PVP Based Blocking Buffers
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- See the table below
PVP Based Blocking Buffers
Two protein-free polyvinylpyrrolidone formulations, PBS-based and TBS-based, each in two fill sizes. This is a category page, not a product page; open the formulation you need with View.
| Name | Cat. No. | Size | Product Page |
|---|---|---|---|
| PVP in PBS Blocking BufferPhosphate-buffered saline base | DCP-PVPPBS1X_500 ml | 500 ml | Viewarrow_forward |
| PVP in PBS Blocking BufferPhosphate-buffered saline base | DCP-PVPPBS1X_1000 ml | 1000 ml | Viewarrow_forward |
| PVP in TBS Blocking BufferTris-buffered saline base | DCP-PVPTBS1X_500 ml | 500 ml | Viewarrow_forward |
| PVP in TBS Blocking BufferTris-buffered saline base | DCP-PVPTBS1X_1000 ml | 1000 ml | Viewarrow_forward |
PBS or TBS? Compare the two bases · See applications by assay · Read the FAQ
What PVP blocks, and why it is not a protein
PVP (Polyvinylpyrrolidone) based Blocking Buffers are used in various immunoassays, such as Western blotting and ELISA, to reduce non-specific binding and improve assay sensitivity. PVP is a synthetic polymer, which means it does not contain proteins that could potentially interfere with the detection of protein targets.
- Two formulations, identical except for the saline base: PBS or TBS.
- Polyvinylpyrrolidone is a synthetic polymer, not a protein blocker — that is the defining property of this family.
- No protein content means nothing in the blocker can interfere with the detection of protein targets.
- Two named immunoassay formats: Western blotting and ELISA.
- Stated purpose: reduce non-specific binding and improve assay sensitivity.
- Two fill sizes per formulation: 500 ml and 1000 ml, four catalog numbers in total.
- pH 7.5, stored at 4 °C.
- Sterility: filtered 0.1 µm twice and 0.04 µm twice in a sterile environment. Customization available on inquiry.
- Formulations in this family2
- Catalog numbers4 (2 formulations × 2 sizes)
- Blocking agentPolyvinylpyrrolidone (PVP)
- Agent classsynthetic polymer · protein-free
- Saline bases offeredPBS, TBS
- Named applicationsWestern blotting, ELISA
- Fill sizes500 ml, 1000 ml
- pH7.5
- Storage4 °C
- Sterility0.1 µm ×2, 0.04 µm ×2
The blocker that cannot be mistaken for your target
Every protein blocker — milk, BSA, casein — puts more protein on the membrane than your sample did. PVP does not. That single difference is what this family is for.
Fewer false signals by construction
PVP is a synthetic polymer, so it does not contain proteins that could potentially interfere with the detection of protein targets. Nothing in the blocker can be recognised by a primary or secondary antibody.
It binds the membrane, not your antibodies
PVP is a water-soluble polymer that readily binds to nitrocellulose and PVDF, the two membranes used in most Western blots, forming a hydrophilic barrier that lowers background without interacting with the proteins in the assay.[1,2,4]
Useful where big blockers get in the way
PVP is particularly useful for detecting small proteins, which can be masked by larger blocking molecules such as BSA.[1,2]
Improved sensitivity is the stated goal
The source frames these buffers as reducing non-specific binding and improving assay sensitivity — two related but separate outcomes, and the second is what a protein-free blocker is usually chosen for.
PBS interferes with alkaline phosphatase
If the detection conjugate is alkaline phosphatase, take the TBS-based formulation: a TBS-based blocking buffer should be selected because phosphate-buffered saline interferes with AP activity.[3]
Particulate control is built in
Both formulations are filtered 0.1 µm twice and 0.04 µm twice in a sterile environment — a sub-0.1 µm polish, which matters for a reagent applied across the whole detection surface.
