Modelling random antibody adsorption and immunoassay activity

Abstract

One of the primary considerations in immunoassay design is optimizing the concentration of capture antibody in order to achieve maximal antigen binding and, subsequently, improved sensitivity and limit of detection. Many immunoassay technologies involve immobilization of the antibody to solid surfaces. Antibodies are large molecules in which the position and accessibility of the antigen-binding site depend on their orientation and packing density. In this paper we propose a simple mathematical model, based on the theory known as random sequential adsorption (RSA), in order to calculate how the concentration of correctly oriented antibodies (active site exposed for subsequent reactions) evolves during the deposition process. It has been suggested by experimental studies that high concentrations will decrease assay performance, due to molecule denaturation and obstruction of active binding sites. However, crowding of antibodies can also have the opposite effect by favouring upright orientations. A specific aim of our model is to predict which of these competing effects prevails under different experimental conditions and study the existence of an optimal coverage, which yields the maximum expected concentration of active particles (and hence the highest signal).

Biparatopic Nanobody-Based Immunosorbent for the Highly Selective Elimination of Tumor Necrosis Factor-α

“…These results suggested that even though more NbC21 was conjugated to the resin, the relative activity of immobilized NbC21 decreased. This phenomenon can be attributed to the nondirectional immobilization of NbC21 and the increased steric hindrance caused by higher coupling densities. , Consequently, a further increase of D C for NbC21 is deemed counterproductive. Ultimately, taking into account the aforementioned four factors ( D C , E C , C A , and R C ) holistically, the immunosorbent with a D C of 32.3 mg/g gel (0.93 μmol/g gel) was employed in all subsequent experiments.…”

Application and development of aptamer in cancer: from clinical diagnosis to cancer therapy

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