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1.
Food Chem ; 375: 131888, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34974348

RESUMO

In this study, an ultrasensitive monoclonal antibody (mAb) was produced and used to develop a gold nanoparticle-based lateral flow immunochromatographic (ICA) strip for screening of clomazone (CLO) in potato and pumpkin samples. With assayed by indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method, the mAb belonging of IgG2 subclass showed a half-maximal inhibitory concentration (IC50) of 3.47 ng/mL and a linear range of detection of 0.43-28.09 ng/mL. A cross-reactivity test revealed that the mAb had good specificity for CLO. The strip assay had a visual limit of detection (LOD) of 5 µg/kg and a cut-off value of 50 µg/kg for CLO pumpkin samples (potato samples was 100 µg/kg) when evaluated with the naked eye. The results were consistent with ic-ELISA and high performance liquid chromatography tandem mass spectrometry (HPLC-MS). Thus, this ICA strip assay represents a potentially tool for on-site and rapid initial detection of CLO in potato and pumpkin samples.


Assuntos
Cucurbita , Nanopartículas Metálicas , Solanum tuberosum , Ensaio de Imunoadsorção Enzimática , Ouro , Coloide de Ouro , Imunoensaio , Isoxazóis , Limite de Detecção , Oxazolidinonas
2.
J Chromatogr A ; 1662: 462729, 2022 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-34998472

RESUMO

In this work, a novel sorbent, based on UVM-7 mesoporous silica doped with Au, has been proposed for organochlorine pesticides extraction. Cartridges containing this material have been applied to the preconcentration of 20 pesticides from water samples, through a solid-phase extraction (SPE) protocol, with their later determination by gas chromatography with an electron capture detector. First, UVM-7 materials were properly characterized by X-ray diffraction, N2 adsorption-desorption, electron microscopy techniques, and UV-Vis spectroscopy, thus confirming their structure and Au incorporation. After optimization of main extraction parameters, recoveries in the range of 80-110% were obtained for most of the analytes, with enrichment factors comprised between 275 and 430. The obtained sensitivity was comparable with other reported methods, with limits of quantification in the range of 0.3-20 ng L-1, thus allowing the determination of these compounds according to European legislation. The developed method has been successfully applied to the analysis of real spiked samples in comparison with a reference method, thus being this sorbent an alternative for organochlorine pesticide enrichment, through a simple, reusable, cheap, and environmentally friendly SPE procedure.


Assuntos
Nanopartículas Metálicas , Praguicidas , Poluentes Químicos da Água , Ouro , Praguicidas/análise , Dióxido de Silício , Extração em Fase Sólida , Água , Poluentes Químicos da Água/análise
3.
J Nanobiotechnology ; 20(1): 6, 2022 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-34983543

RESUMO

BACKGROUND: Gold nanoparticles (AuNPs) have been widely used in local surface plasmon resonance (LSPR) immunoassays for biomolecule sensing, which is primarily based on two conventional methods: absorption spectra analysis and colorimetry. The low figure of merit (FoM) of the LSPR and high-concentration AuNP requirement restrict their limit of detection (LOD), which is approximately ng to µg mL-1 in antibody detection if there is no other signal or analyte amplification. Improvements in sensitivity have been slow in recent for a long time, and pushing the boundary of the current LOD is a great challenge of current LSPR immunoassays in biosensing. RESULTS: In this work, we developed spectral image contrast-based flow digital nanoplasmon-metry (Flow DiNM) to push the LOD boundary. Comparing the scattering image brightness of AuNPs in two neighboring wavelength bands near the LSPR peak, the peak shift signal is strongly amplified and quickly detected. Introducing digital analysis, the Flow DiNM provides an ultrahigh signal-to-noise ratio and has a lower sample volume requirement. Compared to the conventional analog LSPR immunoassay, Flow DiNM for anti-BSA detection in pure samples has an LOD as low as 1 pg mL-1 within only a 15-min detection time and 500 µL sample volume. Antibody assays against spike proteins of SARS-CoV-2 in artificial saliva that contained various proteins were also conducted to validate the detection of Flow DiNM in complicated samples. Flow DiNM shows significant discrimination in detection with an LOD of 10 pg mL-1 and a broad dynamic detection range of five orders of magnitude. CONCLUSION: Together with the quick readout time and simple operation, this work clearly demonstrated the high sensitivity and selectivity of the developed Flow DiNM in rapid antibody detection. Spectral image contrast and digital analysis further provide a new generation of LSPR immunoassay with AuNPs.


