The analytical protein arrays are used to detect target molecules in mixtures such as plasma or tissue extracts. Typically a complex mixture would be applied to arrays of possibly thousands of specific binders, and the individual bound analytes detected in parallel by appropriate labelling and scanning.

In diagnostics, it can be used to carry out multiple immunoassays in parallel, both testing for several analytes in individual sera for example and (by segmenting the array) testing many serum samples simultaneously.

In proteomics it is used to quantitate and compare the levels of proteins in different samples in health and disease, i.e. protein expression profiling. Functional protein arrays are used in for in vitro functional interaction screens and particularly to detect antibodies in individual patient or animal sera, during disease or to monitor immune responses.

The capture reagents themselves will need to be selected and screened for cross-reactivity against many proteins, which can also be done in a multiplex array format against multiple protein targets.

Protein chip technology allows thousands of samples to be analysed simultaneously on the same platform, greatly increasing throughput and simplifying quantitative analysis between samples.

Furthermore, an exceedingly small amount of sample is required for printing the arrays, thus permitting the analysis of rare and valuable patient samples.

Thus, broadly speaking, there are at least four major areas where protein arrays are being applied, each of which requires appropriate formats and readout methods:

• Diagnostics: detection of antigens and antibodies in blood samples; profiling of sera to discover new disease markers; environment and food monitoring. Applications in autoimmunity, allergy and cancer

• Proteomics: Protein expression profiling.



• Protein function analysis: protein-protein interactions; ligand-binding properties of receptors; enzyme activities.


• Antibody characterisation: cross reactivity and specificity, epitope mapping