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Aqueous buffer-based assays

As mentioned above, most studies published thus far have dealt with organic solvent-based samples or used liquid-liquid extraction prior to analysis. To become a true alternative to conventional immunoassay techniques which use antibodies. [Pg.346]

Application of molecularly imprinted polymers in competitive ligand binding [Pg.348]

In most studies, the selectivities of the MIPs have been estimated by measuring the amount of each ligand required to displace 50% of the binding of radiolabelled imprint species to the MIP (IC50). The first MIA study reported excellent selectivity of the theophylline method for theophylline (1,3-dimethylxanthine) in the presence of the structurally related compound caffeine (1,3,7-trimethylxanthine) [3]. Despite their close resemblance (they differ by only one methyl group), caffeine showed less than 1 % cross-reactivity. A similar level of specificity was recorded for cortisol and corticosterone MIPs, which were able to detect the absence and presence of single hydroxyl groups and double bonds in the steroid structure [13]. [Pg.348]

An interesting point is the differing selectivities obtained for the organic solvent and aqueous buffer-based assays. This was first demonstrated for (5)-propranolol [Pg.348]

Structure of propranolol. The chiral carbon is indicated by the arrow and the hydrophobic naphthyl group is encircled. [Pg.349]


As described above, the dendrimer-coupled antibody conjugates show uniquely enhanced properties compared to the classical double antibody systems. Important characteristics such as complete solubility in aqueous buffers, flexibility in immunoassay format, ability to improve assay sensitivity, consistent, reproducible manufacturing and favorable stability has driven the utilization of these dendrimer-based reagents in Stratus CS, the latest member of the Stratus family of immunochemistry analyzers. In this new analyzer system, the primary... [Pg.476]

The recent identification of selective protease substrates to simultaneously measure markers of both viable and dead cells led to the development of optional methods for HTS that provide flexibility and added advantages (Niles et al. 2007a). The assay to measure viable cells is based on a cell-permeable protease substrate called glycyl-phenylalanyl-aminofluorocoumarin (GF-AFC). The procedure is a homogeneous add-incubate-measure method that is faster, more sensitive, and less toxic to cells than the tetrazolium and resazurin reduction assays. The substrate can be prepared in an aqueous buffer and is added directly to samples containing cells. The substrate permeates viable cells where constitutive protease activity in the cytoplasm rapidly removes the amino acids, yielding free AFC. The amount of AFC released is directly proportional to viable cell numbers and shows improved sensitivity compared to the resazurin assay (Figure 6.5). The AFC is detected via a microplate fluo-rometer equipped with a (380- to 400-nm excitation/505-nm emission) filter set. [Pg.111]

Permits assay development based on both organic solvent and aqueous buffer Young technology further research focusing on the analytical performance is warranted... [Pg.343]

It is a version of this latter assay that has been established as our current frontline solubility measurement in the hit identification phase of discovery [23]. The assay uses 10 mM DMSO stock solution, which is diluted into aqueous buffer at pH 7.4 to give a final DMSO composition of 1%. Samples are agitated for 24h using magnetic stirrer bars prior to plate filtration to remove precipitate. This sample is further diluted and compared against a calibration solution of known concentration also taken from the 10 mM DMSO stock and diluted to the same solvent composition. The assay is based on a 96-well plate format using a UV diode array plate reader. This has enabled full automation of the assay with over 600 compounds measured in each run. [Pg.15]

The MIPs have also been utilized as the recognition elements in pseudoimmunoassays. " In this approach, MIPs are substituted for antibodies to quantify the amount of analyte in a biological sample, such as blood plasma. Most MIP immunoassays are competitive binding studies in which a radio- or fluorescent-labeled analyte is added to a mixture of the MIP and imlabeled analyte. After equilibrium is reached, some fraction of the labeled species is bound to the polymer surface and thus can be separated from the supernatant. The supernatant is then analyzed via scintillation or fluorescence techniques to determine the concentration of the original unlabeled analyte. Mosbach et al. have demonstrated that MIP-based immunoassays can rival the selectivity of antibody-based assays. Imprinted polymers for the opioid receptor ligands enkephalin and morphine were prepared and showed submicromolar (pM) level selectivity in a radioligand competition assay in aqueous buffers. The analysis... [Pg.1743]

Andersson, L.I. (1996) Application of molecular imprinting to the development of aqueous buffer and organic solvent based radioligand binding assays for (5) propranolol. Analytical Chemistry, 68, 111 117. [Pg.375]

If the assay is to be optimized for performance in an aqueous solution, it is usual to begin with a buffer solution such as phosphate pH 7. Since the MIP itself is often relatively hydrophobic, its surface may be poorly wetted if aqueous buffer alone is used as the solvent (this is certainly true of conventional macroporous MIPs cross-linked with large fractions of ethyleneglycoldimethacrylate (EDMA) or divinylben-zene (DVB)). Thus, a small amount of a nonionic surfactant such as Triton X-100 (c 0.5 % w/v) or a miscible organic solvent such as ethanol (c 5 % v/ v) is usually added to reduce the surface tension. For MIPs based on EDMA or DVB, the additive also serves to reduce hydrophobic interactions, which may be less specific than hydrogen bonds or ion pairs. [Pg.654]

At the practical level, it should be borne in mind that RRAs can be subject to a number of confounding factors. Chief among these is the possibility that substances contained in samples may interfere with assay specificity. Samples processed with acids or bases, if not properly neutralized, may yield falsepositive data since RRAs are pH dependent. It would be ill advised to add organic extracts directly to an RRA since assays are performed in aqueous buffers that are not miscible with all organic solvents. [Pg.4185]


See other pages where Aqueous buffer-based assays is mentioned: [Pg.343]    [Pg.346]    [Pg.343]    [Pg.346]    [Pg.317]    [Pg.75]    [Pg.96]    [Pg.662]    [Pg.135]    [Pg.347]    [Pg.350]    [Pg.1166]    [Pg.129]    [Pg.182]    [Pg.155]    [Pg.46]    [Pg.707]    [Pg.1760]    [Pg.178]    [Pg.1094]    [Pg.640]    [Pg.59]    [Pg.258]    [Pg.15]    [Pg.117]    [Pg.323]    [Pg.388]    [Pg.160]    [Pg.554]    [Pg.430]    [Pg.181]    [Pg.148]    [Pg.202]    [Pg.134]    [Pg.310]    [Pg.709]   
See also in sourсe #XX -- [ Pg.346 , Pg.347 ]




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Aqueous base

Base buffer

Based Assays

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