Assuntos
Teste Sorológico para COVID-19/métodos , COVID-19/diagnóstico , SARS-CoV-2/isolamento & purificação , Ressonância de Plasmônio de Superfície/métodos , Anticorpos Antivirais/imunologia , COVID-19/imunologia , Teste Sorológico para COVID-19/instrumentação , Desenho de Equipamento , Ouro/química , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Nanopartículas Metálicas/química , SARS-CoV-2/imunologia , Saliva/virologia , Glicoproteína da Espícula de Coronavírus/imunologia , Ressonância de Plasmônio de Superfície/instrumentação
4.
J Colloid Interface Sci ; 608(Pt 1): 219-226, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34626968

RESUMO

Riboflavin (RF) is one of the necessary vitamins. If human body lacks RF, it will lead to inflammation and dysfunction of mouth, lips and skin. Thus sensitive and accurate determination of RF is necessary. Here, an electroactive covalent-organic framework nanobelt (COFTFPB-Thi) with thickness of 1.4 nm was prepared by amine-aldehyde condensation reaction between thionine and 1, 3, 5-tris (p-formylphenyl) benzene, which was then grown vertically on three-dimensional porous carbon derived from kenaf stem (3D-KSC) for double signal ratiometric electrochemical detection of RF. The resulted 3D-KSC/COFTFPB-Thi showed two reduction peaks at -0.08 V and -0.23 V, which came from the reduction of COFTFPB-Thi and the conjugated structure of COFTFPB-Thi, respectively. In the presence of RF, those RF molecules near the electrode surface were oxidized at 0.6 V. Then some oxidized RF (RFox) adsorbed on COFTFPB-Thi would oxidize COFTFPB-Thi into COFTFPB-Thi(ox) while other RFox adsorbed on 3D-KSC kept unchanged. When the potential was scanned from 0.6 V to -0.6 V, both COFTFPB-Thi(ox) and RFox adsorbed on 3D-KSC were reduced at -0.08 V and -0.45 V accordingly, while the reduction peak of -0.23 V of the conjugated structure of COFTFPB-Thi kept constant. When j-0.45/j-0.23 was used as the response signal, the detection limit was 44 nM and the linear range was 0.13 µM -0.23 mM. By using j-0.08/j-0.23 as the response signal, a detection limit of 90 nM and a linear range of 0.30 µM-0.23 mM (S/N = 3) were obtained. By using double signals, the measurement results can be corrected to make the results more accurate and reliable. The sensor also showed good selectivity, reproducibility and stability, which provided a good application prospects.


Assuntos
Técnicas Biossensoriais , Estruturas Metalorgânicas , Carbono , Técnicas Eletroquímicas , Eletrodos , Ouro , Humanos , Limite de Detecção , Fenotiazinas , Reprodutibilidade dos Testes , Riboflavina
5.
Biosens Bioelectron ; 196: 113697, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34649096

RESUMO

Rapid and accurate detection of nucleic acids is of paramount importance in many fields, including medical diagnosis, gene therapy and virus identification. In this work, by taking advantage of two DNA hybridization probes, one of which was immobilized on the surface of gold nanoparticles, while the other was free in solution, detection of short length nucleic acids was successfully achieved using a large size (20 nm tip diameter) polyethylene terephythalate (PET) nanopore. The sensor was sensitive and selective: DNA samples with concentrations at as low as 0.5 nM could be detected within minutes and the number of mismatches can be discerned from the translocation frequency. Furthermore, the nanopore can be repeatedly used many times. Our developed large-size nanopore sensing platform offers the potential for fieldable/point-of-care diagnostic applications.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Nanoporos , Ácidos Nucleicos , Ouro
6.
Biosens Bioelectron ; 196: 113688, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34700264

