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ADC Internalization Detection Antibody – Labeled with pH-Sensitive Fluorescent Dye

Antibody-drug conjugates (ADCs) are targeted cancer treatments consisting of a monoclonal antibody linked to a cytotoxic drug. The antibody targets specific cancer cell antigens, allowing the drug to be delivered directly to tumors while reducing off-target effects. A key step in the mechanism of action (MOA) of ADCs is receptor-mediated endocytosis.

Internalization testing is not only a critical step in drug screening but also a core tool for mechanism optimization. By quantifying internalization efficiency, researchers can accurately predict ADC behavior in vivo, providing key data support for clinical trials.

To support ADC internalization research, we have developed a specialized Antibody Internalization Detection Reagent (Cat. No. IGG-PZF2001), featuring a pH-sensitive red fluorescent dye that labels the human IgG Fc region. The reagent forms a stable fluorescent complex within 10 minutes, enabling rapid assessment of antibody internalization processes. After labeling, antibodies can be detected using various methods including flow cytometry or cell imaging techniques.

Classic mechanism of action of ADC drugs

Product List

Cat. No.	Product Description	Order Now
IGG-PZF2667	VHH-Based Antibody Internalization Detection Reagent	Order
IGG-PZF2001	Antibody Internalization Detection Reagent	Order

Product Features

High Signal-to-Noise Ratio: Strong fluorescence with minimal background

Quick Labeling: Complete in just 10 minutes

pH-Sensitive: Bright signal in acidic intracellular compartments

Fab Region Preserved: Not affect antibody binding

Principles & Applications

Principles

Schematic of antibody internalization detection reagent principle

Applications

Discovery stage:
To identify antibodies that not only bind specifically to tumor-associated antigens but also internalize efficiently.
Lead optimization:
To evaluate how variations in antibody structure or conjugation chemistry affect internalization and intracellular trafficking.
Preclinical development:
To confirm that the selected ADC candidate exhibits consistent internalization behavior across relevant cell models.
Mechanism-of-action studies:
To validate the intracellular delivery of the payload and its correlation with cytotoxic effects.

Validation Data

FACS Analysis of Antibody Internalization

Anti-CD20 Abs and Human IgG1 isotype control were labeled with Antibody Internalization Detection Reagent (Cat.No.IGG-PZF2001). Raji cells were treated with Anti-CD20 Abs-Internalization Detection Reagent conjugate and Isotype control-Internalization Detection Reagent conjugate separately for 2 hours, then analysis by Flow cytometric. APC signal was used to evaluate the activity (Routine tested).

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Anti-Her2 Abs and Human IgG1 isotype control were labeled with Antibody Internalization Detection Reagent (Cat.No.IGG-PZF2001). SK-BR-3 cells were treated with Anti-Her2 Abs-Internalization Detection Reagent conjugate and Isotype control-Internalization Detection Reagent conjugate separately for 2 hours, then analysis by Flow cytometric. APC signal was used to evaluate the activity (Routine tested).

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Fluorescence Imaging of Antibody Internalization

SK-BR-3 cells were treated with CellLights Lysosome GFP (green) for 16 hours followed by treatment with Anti-Her2 Abs-Internalization Detection Reagent conjugate and IgG1 Isotype-Internalization Detection Reagent conjugate separately for 16 hours (red), then stained with NucBlue Live ReadyProbes(blue) for 20 minutes and imaged on the EVOS M7000. A. Antibody Internalization Detection Reagent (Cat.No.IGG-PZF2001). B. IgG1 Isotype-Internalization Detection Reagent conjugate. C. Anti-Her2 Abs-Internalization Detection Reagent conjugate. D. Anti-Her2 Abs-Internalization Detection Reagent conjugate(Z-stacking).

Resources

Webinar playback and appointment

‘ADC Potency Analysis and Quality Control Technology Breakthrough’ Webinar Series

ACROBiosystems proudly presents the flagship 'ADC Potency Analysisand Quality Control Technology Breakthrough' live webinar series. This series will systematicallydeconstruct critical aspects ofADC drug development through five coremodules-from potency analysis to quality control technologiesempowering breakthroughs in ADC therapeutics by overcoming keytechnical bottlenecks.

