Plasmonic ELISA

The plasmonic ELISA links the color of plasmonic nanoparticles to the presence or absence of the analyte. The assay uses enzymes to control the particle synthesis for generating plasmonic particles with different sizes [65,66], which exhibit distinct solution colors caused by different localized SPR. In one of the demonstrations that utilize p24 as the target analyte, the assay incorporates catalase to regulate the hydrogen peroxide concentration. 

FIGURE 4.1.3 In plasmonic ELISA the biocatalytic cycle of the enzyme generates colored nanoparticle solutions of characteristic tonality. S, substrate P, product NP, nanoparticle. Reproduced from Ref. [64], with permission from the Nature Publishing Group. 

Screening in early work sought to identify high affinity of the antibody for the TSA, using a process known as ELISA. This search can now be performed more quantitatively by BIAcore analysis, based on surface plasmon resonance methodology (Lof s and Johnsson, 1990). A subsequent development is the catELISA assay (Tawfik et al., 1993), which searches for product formation and hence the identification of abzymes that can generate product. 

SpA, Staphylococcal protein A PpL, protein L from Peptostreptococcus Magnus IgG, immunoglobulin G Gla, y-carboxyglutamic acid SPR, surface plasmon resonance ELISA, enzyme-linked immunosorbent assay FITC, fluorescein isothiocyanate NMR, nuclear magnetic resonance... 

Pharmacokinetic data analysis requires determination of the analyte in various body fluids. In the case of therapeutic antibodies, serum is the most common matrix to be analyzed. For a critical interpretation of pharmacokinetic data the chosen bioanalytical methods must be considered. The most frequently used for mAbs include enzyme-linked immunosorbent assay (ELISA), capillary electrophoresis (CE)/polyacrylamide gel electrophoresis (PAGE), fluorescence-activated cell sorting (FACS), and surface plasmon resonance (SPR). The challenges and limitations of bioanalytical methods used for the analysis of mAb concentrations are discussed in detail in Chapter 6. 

Cetuximab serum concentrations were measured using validated enzyme-linked immunosorbent assay (ELISA) methods or a validated surface plasmon resonance assay. These bioanalytical assays were crossvalidated to allow pooling of PK data across studies. 

Guidi, A., Laricchia Robbio, L., Gianfaldoni, D., Revoltella, R., and Del Bono, G. (2001) Comparison of a conventional immunoassay (ELISA) with a surface plasmon resonance based biosensor for IGF 1 detection in cows milk. Biosensors and Bioelec Ironies, 16, 971 977. 

Presented experimental results suggest that application of herbicide-binding protein in sensor technology has a high potential. Several detection systems were tested in combination with D1 protein electrochemical (amperometry and cyclic voltammetry), optical (surface plasmon resonance and ellipsometty) and assays (ELISA and D1 protein- containing liposomes and DELFIA fluori-metric assay). The main mechanisms of D1 action are either on the ability of herbicides to replace the plastoquinone molecule in D1 protein and in this way change the electrochemical and optical... 

Immunoassays— ELISA lateral flow immuno-chromatography (LFIC) surface plasmon resonance (SPR)... 

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