RESUMO

Detection of multiple analytes simultaneously in small liquid samples with high efficiency and precision is highly important to the fields like water quality monitoring. In this letter, we present a multiplexed nanosensors with position-encoded aptamer functionalized gold nanorods for heavy metal ions detection. The individual gold nanorods respond specifically to two different heavy metal ions (Pb2+ and Hg2+) with a spectral shift in the scattering spectrum. We used a home-built spectral imaging dark-field microscope to measure the response of thousands of single plasmonic nanosensors with relatively high time resolution and precision. To explore the performance and limit of detection (LOD) of our nanosensor and setup, we recorded the concentration-dependent response of our position-encoded nanosensors with a series of mixture solutions that contain different concentrations of Hg2+ and Pb2+ ions. The LOD levels of our system are around 5 nM for Pb2+ ions and 1 nM for Hg2+ ions. Our method and results demostrate the nanomolar sensitivity and the potential to detect more different heavy metal ions.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Metais Pesados , Ouro , Íons
7.
Food Chem ; 373(Pt A): 131415, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34710699

RESUMO

Developing an effective method for the detection of aflatoxin B1 (AFB1) remains an arduous task due to the high toxicity of AFB1 to a health concern. In this study, a sensitive and reliable electrochemical aptasensor based on carbon dots/α-Fe2O3-Fe3O4 nanocomposite (CDs/α-Fe2O3-Fe3O4) is constructed for the determination of AFB1. The CDs have good electrical conductivity and large specific surface areas to improve the aptasensor's sensitivity. The α-Fe2O3-Fe3O4 can not only improve the catalytic performance of the aptasensor but also have magnetism, which can realize the recovery of CDs/α-Fe2O3-Fe3O4 to avoid material waste and environmental pollution. This electrochemical aptasensor can achieve a good linear (0.001-100.0 nM) and excellent detection limit (0.5 pM) for the determination of AFB1. In addition, the aptasensor was also applied to determine AFB1 in beer, rice, and peanuts, all results were in good agreement with HPLC, indicating that the electrochemical aptasensor has a broad application prospect.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanocompostos , Aflatoxina B1/análise , Carbono , Técnicas Eletroquímicas , Ouro , Limite de Detecção
8.
J Environ Manage ; 302(Pt A): 113979, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34715613

RESUMO

Mine tailings are a potential source of environmental pollution because they typically contain potentially toxic elements (PTEs) and the residue of chemical compounds used during extraction processes. The Remance gold mine (NW Panama) is a decommissioned mine with mining activity records dating from the 1800s and several periods of abandonment. Very little remediation work has been performed, and waste is exposed to climatic conditions. This study aimed to evaluate the PTEs and cyanide contents in mine waste after mining operations ceased some 20 years ago, and to evaluate the degree of pollution and the environmental risks they pose with the use of the Pollution Load Index (PLI) and the Ecological Risk Index (RI). Although the total cyanide (T-CN) concentration (1.4-1.9 mg kg-1) found in most of the study area falls within the limits of gold mining tailing values for American sites (1.5-23 mg kg-1), it is worth noting that the values of the tailings of the last used mining operation exceed it (25.2-518 mg kg-1) and persist at the site. The PLI and RI suggest that the tailings from the mine and mine gallery sediments represent a source of pollution for soils and surrounding areas given their high content of PTEs (As, Cu, Sb, Hg) and T-CN, which pose serious ecological risks for biota. Therefore, it is necessary to draw up a remediation plan for this area.


Assuntos
Metais Pesados , Poluentes do Solo , América Central , Monitoramento Ambiental , Ouro , Metais Pesados/análise , Mineração , Medição de Risco , Poluentes do Solo/análise
9.
Food Chem ; 373(Pt A): 131411, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34715634

RESUMO

Due to the costly and time-consuming traditional techniques, providing a low-cost, portability and flexibility diagnostic tool with the ability to monitor and detect various animal feed additive is highly demanded. Over the years, paper-based biosensors have emerged as point of care (POC) diagnostic, easy-to-use and miniaturized tools. However, they have been suffered from low sensitivity. Aptamer as appropriate bioreceptor can overcome the most common disadvantage of paper based sensor by increasing selectivity and sensitivity. In this study, a novel paper-based electrochemical aptasensor was successfully developed to detection of ractopamine (RAC). RAC concentration was evaluated using a designed three-electrode paper based biodevice system. Under the optimal experimental conditions, the engineered aptasensor provided good sensitivity and selectivity for the detection of RAC. Using proposed flexible sensor RAC was determined in the range of 0.001 µM to 100 mM which the lower limit of quantitation (LLOQ) was obtained as 0.01 µM. Finally, aptasensor was used to the monitoring of RAC in untreated human plasma specimens which LLOQ and linear range were 0.01 µM and 0.01 µM to 10 mM, respectively. We hope that the exploitation of aptamer in electrochemical paper based sensor will be able to broaden our understanding for developing the application of low-cost and portable biodevices for the sensitive and selective paper-based sensor to identify other chemical and biological compounds.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Ração Animal , Animais , Técnicas Eletroquímicas , Eletrodos , Análise de Alimentos , Ouro , Humanos , Limite de Detecção , Fenetilaminas , Tecnologia
10.
Biosens Bioelectron ; 196: 113729, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34736101

