Respiratory viral infectious usually exhibit similar clinical symptoms, making a great challenge for their accurate diagnostic in early stages. Herein, we developed a dual-mode and multiplex lateral flow immunoassay (LFIA), in which near-infrared (NIR)-responsive Janus Au-FeO nanoparticles (NPs) were synthesized as new reporters for highly sensitive colorimetric/photothermal detection of H3N2 influenza and SARS-CoV-2 viruses in a single assay. The Janus Au-FeO well combined the NIR responsiveness and high molar absorption coefficient of Au and magnetic properties of FeO.
View Article and Find Full Text PDFWith SARS-CoV-2 N protein as a model target, a signal-enhanced LFIA based on Au@Pt nanoparticles (NPs) as labels is proposed. This Au@Pt NPs combined the distinguished localized surface plasma resonance (LSPR) effect of Au NPs and the ultrahigh peroxidase-like catalytic activity of Pt NPs. Au@Pt NPs could trigger substrate chromogenic reaction, generating a color signal orders of magnitude darker than their intrinsic color.
View Article and Find Full Text PDFSensitive, convenient and rapid detection and subtyping of influenza viruses are crucial for timely treatment and management of infected people. Compared with antigen detection, nucleic acid detection has higher specificity and can shorten the detection window. Hence, in this work, we improved the lateral flow assay (LFA, one of the most promising user-friendly and on-site methods) to achieve detection and subtyping of H1N1, H3N2 and H9N2 influenza virus nucleic acids.
View Article and Find Full Text PDFLateral flow immunoassay (LFIA) has played a vital role in point-of-care (POC) testing on account of its simplicity, rapidity, and low cost. However, the low sensitivity and difficulty of quantitation limit its further development. Sensitive markers with new detection modes are being developed to dramatically improve LFIA's performance.
View Article and Find Full Text PDFTraditional lateral flow immunoassays (LFIA) suffer from insufficient sensitivity, difficulty for quantitation, and susceptibility to complex substrates, limiting their practical application. Herein, we developed a polyethylenimine (PEI)-mediated approach for assembling high-density Au nanoshells onto FeO nanoclusters (MagAu) as LFIA labels for integrated enrichment and photothermal/colorimetric dual-mode detection of SARS-CoV-2 nucleocapsid protein (N protein). PEI layer served not only as "binders" to FeO nanoclusters and Au nanoshells, but also "barriers" to ambient environment.
View Article and Find Full Text PDFRapid screening of multiple pathogens will greatly improve the efficiency of pandemic prevention and control. Colorimetric methods exhibit the advantages of convenience, portability, low cost, time efficiency, and free of sophisticated instruments, yet usually have difficulties in simultaneous detection and suffer from monotonous color changes with low visual resolution and sensitivity. Hence, coupled three kinds of plasmonic nanoparticles (NPs) with magnetic separation, we developed an achromatic colorimetric nanosensor with highly enhanced visual resolution for simultaneous detection of SARS-CoV-2, Staphylococcus aureus, and Salmonella typhimurium.
View Article and Find Full Text PDFAu-FeO multifunctional nanoparticles (NPs) were synthesized and integrated with lateral flow immunoassay (LFIA) for dual-mode detection of Salmonella typhimurium. The Au-FeO NPs not only combined excellent local surface plasmon resonance characteristics and superparamagnetic properties, but also exhibited good photothermal effect. In the detection, antibody-conjugated Au-FeO NPs first captured S.
View Article and Find Full Text PDFImmunoglobulin detection is essential for diagnosing progression of SARS-CoV-2 infection, for which SARS-CoV-2 IgG is one of the most important indexes. In this paper, Ag nanoparticles with ultrathin Au shells (∼2 nm) embedded with 4-mercaptobenzoic acid (MBA) (Ag@Au) were manufactured via a ligand-assisted epitaxial growth method and integrated into lateral flow immunoassay (LFIA) for colorimetric and SERS dual-mode detection of SARS-CoV-2 IgG. Ag@Au possessed not only the surface chemistry advantages of Au but also the superior optical characteristics of Ag.
