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Constructing versatile metal nanoclusters (NCs) assemblies through noncovalent weak interactions between inter-ligands is a long-standing challenge in interfacial chemistry, while compelling interfacial hydrogen-bond-driven metal NCs assemblies remain unexplored so far. Here, the study reports an amination-ligand o-phenylenediamine-coordinated copper NCs (CuNCs), demonstrating the impact of interfacial hydrogen-bonds (IHBs) motifs on the luminescent behaviors of metal NCs as the alteration of protic solvent. Experimental results supported by theoretical calculation unveil that the flexibility of interfacial ligand and the distance of cuprophilic CuI···CuI interaction between intra-/inter-NCs can be tailored by manipulating the cooperation between the diverse IHBs motifs reconstruction, therewith the IHBs-modulated fundamental structure-property relationships are established. Importantly, by utilizing the IHBs-mediated optical polychromatism of aminated CuNCs, portable visualization of humidity sensing test-strips with fast response is successfully manufactured. This work not only provides further insights into exploring the interfacial chemistry of NCs based on inter-ligands hydrogen-bond interactions, but also offers a new opportunity to expand the practical application for optical sensing of metal NCs.
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Baijiu, a traditional Chinese alcoholic beverage, carries China's rich historical and cultural heritage. Consumers experience varying levels of relaxation and pleasure after consuming different types of Baijiu, with the biological basis of delectation influenced by serotonin and dopamine. In this study, we prepared carbon fiber electrodes modified with surface decorated gold nanoparticles to directly measure the electrochemical response signals in the serum of mice before and after gavage with different types of Baijiu. It was observed that the serum signal change in mice after consuming Baijiu sample 1 (J1) was higher than that of the other two types of Baijiu. Consequently, trace flavor compounds in the Baijiu samples were detected using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), revealing the highest content of L-lactic acid in J1. Mice were intraperitoneally injected with 200 mg kg-1 of L-lactic acid. The changes in dopamine and serotonin in the serum of the injected mice were monitored using a biosensor, and the results were compared with the results of high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-MS). The findings confirmed that L-lactic acid could indeed stimulate the secretion of both neurotransmitters in mice, suggesting that the trace components in J1 may even exhibit synergistic effects. This study contributes to a deeper understanding of the effects of Baijiu on the body and provides a scientific basis for the production and consumption of Baijiu.
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Fluorescent lateral flow immunoassay (FLFIA) is widely used mainly because of its low cost and instant detection. Its limit of detection (LOD) is closely related to fluorescence signals, and the development of fluorescence signals with fine performance remains a challenge. In this work, dendritic mesoporous silica nanoparticles (DMSNs) were used as fine carriers due to their large pore size and stable performance. We successfully synthesized carbon dots (CDs) with a 560 nm maximum emission wavelength (CD560) by the hydrothermal method. A new type of fluorescence signal for FLFIA was observed by loading CD560 on DMSNs through the Si-O bond which is denoted as DMSNs@CD560. Applying DMSNs@CD560 to the FLFIA can eliminate the influence of interfacial background blue fluorescence thus improving its detection sensitivity. The formed DMSNs@CD560-FLFIA achieved high sensitivity detection of ovarian cancer biomarkers carbohydrate antigen 125 (CA125) and human epididymal protein 4 (HE4). The LOD of CA125 is 0.5 U mL-1 and the correlation coefficient R2 = 0.985, and the LOD of HE4 reaches 0.05 ng mL-1 and the correlation coefficient R2 = 0.981. The DMSNs@CD560-FLFIA is sensitive and efficient providing a new method for the early diagnosis of ovarian cancer.
