A Reverse Phase Array (RPA) is a type of protein array where lysates generated from cell lines, tissue samples, blood samples, or any other source of proteomic material are arrayed in a micro dot-blot format.  The technique, originally introduced by Dr. Lance Liotta and Dr. Emanuel Petricoin, provides a new platform for measuring protein expression levels in a large number of biological samples simultaneously.  

One common detection methodology for RPAs involves colorimetric detection via amplification step involving tagged secondary antibodies. The RPA data, viewed as series of dilution curves, provides a sensitive, quantitative, and much higher throughput alternative to Western blotting.

Image 1. Reverse Phase Array (Low Density Lysate and Serum Array)

Low density arrays (Image 1) employing fairly large features are useful for clinical sample profiling where the sample number is small, while high density arrays (Image 2) are essential for large-scale pathway analysis.

Image 2. Reverse Phase Array (High Density Lysate and Serum Array)

Aushon BioSystems’ 2470 arrayer is a proven technology for building exceptionally high quality Reverse Phase Protein Lysate microarrays. The 2470 can produce arrays of the often viscous lysate material with the linearity and consistency to permit data extraction from dilution series curves.

Antibody arrays are another type of protein array where purified antibodies are immobilized on the slide surface.  These arrays are used for diagnostic chips as well as expression profiling.  The protein binding to the capture antibody in an array can be detected directly or by means of a second antibody in a sandwich assay.  Antibody microarrays provide a high-throughput platform for protein expression profiling.  The high quality printing provided by the Aushon 2470 arrayer is ideal for the unique challenges of antibody array fabrication.

Image 3. Clontech Laboratories - Antibody Array

Focused genomic arrays represent a more traditional microarray format.  Genomic arrays have a wide range of uses including single nucleotide polymorphism (SNP) analysis and comparative genomic hybridization (CGH) assays

Image 4. Focused Genomic Array

The microtiter plate is a standard tool in analytical research and clinical diagnostic testing labs.  In addition to standard microscope slides, the Aushon 2470 can print arrays into the wells of 96- and 384-well plates.  The number of features per well depends on the well size and the desired spot size and spacing.  Well-plate based arrays can be either DNA or protein based.  This image also highlights the flexibility of our printing software which allows the user to completely control their array layout.  

Image 5. Microtiter Plate-based Array