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SERS detection of mercury (II)/lead (II): A new class of DNA logic gates
摘要： A conceptually new class of DNA logic gates for Hg2+ and Pb2+ ion simultaneous detection has been constructed based on the activity of DNAzyme dependent on metal ions. For sensitive and specific detection of Hg2+ and Pb2+ ions, we demonstrate a surface-enhanced Raman scattering (SERS)-active platform by employing the oligonucleotide-functionalized and gold coated polystyrene microspheres (PSMPs). In this work, Hg2+ and Pb2+ were used as the input, and the SERS signals were the output. Hg2+ ions were captured by a mismatched T-Hg-T bridge. Pb2+ ions were bound to 8–17DNAzyme to break the cleavage substrate. The limit of detection (LOD) of Hg2+ is 0.1 nmol L?1 and Pb2+ is 1.0 nmol L?1, which is far below the limit of 10.0 ppb (31 nmol L?1) and 10.0 ppm (3.02 × 104 nmol L?1) for drinking water stipulated by the World Health Organization. Additionally, this system has the potential to be ideal candidates for intelligent DNA calculator design applications. Furthermore, the designed strategy could be extended to other multiplex metal ions that can be combined with DNA molecules, and can be applied to many other fields such as environmental detection, toxin detection and liquid analysis.
关键词： SERS,DNA logic gates,Simultaneous detection
更新于2025-09-23 15:22:29
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A sensitive immunoassay for simultaneous detection of foodborne pathogens using MnO2 nanoflowers-assisted loading and release of quantum dots
摘要： In this study, a sensitive immunoassay using immunomagnetic nanobeads (MNBs), manganese dioxide nanoflowers (MnO2 NFs) and quantum dots (QDs) was developed for simultaneous detection of E. coli O157: H7 and Salmonella typhimurium. MnO2 NFs were synthesized, functionalized and incubated with QDs to obtain QDs@MnO2 nanocomposites, followed by modification with antibodies (pAbs) to obtain pAb-QDs@MnO2 nanocomposites (QM NCs). Target bacteria were first conjugated with MNBs and QM NCs to form MNB-bacteria-QM complexes. Then, QDs were quickly released from the complexes using glutathione to reduce MnO2 to Mn2+. Finally, fluorescent intensity at characteristic wavelength was measured by optical detector to determine target bacteria. This immunoassay could simultaneously and quantitatively detect E. coli from 1.5 × 101 to 1.5 × 106 CFU/mL with detection limit of 15 CFU/mL and Salmonella from 4.0 × 101 to 4.0 × 106 CFU/mL with detection limit of 40 CFU/mL in 2 h. The mean recovery for both bacteria in spiked chicken samples was ～96%.
关键词： Pathogenic bacteria,Quantum dots,Simultaneous detection,Manganese dioxide nanoflowers,Fluorescent immunoassay
更新于2025-09-23 15:21:01
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Simultaneous detection of fumonisin B1 and ochratoxin A using dual-color, time-resolved luminescent nanoparticles (NaYF4: Ce, Tb and NH2-Eu/DPA@SiO2) as labels
摘要： A rapid and highly sensitive time-resolved fluorescence (TRF)-based aptasensor for simultaneous recognition of mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) was developed using multi-color, Ln3+-doped time-resolved fluorescence nanoparticles (TRF-NPs) (NaYF4: Ce, Tb and NH2-Eu/DPA@SiO2 NPs) coupled with complementary strand DNA (cDNA) as luminescence probe and aptamers-conjugated amine-functionalized Fe3O4 magnetic nanoparticles (MNPs) act as a capture probe. Under the optimized conditions, the time-resolved fluorescence intensities at 544 and 618 nm corresponded with Tb3+ and Eu3+, respectively, were used to measure FB1 (Y = 19,177.1 + (? 12,054.4)x, R2 = 0.9917) and OTA (Y = 4138.8 + (? 11,182.6)x, R2 = 0.9924), respectively. The limits of detection (LODs) for FB1 and OTA were 0.019 pg mL?1 and 0.015 pg mL?1, respectively, which were much lower than previously described methods for simultaneous recognition of mycotoxins OTA and FB1 while detection range varied from 0.0001–0.5 ng mL?1. This aptasensor was effectively applied to quantity FB1 and OTA in maize samples and results were compared with ELISA method. This is the first reported time-resolved fluorescence (TRF)-based aptasensor to detect two agriculturally important toxins in the maize. The developed aptasensor has potential to be used for detection of toxins in food safety fields.
