Accordingly, the corresponding LOD values , dynamic detection range, and Hook effect point are summarized in Table 1. The results indicated that the AuNP120-LFIA strip exhibited the lowest LOD value of 0.97 mIU/mL, which was ca. 20.1-, 4.02-, and 2.01-fold lower than those of AuNP40 (19.5 mIU/mL), AuNP80 (3.9 mIU/mL), and AuNP180 (1.95 mIU/mL), respectively. The linear detection of AuNP120-LFIA strip ranged from 1.9 mIU/mL to 1000 mIU/mL. Thus, we conclude that the LFIA sensitivity increased when AuNP size was increased from 40 nm to 120 nm. However, when AuNP size was further increased to 180 nm, the sensitivity decreased despite the increased optical signal. We speculate that this result may be due to the significantly enhanced Qsca rather than Qabs for increased Qext of AuNP180, conflicting with absorption-dominated signal output of AuNP-LFIA.
The optimal LFIA labels should meet several quality criteria, including ease of preparation, high optical response, and the saving of antibodies’ affinity during conjugation . Most of the existing colorimetric immunochromatographic systems are based on the use of gold nanoparticles . Dyed polystyrene particles and cellulose beads can be used for increasing visible signatures on strips.
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As a result, such AuNP tonality is not conducive to confident naked-eye detection. Plasmonic coupling is associated with interparticle gaps between AuNPs within the assemblies, and with increasing the interparticle distance, the plasmonic coupling weakens or disappears. Consequently, AuNP assemblies display similar LSPR absorption and color but stronger absorbance relative to the isolated AuNPs, thereby enabling increased sensitivity. Byzova N.A., Zherdev A.V., Pridvorova S.M., Dzantiev B.B. Development of rapid immunochromatographic assay for D-dimer detection.
Both RSA were obtained with high purity , and were applied as antigenic tools in different ELISA assays to assess whether specific anti-P. jirovecii antibodies can be detected in human sera at the time of patient’s presentation with symptomatology compatible with PcP. Thus, 76 serum specimens collected at the time of patient’s BAL procedure for PcP routine diagnosis were analyzed by these optimized indirect ELISA with both RSA, for detection of IgG and IgM anti-P. IgG ELISA results showed that, even though IgG response is detected with both RSA, it is not possible to distinguish patients with PcP from patients without P. jirovecii infection by their IgG levels . The software used for color intensity analysis was unable to detect color on the test lines of the strips with negative samples, and detect similar color intensity for the control and test lines on the strips with positive samples . After optimization, LFIA strips were tested with sera pools from patients with and without PcP, in triplicate experiments .
Thus, J. Dong et al. described a technique that decreased the RSD of the GNPs diameter to 8–10% with an aspect ratio of 1.10–1.22 . Kimimg et al. modified the Turkevich–Frens method, providing an RSD of the GNP diameter from 13% to 16% for a preparation range of up to 40 nm. Shiba described a finely dispersed preparation with an RSD of 7.6%, but this was only the case where the diameter was equal to 14 nm. et al. reached the gain in homogeneity with a decrease in RSD from 8% to 3%, but only for small GNPs with a diameter of 12 nm. Xia et al. described an improved synthesis of citrate GNPs (C-GNPs) in the 12–36 nm range characterized by an RSD of 9% or higher.
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From bottom to top, strips were composed by the sample pad, the conjugate pad, the nitrocellulose membrane with the test and control lines and the absorbent pad. Quantification of color intensity of the control and test lines present in all replicates, where the intensity shown in each line corresponds to the maximum height of the Gaussian line fitted by eReuss software and the error bars represent the standard deviation values.
However, these methods Conjugate Pad Strip Cutter typically suffer from long analysis times and complex procedures, which hinder their applications . The use of gold nanoparticles as labeling carriers in combination with the enzymatic activity of the Horseradish Peroxidase in order to achieve an improved optical lateral flow immunoassay performance is here presented. Due to their specific optimal properties, nanoparticles have been used as a tracer for LFA development. They possess specific nanostructures which are responsible for the production of optical signal i.e. fluorescence or color changes by assemblies and aggregations. Materials such as colloidal gold, silver, and carbon nanoparticles, carbon nanotubes have been applied in the development of LFAs for various analysis. Anteo Technologies currently has a kit available with Magnetic nanoparticles pre-activated with Mix&Go for use in lateral flow assays, with a forthcoming pre-activated gold nanoparticle kit due out in 2016.
