Enzyme-Linked Immunosorbent Assay (ELISA) is a useful, highly sensitive and powerful technique for the detection of proteins, chemicals, and drugs (antigens) in biological samples, including serum, blood and urine. The key to an ELISA is the interaction of a known antibody with the antigen of interest. Although the antibody antigenicity is the major limiting factor to ELISA, a second factor must be considered; how to visually detect the antibody:antigen interaction. Two commonly used techniques for detection are the attachment of horseradish peroxidase (HRP) or alkaline phosphatase (AP) to the primary or a secondary antibody and the subsequent addition of a colorimetric substrate.
Although the principle of ELISA is very simple, the optimization and perfection of the assay is not. To aid researchers, we manufacture a kit that contains all the crucial reagents necessary for a successful ELISA, including an enhanced blocking agent, washing buffer and an ultra sensitive colorimetric enzyme substrate.
femto-ELISA™ kits utilize a non-animal protein blocker, NAP-BLOCKER™ that minimizes cross-reactivity with researcher's antigens and antibodies.
For the detection of HRP, we supply an improved, ultra sensitive, non-volatile, stable colorimetric substrate based on tetramethyl benzidine (TMB). Our reagent does not require hydrogen peroxide that can have detrimental effects on many biological factors, which may ultimately affect your assays. Figure 1 shows that our substrate is able to detect as little as 100pg of HRP. For the detection of alkaline phosphatase, we offer a p-nitrophenylphosphate (pNPP) based substrate that has superior stability compared to commonly used pNPP tablets and solutions. The improved stability ensures minimal background O.D. over longer periods compared to normal pNPP substrates. Our AP substrate has superior sensitivity, highly rapid (figure 2) and requires no preparation time.
- Choice of HRP or AP colorimetric substrates
- High sensitivity
- Non-animal blocking agent to minimize cross reactivity and lower background
- ELISA kits and substrates for highly sensitive colorimetric detection of HRP or AP.