determination of l-cysteine with carbon quantum dots and Au nanoparticles as a probe

Citric acid and urea were used as precursors for the preparation of carbon quantum dots (CQDs) which exhibited a maximum emission wavelength at 515 nm when excited at 410 nm. Upon addition of citrate-stabilized Au nanoparticles (AuNPs) with the maximum absorption wavelength at 520 nm, the fluorescence of the CQDs could be efficiently quenched, attributed to the energy transfer between CQDs and AuNPs. However, the further introduction of l-cysteine (Cys) could cause the aggregation of AuNPs along with a drop in absorption at 520 nm, resulting in the fluorescence recovery of the CQDs–AuNPs system. Therefore, a simple and reliable switch on fluorescence sensing platform for determination of Cys was constructed. The significant factors, such as pH and incubation time, that affected the detection of Cys were optimized with the AuNP concentration set as 2.50 nM at room temperature. Under the optimized conditions, the fluorescence recoveries (ΔF) were strongly correlated with Cys concentration in the 0.20 to 4.0 μM range, and the detection limit is 0.012 μM. More importantly, our CQD-based sensing platform was successfully used for the detection of Cys in milk samples with high precision and accuracy, indicating the potential of the probe in practical applications.

We demonstrated a fluorescence probe composed of CQDs and AuNPs for switch on detection of Cys, where CQDs as fluorescence reporters and AuNPs as fluorescence quenchers were chosen.

Influence of gold nanoparticles in different aggregation states on the fluorescence of carbon dots and its application

Herein, gold nanoparticles (Au NPs) in solution protected by various concentration of DNA at different aggregation states were found to have different quenching effect to the fluorescence of carbon dots (CDs). Au NPs wrapped up in more amount of DNA were able to quench the fluorescence of CDs more effectively, and vice versa. Based on this phenomenon, a facile and novel fluorescence sensing platform without labeling was constructed by designing the sequence of DNA as the aptamer of the detection target. With the addition of specific molecule, taking acetamiprid as representative, DNA was prior to bind with target and the Au NPs became less protected, leading to the fluorescence recovery of the CDs. Experimental results showed that the fluorescence of CDs was linearly recovered by acetamiprid in the concentration range of 7.8 × 10^-9-1.4 × 10^-6 mol/L, with the detection limit of 1.5 × 10^-9 mol/L. This promising sensor might provide a new aspect for exploring the versatile application of CDs in various fields.