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Nanopartículas , Neoplasias Ovarianas , Feminino , Humanos , Biomarcadores Tumorais , Antígeno Ca-125 , Carbono/química , Imunoensaio/métodos , Neoplasias Ovarianas/diagnóstico , Sensibilidade e EspecificidadeRESUMO
To combat the ongoing threat posed by severe fever with thrombocytopenia syndrome virus (SFTSV), especially in underserved areas, there is an urgent need for an affordable and reliable point-of-care diagnostic tool. This study presents a carbon black-based immunochromatographic test strip (CB-ICTS) for the detection of SFTSV, which is both quick and easy to operate. The study optimized the specific steps for carbon black-labeled antibodies, as well as the amount of carbon black and anti-SFTSV antibody used. Under optimal experimental conditions, the linear range and limit of detection of the CB-ICTS were evaluated using different concentrations of SFTSV standard samples. The detection range of the CB-ICTS for SFTSV was found to be 0.1-1000 ng mL-1, with a limit of detection of 100 pg mL-1. The precision and accuracy of the CB-ICTS were assessed by examining spiked healthy human serum samples, which displayed recoveries ranging from 91.58 to 105.4% with a coefficient of variation of less than 11%. This work evaluated the specificity of the CB-ICTS using various biomarkers (CA125, AFP, CA199, CEA, and HCG) and demonstrated that the CB-ICTS is highly specific for detecting SFTSV, suggesting its potential for the early diagnosis of SFTSV. In addition, the study evaluated the CB-ICTS in serum samples from patients with SFTSV, and the results were highly consistent with those detected by the polymerase chain reaction (PCR) method. Overall, this study demonstrates the feasibility and effectiveness of using the CB-ICTS as a reliable point-of-care diagnostic tool for the early detection of SFTSV.
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Colorimetria , Febre Grave com Síndrome de Trombocitopenia , Fuligem/química , Colorimetria/métodos , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , Febre Grave com Síndrome de Trombocitopenia/virologia , Cromatografia de Afinidade/métodos , Anticorpos Monoclonais/imunologiaRESUMO
The sensitivity of fluorescent lateral flow immunoassay (LFIA) test strips is compromised by the low fluorescence intensity of the signaling molecules. In this study, we synthesized novel phosphorus-doped carbon-dot-based dendritic mesoporous silica nanoparticles (DMSNs-BCDs) with a quantum yield as high as 93.7% to break this bottleneck. Meanwhile, the in situ growth method increased the loading capacity of carbon dots on dendritic mesoporous silica, effectively enhancing the fluorescence intensity of the composite nanospheres. Applied DMSNs-BCDs in LFIA can not only semi-quantitatively detect a single component in a short time frame (procalcitonin (PCT), within 15 min) but also detect the dual components with a low limit of detection (LOD) (carbohydrate antigen 199 (CA199) LOD: 1 U/mL; alpha-fetoprotein (AFP) LOD: 0.01 ng/mL). And the LOD of PCT detection (0.01 ng/mL) is lower by 1.7 orders of magnitude compared to conventional colloidal gold strips. For CA199, the LOD is reduced by a factor of four compared to LFIA using gold nanoparticles as substrates, and for AFP, the LOD is lowered by two orders of magnitude compared to colloidal gold LFIA. Furthermore, the coefficients of variation (CV) for intra-assay and inter-assay measurements are both less than 11%.
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Nanopartículas Metálicas , alfa-Fetoproteínas , Ouro , Corantes , Carbono , Coloide de Ouro , ImunoensaioRESUMO
Limited light absorption and rapid photo-generated carriers' recombination pose significant challenges to the practical applications of photocatalysts. In this study, we employed an efficient approach by combining the slow-photon effect with Z-scheme charge transfer to enhance the photo-degradation performance of antibiotics. Specifically, we incorporated 0D ZnIn2S4 quantum dots (QDs) into a 3D hierarchical inverse opal (IO) TiO2 structure through a facile one-step process. This combination enhanced the visible light absorption and provided abundant active surfaces for efficient photo-degradation. Moreover, the ZnIn2S4 QDs formed an artificial Z-scheme system with IO-TiO2, facilitating the separation and migration of charge carriers. To achieve a better band alignment with IO-TiO2, we doped Ag into the ZnIn2S4 QDs (Ag: ZIS QDs) to adjust their energy levels. Through an investigation of the different Ag contents in the ZnIn2S4 QDs, we found that the optimal photo-degradation performance was achieved with Ag (2.0): ZIS QDs/IO-TiO2, exhibiting degradation rates 19.5 and 14.8 times higher than those of ZnIn2S4 QDs and IO-TiO2, respectively. This study provides significant insights for elevating the photocatalytic capabilities of IO-TiO2 and broadening its prospective applications.
