Red Silica Nanoparticles Research Articles

High-sensitivity detection of two H7 subtypes of avian influenza viruses (AIVs) by immunochromatographic assay with highly chromatic red silica nanoparticles.

In this work, a sensitive and quantitative immunochromatographic assay (ICA) detection method for avian influenza viruses (AIVs) of the H7 hemagglutinin (HA) antigen was established based on highly chromatic red silica nanoparticles (SiNPs). It can detect two H7 subtypes of influenza viruses, H7N2 and H7N9. The highly chromatic red SiNPs were prepared by adsorbing C.I. Direct Red 224 on the surface of the SiNPs for multiple times using the layer by layer (LbL) self-assembly method under the electrostatic action of ethylene imine polymer (PEI) and poly(sodium-p-styrenesulfonate) (PSS). The highly chromatic red silica nanoparticles modified with anti-H7 HA mAb1 were used as immunodetection probes. The accumulated highly chromatic red SiNPs on the T-line can be observed by the naked eye to qualitatively detect the H7 HA antigen. The quantitative analysis is carried out by using a camera and Image J software. Within the range of 0.1-10 ng mL-1, the linear equation between the H7 HA antigen concentration and the peak area of the T-line gray value was y = 868.9722 + 435.4836X (R2 = 0.9716), and the limit of detection (LOD) of this method was 0.08 pg mL-1 (S/N = 3). The highly chromatic red SiNP based ICA for the detection of H7 HA has no cross activity with other subtypes of influenza viruses. This method of combining highly chromatic colored markers with ICA has great potential in practical applications for the rapid and quantitative detection of other types of AIVs.

Determination of trace aflatoxin M1 (AFM1) residue in milk by an immunochromatographic assay based on (PEI/PSS)4 red silica nanoparticles.

Aflatoxin M1 (AFM1) residues in milk pose a major threat to human health, so there is an urgent need for a simple, rapid, and sensitive method for the determination of trace AFM1 in milk. In this study, a competitive immunochromatographic assay (ICA), using visual (PEI/PSS)4 red silica nanoparticles (SiNPs) as signal amplification probes, was used for the highly sensitive detection of AFM1. The (PEI/PSS)4 red SiNPs were used to label AFM1 monoclonal antibody (mAb) to prepare ICA for the detection of AFM1. After exploring the optimal conditions of mAb and immunoprobe dosage conditions, the lowest visual detection limit (VDL) of AFM1 in phosphate-buffered saline with Tween 20 (PBST, 10mM, pH7.4, containing 1% BSA, 3% sucrose, 1% trehalose, and 0.5% Tween 20) can reach 0.1pg/mL. The intuitive visually visible value of AFM1 in both PBST and milk was 10pg/mL. The results showed that the immunochromatographic system based on high chroma color (PEI/PSS)4 red SiNPs has high sensitivity and broad application prospects for the detection of trace AFM1 residues in milk. The high chroma (PEI/PSS)4 red SiNPs are expected to be a convenient biomarker for improving the sensitivity of immune chromatography bands. Graphical abstract The schematic diagram shows the detection principle. In this work, in the competitive experiment, (PEI/PSS)4 red SiNPs were selected as visual labeling materials, and the specific antibody combined with the labeled material was selected as an immune probe. The AFM1-BSA antigen coupled with the macromolecular BSA was fixed on the T line of the nitrocellulose (NC) membrane. The AFM1 in sample solution competes with AFM1-BSA for the specific binding site of immune probe. The detection sensitivity of this method for AFM1 is obtained by judging the change of the red signal intensity produced by the positive sample, compared with the color at the T line of the negative sample.

