ProArray Ultra®

ligand Binding Assays as a Service


Why do ELISAs yourself when you can

  • outsource them for less than your in-house labor and consumable costs,
  • miniaturize them to require just microliters of precious samples,
  • and scale up your assays cost effectively to ensure that you achieve statistical power?

We now offer a unique new service to carry out ligand binding assays powered by ProImmune’s ProArray Ultra® customizable protein microarrays.

How Does the Assay Service Work?

Similarities to ELISA and other ligand binding assays:

  • Similar in principle to ELISA – with better sensitivity, lower costs, and you don’t have to do the work!
  • Set-up options as per a plate-based ligand binding assay, e.g. direct assay, sandwich assay, etc.
  • Existing assay protocols can simply be transferred.
  • Customer can supply their own proteins / antibodies / sera.


Figure 1: ProArray Ultra® ligand binding assays can be produced in line with typical configurations for microtiter plates. Antisera or plasma can be used In place of antibodies and any protein-protein interaction can be explored. Linker or biotin-streptavidin linked formats can also be used.  The customer retains the freedom to set up and optimize the assays for their specific purposes.

What do we do differently?

  • The ProArray Ultra® microarray has more than 30,000 features per slide, compared to 96 wells in a microtiter plate.
  • Reagent consumption at all stages is vastly reduced, slashing the cost of the analytes and allowing a greater number of samples to be analysed.
  • Detection is carried out using a fluorescence microarray reader, resulting in better sensitivity than standard ECL ELISA.
  • The array can be split into 1/2/4/8 or 24 subarrays. A 24 subarray format still has nearly 1000 features available per sub-array.


Figure 2: ProArray Ultra® schematic in 24 sub-array configuration. Each sub-array offers nearly 1000 features which can be incubated separately.


What is the result?

  • ProImmune can carry out your assays at high quality and low cost with rapid turnaround.
  • For larger projects we can often deliver the full assay and report for less than your in-house labor and consumable costs.
  • Even better savings for follow on projects using the same materials.
How to use our comprehensive assay service: it’s as easy as 1-2-3

  1. Contact us with your specific requirements. Our PhD qualified representatives will understand your project quickly and provide you with a fully-costed proposal, usually within one day.
  2. Our customer service team will provide instructions on sending your samples to ProImmune for analysis.
    1. ProImmune will receive and store your samples and obtain any additional peptides or proteins (as agreed in advance) that may be needed for the assay.
    2. All samples will be stored in our fully tracked sample banks.
    3. ProImmune will carry out all testing.
    4. A full analysis report and data tables will be compiled.
  3. The report, along with accompanying data files, are available for download from our secure web-server.

How does ProImmune’s assay service compare to other platforms, such as Luminex® and MSD®?

  • Our assays are provided as a comprehensive service, so you don’t need to supply consumables or allocate equipment and bench-space for the assay.
  • Luminex® and MSD® consumables can still be quite expensive. With our service, ProImmune can use your supplied reagents ensuring reagent consumption is absolutely minimal and bringing you significant cost benefits.  In some cases ProImmune may be able to carry out an entire project for less than the consumable costs on another platform.
  • Luminex® offers up to 50-plex reactions per well and MSD® offers up to 100-plex for some 24 well plates. In contrast ProArray Ultra® can accommodate up to 38,000-features per array and has very significant scale economies, especially for larger projects.
Cost comparison between ELISA, MSD®, Luminex® and our assay service.


Please note that in the above table we have compared the consumable-only cost per ELISA plate equivalent for ELISA, MSD® and Luminex® with the all-in service cost of our assay service.

Additionally, what are your salary costs for standard plate based assays? The fully loaded salary cost (base salary + direct salary overheads) for your technician may be $40,000 per annum and you may expect them to work 1,800 hours per year costing you approximately $22 per hour. A ligand binding assay with, e.g. 100 plates would take about two weeks to perform, analyse and report at a direct technician salary cost of $1,760, costing you $17.60 per plate. The consumables alone could increase this cost to almost $80 per plate. And again this does not account for any further overheads – only direct material and labor cost.

Both Luminex® and MSD® additionally require the purchase of proprietary equipment and software, which also has to be maintained. Furthermore each instrument is clearly limited in its peak capacity and by its physical location. Anyone can use our all-inclusive fixed cost service at any time.

Depending on the assay setup we often match such costs, meaning that you can break-even without taking into account any further overheads, such as equipment, lab-space, supervisory or administration. When you consider these factors, the question becomes not whether you can afford to outsource, but whether you can afford not to.

