QF-Pro | QF-Pro Glossary

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Definition

QF-Pro is a patented FRET reagent kit developed by HAWK Biosystems for quantitative detection of protein-protein interactions at molecular distances (1–10 nm). Read on the Violet 3.0 benchtop FLIM system, the combined workflow forms a time-domain FLIM-FRET platform: by measuring donor fluorescence lifetime changes rather than intensity, the system detects genuine molecular engagement in FFPE tissue sections–enabling functional biomarker analysis compatible with standard clinical pathology workflows.

Video Segments

Technology Comparison: Coloc vs PLA vs QF-Pro

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The QF-Pro Reagent Kit & Workflow

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QF-Pro Score: How FRET Efficiency Is Calculated

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Applications Beyond Oncology

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Related Segments

Violet 3.0: Benchtop FLIM Microscope

1–10 nm detection range

True molecular engagement

Lifetime-based readout

Intensity-independent quantification

High-throughput acquisition

Automated ROI detection

Standard tissue compatibility

Clinical workflow integration

How QF-Pro Works

QF-Pro employs a two-site labeling approach using species-specific secondary antibodies conjugated to donor (ATTO488) and acceptor (Alexa594) chromophores. When the target proteins are within 1–10 nm–indicating true molecular engagement–energy transfers from the excited donor to the acceptor, reducing donor fluorescence lifetime.

The Violet 3.0Loading... benchtop FLIM system measures this lifetime reduction with high throughput. Unlike intensity-based methods, lifetime measurement is intrinsically ratiometric and remains accurate even when protein expression is low–precisely the clinical scenario where expression-based biomarkers fail.

Tyramide signal amplificationLoading... (TSA) is incorporated to enhance acceptor chromophoreLoading... deposition, improving signal-to-noise ratios and enabling detection of sparse protein complexes in clinical tissue samples.

Clinical Evidence: See QF-Pro Applications & Clinical Evidence for validated targets, cancer indications, and full citations.

Simplified

The Core Technology: QF-Pro combines FRET (detecting protein interactions at 1-10nm) with FLIM (measuring fluorescence lifetime for quantitative readout).

In Practice: Two antibodies labeled with donor and acceptor fluorophores bind target proteins. If the proteins are interacting (close enough for FRET), the donor lifetime changes. This change is measured and quantified.

Why Lifetime-Based FRET Is Uniquely Suited

Proximity-specific: Signal arises only from interacting molecules within 1–10 nm. Proteins merely colocalized in the same cellular region generate no FRET signal, eliminating the false positives that plague proximity ligation and colocalizationLoading... assays.

Intensity-independent: Fluorescence lifetime is an intrinsic property of the chromophore. Low protein expression does not compromise accuracy–critically important for detecting biologically decisive PPIs at sparse immune synapses or in heterogeneous tumor microenvironments.

Quantitative and reproducible: FRET efficiencyLoading... is calculated using the standardized equation E_f = [1 - (τ_DA/τ_D)] × 100, providing continuous numerical output compatible with regulatory validation requirements for companion diagnosticsLoading....

FFPE-compatible: Operates on standard formalin-fixed paraffin-embedded tissue sections, enabling retrospective analysis of biobanked samples and integration with existing clinical pathology infrastructure.

For clinical evidence and validated applications, see QF-Pro Applications & Clinical EvidenceLoading...

Simplified

Key Advantages:

• Proximity-specific: Only detects genuine interactions (1-10nm)

• Intensity-independent: Works even when protein levels are low

• Quantitative: Provides numbers, not just positive/negative

• FFPE-compatible: Works with standard clinical samples

Explore QF-Pro Applications

QF-Pro has been validated across multiple cancer types and clinical contexts, with evidence published in peer-reviewed journals spanning 2014—2025.

QF-Pro Applications & Clinical Evidence →

Navigate validated indications (melanoma, breast, RCC, colorectal, lung), landmark findings (PD-1/PD-L1, PKB/Akt, CTLA-4/CD80), clinical applications, and the exploratory pipeline.

20 Validated Applications 13 Exploratory Targets 400+ Patients

Simplified

QF-Pro has validated clinical applications across multiple cancers and targets.

QF-Pro Applications & Clinical Evidence →

Explore all validated indications, landmark findings, and the development pipeline.

20 validated applications · 13 exploratory targets · 400+ patients studied

Expression-Based IHC

"How much protein is present?"
Measures abundance only
Misses low-expression engagement

QF-Pro FLIM-FRET

"Is the protein functionally engaged?"
Measures molecular interaction
Detects biology IHC cannot see

Clinical Validation Highlights

PD-1/PD-L1Loading... in melanoma and NSCLC: iFRETLoading...-measured interaction state directly correlated with overall survival, while PD-L1 expression alone did not predict patient outcome
PKB/Akt activationLoading... in breast and renal cell carcinoma: Oncoprotein activation state (measured by FRET efficiency) correlated with worsened patient outcome, whereas expression levels showed no predictive value
Inter- and intra-patient heterogeneity: Quantitative mapping reveals checkpoint engagement variability that expression-based methodsLoading... cannot capture
Workflow compatibility: Tissue preparation identical to routine IHCLoading...; automated acquisition reduces operator bias and enables reproducible quantification across institutions

Connected Terms

FLIM Category Cross-ref Related Learning Path Video
Fluorescence Lifetime Category Cross-ref Related Learning Path Video
iFRET Category Cross-ref Related Learning Path
FRET Category Cross-ref Related Learning Path
Violet 3.0 Category Cross-ref Related Video
FFPE Cross-ref Related Video
Functional Biomarkers Cross-ref Related Video
TSA Category Cross-ref Related