RESUMO

Herein, a novel molecularly imprinted polymer (MIP) based electrochemical sensor for the determination of the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-RBD) has been developed. For this purpose, first, a macroporous gold screen-printed electrode (MP-Au-SPE) has been fabricated. The MIP was then synthesized on the surface of the MP-Au-SPE through the electro-polymerization of ortho-phenylenediamine in the presence of SARS-CoV-2-RBD molecules as matrix polymer, and template molecules, respectively. During the fabrication process, the SARS-CoV-2-RBD molecules were embedded in the polymer matrix. Subsequently, the template molecules were removed from the electrode by using alkaline ethanol. The template molecules removal was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and attenuated total reflectance spectroscopy (ATR). The fabricated MIP film acted as an artificial recognition element for the measurement of SARS-CoV-2-RBD. The EIS technique was used for the measurement of the SARS-CoV-2-RBD in the saliva solution. The electron transfer resistance (Ret) of the MIP-based sensor in a ferri/ferrocyanide solution increased as the SARS-CoV-2-RBD concentration increased due to the occupation of the imprinted cavities by the SARS-CoV-2-RBD. The MIP-based sensor exhibited a good response to the SARS-CoV-2-RBD in the concentration range between 2.0 and 40.0 pg mL-1 with a limit of detection of 0.7 pg mL-1. The obtained results showed that the fabricated MIP sensor has high selectivity sensitivity, and stability.


Assuntos
Técnicas Biossensoriais , COVID-19 , Impressão Molecular , Técnicas Eletroquímicas , Eletrodos , Ouro , Humanos , Limite de Detecção , Polímeros Molecularmente Impressos , SARS-CoV-2
11.
Biosens Bioelectron ; 196: 113733, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34736102

RESUMO

Strong and stable electrochemical beacons are critical for the achievement of sensitive and reliable electroanalysis applications. In this work, the electrochemical oxidation performance of AuPt NPs was studied and firstly found to be largely enhanced under light illumination. Plasmonic AuPt NPs collected light energy after local surface plasmon resonance (LSPR) excitation and generated much more holes to participate in the electrochemical oxidation process of Pt0 in AuPt NPs. AuPt NPs with the electrochemical oxidation peak at around -0.7 V were utilized as detection probes for the fabrication of ratiometric electrochemical aptasensor, by introducing Co-MOF/Fe3O4/Ag nanosheets (NSs) with the electrochemical oxidation peak at 0.1 V as reference beacons. The aptamers of epithelial cell adhesion molecule (EpCAM) modified AuPt NPs were assembled with Co-MOF/Fe3O4/Ag NSs, which generated strong detection and reference signals at -0.7 V and 0.1 V, respectively. The high affinity between EpCAM and aptamers induced the separation of AuPt NPs from Co-MOF/Fe3O4/Ag NSs, resulting in the decrease of detection signal at -0.7 V and unchanged reference signal at 0.1 V. A ratiometric electrochemical aptasensor was achieved for the sensitive and reliable quantification of EpCAM in the range from 100 pg/mL to 100 ng/mL. The limit of detection (LOD) was calculated to be 13.8 pg/mL for EpCAM. Plasmon-driven electrochemical oxidation enhancement principle provides the possibility for the design and fabrication of more strong and anti-interference electroactive plasmonic metal-Pt composite nanostructures for the electroanalysis applications.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanopartículas Metálicas , Nanoestruturas , Técnicas Eletroquímicas , Ouro , Limite de Detecção , Oxirredução
12.
Biosens Bioelectron ; 197: 113735, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34736114