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Lower light absorption and faster carrier recombination are significant challenges in photocatalysis. This study introduces a novel approach to address these challenges by anchoring cadmium sulfide quantum dots (CdS QDs) on inverse opal (IO)-TiO2, which increases light absorption and promotes carriers' separation by coupling slow-photon effect with Z-scheme charge transfer. Specifically, the IO-TiO2 was created by etching a polystyrene opal template, which resulted in a periodic structure that enhances light absorption by reflecting light in the stop band. The size of CdS quantum dots (QDs) was regulated to achieve appropriate alignment of energy bands between CdS QDs and IO-TiO2, promoting carrier transfer through alterations in charge transfer modes and resulting in synergistic-amplified photocatalysis. Theoretical simulations and electrochemical investigations demonstrated the coexistence of slow-photon effects and Z-scheme transfer. The system's photodegradation performance was tested using rhodamine B as a model. This novel hierarchical structure of the Z-scheme heterojunction exhibits degradability 7.82 and 4.34 times greater than pristine CdS QDs and IO-TiO2, respectively. This study serves as a source of inspiration for enhancing the photocatalytic capabilities of IO-TiO2 and broadening its scope of potential applications.
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Photonic crystals (PCs) have emerged as a promising electrochemiluminescence (ECL) matrix in the domain of immunoassay. Making maximum use of light manipulation properties of PCs is highly desired for improving the sensitivity. In this work, we proposed a band-edge effect-induced ECL enhancement strategy based on silica inverse opal PCs (SIOPCs). By fine-tuning the lattice constant and carefully calibrating the stopband position, we found that the band edge of the stopband exerted significant influences on the ECL intensity and spectral distribution. The high density of states at the blue edge of the photonic band gap increased the radiative transition probability of ECL emitters and enhanced the photon extraction during propagation, giving rise to â¼20-fold ECL signal amplification accompanied by a redistributed ECL spectrum for the Ru(bpy)32+-TPrA system. In combination with the intrinsic structural superiority, like large specific surface area and interconnected macropores, the developed SIOPC electrode was successfully applied in constructing a sandwich-type immunosensor. The fabricated immunosensor displayed a very low detection limit of 0.032 pg/mL and a wide linear range of 0.1 pg/mL-150 ng/mL for a carcinoembryonic antigen assay, showing its potential application in disease diagnosis.
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Técnicas Biossensoriais , Antígeno Carcinoembrionário , Técnicas Eletroquímicas , Imunoensaio , Limite de Detecção , Medições Luminescentes , Dióxido de Silício/químicaRESUMO
Early diagnosis of tumor markers is of great importance for the successful treatment of cancer. As a high-throughput and high-sensitivity detection technology, liquid suspension biochips based on quantum dot (QD) encoded microspheres have been widely used in the immunodetection of tumor markers. In this work, maleic anhydride grafted PLA (PLA-MA) microspheres based on quantum dot encoding were used as carriers for liquid phase suspension biochips for the immunoassay of tumor markers. PLA-MA fluorescent beads are prepared by embedding CdSe/ZnS quantum dots in PLA-MA using Shirasu porous glass (SPG) membrane emulsification technology, which has high fluorescence intensity, good stability, and good dispersion. Fluorescent immunoassays on dipsticks found that PLA-MA microspheres have high biological activity and good stability, which is conducive to immunoassays. Based on this, using the characteristics of CdSe/ZnS quantum dots and flow cytometry, monochromatic and two-color coding methods were developed, and 9 distinguishable coding beads were prepared. The results showed that PLA-MA fluorescent microspheres exhibited good biocompatibility, stable coding signals, low background noise, and low detection limits when performing quaternary immunoassays on tumor markers CA125, CA199, CA724, and CEA by CdSe/ZnS QD-encoded PLA-MA microsphere binding flow cytometry.