Preparing high chroma colored silica nanoparticles based on layer-by-layer self-assembled technique

In this paper, monodisperse high chroma colored silica nanoparticles (SiNPs) were efficiently prepared by layer-by-layer (LbL) self-assembled technique. Poly(sodium-p-styrenesulfonate) (PSS) and Poly(ethyleneterephthalate) (PEI) were respectively used as polyanion and polycationic electrolytes. The monodisperse SiNPs with negative charge on the surface were used as the matrix. Direct dye (C.I Direct Red 224) was deposited on the SiNPs surface by means of LbL electrostatic adsorption. PEI and C.I. Direct Red 224 were electrostatically adsorbed on the surface of SiNPs. Then PSS and PEI were adsorbed on SiNPs surface to make the red SiNPs positive negative, respectively. And multilayer film-coated high chroma red SiNPs were prepared by repeating the above steps 4 times. The effects of concentration of polyelectrolyte, supporting salt (NaCl), amount of C.I Direct Red 224 and deposition time on dye coupling rate were studied. The multilayer film-coated high chroma red SiNPs were characterized using Scanning Electron Microscopy (SEM), Nano ZS potential laser particle analyzer and UV–vis spectrophotometer. The nanoparticles show good dispersibility due to the mutual repulsion of the same charge, and deep color. In addition, dense nano-film formed prevents the detachment of the dye and prevent the dye from falling off. This high chroma red SiNPs is expected to become a probe of visual marker and amplify the signal in immunoassay.

A silica nanoparticle based 2-color immunochromatographic assay for simultaneous determination of clenbuterol and ractopamine

An immunochromatographic assay (ICA) is presented that can be applied to simultaneous detection of clenbuterol (CLE) and ractopamine (RAC). It is making use of two red and blue silica nanoparticles (SiNPs) that act as labels for encoding the antibodies. This design permits multiplexed analysis in a single test line and does not require an external source for photoexcitation. Anti-CLE was labeled with red SiNPs, and anti-RAC with blue SiNPs. The capture antigens CLE-BSA and RAC-BSA were placed onto the conjugate pad and the test line of the test strip, respectively. Under bare eye examination, no cross-colored lines or nonspecific bioconjugate adsorption were observed, and the visible limit of detections for CLE (red) and RAC (blue) are 3 and 2ng‧mL-1, respectively. This design allows for multiplexed detection with reduced device dimensions and costs, and with easy integration and manufacturing. Conceivably, the method may be extended to simultaneous determination of numerous other analytes. Graphic abstract The principle of qualitative detection strategy of multiplex immunochromatographic assay for clenbuterol (CLE) and ractopamine (RAC) is schematically illustrated. Depending on the type and ratio of organic dyes, the color of colored silica nanoparticle can be tuned from red to purple and even to black (lower right corner).

A sensitive and quantitative immunochromatographic assay for HBsAg based on novel red silica nanoparticles

An immunochromatographic assay (ICA) based on red silica nanoparticles (red-SiNPs) was developed for quantitative detection of hepatitis B surface antigen (HBsAg) in serum.

Core-shell red silica nanoparticles based immunochromatographic assay for detection of Escherichia coli O157:H7

In this paper, a new type immunochromatographic assay (ICA) based on core-shell red silica nanoparticles (core-shell red SiO2NPs) was proposed and used to detect Escherichia coli O157:H7 (E. coli O157:H7). This is the first report of qualitative ICA for detecting E. coli O157:H7 in phosphate buffer saline (PBS) and food sample using core-shell red SiO2NPs. Monodispersed red SiO2NPs were synthesized in the aqueous solution by modifying amino silane and C.I Reactive Red 136 on unmodified silica nanoparticles. The limit of detection (LOD) of this core-shell red SiO2NPs based ICA for E. coli O157:H7 was 4.5 × 105 CFU/mL in sterile PBS within 20 min. The LOD of this ICA strip for E. coli O157:H7 in milk and pork samples both were 4.5 × 106 CFU/mL. The core-shell red SiO2NPs based ICA for detection of E. coli O157:H7 has no cross activity with other bacteria. All these results show that this new kind of core-shell colored SiO2NPs is promising for the practical applications in ICA and other rapid detection fields.