RESUMO

In an aim of developing portable biosensor for SARS-CoV-2 pandemic, which facilitates the point-of-care aptasensing, a strategy using 10 µm gap-sized gold interdigitated electrode (AuIDE) is presented. The silane-modified AuIDE surface was deposited with ∼20 nm diamond and enhanced the detection of SARS-CoV-2 nucleocapsid protein (NCP). The characteristics of chemically modified diamond were evidenced by structural analyses, revealing the cubic crystalline nature at (220) and (111) planes as observed by XRD. XPS analysis denotes a strong interaction of carbon element, composed ∼95% as seen in EDS analysis. The C-C, CC, CO, CN functional groups were well-refuted from XPS spectra of carbon and oxygen elements in diamond. The interrelation between elements through FTIR analysis indicates major intrinsic bondings at 2687-2031 cm-1. The aptasensing was evaluated through electrochemical impedance spectroscopy measurements, using NCP spiked human serum. With a good selectivity the lower detection limit was evidenced as 0.389 fM, at a linear detection range from 1 fM to 100 pM. The stability, and reusability of the aptasensor were demonstrated, showing ∼30% and ∼33% loss of active state, respectively, after ∼11 days. The detection of NCP was evaluated by comparing anti-NCP aptamer and antibody as the bioprobes. The determination coefficients of R2 = 0.9759 and R2 = 0.9772 were obtained for aptamer- and antibody-based sensing, respectively. Moreover, the genuine interaction of NCP aptamer and protein was validated by enzyme linked apta-sorbent assay. The aptasensing strategy proposed with AuIDE/diamond enhanced sensing platform is highly recommended for early diagnosis of SARS-CoV-2 infection.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , COVID-19 , Doenças Transmissíveis , Nanodiamantes , Técnicas Eletroquímicas , Eletrodos , Ouro , Humanos , Limite de Detecção , Proteínas do Nucleocapsídeo , SARS-CoV-2
13.
Biosens Bioelectron ; 196: 113743, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34740115

RESUMO

Lipoproteins are composed of lipid and apolipoproteins in conjunction with noncovalent bonds. Different lipoprotein categories, particularly Low-Density Lipoprotein (LDL), High-Density Lipoprotein (HDL) and Very Low-Density Lipoprotein (VLDL) disagree in roles for the occurrence and development of cardiovascular disease, and their exact discrimination are critically required. Herein, a multiplexed sensor platform combined with an encoder system is introduced for accurate analysis of multiple lipoproteins in complex matrix. Three encoders, i.e., bare AuNPs, AuNPs-anti-LDL aptamer (AuNPs-apt) and AuNPs-non-aptamer DNA (AuNPs-n), facilitate precise discrimination for lipoprotein subclasses at a fairly low level of 0.490 nM. The binding of single-stranded DNA (ssDNA) with AuNPs prevents them from gathering in a relatively higher level of salt. In targets stimuli, the weaker binding between ssDNA and AuNPs is destroyed to certain degrees depending on the differential affinities among DNA, AuNPs, and multifarious proteins. It results in distinct aggregation states of encoders to cause diverse ultraviolet absorption, which may be statistically characterized to achieve highly facile and precise identification for lipoprotein subclasses. Remarkably, LDL at 0.05-37.5 µg/mL could be identified by the encoder system. 11 typical proteins including three lipoprotein subclasses in human serum were also precisely discriminated. Furthermore, the accurate identification of lipoprotein subclasses with different molar ratios from real clinical serum samples were obtained.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Ouro , Humanos , Lipoproteínas , Lipoproteínas LDL , Lipoproteínas VLDL
14.
Biosens Bioelectron ; 197: 113742, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34740121

RESUMO

A major aspect of this work is the synergistic application of a poly(diphenylbutadiene)-BiOBr composite and a gold nanoparticle-linked CeO2 octahedron to develop a photoelectrochemical aptasensor with an easily measurable detection signal change. Specifically, poly(diphenylbutadiene) nanofiber-immobilised BiOBr flower-like microspheres were developed as a hybrid material with a heterojunction that facilitates high visible light absorption and efficient photo-generated charge separation, which are essential features for sensitive photoelectrochemical sensors. The model analyte acetamiprid was attached via its specific aptamer on the aptasensor. Separately, a gold nanoparticle-linked CeO2 octahedron was strategically used to significantly diminish the photocurrent by impeding electron transfer at the aptasensor surface. After acetamiprid binding, the CeO2 octahedrons were displaced from the aptasensor. This caused a weakened quenching effect and restored the photocurrent to accomplish an "on-off-on" detection mechanism. This photoelectrochemical aptasensor exhibited a detection limit of 0.05 pM over a linear range of 0.1 pM-10 µM acetamiprid. The use of an aptamer has provided good specificity to acetamiprid and anti-interference. In addition, an ∼5.8% relative standard deviation was estimated as the reproducibility of the photoelectrochemical aptasensor. Furthermore, nearly 90% of the initial photocurrent was still measurable after storing these aptasensors at room temperature for 4 weeks, demonstrating their stability.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanopartículas Metálicas , Bismuto , Butadienos , Técnicas Eletroquímicas , Ouro , Limite de Detecção , Reprodutibilidade dos Testes
15.
Colloids Surf B Biointerfaces ; 209(Pt 1): 112184, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34741910

