• E11 - first generation IgG
• 3.3 - second generation IgG
• 6.3 - high affinity IgG
• r33G - new high affinity IgG
• 15-2b - high affinity anti-mPEG IgG
• 2B5 - temperature responsive IgG


• AGP3 - first generation IgM
• AGP4 - second generation IgM
• rAGP6 - high affinity IgM


• c3.3-IgG - human anti-PEG IgG std
• cAGP4-IgM - human anti-PEG IgM std
• Hu-6.3 IgG - high affinity human anti-PEG IgG antibody
• Hu-6.3 IgE - high affinity human anti-PEG IgE antibody
• c3.3-IgG2 - human anti-PEG IgG2 std
• c3.3-IgG3 - human anti-PEG IgG3 std
• c3.3-IgG4 - human anti-PEG IgG4 std

All antibodies (except 15-2b) bind to the repeating ethylene oxide subunits in the backbone of PEG.

The minimum size of PEG that can be recognized depends on the individual antibody. 3.3 binds poorly to PEG molecules less than 750 Da in size, whereas 6.3 binds a smaller epitope. AGP4 and rAGP6 appear to bind an even smaller epitope. The rough ranking of the antibodies (from large PEG epitope to small PEG epitope) is: 3.3 › AGP3 › E11 › 6.3 › AGP4

15-2b does not bind the PEG backbone. Rather, it binds to the terminal methoxy end of mPEG.

More information can be found on the description page for each antibody.

Any secondary antibodies that bind to the correct species and antibody class are OK.
E11, 3.3, 6.3, 15-2b and 2B5 are mouse IgG monoclonal antibodies.
AGP3 and AGP4 are mouse IgM monoclonal antibodies.
r33G is a rat IgG monoclonal antibody.
rAGP6 is a rat IgM monoclonal antibody.
c3.3-IgG and cAGP4-IgM are humanized IgG and IgM recombinant antibodies, respectively. hu6.3 IgG and hu6.3 IgE and human IgG recombinant antibodies.

Biotin-labeled versions of most antibodies are available.
These work well for detection of PEGylated compounds in applications such as immunoblotting and ELISA.

More information is available here.

In general, IgM works best for capture and IgG works best for detection.
We have found the following antibody pairs work well together for sensitive detection with low background:

AGP4 for capture and 3.3-biotin for detection
rAGP6 for capture and 6.3-biotin for detection.
AGP4 for capture and 15-2b-biotin for detection

15-2b is a suitable detection antibody for PEGylated nanoparticles and liposomes due to its high affinity and the large number of methoxy-PEG groups displayed on the particle surface.

rAGP6 in combination with 6.3-biotin can quantify PEG-Intron, which is difficult to detect due to the presence of a single, relatively short PEG chain.

Tween 20 should be used in wash buffers when AGP4 or 3.3 (including AGP4-biotin or 3.3-biotin) are used but it should be substituted with other detergents such as CHAPS when other antibodies are used.

Optimized methods for sandwich ELISA are available in protocols.

Antibodies shipped in 50% glycerol can be stored long-term at -20^oC.
Antibodies shipped on dry ice can be stored at -80^oC. Upon the first use, aliquot the antibodies into working amounts and freeze them at -80^oC or -20^oC for long-term storage. The antibodies are also stable for months at 4^oC as long as they are not contaminated with microbes. You can also add 50% glycerol to the antibodies and keep them for at least 1 year at -20^oC. Do not dilute the antibodies before storing them! Do not repeatedly freeze-thaw the antibodies.

Anti-PEG antibodies are stable for a minimum of 3 years when stored undiluted at -80^oC. They are also stable for at least a year when stored in 50% glycerol at -20^oC.

Yes. All the anti-PEG antibodies can bind to both linear and branched PEG molecules.

Detergents like Tween 20 have a PEG-like structure (ethylene oxide subunits) that can compete binding of anti-PEG antibodies to PEGylated compounds. We recommend the following detergents for anti-PEG antibodies:

3.3 and AGP4 - use 0.05% Tween 20 for best results (to reduce background but maintain sensitive detection).

6.3 and 6.3-biotin - DO NOT use tween 20, substitute with 0.05% CHAPS.

All other antibodies - 0.05% CHAPS is recommended but Tween 20 can be used although the response will be reduced somewhat.

Yes and No.

Yes: The antibodies can bind to PEG as long as it is "immobilized". So, for example, amino-terminal PEG can stick to ELISA plates. The antibodies bind very strongly to such PEG-coated microtiter plates. Likewise, the antibodies bind to PEG in immunohistochemical sections and to PEG on nitrocellulose paper. The antibodies bind best to PEG that is physically attached to proteins, liposomes, cells and nanoparticles.

No: Free PEG chains in solution are bound with low affinity by the antibodies. Thus, detection of free PEG molecules by ELISA is not very sensitive. This means that unconjugated PEG will not interfere with assays.

The exception to the rule is 6.3. It can bind free PEG although not as well as when the PEG is immobilized. You can also our cell-based assay system to measure the concentration of free PEG or mPEG.

1. Provide your FedEx account number along with your official purchase order (PO).

2. Choose shipping in a FedEx Priority Box. There is no dry ice but you should receive your antibodies within 48 hours of shipping.

In our experience, assay sensitivity is decreased if coated ELISA plates are dried. They can be coated and stored in blocking buffer for up to three days with no effect on assay sensitivity. We usually coat the plates with anti-PEG antibodies overnight, block with 5% skim milk/PBS for 2 hours and then wash once with PBS immediately before assay of PEGylated compounds.