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DOT ELISA ANDDOT ELISA AND

IMMUNOSTRIPSIMMUNOSTRIPS

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DOT ELISA :

DOT ENZYME LINKED

The dot ELISA, a qualitative ELISA test,can be performed more quickly with theend detection done visually.

Dot ELISA is a micro ELISA utilizingantigen dotted onto nitrocellulose filterdiscs that has been used for 25 years.

Because of its relative speed andsimplicity, the dot ELISA is an attractivealternative to standard ELISA

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FABRICATION

Polystyrene Chip

Straight channels made via CNCmachining

Surface modified via allydextran Thin film of PS between two PS sheets to

allow flow

Nitrocellulose in well

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LIMITATIONS

Bubble Formation in Channels

Non-specific binding

Dot ELISA only qualitative

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BUBBLES FORMATION IN

CHANNELS

Caused by difference in fluid properties ofbuffers

Non-uniform distribution of reagentsCauses faint lines in results

Reduction in colormetric signal

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NON-SPECIFIC BINDING

Binding of secondary or non-targetmolecules on

reaction surface

Low signal-to-noise ratioBetter immobilization of monoclonal

antibody

Surface modification

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DOT ELISA

Dot ELISA is only qualitative.

Other ELISA methods, such as sandwichELISA

would provide quantitative measurements

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Identification of novel clinical markers,stricter environmental legislation, growingconsumer concern regarding food safety

and focus on disease self-management,are just a few of the factors leading to therequirement for an array of sensitive andspecific assays that are inexpensive,

easy to use and portable.

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with the development of a genericquantitative immunostrip technology, thatmay act as a platform for adaptation of

any laboratory based immunoasssay to aquantitative rapid test format.

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The scope of application of the developed technology isenormous. In recent years, advances in the production ofmonoclonal antibodies has facilitated detection ofpractically any desired analyte, from heavy metals to drugs,and clinical markers to food pathogens usingimmunoassay.

The potential market for disposable, tests capable of rapid,low cost, quantitative immunoassay is a billion dollarmarket with applications in the sectors of clinicaldiagnostics, food quality, police control, veterinarydiagnostics, military security and environmental monitoring,to name a few.

The team at BBG offers the development of an individuallytailored package, comprising reading device, sampleprocurement and, if required, pre-treatment device anddisposable immunostrips. monitoring.

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Our technology: BBG possesses proprietary knowledge

in the area ofmolecular wiring, whichemploys redox polymers with non-diffusional mediators that can transfer

electrons from the redox centres of theenzyme label (HRP/GOX) to theelectrode. Additionally, the group hasdeveloped novel substrates for ALPlabels as well as the use of novel tailordesigned genetically modified enzymes

as labels, thus achieving very highsensitivity (GOX = Glucose oxidase; ALP= Alkaline phosphatase; HRP= Horseradish peroxidase).

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BBG has developed immunostrips based on bothdiffusional and non-diffusional transduction, capable of ng/L(ppt) detection limits. Typical response times are 15-20minutes and sample volumes can be as low as a fewhundred nanolitres. Typical immunostrip membranes areemployed and the electrodes are produced by thick film

technology, thus allowing a low cost production. Theimmunostrip format can be modified for dual and multipleanalyte detection.

The group has developed immunostrips for bothcompetition and sandwich immunoassays. Competitionassays are generally employed for small molecules andsandwich for larger molecules.The team has alsoestablished the biocompatibility of the immunostrip formatswith various solvents and possible sample matrices.

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IMMUNOSTRIP SIMILAR TOIMMUNOSTRIP SIMILAR TO

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Antibody 1

monoclonalspecific to antigen(one epitope)

tagged with coloreddye

Antibody 2

monoclonalspecific to antigen(second epitope)

fixed to membrane

Antibody 3

specific toantibody 1

fixed tomembrane

IMMUNOSTRIP SIMILAR TOIMMUNOSTRIP SIMILAR TO

ELISAELISA