When to reach for this family instead of a protein blocker
When the antibody or the read-out reacts with something in a protein blocker — a phospho-epitope competing with casein, a biotin–avidin system meeting milk biotin, a secondary that recognises bovine IgG in BSA — the fix is often to stop adding protein at all. That is the case a protein-free blocker is built for, and the base is then chosen from the detection chemistry.[3,5]
Four membrane passes, two of them sub-0.1 µm
The source specifies one sterility process for both formulations: filtered 0.1 µm twice and 0.04 µm twice, in a sterile environment — two coarse passes followed by two sub-0.1 µm polishing passes.
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1
0.1 µm Pre-filtration I
First 0.1 µm membrane pass. Removes bulk particulates and the microbial load carried in from raw materials and make-up water before any polishing step sees the solution.
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2
0.04 µm Pre-filtration II
First sub-0.1 µm pass. Takes out the fine fraction a 0.1 µm or 0.2 µm membrane lets through — the range that deposits on a blot as diffuse background rather than as a band.
-
3
0.1 µm Sterile-filtration I
Second 0.1 µm pass, performed in a sterile environment. This is the sterilizing step of the sequence rather than a clarifying one.
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4
0.04 µm Sterile-filtration II — Final Polish
Second sub-0.1 µm pass, immediately before fill. The final polish is what distinguishes this architecture from a conventional single-membrane sterile filtration.
Why a protein-free blocker still needs the polish
Removing the protein removes one source of background; it does not remove particulates. A blocking buffer is applied across the entire membrane or plate, so anything suspended in it is deposited over the whole detection surface. On a reagent chosen specifically to lower background, that is the last place to accept carry-over.
PBS base or TBS base — how to choose
The catalog difference is one column wide: which saline the PVP is dissolved in. The consequences sit downstream, in the detection chemistry.
| Property | PVP in PBS | PVP in TBS |
|---|---|---|
| Catalog numbers | DCP-PVPPBS1X_500 ml DCP-PVPPBS1X_1000 ml |
DCP-PVPTBS1X_500 ml DCP-PVPTBS1X_1000 ml |
| Saline base | Phosphate-buffered saline | Tris-buffered saline |
| Blocking agent | Polyvinylpyrrolidone — synthetic polymer | Polyvinylpyrrolidone — synthetic polymer |
| HRP-conjugated detection | check_circle Both bases are in common use[1] | check_circle Both bases are in common use[1] |
| Alkaline phosphatase (AP) conjugates | cancel PBS interferes with AP activity[1,3] | check_circle Preferred base for AP-labelled antibodies[1,3] |
| Fill sizes | 500 ml, 1000 ml | 500 ml, 1000 ml |
| pH · storage | 7.5 · 4 °C | 7.5 · 4 °C |
Protein-free versus protein blockers — what actually changes
| Consideration | PVP — synthetic polymer | Protein blockers — milk, BSA, casein |
|---|---|---|
| What is added to the membrane | A water-soluble polymer that binds nitrocellulose and PVDF[1,2] | Additional protein, on a membrane chosen for its high affinity for protein[5] |
| Can the blocker itself be detected? | check_circle No proteins that could interfere with detection of protein targets | Possible — this is the source of the familiar phospho, biotin and cross-reactivity caveats[5] |
| Small or low-molecular-weight targets | check_circle Particularly useful; large blockers can mask them[1,2] | Larger blocking molecules such as BSA may mask small proteins[2] |
| Membrane compatibility | Nitrocellulose and PVDF[1,2] | Nitrocellulose and PVDF |
| Typical role in a protocol | Alternative when a protein blocker interferes; also used in combination with other blocking agents[1,2] | Routine first choice for most standard targets |
The two immunoassay formats named by the source
Western blotting and ELISA are the two applications the source names. Notes that go beyond the source are footnoted to their external authority.
- Reducing non-specific binding and improving assay sensitivity in Western blotting.
- PVP binds readily to nitrocellulose and PVDF, the two membranes used in most Western blots.[1,2]
- Detection of small proteins, which larger blocking molecules such as BSA can mask.[1,2]
- Blots where a protein blocker itself produces signal — PVP contributes no protein that an antibody could recognise.
- PVP is also used in combination with other blocking agents such as purified casein, rather than only on its own.[1,2]
- Reducing non-specific binding and improving assay sensitivity in ELISA.