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Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Biomarcadores Tumorais , Corantes , Imunoensaio/métodos , Anidridos Maleicos , Microesferas , Poliésteres , Sulfetos , Compostos de ZincoRESUMO
In this work, a low triggered potential electrochemiluminescence strategy based on gold-filled photonic crystals (GPCs) electrodes composed of photonic crystals self-assembled with polystyrene spheres and gold nanoparticles embedded in the gaps of the photonic crystals was proposed. The GPCs electrodes served as the detection platform to bind antigen, and Ru(bpy)32+-COOH as a luminophore was labeled on the antibody (Ab). Then, Ru(bpy)32+-COOH/Ab was connected to the immobilized antigen on the surface of the photonic crystals by the immunoreaction to avoid direct contact with the gold nanoparticles surface. ECL emission can only be initiated by electrochemical oxidation of tripropylamine (TPrA) since Ru(bpy)32+-COOH cannot be oxidized directly on the electrode surface. The TPrA·+ and TPrA· radicals generated by the oxidation of TPrA can spread to the vicinity of Ru(bpy)32+-COOH over a short distance and react with the Ru(bpy)32+-COOH, eventually producing ECL emission. The potential of ECL emission caused by TPrA oxidation was about 300 mV lower than that caused by Ru(bpy)32+-COOH oxidation because the oxidation potential of TPrA (0.95 V vs SCE) was lower than Ru(bpy)32+-COOH (1.25 V vs SCE). Furthermore, the photonic crystals nanomembrane has the capability to enhance electrochemiluminescence. Thereafter, tetracycline antibiotic as a model compound was successfully detected via competitive immunoassay on GPCs electrodes with a detection limit of 0.075 pg/mL (S/N = 3), which has broad application prospects in the field of analysis and detection.
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Ouro , Nanopartículas Metálicas , Antibacterianos , Medições Luminescentes , Poliestirenos , TetraciclinasRESUMO
It is imminent to develop a new type of rapid COVID-19 detection method with high sensitivity. Here, we used novel red emission-enhanced carbon dot (CD)-based silica (RCS) spheres as the signals of lateral flow immunochromatography (LFI) to ultrasensitively detect novel severe acute respiratory syndrome coronavirus 2 nucleocapsid proteins (SARS-CoV-2 NPs). The red emission of CDs can be enhanced and enriched in silica spheres by a simple way. The amino ends of the N-ß-(aminoethyl)-γ-aminopropyltrimethoxy anchor carboxyl-rich CDs and enhance the red emission, while the other end is embedded in the silica carrier. Then, the composite silica spheres werecoated with 3-(triethylsilyl) propylamine to protect the CDs, promote bioconjugation and obtain RCS spheres. The optimal emission peaks of the aqueous solution and the solid state of RCS spheres were at 634 nm and 638 nm, respectively, with quantum yields (QYs) of 48.5% and 35.7%, respectively. Their red emission has a wide excitation range (from the ultraviolet region to the red region), and the best excitation wavelength is about 580 nm. Two fluorescence detection modes of the RCS-LFI technology for the SARS-CoV-2 NP assay are available: the simple mode of observation under ultraviolet light has a sensitivity of 100 pg mL-1; the advanced mode of detection under a fluorescence microscope has a sensitivity of 10 pg mL-1. This assay also exhibits the advantages of fast detection speed, high specificity, and simple operation. In addition, the feasibility of this method in actual sample detection was verified in human serum by the standard-addition method, and the results show that the method has excellent practicability. We believe that this method will be a valuable supplement for the diagnosis of COVID-19.
