Nanotechnology-Based Reagents for ELISA

Application: ELISA

Enzyme-linked immunosorbent assay (ELISA) is an analytical technique in which, usually, one of the reaction components is adsorbed to the surface of a microtiter well of a multi-well plate to facilitate the separation of bound and free-labeled reactants. In the most employed analyses, the sample containing the antigen to be detected is added to the microtiter wells and allowed to bind with the antibody-coated bottom. After washing, an enzyme-labeled secondary antibody is added to generate a “sandwich” of coated Ab-Ag-Ab enzyme. Unbound reagent is then flushed away, and enzyme substrate is added to each well. The amount of product generated is proportional to the quantity of antigen in the sample and it is revealed using appropriate instruments (usually plate readers). On the other hand, specific antibodies in a sample can be detected and quantified using an ELISA modified procedure in which the antigen is coated to the microtiter well bottom. In this case the reagent to be added is an enzyme-labeled antibody specific to the analyte antibody. The successive phases of the analyses are the same described above.

State of the art

Even if ELISA is a long-standing technique used in world-wide laboratories, it is not exempt from frequent issues which cause time and money losses due to the need for assay repetition. This problem’s main cause is universally recognized in reagent instability. The secondary antibody needed for the reaction’s detection may precipitate or be degraded, determining a decrease in its concentration which may be fixed, in emergency, by a new titration which does not exempt money and time losses. In addition, the small quantity of enzyme conjugated per secondary antibody may lead to false negative results especially in the detection of low abundance analytes.

AcZon’s solution

AcZon definitely fixed these issues by applying long-term know-how in terms of purification and bioconjugation of biomolecules to obtain the highest quality of the polyclonal secondary antibodies employed for the detection. In addition, the employment of AcZon fluorescent silica nanoparticles in NanoLISA & NanoLISA-F allows the conjugation of more enzymes per antibody, ensuring a stronger colorimetric detection, and the possibility to use intrinsic nanoparticle fluorescence to reaction revealing.