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HIGH QUALITY & SENSITIVITY AN ELISA KITS

HIGH QUALITY & SENSITIVITY AN ELISA KITS
By Admin

ELISA (enzyme-linked immunosorbent assay) is an assay based on the principle of antigen for detection and quantification of peptides, proteins, antibodies and hormones typically secreted or released from the cells.  An antigen is immobilized to a surface which is then complexed with an enzyme linked antibody. Substrate is incubated with conjugated enzyme for detection signal. A highly specific antibody-antigen interaction is the most critical element for the detection strategy. They are sensitive assays because of the binding characteristics of the antibodies and the amplification or different read-out systems used.  ELISA has become a critical tool in the field of human medicine, veterinary medicine, food testing, and agriculture. A variety of samples can be used in ELISA for the detection of specific target including serum, plasma, cell culture supernatant, cell lysates, saliva, tissue lysates, and urine.

 

ELISA can measure both antigens and antibodies and requires 3 necessary reagents:

1.      Solid-phase antigen or antibody

2.      Enzyme-labelled antigen or antibody

3.      Substrate for enzyme action

 

The results achieved by ELISA can be of three different types:

 1)  Quantitative: ELISA data can be interpreted for measuring the antigen concentration in the sample by using a standard curve.

 2)  Qualitative: ELISA can also be used to analyse the presence or absence of the antigen only.

 3)  Semi-Quantitative: This type of data is used for comparing the relative antigen level in the sample.


Types of ELISA

ELISAs are of: direct, indirect, sandwich or competitive. The main step is the immobilization of the antigen of interest either by direct adsorption to the assay plate or indirectly with aid of capture antibody already been attached to the plate. The antigen is then detected either directly (enzyme-labeled primary antibody) or indirectly (enzyme-labeled secondary antibody). The detection antibodies are usually labeled with alkaline phosphatase (AP) or horseradish peroxidase (HRP). A large selection of substrates is available for performing the ELISA with an HRP or AP conjugate. The choice of substrate depends upon the required assay sensitivity and the instrumentation available for signal-detection (spectrophotometer, fluorometer or luminometer).




 

Advantages

Disadvantages

Direct

     ·  Overall easy assay set-up 

        ·  Each antibody used for detection         must be conjugated

        ·  Potential for higher background

        ·  No Signal Amplification

        ·  Less Specificity

        ·  Not amenable to multiplexing

Indirect

     ·   Higher sensitivity than             Direct ELISA

     ·  Possibility of using the              conjugated second antibody    for multiple assays

     ·   Second antibody will give an    amplification of signal

     ·   Cost-effective

        ·  Due to the number of steps, the          protocol typically will take longer          and could be more prone to error

        ·  Potential for cross reactivity                caused by secondary antibody.

Sandwich

     ·  High Specificity

     ·  High sensitivity

     ·  Compatible with complex          sample matrices

       ·  Development of matched antibody      pair can be costly and time                  consuming.

       ·  Longer Protocol

Competitive

    ·  Useful for quantitative     measurement of a sample   with low analyte concentration

    ·  Suitable for small antigens

       ·  Requires conjugated antigen.


Advantages of ELISA

1. ELISA technique could be used for both quantitative and qualitative analysis.

2. The ELISA has high sensitivity and specificity achieved by the coating of the plate with a high-affinity antibody.

           3. The test is strongly specific due to the selective of antigen or the antibody.

           4. Sample volumes can also be adjusted in case of very low abundant protein. 

           5. ELISA with micro and nano-fabrication strategies and integration of the assay with lab-on-chip (LOC) and lab-on-compact-disk (LOCD) devices provides detection at micro and nano level.

           6. ELISA has promising great potential from point-of-care (POC) due to its cost-effectiveness.               

           7. Multiplexing version of ELISA provides convince of detecting multiple parameters simultaneously in the     same sample.  

           8. Useful in detecting diseases outbreak, can also be used in toxicology as a rapid presumptive screen for certain class of drugs. 

           9. Useful in the detection of microbes in foodstuff.



Multiplex ELISA

A multiplex ELISA enables a researcher to assess the levels of more than one protein target at a time, and it is typically used to determine the expression of multiple cytokines simultaneously. Unlike traditional ELISA formats, multiplex ELISA methods utilize one or more of the following techniques: flow cytometry, fluorescence, chemiluminescence, or electrochemiluminescence.



                                                Fig: Advantages of Multiplex ELISA.



Universal Biotechnology Private Limited is the leading ELISA kit supplier in India provides the research community 8000+ high-sensitivity ELISA kits cover about 16 species not only regular species like Human, Rat, Mouse, but also rare species like Bovine, Chicken, Canine and many more. These species-specific ELISA kits help the scientists in conducting experiments for animal models used in the research. ELISA kits are available in various pack size 24T, 48T, 96T and 5*96T

Because of its applications advantageous in various fields of biotechnology, clinical diagnosis, plant pathology, diseases conditions, food technology for the detection of disease markers, food allergens and unknown proteins etc. Hence, we being the ELISAkit Distributor welcomes your enquiries at info@unibiotech.com .