- Assays where the blocking agent must not contribute protein that could interfere with the detection of protein targets.
- Blocker concentration is worth titrating in either format: too little leaves background, too much can mask the antibody–antigen interaction or inhibit the marker enzyme.[3]
- For AP-based colorimetric read-outs, use the TBS formulation.[1,3]
- Alkaline phosphatase conjugate: choose DCP-PVPTBS1X, because PBS interferes with AP activity.[1,3]
- Horseradish peroxidase conjugate: either base is in common use for most applications.[1]
- Phospho-specific primary antibodies: Tris-based buffers are generally preferred over phosphate-based ones, which points to the TBS formulation.[1]
- The source does not indicate a detergent in either formulation, and none is stated here. If your protocol needs one present in the bottle, ask about customization.
Identical across both formulations
Only the saline base changes between the two catalog lines. Everything below is common to all four catalog numbers.
| Attribute | Specification, as stated by the source |
|---|---|
| Blocking agent | PVP (Polyvinylpyrrolidone) |
| Agent class | Synthetic polymer — contains no proteins that could potentially interfere with the detection of protein targets |
| Stated purpose | Reduce non-specific binding and improve assay sensitivity |
| Named applications | Various immunoassays, such as Western blotting and ELISA |
| PVP concentration | Not stated in the source — request the Certificate of Analysis |
| Fill sizes | 500 ml and 1000 ml |
| pH | 7.5 |
| Storage | 4 °C |
| Sterility | Filtered 0.1 µm twice and 0.04 µm twice, in a sterile environment |
| Customization | Other concentrations; additions of chemicals, compounds, proteins, or supplements; different pH; further modifications — on inquiry |
| Intended use | Research Use Only (RUO) |
Questions this catalog gets asked
Primary literature and cited sources
The source description carries no citation or reference list. The entries below are supporting literature for the blocking agent and for the two assay formats the source names, followed by the external technical sources footnoted on this page. No DOI is shown where one could not be confirmed — none has been invented.
Supporting Literature
- Haycock JW. Polyvinylpyrrolidone as a blocking agent in immunochemical studies. Analytical Biochemistry. 1993;208(2):397–399. PMID 8095775 — the report that introduced PVP as a blocking agent for immunochemistry.
- Towbin H, Staehelin T, Gordon J. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proceedings of the National Academy of Sciences USA. 1979;76(9):4350–4354. — the founding Western blot method, the format in which membrane blocking became necessary.
- Engvall E, Perlmann P. Enzyme-linked immunosorbent assay (ELISA). Quantitative assay of immunoglobulin G. Immunochemistry. 1971;8(9):871–874. — the founding ELISA method, the second format the source names.
Footnoted Technical Sources
- G-Biosciences. Western Blot Blocking: Tips and Tricks for Blocking Agents — PVP as a non-protein blocking alternative useful for small proteins, a water-soluble polymer binding nitrocellulose and PVDF, generally used at 0.5–2 % and often combined with purified casein; also the note that PBS can interfere with alkaline phosphatase, so TBS should be used with AP substrates. gbiosciences.com
- Bitesize Bio. Block, Stock and Barrel — A Guide to Choosing Your Blocking Buffer; PVP as a non-protein alternative first published in 1993, binding readily to nitrocellulose and PVDF, generally used at 0.5–2 %, and particularly useful for small proteins that larger blocking molecules such as BSA might mask. bitesizebio.com
- Thermo Fisher Scientific. Blocking Buffers for Western Blot and ELISA — select a TBS-based blocking buffer with alkaline phosphatase conjugates because PBS interferes with AP activity, and the effect of too little or too much blocker. thermofisher.com
- Abcam. Western blot blocking methods and best practices — PVP reduces non-specific binding by creating a hydrophilic barrier on membranes, minimizing background signal without interacting with the proteins in the assay. abcam.com
- Azure Biosystems. Getting Rid of the Noise: Western Blot Blocking — PVDF and nitrocellulose membranes have a high binding affinity for all proteins, and the blocking agent may be protein or non-protein based, with polyvinylpyrrolidone among the commonly used agents. azurebiosystems.com