关键词： Simultaneous detection,Aptamer,Time-resolved fluorescence nanoparticles,Mycotoxins
更新于2025-09-19 17:15:36
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Development of dual quantum dots-based fluorescence-linked immunosorbent assay for simultaneous detection on inflammation biomarkers
摘要： Simultaneous detections of di?erent but clinically relevant biomarkers are of extremely importance in biomedicine. Due to their unique photophysical properties, quantum dots (QDs) are ideally suited for highly sensitive multiplexed determination. Herein, a dual quantum dots-based ?uorescence-linked immunosorbent assay (dQDs-FLISA) for simultaneous and quantitative detection of in?ammation biomarkers (i.e. serum amyloid A (SAA) and C-reactive protein (CRP)) has been established. After being coated by amphiphilic oligomers (poly-maleic acid n-hexadecanol ester, PMAH), the red-QD and green-QD with high quantum yields were used as ?uorescence probes to couple SAA and CRP antibodies, respectively. Cross-reactivity among the SAA and CRP’s antibodies and antigens have been carefully examined by interference experiments, and it was successfully avoided by the speci?c probe adding sequence. Therefore, the assay provided a broad linear analytical range, including SAA quantitative range of 10–1,000 ng mL?1 with linear correlation (R2) of 0.992, and CRP quantitative range of 10–1,000 ng mL?1 with R2 of 0.998. The limit of detections (LODs) for SAA and CRP using dQDs-FLISA were 2.39 ng mL?1 and 6.37 ng mL?1, respectively. The accuracy of the assay has been con?rmed with recoveries of 92.13%–101.85%. More importantly, the assay results showed good speci?city, the QD-antibody probe could couple corresponding antigen (CRP or SAA) high-e?ciently and it could be out of interference of other antigens and substances in serum. Given its good performance, the proposed dQDs-FLISA method o?ers great potential for simultaneous and quantitative detection of other biomarkers in in vitro diagnostic (IVD).
关键词： Quantum dot-based ?uorescence-linked immunosorbent assay,In?ammation biomarkers,Simultaneous detection,Quantum dots
更新于2025-09-19 17:13:59
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Dual-color magnetic-quantum dot nanobeads as versatile fluorescent probes in test strip for simultaneous point-of-care detection of free and complexed prostate-specific antigen
摘要： Simultaneous detection of free and complexed prostate-specific antigen (f-PSA and c-PSA) is critical to the prostate cancer (PCa) diagnostic accuracy for clinical samples with PSA values in the diagnostic gray zone between 4 and 10 ng mL?1. Herein, red and green magnetic-quantum dot nanobeads (MQBs) with superior magnetic property and high luminescence were fabricated via polyethyleneimine-mediated electrostatic adsorption of numerous quantum dots onto superparamagnetic Fe3O4 magnetic cores, and were conjugated with f-PSA antibody and c-PSA antibody, respectively, as versatile fluorescent probes in test strip for immune recognition, magnetic enrichment, and simultaneous detection of f-PSA and c-PSA analytes in complex biological matrix with t-PSA antibody on the test line. A low-cost and portable smartphone readout device with an application was also developed for the imaging of dual-color test strips and data processing. This assay can simultaneously detect f-PSA and c-PSA with the limits of detection of 0.009 ng mL?1 and 0.087 ng mL?1, respectively. Clinical serum samples of PCa and benign prostatic hyperplasia patients were evaluated to confirm the clinical feasibility. The results suggest that the proposed dual-color MQBs-based fluorescent lateral flow immunoassay is a promising point-of-care diagnostics technique for the accurate diagnosis of PCa even in resource-limited settings.