View Article and Find Full Text PDFIn this work, we developed an ultrasensitive colorimetry for Salmonella typhimurium detection with multifunctional Au-FeO dumbbell-like nanoparticles (DBNPs) which possessed easy bio-modifiability, excellent LSPR characteristics, superparamagnetic properties and super peroxidase-like activity. In the detection, the anti-S. typhimurium antibody modified DBNPs (IDBNPs) bound with S.
View Article and Find Full Text PDFMagnetic relaxation switching (MRS) sensors have shown great potential in food safety monitoring due to their high signal-to-noise ratio and simplicity, but they often suffer from insufficient sensitivity and stability due to the lack of excellent magnetic nanoprobes. Herein, dumbbell-like Au-Fe O nanoparticles are designed as magnetic nanoprobes for developing an aflatoxin B1-MRS immunosensor. The Fe O portion in the Au-Fe O nanoparticles functions as the magnetic probe to provide transverse relaxation signals, while the Au segments serve as a bridge to grow Ag shell and assemble the Au-Fe O nanoparticles, thus modulating transverse relaxation time of surrounding water molecular.
View Article and Find Full Text PDFJ Food Drug Anal
December 2020
Microbial toxins generated by bacteria, fungi and algae cause serious food-safety problems due to the frequent contamination of foodstuffs and their poisonous nature. Becoming acquainted with the contamination condition of foodstuffs is highly dependent on developing sensitive, specific, and accurate methods for targeting microbial toxins. Aptamers, obtained from systematic evolution of ligands by exponential enrichment (SELEX), have significant advantages for microbial toxin analysis, such as small size, reproducible chemical synthesis, and modification, as well as high binding affinity, specificity, and stability.
View Article and Find Full Text PDFPlasmonic nanostructures have been broadly used for chemical detections, but their applications are limited by slow detection rates, insufficient visual resolution and sensitivity due to the chemical and structural stability of conventional plasmonic nanomaterials. It is thus essential to develop strategies to enhance the detection kinetics while promoting their excellent plasmonic properties. In this work, a colorimetric assay for HCHO measurement is developed based on the fact that HCHO can react with Tollens' reagent to anisotropically deposit a layer of silver shells onto the bone-shaped gold nanorod (Au NR) cores.
View Article and Find Full Text PDFNucleic acid isolation and purification are essential steps in molecular biology. Currently-used isolation methods focus on the extraction of all the nucleic acids from crude samples, yet ignore the specific nucleic acids of interest, which may induce the loss of the specific nucleic acids and hinder their analyses. Herein, a magnetic nanospheres (MNs)-based strategy for efficient capture and release of specific nucleic acids is developed.
View Article and Find Full Text PDFThree-dimensional (3-D) graphene was synthesized by the assembly of graphene oxide with phenolic resin, followed by carbonization in argon. The as-synthesized 3-D graphene has excellent conductivity, good thermal stability, large specific surface area (1511 m² g) and pore volume (0.90 cm g).
View Article and Find Full Text PDFA one-step sandwich method is described for detecting proteins with magnetic nanospheres (MNs) and fluorescent nanospheres (FNs). Thrombin is selected as a model analyte to validate the method. Two DNA aptamers (Apt 29 and Apt 15 targeting two different exosites of thrombin) are chosen as recognition elements to modify MNs and FNs.
View Article and Find Full Text PDFInfluenza viruses have threatened animals and public health systems continuously. Moreover, there are many subtypes of influenza viruses, which have brought great difficulties to the classification of influenza viruses during any influenza outbreak. So it is crucial to develop a rapid and accurate method for detecting and subtyping influenza viruses.