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COVID-19 , SARS-CoV-2 , Anticorpos Antivirais , Carbono , Humanos , Imunoensaio , Proteínas do Nucleocapsídeo , Sensibilidade e Especificidade , Dióxido de SilícioRESUMO
Quantum dot (QD)-encoded microbeads as optical barcode with high fluorescence intensity and fluorescence uniformity, excellent stability and dispersity are greatly important for suspension array (SA). However, the size distribution of the microbeads mass-produced by the membrane emulsification method usually shows polydispersity, which leads to obstacles, imposing labour-intensive experimental iterations for the application of fluorescence-encoded microbeads as a distinguishable barcode. Herein, a simple simulation strategy based on a multicolor fluorescence model (MFM) was used to predict the influence of the microbeads' size distribution on the barcode signals. The point L and S respectively represent the two end points of the barcode, and the line segment LS can be considered as a cluster of the QD-encoded microbeads (simulated barcode). Experimental clusters of fluorescent microbeads were found to be in good agreement with the simulated barcodes. This simple simulation strategy can effectively simplify the experimental iteration process because the fluorescence-encoded microbeads are not decoded by a flow cytometer. Moreover, when applied for the high-throughput ultrasensitive detection of three tumor markers (CEA, CA125 and CA199) in a single sample, these barcodes exhibit superior detection performance. Detection limits of 0.028 ± 0.001 ng mL-1 for CEA, 1.5 ± 0.02 KU L-1 for CA125 and 0.8 ± 0.1 KU L-1 for CA199 are achieved, which meet the sensitivity criteria of tumor marker analysis. Therefore, this simple simulation strategy helps to overcome technical and economic obstacles for the widespread application of SA.
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Pontos Quânticos , Corantes , Citometria de Fluxo , Microesferas , SuspensõesRESUMO
Enhanced electrochemiluminescence (ECL) signals of CdS quantum dots capped with 3-mercaptopropionic acid (MPA@CdS QDs) have been observed after using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) to activate the carboxyl groups. The generated ECL signals are strong enough that their images can be captured using a Huawei mobile phone. A possible mechanism for the generation of enhanced ECL signals has been proposed. Then, a sandwich immunosensor platform for detecting Zika virus (ZIKV) was fabricated with silica microspheres as the carrier and MPA@CdS QDs as ECL signal labels. Due to the dual signal amplification of EDC activation and microsphere enrichment, good linearity from 1.0 fg mL-1 to 1.0 ng mL-1 was exhibited by the QD-based ECL immunosensor for ZIKV detection. The detection limit was 0.3 fg mL-1.
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Técnicas Biossensoriais , Compostos de Cádmio , Pontos Quânticos , Infecção por Zika virus , Zika virus , Humanos , Imunoensaio , Medições LuminescentesRESUMO
Here a novel strategy is reported of assembling silanized carbon dots (CDs) with porous silica templates to form fluorescent CD-based silica (FCS) colloids with uniformly packed CDs throughout the silica matrix. Dendritic silica spheres with highly accessible central-radial pores are adopted as a powerful absorbent host, which can form Si-O bonds with silane to directly fix the silanized CDs. The appropriate loading content of CDs on the inner surface of dendritic silica spheres is beneficial for the maximum fluorescence intensity of FCS colloids. High-quality silanized CDs endow multiple CD embedded silica spheres with excellent properties, including good fluorescence performance, excellent colloidal/optical stabilities and convenient biofunctionalization. The integration of these FCS colloids with a lateral flow strip platform provides an ultra-sensitive, specific and robust immunoassay method for the Zika NS1 protein with a visual detection limit of 10 pg mL-1, and has been successfully applied to the detection of Zika virus in clinical samples. In addition, we also prepared conventional Au NP-based lateral flow test strips and applied them to the detection of Zika NS1 protein. By comparison, the detection limit of immunofluorescent CD-based silica (iFCS)-based lateral flow test strips is 100-fold lower than that of Au NP-based lateral flow strips.
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Carbono/química , Imunoensaio/métodos , Limite de Detecção , Nanopartículas/química , Dióxido de Silício/química , Zika virus/isolamento & purificação , Coloides , HumanosRESUMO
Low-toxicity gold nanoclusters-decorated Ag@SiO2 (Au NCs-Ag@SiO2) nanocomposites modified plasmonic photoelectrodes were first fabricated to improve the photoelectric properties of Au NCs and practical application in biological detection. Through adjusting distance between Au NCs and plasmonic silver nanoparticles (Ag NPs), the photocurrent intensity of Au NCs enhanced by 3.8 times attributed to strong competition between enhancement functions of hot electron transfer, local electric field, light scattering effects, and quenching functions of nonradiative energy transfer. Further comparison between experimental results and theoretical simulations were conducted to gain a deeper understanding toward the photoelectric enhancement mechanism. Moreover, Au NCs-Ag@SiO2 nanocomposites was successfully applied to the construction of photoelectrochemical (PEC) biosensors for sensitively detecting alkaline phosphatase activity. This proposed PEC biosensor showed a wide linear range from 0.04 to 400 U·L-1, and a low detection limit of 0.022 U·L-1.