RESUMO

Single-base mutations of Factor V Leiden G1691A and Prothrombin gene G20210A are the main genetic risk factors for inherited thrombotic tendency. The establishment for rapid and efficient detection method is of great significance to the prevention of venous thrombosis. In this work, a multiplexed, highly sensitive and regenerable surface plasmon resonance imaging (SPRi) sensor is described to identify and detect the two pathogenic genes by fixing probes in one-step. The probes are fixed by ployA, which is a simpler, faster and lower cost modification method compared with traditional thiol (-SH). PolyA-DNA-AuNPs is used to amplify the signal to improve sensitivity. The detection limit of the sensor is 8 pM, and it has a wide dynamic range between 8 pM and 100 nM and a good linear relationship between 8 pM to 50 pM. The equilibrium dissociation constant (KD) of 3.0 (± 0.3) pM indicates a high binding capacity. Based on the advantages of high-throughput detection, the SPRi chip can simultaneously identify and detect two genes related to thrombotic Diseases. In addition, more than 90% signal intensity can still be obtained on the surface of the chip after being regenerated of 25 times, indicating that this SPRi sensor has good stability and reproducibility. The established SPRi sensor has the advantages of high-throughput, high-sensitivity, label-free and no need for amplification, which is expected to become an effective technical means for real-time online detection of gene point mutations, and can be extended to detect and quantify a wider range of DNA mutation diseases.


Assuntos
Nanopartículas Metálicas , Ressonância de Plasmônio de Superfície , Ouro , Oligonucleotídeos/genética , Poli A , Reprodutibilidade dos Testes
16.
Biosens Bioelectron ; 197: 113736, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34741957

RESUMO

The reverse transcription-polymerase chain reaction (RT-PCR) method has been adopted worldwide to diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although this method has good sensitivity and specificity, there is a need to develop a more rapid diagnostic technology, given the virus's rapid spread. However, the RT-PCR method takes a long time to diagnose SARS-CoV-2 because of the required thermocycling steps. Therefore, we developed a surface-enhanced Raman scattering (SERS)-PCR detection method using an AuNP-internalized Au nanodimple substrate (AuNDS) to shorten the diagnosis time by reducing the number of thermocycling steps needed to amplify the DNA. For the representative target markers, namely, the envelope protein (E) and RNA-dependent RNA polymerase (RdRp) genes of SARS-CoV-2, 25 RT-PCR thermocycles are required to reach a detectable threshold value, while 15 cycles are needed for magnetic bead-based SERS-PCR when the initial DNA concentration was 1.00× 105 copies/µL. However, only 8 cycles are needed for the AuNDS-based SERS-PCR. The corresponding detectable target DNA concentrations were 3.36 × 1012, 3.28 × 109, and 2.56 × 107 copies/µL, respectively. Therefore, AuNDS-based SERS-PCR is seen as being a new molecular diagnostic platform that can shorten the time required for the thermocycling steps relative to the conventional RT-PCR.


Assuntos
Técnicas Biossensoriais , COVID-19 , Nanopartículas Metálicas , Ouro , Humanos , Reação em Cadeia da Polimerase , RNA Viral , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SARS-CoV-2 , Sensibilidade e Especificidade
17.
Food Chem ; 373(Pt A): 131321, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34742040

RESUMO

Accurate and rapid detection of Aflatoxins as one of the most hazardous compounds in foodstuffs is very important. In this study, a label-free electrochemical aptasensor was developed to identify aflatoxin M1 using a reduced graphene oxide (rGO) and gold nanoparticles (AuNPs)-based pencil graphite electrode (PGE). The morphological characteristics of the electrode surface were investigated using SEM and rGO functional groups were confirmed by FTIR. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used to characterize various stages of electrode modification. In order to optimize the impedimetric response of the aptasensor, aptamer immobilization time, aptamer concentration, and binding aflatoxin M1 with aptamer time were optimized. Under optimal conditions, the linear concentration range of 0.5-800 ng/L and limit of detection (LOD) of 0.3 ng/L were obtained for aflatoxin M1 by measuring the resistance charge transfer data. Finally, the fabricated aptasensor was successfully used to measure AFM1 compared to HPLC method.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Aflatoxina M1/análise , Animais , Técnicas Eletroquímicas , Eletrodos , Ouro , Leite/química
18.
Food Chem ; 373(Pt A): 131443, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34742048

