F(ab')2 and Fab antibody fragments and VHH Nanobodies®

High-specificity antibody fragments for advanced immunodetection and discovery workflows

Antibody fragments provide powerful alternatives to whole IgG antibodies, enabling greater precision, reduced background, and enhanced tissue penetration. These engineered antibody formats are ideal for applications requiring minimal steric hindrance, improved accessibility to epitopes, and flexible assay design across research and diagnostic settings.

Key features

Greater flexibility in experimental design
Improved signal-to-noise ratio
Enhanced access to difficult targets
Reduced assay interference
Compatibility with advanced imaging techniques

Antibody fragments and Nanobodies^®

F(ab')₂ antibody fragments

F(ab')₂ antibodies are derived from pepsin digestion of the whole IgG antibody to most of the Fc fragment whilst leaving the hinge region intact.

Bivalent antigen binding maintains strong signal while reducing non-specific binding
Lower background staining due to reduced Fc-region lowering binding to Fc receptors
Enhanced tissue penetration due to smaller size means better access to epitopes
Ideal for live-cell applications minimises receptor activation and internalisation

Fab antibody fragments

Fab (fragment antigen-binding) antibodies are derived from papain digestion of the whole IgG antibody to remove the entire Fc fragment, including the hinge region.

Monovalent antigen binding reduces crosslinking and aggregation
Minimal steric hindrance improves penetration in dense tissues and complex samples
Reduced Fc-mediated interactions eliminate binding to fc receptor lowering background noise
Ideal for blocking and labelling, enabling use of primary antibodies from the same species

VHH NANOBODIES^™

Camelid species such as alpacas and llamas produce a distinctive class of antibodies that consist solely of heavy chains. Their antigen-binding fragments (Fab), also known as variable heavy-chain–only fragments (VHHs) or NANOBODIES^®, represent an innovative and promising antibody format.

Antibody fragment with a single binding domain antibody maintains high specificity and affinity
Ultra small size enables superior tissue penetration and epitope accessibility
Recombinant production ensures batch-to-batch consistency and scalability
Fast discovery timelines due to efficient screening and selection processes

Schematic comparison of IgG-derived fragments and Camelid-derived VHH Nanobodies

Fab, F(ab')2 and VHH nanobodies

From left to right:

Top line

1. Full-length immunoglobulin (IgG): A conventional Y-shaped antibody composed of two identical heavy chains and two identical light chains linked by disulfide bonds.

2. F(ab′)₂ fragment: A bivalent antibody fragment generated by enzymatic cleavage below the hinge region, consisting of two Fab arms connected by disulfide bonds. The Fc region is absent, but both antigen-binding sites are retained.

3. Fab fragment: A monovalent antigen-binding fragment consisting of one complete light chain and the corresponding portion of one heavy chain, connected by a disulfide bond.

Bottom Line

4. Full-length Camelid Immunoglobulin IgG2: A Y-shaped antibody composed of two identical heavy chains, but no light chains (HCAbs) linked by disulfide bonds.

5. V_HH fragment: A monovalent antigen-binding portion of a camelid heavy-chain antibody is a single small domain called a VHH, often referred to as a nanobody.

Colour key: Heavy chains, green; light chains, blue; variable antigen-binding region, purple; disulfide bonds, white.

Related products

AffiniPure-VHH^® Secondary Antibodies are polyclonal VHH Fragment antibodies (NANOBODIES^®) produced in Alpacas

Choosing the right format

By selecting the appropriate format, you can optimise sensitivity, specificity, and experimental outcomes across a wide range of applications

Format	Size	Valency	Fc Region	Key advantage	Best Use Case
Whole IgG	~150-160 kDa	Divalent	Present	Strong signal, versatile	General immunodetection
F(ab')₂	~110 kDa	Divalent	Absent	Reduce background, good signal	Live cells, multiplex assays
Fab	~50 kDa	Monovalent	Absent	Precision targeting, minimal crosslinking	Blocking, same-species labelling
VHH Nanobody^®	~15 kDa	Monovalent	Absent	Ultra-small, highly stable	Deep tissue imaging, discovery

Materials available for download

VHH Discovery

AffiniPure-VHH secondary antibodies for flow cytometry

Anti-Alpaca VHH Booklet

Anti-VHH handout

Fab fragments, F(ab')₂ antibodies, VHH nanobodies, antibody fragments, nanobody discovery, secondary antibody fragments, immunodetection tools, flow cytometry antibodies, immunohistochemistry antibodies, fluorescence microscopy antibodies, low background antibodies, Fc-free antibodies, monovalent antibody fragments, divalent antibody fragments, recombinant nanobodies, antibody engineering, multiplex immunoassays, live cell imaging antibodies

Products

Note: product availability depends on country - see product detail page.

Details	Cat number & supplier	Size	Price
Goat Anti-Human IgG, F(ab')2 Fragment Specific 109-001-006 · Jackson ImmunoResearch	109-001-006 Jackson ImmunoResearch	2 ml	£79.00 2 ml view
AffiniPure® F(ab')2 Fragment Goat Anti-Mouse IgG, Fcγ Fragment Specific 115-006-008 · Jackson ImmunoResearch	115-006-008 Jackson ImmunoResearch	1 mg	£177.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Mouse IgG, F(ab')2 Fragment Specific 115-006-006 · Jackson ImmunoResearch	115-006-006 Jackson ImmunoResearch	1 mg	£177.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Human IgA + IgG + IgM (H+L) 109-006-064 · Jackson ImmunoResearch	109-006-064 Jackson ImmunoResearch	1 mg	£180.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Human Serum IgA, α Chain Specific 109-006-011 · Jackson ImmunoResearch	109-006-011 Jackson ImmunoResearch	1 mg	£180.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Human IgG, Fcγ Fragment Specific 109-006-008 · Jackson ImmunoResearch	109-006-008 Jackson ImmunoResearch	1 mg	£180.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Human IgG, F(ab')2 Fragment Specific 109-006-006 · Jackson ImmunoResearch	109-006-006 Jackson ImmunoResearch	1 mg	£180.00 1 mg view
AffiniPure® F(ab')2 Fragment Goat Anti-Human IgG (H+L) 109-006-003 · Jackson ImmunoResearch	109-006-003 Jackson ImmunoResearch	1 mg	£132.00 1 mg view
AffiniPure® Goat Anti-Human IgG, F(ab')2 Fragment Specific 109-005-006 · Jackson ImmunoResearch	109-005-006 Jackson ImmunoResearch	2 mg	£141.00 2 mg view
Goat Anti-Human IgM, Fc5µ Fragment Specific 109-001-043 · Jackson ImmunoResearch	109-001-043 Jackson ImmunoResearch	2 ml	£104.00 2 ml view
Goat Anti-Human IgG, Fc Fragment Specific 109-001-008 · Jackson ImmunoResearch	109-001-008 Jackson ImmunoResearch	2 ml	£79.00 2 ml view
AffiniPure® F(ab')2 Fragment Goat Anti-Mouse IgM, µ Chain Specific 115-006-020 · Jackson ImmunoResearch	115-006-020 Jackson ImmunoResearch	1 mg	£224.00 1 mg view

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