Applicable Program Areas

The ProArray Ultra® technology is appropriate for a range of programs and projects, including:

  • Serum screening

    Screen sera for multiple protein reactivities. If you have access to large scale, historical serum banks 1000s of sera could be screened against dozens of proteins using minimal sample volumes.

  • Antigen discovery

    Reverse immunology on proteins or entire pathogen proteomes.
    Screen sera from disease state or convalescent donors against overlapping peptides.

  • Biomarker discovery and screening

    Cancer, infectious diseases, cardiovascular, metabolic, CNS – your imagination is the limit.

  • Mapping of monoclonal antibody binding sites

    Mapping is linear in the first instance (unless conformational peptides are used), but strong conformational epitopes will be detected in linear sequences too.
    The platform also allows for the use of constrained peptides, e.g. cyclized peptides.

  • Understanding the epitopes presented and recognized

    Disease progression cycle.
    Pathogen life cycle and recovery phases.

  • Batch release testing: vaccines, biologics

  • Cytokine arrays

    For example: ProArray Ultra® was used for measuring release of the cytokine IL-6 in whole blood caused by the therapeutic antibody Campath® in a dose escalation study (see full information on the ProStorm® Cytokine Release Assay here).

ProArray Ultra® has been specifically developed as a combined peptide and protein array platform; combining the epitope/interaction site resolving power of scanning peptide arrays with that of high throughput and protein interaction screening.

ProArray Ultra® achieves full compatibility for overlapping peptide libraries and proteins, and uses a flexible peptide synthesis platform to enable printing of arrays optimized for specific applications. Moreover, our design improvements result in greater uniformity of spot morphology between peptides and proteins, reduced background signal and improved assay performance in terms of sensitivity, dynamic range, and variance.

The result is a protein array platform that is comparable in analytical performance to MSD® technology and that outperforms ECL ELISA assays, while at the same time tens of thousands of interactions can be detected in a single experiment. More importantly, only microliter amounts of sample are required for each analysis, enabling projects using limited amounts of sample that are simply impossible to carry out with 96-well plate-based assays.

Better Design Leads to Ultra Performance

The design of ProArray Ultra® overcomes the compromise between the analytical quality of multi-well immunoassay platforms and the scalability of existing protein and peptide array technology. Evaluation of our new design features against other more conventional assay methodologies, such as optimized ECL ELISA and the MSD® technology shows that ProArray Ultra® compares favourably to both plate-based platforms, and has lower background and better overall signal to noise performance (figure 1).

Comparison of ProArray Ultra™ with MSD® ELISA technology


Figure 1: Results of a direct comparison of ProArray Ultra® (blue bars) and high-performance 96-well MSD® assay technology (red bars) for identical peptide libraries derived from the well-characterized Hepatitis B Virus surface Antigen (HBVsAg) incubated with the same anti-HBVsAg seropositive serum sample. All data include error bars reflecting standard error of the mean (SEM) values. ProArray Ultra® compares favourably to both ECL ELISA and the MSD® plate-based platform, and has lower background and better overall signal to noise performance. The peptides identified as epitopes by ProArray Ultra®correlate with results from the MSD® assay.

Limit of detection comparison of ProArray Ultra and MSD technologies

Figure 2: Limit of Detection (LOD) comparison for MSD® and ProArray Ultra® using a specific monoclonal antibody. A saturation curve profile was obtained with a linear range of approximately 2.5 logs for both ProArray Ultra® and MSD® assay. Very low signal variation was found for both technologies in terms of signal detected. The limit of physical detection can be seen as ~0.5ng/ml.

Flexible Array Design

Our printing technology confers complete flexibility for design around your requirements.

The ProArray Ultra® microarray setup is based on five printing layouts of 1, 2, 4, 8 or 24 identical sub-arrays per slide. The slides can be overlaid with a separation gasket allowing each sub-array to be incubated with an individual antibody-sample, i.e. up to 24 separate samples can be analyzed per slide.

The exact print setup is based on the number of peptides or proteins being probed, the number of sample repeats required, and the number of technical repeats required (at least 3 are suggested, up to 6 are recommended). All these factors are taken into account to create the optimal printing layout. The five different print setups can accommodate a large range of custom printed features (peptides & proteins) alongside standard control spots.

Further detailed technical and performance data (PDF)

Contact us to discuss your project and we will design an assay and array format tailored to achieve your objectives.