关键词： Free and complexed prostate-specific antigen,Fluorescent lateral flow immunoassay,Simultaneous detection,Prostate cancer,Magnetic-quantum dot nanobead,Point-of-care
更新于2025-09-16 10:30:52
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Simultaneous detection of mercury (II), lead (II) and silver (I) based on fluorescently labelled aptamer probes and graphene oxide
摘要： We have developed a fluorescence quantitative analysis method for the simultaneous detection of Hg2+, Pb2+ and Ag+ based on fluorescently labeled nucleic acid aptamer probes and graphene oxide. By this method, three nucleic acid aptamer probes (PHg, PPb, PAg) were designed. The carboxyl fluorescein (FAM), tetramethyl-6-carboxyrhodamine (TAMRA) and cyanine-5 (Cy-5) were respectively selected as fluorophore of aptamer probes, and graphene oxide (GO) was chosen as quencher. In general, these probes were on free single-stranded state and adsorbed on the surface of GO via π-π interactions, which brought fluorophores of probes and GO into close proximity. Due to the fluorescence resonance energy transfer (FRET) occurred between fluorophores and GO, the fluorescence was quenched and fluorescence signals were all weak. Under the optimal condition, fluorescence intensities of three fluorophores exhibited a good linear dependence on corresponding ions concentration. The detection limit for Hg2+, Pb2+ and Ag+ were 0.2 nmol/L, 0.5 nmol/L and 2 nmol/L (3σ, n=11). Average recoveries of this method were 97.56 - 104.92%, which indicated the method had a high accuracy and low detection limit. In addition, this proposed method has good selectivity, and there was no crosstalk effect among these probes.
关键词： Graphene oxide,Simultaneous detection,Metal ions,Fluorescence,Aptamer
更新于2025-09-16 10:30:52
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Magnetic quantum dot based lateral flow assay biosensor for multiplex and sensitive detection of protein toxins in food samples
摘要： Protein toxins, such as botulinum neurotoxin type A (BoNT/A) and staphylococcal enterotoxin B (SEB), easily pollute food and water and are ultra-toxic to humans and animals, thus requiring a sensitive on-site detection method. In this study, we reported a novel lateral flow assay (LFA) strip on the basis of magnetic quantum dot nanoparticles (MagQD NPs) for sensitive and multiplex protein toxin detection in food samples. A new type of MagQD NP was prepared by fixing the dense carboxylated QDs on the surface of polyethyleneimine-modified Fe3O4 magnetic NPs (MNPs) and applied in LFA with the following functions: capture and enrich target toxins from sample solutions and serve as advanced fluorescent labels for the quantitative determination of targets on the strip. Through this strategy, the assay realized quantified BoNT/A and SEB detection in 30 min with the limits of detection of 2.52 and 2.86 pg/mL, respectively. The selectivity and the ability of quantitative analysis of the method were validated in real food samples, including milk and juice. This MagQD-LFA biosensor showed considerable potential as a point-of-care testing tool for the sensitive detection of trace toxins.
关键词： Magnetic-quantum dot nanoparticles,Fluorescent lateral flow immunoassay,Simultaneous detection,Botulinum neurotoxin type A,Staphylococcal enterotoxin
更新于2025-09-16 10:30:52
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A multiplexed FRET aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide/Fe3O4 as single energy acceptor?
