What is QF-Pro®?

The spatial biology technology with proven clinical value

Quantifying Functions in Proteins (QF-Pro®) is a state-of-the-art bio-imaging platform able to spatially quantify functional proteomic events within fixed patient samples (FFPE, cell lines, PBMC, etc.), such as protein-protein interactions and protein post-translational modifications, at an unrivalled resolution and dynamic range. It does this by using an adaptation of Förster Resonance Energy transfer (FRET). This patented adaptation allows FRET to work reliably in patient tissue samples, with a high signal to noise ratio, for the first time.

Unlike competing technologies, such as the proximity ligation assay (PLA) or colocalisation experiments, QF-Pro® precisely measures these events at a ≤10nm resolution. Quantifying protein functions at this resolution yields mechanistic insights into signalling pathways and drug targets directly within samples.

QF-Pro® reagent kits

Realise the potential of QF-Pro® with our flexible reagent kits.


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Violet 3.0

Simplifying FRET/FLIM to empower life science research.

Protein-Protein Interactions

QF-Pro® can be used in order to quantify a range of protein-protein interactions (PPIs) within tissue samples.

This includes intracellular PPIs such as HER2/HER3 dimerisation or Akt/PDK1 interaction states. QF-Pro® can also quantify intercellular interaction states such as those of immune checkpoints, i.e., PD-1/PD-L1, CTLA-4/CD80, TIGIT/CD155.

These intercellular PPIs are quantified in-situ without the need for cell permeabilisation. Other interaction states that can be quantified include DNA-protein interactions.

Post-Translational Modifications

Our intracellular PTM assays quantify events such as the phosphorylation or methylation states of intracellular proteins. The spatial mapping of these PTMs allows the user to quantify the functional states (e.g. activation) of proteins within samples. PTMs that can be quantified by QF-Pro® also include glycosylation and acetylation events. These readouts are particularly useful for gaining insights on intracellular signalling pathway dynamics and designing small molecule therapeutics.

Optimised biomarkers include Akt activation state, PD1 activation state and STAT3 (Y705 or S727) activation state quantification.

How does QF-Pro® work?

QF-Pro® Assay Overview

QF-Pro® has modified established technologies (FRET/FLIM) to create a patented assay which is able to spatially quantify protein functions in situ within FPPE tissue samples for the first time at an unprecedented resolution. This is a feat that is unachievable with existing technologies.

Utilisation of Advanced Technologies

QF-Pro® utilises a two-site immunofluorescence-styled assay in conjunction with amplified Förster Resonance Energy Transfer (FRET) and Fluorescence Lifetime Imaging Microscopy (FLIM). Essentially operating as a “biochemical ruler”, QF-Pro® makes 1-10nm measurements within samples to quantify protein functional states. Our patented amplification step has allowed these readouts to perform in patient tissue samples, a feat that has been unachievable with previous FRET-based technologies.

Antibody Labeling Strategy

Two epitopes are labelled simultaneously using species-distinct antibodies. These are then detected with QF-Pro® secondary labelling reagents, one combined with a green chromophore (the donor) and the other to an amplified red chromophore (the acceptor).


Violet 3.0 and our QF-Pro® software then automatically measures the distance between the donor and acceptor chromophore, based on the amount of energy given from the donor to the acceptor (this is FRET). This allows us to quantify the interaction or post-translational modification of a protein and spatially measure these events across a sample. Violet 3.0 makes FRET imaging easier and more accessible than ever before.

Violet 3.0

Our flagship microscopy platform, Violet 3.0, simplifies FRET/FLIM to empower the use of QF-Pro®, removing all the complexity from this technology to make it accessible to researchers and clinicians of all backgrounds.

QF-Pro® Reagent Kits

Discover our flexible reagent kits which allow QF-Pro® to be used in any laboratory setting. Our kits contain everything you need to perform QF-Pro® analytics in house, and can be applied to any biomarker.

Validated Biomarkers

Discover the wide range of QF-Pro® validated assays that we offer, ranging from immune checkpoints to kinase activation states. Our flexible technology can be applied to quantify the function of any biomarker in any disease setting.

Download QF-Pro® Brochure

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