Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new fluorescence immunoassay strategy based on a target-induced displacement reaction with cargo release from protein-gated carbohydrate-functionalized magnetic mesoporous silica nanoparticles (MMSN) was developed for sensitive detection of small molecular mycotoxins (aflatoxin B1, AFB1 used in this case). To construct such an assay system, MMSN was initially functionalized with mannose-terminated silanes, then capped with biotinylated concanavalin A (Con A) entrapped rhodamine B (RB) within the pores through the carbohydrate-protein interaction, and then biotinylated monoclonal anti-AFB1 capture antibody was conjugated to Con A-functionalized MMSN by the streptavidin-biotin chemistry. Gold nanoparticles (AuNP) heavily functionalized with invertase and bovine serum albumin-AFB1 conjugate were utilized as the trace tag. With AFB1 introduction, a competitive immunoreaction for the immobilized anti-AFB1 antibody on the MMSN was started between target analyte and the labeled AFB1 on the AuNP. Accompanied by AuNP, the carried invertase hydrolyzed sucrose in glucose and fructose. The generated glucose competed with the mannose for Con A and displaced the Con A-antibody complex from the MMSN, resulting in the opening of molecular gates owing to the uncapping of MMSN, thereby the entrapped RB could release from the pores. The released RB could be quantitatively determined by a fluorometer. Under optimal conditions, the fluorescence intensity decreased with the increasing AFB1 concentration in the range from 0.01 to 5 ng mL(-1) with a detection limit (LOD) of 8 pg mL(-1) at the 3sblank criterion. Intra- and interbatch assay precisions were lower than 9 and 9.5% (CV), respectively. The method featured unbiased identification of negative (blank) and positive samples. No significant differences at the 0.05 significance level were encountered in the analysis of naturally contaminated peanut samples between the fluorescence immunoassay and a commercialized enzyme-linked immunosorbent assay (ELISA) method.
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PMID:Target-induced displacement reaction accompanying cargo release from magnetic mesoporous silica nanocontainers for fluorescence immunoassay. 2407 Feb 67

A novel (invertase) enzymatic hydrolysate-triggered displacement reaction strategy with multifunctional silica beads, doped with horseradish peroxidase-thionine (HRP-Thi) conjugate, was developed for competitive-type electrochemical immunoassay of small molecular aflatoxin B1 (AFB1). The competitive-type displacement reaction was carried out on the basis of the affinity difference between enzymatic hydrolysate (glucose) and its analogue (dextran) for concanavalin A (Con A) binding sites. Initially, thionine-HRP conjugates were doped into nanometer-sized silica beads using the reverse micelle method. Then monoclonal anti-AFB1 antibody and Con A were covalently conjugated to the silica beads. The immunosensor was prepared by means of immobilizing the multifunctional silica beads on a dextran-modified sensing interface via the dextran-Con A binding reaction. Gold nanoparticles functionalized with AFB1-bovine serum albumin conjugate (AFB1-BSA) and invertase were utilized as the trace tag. Upon target AFB1 introduction, a competitive-type immunoreaction was implemented between the analyte and the labeled AFB1-BSA on the nanogold particles for the immobilized anti-AFB1 antibody on the electrode. The invertase followed by gold nanoparticles hydrolyzed sucrose into glucose and fructose. The produced glucose displaced the multifunctional silica beads from the electrode based on the classical dextran-Con A-glucose system, thus decreasing the catalytic efficiency of the immobilized HRP on the electrode relative to that of the H2O2-thionine system. Under optimal conditions, the detectable electrochemical signal increased with the increasing target AFB1 in a dynamic working range from 3.0 pg mL(-1) to 20 ng mL(-1) with a detection limit of 2.7 pg mL(-1). The strong bioconjugation with two nanostructures also resulted in a good repeatability and interassay precision down to 9.3%. Finally, the methodology was further validated for analysis of naturally contaminated or spiked AFB1 peanut samples, giving results matched well with those from a commercialized AFB1 enzyme-linked immunosorbent assay kit. Importantly, the system provides a signal-on competitive-type immunosensing platform for ultrasensitive detection of small molecules.
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PMID:Enzymatic hydrolysate-induced displacement reaction with multifunctional silica beads doped with horseradish peroxidase-thionine conjugate for ultrasensitive electrochemical immunoassay. 2618 87

Recently, there is an increase in interest to develop user-friendly monitoring devices in healthcare, environmental, and agrofood fields for a fast detection of contaminants. Aflatoxins (AFs) are a group of toxic substances produced by the fungi of species Aspergillus that contaminate cereals and dried fruits. When dairy cows ingest feed contaminated with aflatoxin B1 (AFB1), it is metabolized and transformed in the liver into a carcinogenic form aflatoxin M1 (AFM1), which is eliminated through the milk. In this work, we developed a sensor assay to detect low amounts of AFM1 directly in whole milk. For this purpose, we produced monospecific polyclonal antibody (IgGMS-M1) that was able to bind with high avidity to AFM1. Then, we conjugated the antibody to the invertase enzyme from Saccharomyces cerevisiae. This enzyme is able to convert sucrose into fructose and glucose. After incubation of invertase-conjugated anti-AFM1 antibody with milk containing AFM1, we measured the produced glucose by a glucometer. The produced glucose was then correlated to the amount of AFM1 present in the milk. The obtained results show that the assay is easily customizable as a portable instrument for on-site AFM1 measurements. In addition, the results point out that the assay is very sensitive since it can detect the presence of 27 parts per trillion (ppt) of AFM1 in whole milk, a value lower than the AFM1 quantities in milk and dairy products set by the European Commission (50 ppt).
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PMID:Sweet Sensor for the Detection of Aflatoxin M1 in Whole Milk. 3146 Apr 4