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Addressing Challenges in Antibody-Drug Conjugate Development

Here is the brief recap of the webinar:ADCs have the potential to enable 'precision medicine' with a wide market reach.Challenges in ADCs include managing Target Affinity, enhancing payload conjugation, and assessing Payload Delivery in vivo Pharmacokinetics. We can provide high-quality solutions to address these challenges.

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Building the Perfect Antibody-based Therapeutic from Selection to Engineering and Manufacturing

In this webinar, discover how advanced techniques such as Al-driven candidate selection optimization of antibody sequences, and precise conjugation methods come together to address some of the current challenges in antibody-based therapeutics.

Watch Now

Resource download

Fc Receptor Proteins - Partners for Antibody Drug Development

[Flyer]Fucntional Cell Lines and Development Service

Poster/Application Note Download

Advanced Endocytosis Assays Sensitive Detection and Parameter Optimization for HER2CD20 Antibody Internalization

Development and validation of bioanalytical assays for the quantification of ADC

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FAQ

How does pH-sensitive fluorescence distinguish internalized antibodies from surface-bound antibodies?

The fluorescent signal remains low at the relatively neutral extracellular pH and increases when the antibody enters acidic endosomal or lysosomal compartments. ACROBiosystems internalization detection reagents bind the Fc region of human IgG to form a pH-sensitive fluorescent complex while leaving the antigen-binding region available. Internalization-associated fluorescence can then be measured by flow cytometry or fluorescence imaging. Internalization-associated fluorescence can then be measured by flow cytometry

What does a pH-sensitive antibody internalization assay measure?

A pH-sensitive assay detects the accumulation of antibody–reagent complexes in acidic intracellular compartments rather than antibody binding at the cell surface alone. The signal does not independently demonstrate payload release, lysosomal degradation, cytotoxicity, or in vivo ADC behavior. Results generated with ACROBiosystems internalization detection reagents should therefore be interpreted as a direct measurement of uptake into acidic compartments.

What is the difference between IGG-PZF2001 and IGG-PZF2667?

IGG-PZF2001 is an anti-human Fc antibody-based internalization detection reagent, while IGG-PZF2667 uses a smaller VHH single-domain antibody with lower steric hindrance. Both reagents carry a pH-sensitive fluorescent dye, recognize the human IgG Fc region, and form a fluorescent complex within 10 minutes. IGG-PZF2667 provides an additional option when a more compact Fc-binding reagent is preferred.

Which antibodies and ADCs are compatible with IGG-PZF2001 and IGG-PZF2667?

Both reagents specifically recognize the Fc region of human IgG and are intended for human IgG-based antibodies and ADCs with an accessible Fc region. Because the fluorescent reagent binds the Fc region, the test antibody does not require direct chemical conjugation with a fluorescent dye. Compatibility with Fc-free antibody fragments, non-human antibodies, or other antibody formats should be evaluated separately.

Can the internalization detection reagents be used for both flow cytometry and fluorescence imaging?

IGG-PZF2001 has been evaluated by flow cytometry using anti-CD20 antibodies with Raji cells and anti-HER2 antibodies with SK-BR-3 cells. It has also been used for fluorescence imaging of anti-HER2 internalization and lysosomal colocalization in SK-BR-3 cells. Flow cytometry supports population-level signal comparison, while imaging provides spatial information on intracellular fluorescence.

How have ACROBiosystems antibody internalization detection reagents been validated?

IGG-PZF2001 has been evaluated with CD20- and HER2-targeting antibodies using flow cytometry and with a HER2-targeting antibody using fluorescence imaging. IGG-PZF2667 has been evaluated by flow cytometry with an anti-CD20 antibody in Raji cells. Together, these data support the use of the reagents across different target–cell models and detection platforms.

References

1. Beck, A., Goetsch, L., Dumontet, C. et al. Strategies and challenges for the next generation of antibody–drug conjugates. Nat Rev Drug Discov 16, 315–337 (2017). https://doi.org/10.1038/nrd.2016.268

2. Romero, D. Pembrolizum*b tunes up chemotherapy in cervical cancer. Nat Rev Clin Oncol 18, 747 (2021). https://doi.org/10.1038/s41571-021-00570-5

Background
Product List
Product Features
Principles & Applications
Validation Data
Resources
Promotion
FAQ
References