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Even though the minimal protective amount was determined to be 10 μg, 2.5 times MPA of anti goat IgG, used for effective conjugation with gold nanoparticles. Contagious agalactia is a notifiable disease listed by World Organisation for Animal Health (WOAH/OIE) and has been responsible for causing severe economic losses to goat and sheep industries. The disease has been reported from India (Vihan, 1989; Srivastava et al., 1996; Mondal et al., 2004; Kumaret al., 2009, 2014) but the prevalence of disease is overlooked due to lack of a rapid field diagnostic test. The isolation and biochemical identification of the organism is more tedious and time consuming (Aluotto et al., 1970; Poveda, 1998).
The composition of the various pads has a dramatic effect on the performance of the strip assay. Among the various alternatives, NC membrane was found to be the most suitable solid support for the adsorption and hybridization of nucleic acids. NC has been widely used as a signal pad in lateral flow strip since it provides sufficient flow rates .
Lateral-flow assay nitrocellulose membranes , sample pads and absorbent materials were all purchased from GE Healthcare . Anti-M13 antibodies (NB ) were purchased from Novus Biologicals and HRP/anti-M13 monoclonal conjugate ( ) were purchased from GE Healthcare Life Sciences . Streptavidin-HRP , 3350 g/mol polyethylene glycol , Triton X-100 , Tween 20 and bovine serum albumin, BSA, were purchased from Sigma Aldrich (St. Louis, MO). PVC backing cards (MIBA-020) and gold nanoparticles (40 nm, OD 1, 1011/mL, CG-020) were purchased from DCN Diagnostics .
- For HCG qualitative assay, the visual LOD , defined as the lowest HCG concentrations for generating a visible red band at the T line, was evaluated .
- Our previous data suggest that a reading at 24 h may also be informative .
- Therefore, the aim of the present study was to develop a novel gold nanoparticle based lateral flow assay platform for rapid diagnosis of contagious agalactia in goats.
- Visible precipitates occurred for the average diameter of C-GNPs, which was equal to 47.5 after one to two months of storage .
- They are designed for disposable single use and for applications where an on/off signal is sufficient .
- Correlation analysis of the detection results between the GSP270-LFIA strip and the clinically well-accepted CLIA kits in 45 human serum samples with HBsAg concentrations of 0.46 ng/mL to 256 ng/mL.
Two tested S-GNP preparations with large diameters (i.e., 90.4 and 115.3 nm) demonstrated shifts in DLS spectra after two months of storage . Due to this, the advantages of S-GNPs can be successfully transformed to lower LODs only in a range of up to 64.5 nm, as stated above. Reagents were applied to membranes comprising the assay system with an IsoFlow automatic dispenser (Imagene Technology; Lebanon, NH, USA).
Two different IgG and IgM ELISA were developed, according to the protocols presented in Table 1, using Kex1 RSA and Msg RSA as coating antigens. jirovecii levels across patients with PcP and without P. jirovecii infection are represented in Figure 3. For synthesis and functionalization of gold nanospheres, all glassware was washed with aqua regia and rinsed thoroughly with deionized water followed by ultrapure water (18.2 MΩ⋅cm–1) before use. The fungus Pneumocystis jirovecii is a pathogen able to cause a fatal pneumonia in immunocompromised patients worldwide (Barry and Johnson, 2001; Huang et al., 2011; Esteves et al., 2014; Matos et al., 2017). Likewise, the rising number of immunocompromised non-HIV-infected patients susceptible to P. jirovecii infection in these countries, warrants the need for improved diagnostic and treatment strategies (Hughes, 2005; Roux et al., 2014). This is an open-access article distributed under the terms of the Creative Commons Attribution License . The use, distribution or reproduction in other forums is permitted, provided the original author and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.
In this regard, an assessment of the possibilities of applying the novel S-GNPs in LFIA, which do not require the complications of the testing methodology, is of great importance. Nanogold based lateral flow assay for the detection of Salmonella typhi in environmental water samples. Gold magnetic nanoparticle conjugate-based lateral flow assay for the detection of IgM class antibodies related to TORCH infections.
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• Although LF assays also use Sandwich and competitive formats they are different from EIAs. The former format is an “open” system while the latter is a “closed” system.