摘要： Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are the most common mycotoxins and often coexist in agricultural products, which are known to be a toxic superposition and even carcinogenic effects on humans. We proposed a multiplexed fluorescence resonance energy transfer (FRET) aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide (GO)/Fe3O4 as single energy acceptor. CdTe quantum dots emitting green (GQDs) and red (RQDs) fluorescence are modified by aptamers specifically for AFB1 and FB1 and used as dual energy donors. Compared with conventional FRET system based on GO quencher, GO/Fe3O4, a single energy acceptor, can not only quench the fluorescence of aptamer-modified GQDs and RQDs with different emission peaks simultaneously, but also be removed by effective magnetic separation to eliminate the interference of background. In the absence of GO/Fe3O4 nanocomposites, the aptamer modified GQDs and RQDs give off strong fluorescence under ultraviolet radiation. The fluorescence of GQDs and RQDs is quenched when GO/Fe3O4 nanocomposites is added to the system owing to the π–π stacking interaction between GO/Fe3O4 nanocomposites and GQDs- and RQDs-labeled aptamer. However, in the presence of AFB1 and FB1, the binding of aptamers to their specific targets will fold their single stranded structures and hinder the contact between base group in aptamers and GO/Fe3O4, which cause the fluorescence recovery of GQDs and RQDs. With the help of one step of magnetic separation, the supernatants can be collected for fluorescence analysis. After optimization of detection conditions, the developed method had a wider linear range of 10 pg mL?1–100 ng mL?1 for AFB1 and 50 pg mL?1–300 ng mL?1 for FB1 and showed no cross-reactivity with other closely related mycotoxins, respectively. The limit of detection for AFB1 and FB1 are calculated to be 6.7 and 16.2 pg mL?1 based on S/N=3. The detection of mycotoxins has been successfully realized in peanut samples and a new application field of FRET system is expected for various targets.
关键词： aptasensor,fluorescence resonance energy transfer,aflatoxin B1,fumonisin B1,simultaneous detection
更新于2025-09-11 14:15:04
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A lysosome-targetable fluorescent probe for simultaneously sensing Cys/Hcy, GSH, and H2S from different signal patterns
摘要： Biothiols, a vital branch of reactive sulfur species (RSS) family, which are indispensable in human physiology. However, the exact functional roles of each biothiols involved in complicated physiological activities were still not fully clarified. A critical barrier is a lack of robust molecular tools which can simultaneously visualize different biothiols with distinct emission signals. Herein, the first lysosome-targetable fluorescent probe, Lyso-RC, which could respond to Cys/Hcy, GSH and H2S with different sets of signal patterns was developed. Lyso-RC responds to Cys/Hcy, GSH and H2S with the fluorescence signal patterns of blue-red, green-red, and red, respectively. Significantly, Lyso-RC is capable of discriminating lysosomal Cys/Hcy, GSH, and H2S in HeLa cells.
关键词： imaging,lysosome-targetable,simultaneous detection,fluorescent probe,biothiols
更新于2025-09-10 09:29:36
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Fabrication of Silver-coated Gold Nanoparticles to Simultaneously Detect Multi-class Insecticide Residues in Peach with SERS Technique
摘要： Fast sampling and multicomponent detections are important in the analysis of pesticide residues detection. In this work, surface-enhanced Raman scattering (SERS) method based on silver-coated gold nanoparticles (Au@Ag NPs) was used to simultaneously detect multi-class pesticide residues such as thiacloprid (carbamate), profenofos (organophosphate) and oxamyl (neonicotinoid) in standard solution and peach fruit. The Au@Ag NPs with 26 nm Au core size and 6 nm Ag shell thickness exhibited significant Raman enhancement, especially by the creation of hot spots through NPs aggregation induced by the connection between Au@Ag NPs and target molecules. The findings demonstrated that the characteristic wavenumber of the pesticides (thiacloprid, profenofos, and oxamyl) could be precisely identified using the SERS method. Compared with earlier studies, the current approach was rapid, inexpensive and without lengthy sample pretreatment. Moreover, the results revealed that the limit of detection (LOD) was 0.1 mg/kg for thiacloprid obtained in the peach extract with determination coefficient (R2) of 0.986. Additionally, LOD for both profenofos and oxamyl was 0.01 mg/kg with a determination coefficient (R2) of 0.985 and 0.988, respectively. Good recovery percentage (78.6 to 162.0 %) showed the high SERS activity with better accuracy for the detection of the thiacloprid, profenofos, and oxamyl in peach. The results of this study could offer a promising SERS platform for simultaneous detection of other contaminants such as thiacloprid, profenofos and oxamyl in multifaceted food matrices.
关键词： oxamyl,substrate,fruit,SERS,thiacloprid,simultaneous detection,profenofos,core-shell nanoparticles
更新于2025-09-04 15:30:14