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Fosfatase Alcalina/análise , Técnicas Biossensoriais , Técnicas Eletroquímicas , Ouro/química , Nanopartículas Metálicas/química , Fosfatase Alcalina/metabolismo , Humanos , Tamanho da Partícula , Processos Fotoquímicos , Dióxido de Silício/química , Prata/química , Propriedades de SuperfícieRESUMO
The ongoing worldwide SARS-CoV-2 epidemic clearly has a tremendous influence on public health. Molecular detection based on oral swabs was used for confirmation of SARS-CoV-2 infection. However, high false negative rates were reported. We describe here the development of a point-of-care (POC) serological assay for the detection of IgG antibody against SARS-CoV-2. The principle of a lateral flow immunoassay strip (LFIAs) consists of fixing SARS-CoV-2 nucleocapsid protein to the surface of the strip and coupling anti-human IgG with colloidal gold nanoparticles (Au NPs). A series of parameters of this method were optimized, including the concentration of coating antigen, BSA blocking concentration and pH value for conjugation. The entire detection process took 15-20 min with a volume of 80 µL of the analyte solution containing 10 µL of serum and 70 µL sample diluent. The performance of the established assay was evaluated using serum samples of the clinically diagnosed cases of Coronavirus Disease 2019 (COVID-19). Our results indicated that the LFIAs for SARS-CoV-2 had satisfactory stability and reproducibility. As a result, our fast and easy LFIAs could provide a preliminary test result for physicians to make the correct diagnosis of SARS-CoV-2 infections along with alternative testing methods and clinical findings, as well as seroprevalence determination, especially in low-resource countries.
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Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/diagnóstico , Imunoensaio/métodos , Imunoglobulina G/sangue , Pneumonia Viral/diagnóstico , Anticorpos Antivirais/sangue , Betacoronavirus/metabolismo , COVID-19 , Infecções por Coronavirus/virologia , Proteínas do Nucleocapsídeo de Coronavírus , Ouro/química , Humanos , Imunoglobulina M/sangue , Nanopartículas Metálicas/química , Proteínas do Nucleocapsídeo/imunologia , Pandemias , Fosfoproteínas , Pneumonia Viral/virologia , Sistemas Automatizados de Assistência Junto ao Leito , Reprodutibilidade dos Testes , SARS-CoV-2RESUMO
Ratiometric fluorescent nanosensors were developed to detect mercury ions (Hg2+) using enhanced dual emissions from glutathione stabilized gold nanoclusters/indium-based metal-organic frameworks modified with cysteine (AuNCs/MIL-68(In)-NH2/Cys). The nanosensors exhibited bright pink fluorescence with AuNCs evenly distributed on MIL-68(In)-NH2. Under 370 nm excitation, the obtained sensor presented double fluorescence emission around 438 nm and 668 nm, which was attributed to MIL-68(In)-NH2 and GSH-AuNCs, respectively. The fluorescence emission was remarkably enhanced after modification with Cys. In the presence of Hg2+, the red fluorescence peak at 668 nm was quenched, while the blue fluorescence peak at 438 nm was slightly altered. The prepared AuNCs/MIL-68(In)-NH2/Cys nanosensors exhibited two linear ranges for the detection of Hg2+, namely from 20 pM to 0.2 µM and 0.2 µM to 60 µM, with a detection limit of 6.7 pM. They also presented high selectivity towards other ions and good performance in real water samples. Moreover, a radial star-shaped microfluidic paper-based analytical device (µPAD), as a straightforward and convenient platform, was successfully fabricated for the visual detection of Hg2+ with a wide detection range from 5 nM to 50 µM.