View Article and Find Full Text PDFDetecting viable circulating tumor cells (CTCs) without disruption to their functions for in vitro culture and functional study could unravel the biology of metastasis and promote the development of personalized anti-tumor therapies. However, existing CTC detection approaches commonly include CTC isolation and subsequent destructive identification, which damages CTC viability and functions and generates substantial CTC loss. To address the challenge of efficiently detecting viable CTCs for functional study, we develop a nanosphere-based cell-friendly one-step strategy.
View Article and Find Full Text PDFEnrichment and purification of bacteria from complex matrices are crucial for their detection and investigation, in which magnetic separation techniques have recently show great application advantages. However, currently used magnetic particles all have their own limitations: Magnetic microparticles exhibit poor binding capacity with targets, while magnetic nanoparticles suffer slow magnetic response and high loss rate during treatment process. Herein, we used a highly controllable layer-by-layer assembly method to fabricate quick-response magnetic nanospheres (MNs), and with Salmonella typhimurium as a model, we successfully achieve their rapid and efficient enrichment.
View Article and Find Full Text PDFNumber concentration of nanoparticles is a critical and challenging parameter to be identified. Recently, gravimetric strategy is a fundamental method for absolute quantification, which is widely accepted and used by researchers, yet limited by the inaccuracy in measuring related parameters (e.g, density).
View Article and Find Full Text PDFSensitive and quantitative detection of protein biomarkers with a point-of-care (POC) assay is significant for early diagnosis, treatment, and prognosis of diseases. In this paper, a quantitative lateral flow assay with high sensitivity for protein biomarkers was established by utilizing fluorescent nanospheres (FNs) as reporters. Each fluorescent nanosphere (FN) contains 332 ± 8 CdSe/ZnS quantum dots (QDs), leading to its superstrong luminescence, 380-fold higher than that of one QD.
View Article and Find Full Text PDFThe detection of circulating tumor cells (CTCs), a kind of "liquid biopsy", represents a potential alternative to noninvasive detection, characterization and monitoring of carcinoma. Many previous studies have shown that the number of CTCs has a significant relationship with the stage of cancer. However, CTC enrichment and detection remain notoriously difficult because they are extremely rare in the bloodstream.
View Article and Find Full Text PDFThe study of cancer is of great significance to human survival and development, due to the fact that cancer has become one of the greatest threats to human health. In recent years, the rapid progress of nanoscience and nanotechnology has brought new and bright opportunities to this field. In particular, the applications of quantum dots (QDs) and magnetic nanoparticles (MNPs) have greatly promoted early diagnosis and effective therapy of cancer.
View Article and Find Full Text PDFAu@Ag core-shell nanoparticles (NPs) were synthesized and coupled with copper ion (Cu(2+)) for the colorimetric sensing of iodide ion (I(-)). This assay relies on the fact that the absorption spectra and the color of metallic core-shell NPs are sensitive to their chemical ingredient and dimensional core-to-shell ratio. When I(-) was added to the Au@Ag core-shell NPs-Cu(2+) system/solution, Cu(2+) can oxidize I(-) into iodine (I2), which can further oxidize silver shells to form silver iodide (AgI).
View Article and Find Full Text PDFAvian influenza A(H7N9) virus, which emerged in China in the spring of 2013, has infected hundreds of people and resulted in many deaths. Herein, a rapid and quantitative assay is proposed for the one-step detection of H7N9 virions. Immunomagnetic nanospheres (IMNs) and antibody-conjugated quantum dots (Ab-QDs) are simultaneously employed to capture and identify the target virus, leading to a high efficiency, good specificity, and strong anti-interference ability.
View Article and Find Full Text PDFBead-based assay is widely used in many bioanalytical applications involving the attachment of proteins and other biomolecules to the surface. For further understanding of the formation of a sphere-biomolecule complex and easily optimizing the use of spheres in targeted biological applications, it is necessary to know the kinetics of the binding reaction at sphere/solution interface. In our presented work, a simple fluorescence analysis method was employed to measure the kinetics for the binding of biotin to sphere surface-bound FITC-SA, based on the fact that the fluorescence intensity of FITC was proportionally enhanced by increasing the binding amount of biotin.
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