RESUMO

Aflatoxin B1 (AFB1) contamination has raised global concerns in agricultural and food industry; thus, sensitive, accurate and rapid AFB1 sensors are essential in many circumstances. Herein, we developed a label-free and immobilization-free ratiometric homogeneous electrochemical aptasensor based on hybridization chain reaction (HCR) for facile and rapid determination of AFB1. Methylene blue (MB) and ferrocene (Fc) were used as label-free probes to produce a response signal (IMB) and a reference signal (IFc) in solution phase, respectively. The ratio of IMB/IFc was used as a yardstick to quantify AFB1. HCR was exploited to enlarge the intensity of IMB as well as ratiometric signal. By combining label-free homogeneous assay and ratiometric strategy, the resulting aptasensor offered sensitive, rapid, and reliable determinations of AFB1 with a detection limit of 38.8 pg mL-1. The aptasensor was then used to determine AFB1 in cereal samples with comparable reliability as HPLC-MS.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Aflatoxina B1/análise , Grão Comestível/química , Técnicas Eletroquímicas , Ouro , Limite de Detecção , Reprodutibilidade dos Testes
19.
Biosens Bioelectron ; 197: 113766, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34753095

RESUMO

Herein, gold nanoparticles (Au NPs) were synthesized by pulsed laser ablation (PLA) in a mixed-phase solvent of acetonitrile and water. The size of Au NPs and the number of graphitic carbon (GC) layers were controlled by varying the ratio of the solvent mixture. The surface-enhanced Raman scattering (SERS) of the Au NPs was investigated using 10-3 M 4-aminobenzenethiol and 10-4 M 4-nitrobenzenethiol as probe molecules. The SERS activity strongly depended on the nanogaps between particles owing to the formation of hot spots. In the present work, the nanogaps were controlled by changing the amount of GC layers. No GC layers were produced in water, resulting low SERS intensity. In contrast, Au NPs prepared in 30 vol% of acetonitrile showed significant SERS enhancement, which was attributed to the optimal size of the GC-coated NPs and a reasonable gap between them. The obtained results revealed that Au NPs produced by PLA in liquid could be applied in SERS-based microsensors.


Assuntos
Técnicas Biossensoriais , Terapia a Laser , Nanopartículas Metálicas , Ouro , Análise Espectral Raman
20.
Biosens Bioelectron ; 197: 113772, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34768067

RESUMO

An outstanding dual-labeling ratiometric electrochemical biosensor based on isothermal strand displacement polymerization reaction (ISDPR) for highly sensitive and selective detection of mecA gene has been proposed. Concretely, in the presence of mecA gene, the addition of methylene blue (MB)-labeled primer and polymerase induced recycling amplification to change the structure of the ferrocene (Fc)-labeled hairpin probe, thereby releasing abundant target gene to realize the signal amplification and dual-signal output. Through this process, the electrochemical responses of Fc (IFc) and MB (IMB) were both substantially reduced and increased proportionally, ensuring that the value of IMB/IFc can accurately reflect the true detection level of mecA gene. Benefiting from the "signal-on/off" strategy, the fabricated biosensor exhibited outstanding sequence specificity to discriminate mismatched mecA gene, which verified to be 2.72 times that of single-label detection for perfect match/single base mismatch (PM/MM) discrimination ratio. This strategy effectively integrated the advantages of signal amplification and ratiometric modes, making the biosensor exhibit a broad working range with 10 fM - 3000 pM and a limit of detection (LOD) with 3.33 fM (S/N = 3). Moreover, the proposed biosensor has good feasibility for mecA gene determination in water samples due to acceptable recoveries (95-115%) and repeatability relative standard deviations (RSD) value of 4%. This will provide a powerful sensing platform for improving accuracy and decreasing background signal of sensor for ARGs screening in environmental monitoring.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Ouro , Limite de Detecção , Polimerização
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