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Two types of lateral flow immunochromatographic test strips (LFITS) using gold nanoparticles and fluorescent CdTe quantum dots (QDs) as signal labels, respectively, were developed for Shiga toxin type II (STX2) assays. Under optimal conditions, the corresponding visual detection limits were 25 ng mL-1 and 5 ng mL-1, respectively. The test results of gold based LFITS can be recognized directly by the naked eye, whereas the visualized results of CdTe QDs based LFITS can be observed by the aid of a UV lamp. Both assays showed good specificity and stability. The inexpensive LFITS were promising for the rapid clinical detection of STX2.
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Cromatografia de Afinidade/métodos , Colorimetria/métodos , Fluorometria/métodos , Fitas Reagentes , Toxina Shiga II/análise , Anticorpos/imunologia , Compostos de Cádmio/química , Cromatografia de Afinidade/instrumentação , Colorimetria/instrumentação , Corantes Fluorescentes/química , Fluorometria/instrumentação , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química , Pontos Quânticos/química , Toxina Shiga II/imunologia , Telúrio/químicaRESUMO
An aptasensor is described for the electrochemical determination of bisphenol A (BPA). Gold-coated multiwalled carbon nanotubes (Au/MWCNTs) and a single-stranded DNA-dye complex are used as a double signal-amplification system. The BPA-binding aptamer was assembled on a disposable electrode modified with Au/MWCNTs. Methylene blue (MB) was then intercalated into the immobilized aptamer with an approximately molecular ratio of 4 to form a complex. Upon interaction with BPA, the immobilized aptamer underwent a conformational change. This causes the intercalated MB to be released from the complex into solution. As a result, the electrochemical signal of the intercalated MB, typically measured using square wave voltammetry at a potential of -0.20 V (vs. Ag/AgCl (saturated KCl)) decreases. The fabrication of the aptasensor was characterized by the scanning electron microscopy, atomic force microscopy, and electrochemical techniques. Under optimal experimental conditions, the current drops linearly with the logarithm of BPA concentrations over the range from 10 fM to 1 nM, and the limit of detection is 8 fM. The assay was applied to the determination of BPA in plastic drinking bottles, tap water, and milk. Graphical AbstractSchematic illustration of fabricating the aptasensor for bisphenol A (BPA) based on double signal amplification via gold-coated multiwalled carbon nanotubes (Au/MWCNT) and an aptamer-dye complex. PET: poly(ethylene terephthalate).
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Aptâmeros de Nucleotídeos/química , Compostos Benzidrílicos/análise , Técnicas Biossensoriais , Técnicas Eletroquímicas , Técnicas de Amplificação de Ácido Nucleico , Fenóis/análise , DNA de Cadeia Simples/química , Ouro/química , Azul de Metileno/química , Nanotubos de Carbono/química , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
BACKGROUND/AIMS: The anatomical complexity of the head and neck region and the lack of sufficiently specific and sensitive biomarkers often lead to the diagnosis of head and neck squamous cell carcinoma (HNSCC) at advanced stages. To identify novel biomarkers for early diagnosis of primary HNSCC through a minimally invasive method, we investigated circulating long noncoding RNA (lncRNA) levels in plasma of HNSCC patients. METHODS: The global lncRNA expression profiles of HNSCC patients were measured using microarray and next-generation RNA-sequencing (RNA-seq) data from both circulating and tissue samples. The diagnosis prediction model based on the lncRNA signatures and clinical features was evaluated by multi-stage validation and risk score analysis. RESULTS: The data showed that 432 lncRNA transcripts were differentially expressed by fold changes of > 4 in circulating samples and 333 in tissues samples, respectively. Only 12 lncRNAs consistently emerged in these two kinds of samples. After the risk score analysis including a multistage validation, we identified three lncRNAs, namely, HOXA11-AS, LINC00964 and MALAT1, which were up-regulated in the plasma of HNSCC patients compared with those in healthy controls with merged areas under the curve (AUCs) in training and validation sets of 0.925 and 0.839, respectively. CONCLUSION: HOXA11-AS, LINC00964 and MALAT1 might be potential circulating biomarkers for the early detection of HNSCC in the future.