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BSA Based Blocking Buffers

Product#: BSABasedBlockingBuffers
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verified 3 % BSA · PBS / PBST / TBS / TBST · pH 7.4

BSA Based Blocking Buffers

Four 3 % bovine serum albumin formulations — two saline bases, each with and without detergent — in two fill sizes. This is a category page, not a product page; open the formulation you need with View.

BSA Based Blocking Buffers — Catalog · 4 Formulations · 8 Catalog Numbers
Pick the base and detergent your detection system needs — click View for the product page. Both fill sizes of a formulation share one product page.
Name Cat. No. Size Product Page
Bovine Serum Albumin (3%) with PBS Blocking BufferPhosphate-buffered saline base DCP-BSAPBS3X_500 ml 500 ml Viewarrow_forward
Bovine Serum Albumin (3%) with PBS Blocking BufferPhosphate-buffered saline base DCP-BSAPBS3X_1000 ml 1000 ml Viewarrow_forward
Bovine Serum Albumin (3%) with PBST Blocking BufferPBS base with detergent DCP-BSAPBST3X_500 ml 500 ml Viewarrow_forward
Bovine Serum Albumin (3%) with PBST Blocking BufferPBS base with detergent DCP-BSAPBST3X_1000 ml 1000 ml Viewarrow_forward
Bovine Serum Albumin (3%) with TBS Blocking BufferTris-buffered saline base DCP-BSATBS3X_500 ml 500 ml Viewarrow_forward
Bovine Serum Albumin (3%) with TBS Blocking BufferTris-buffered saline base DCP-BSATBS3X_1000 ml 1000 ml Viewarrow_forward
Bovine Serum Albumin (3%) with TBST Blocking BufferTBS base with detergent DCP-BSATBST3X_500 ml 500 ml Viewarrow_forward
Bovine Serum Albumin (3%) with TBST Blocking BufferTBS base with detergent DCP-BSATBST3X_1000 ml 1000 ml Viewarrow_forward

Which base, and with or without detergent? Compare the four formulations · See applications by assay · Read the FAQ

Family Snapshot

What BSA blocks, and what changes between the four

Bovine Serum Albumin Blocking Buffers are specialized reagents used in various immunoassays, such as Western blotting, ELISA, and immunohistochemistry. These buffers are designed to minimize non-specific binding, thereby enhancing the sensitivity and specificity of these assays. Bovine Serum Albumin (BSA) serves as the primary blocking agent. BSA is a single purified protein with a high affinity for proteins, making it effective at saturating excess protein-binding sites on membranes and microplates. This helps reduce non-specific binding, which is crucial for obtaining clear and accurate results in assays.

  • Four formulations, identical in BSA content and differing only in the buffer they are made up in: PBS, PBST, TBS, or TBST.
  • 3 % BSA in all four — a single purified protein, not a protein mixture.
  • High affinity for proteins is the stated mechanism: BSA saturates excess protein-binding sites rather than merely coating them.
  • Two surfaces: membranes and microplates.
  • Three named immunoassay formats: Western blotting, ELISA, and immunohistochemistry.
  • Two fill sizes per formulation: 500 ml and 1000 ml, eight catalog numbers in total.
  • pH 7.4, stored at −20 °C.
  • Sterility: filtered 0.1 µm twice and 0.04 µm twice in a sterile environment. Customization available on inquiry.
3 % BSA pH 7.4 · Store at −20 °C RUO
CATEGORY REFERENCE · BSA BASED BLOCKING BUFFERS
The four formulations at a glance — base, detergent, format, and finish
  • Formulations in this family4
  • Catalog numbers8 (4 formulations × 2 sizes)
  • BSA concentration3 %
  • Saline bases offeredPBS, TBS
  • Detergent optionswithout (PBS, TBS) · with (PBST, TBST)
  • Fill sizes500 ml, 1000 ml
  • pH7.4
  • Storage−20 °C
  • Sterility0.1 µm ×2, 0.04 µm ×2
  • Named applicationsWestern blot, ELISA, IHC
Why the Formulation Matters

One blocker, two variables — the base and the detergent

All four formulations carry the same 3 % BSA and block the same way. The catalog splits on two independent questions: which saline the albumin is dissolved in, and whether a detergent is already in the bottle.

shield

Saturation, not just coverage

BSA has a high affinity for proteins, which is what makes it effective at saturating excess protein-binding sites on membranes and microplates — the step that gives clear, accurate results rather than a merely darker blot.

verified_user

A single purified protein

Unlike a milk-based blocker, BSA is one defined protein rather than a mixture. That is why BSA blocking solutions are preferred with biotin labels, alkaline phosphatase labels, and anti-phosphoprotein antibodies — milk carries both casein, itself a phosphoprotein, and endogenous biotin.[2]

science

PBS interferes with alkaline phosphatase

If the detection conjugate is alkaline phosphatase, take one of the Tris-based formulations: TBS and TBST are preferred with AP-labelled antibodies because PBS interferes with the AP signal.[2,4]

bolt

And with phospho-epitopes

PBS is also not recommended when phosphorylated proteins are the focus of the blot, because the primary antibody can bind phosphate in the buffer as well as the target.[5]

water_drop

The T is a detergent, already in the bottle

A small amount of Tween-20 added to blocking and washing solutions reduces background staining; the resulting buffers are the ones written PBST and TBST.[2] The source does not state the detergent identity or concentration in these two formulations — request the Certificate of Analysis for the actual value.

pets

One caveat worth knowing in advance

Most commercial BSA preparations contain trace bovine IgG, which can be a target for anti-bovine, anti-goat, anti-horse, or anti-sheep secondaries — raising background or costing antibody titer. Check the secondary's host and specificity before choosing a BSA blocker.[5]

Two questions pick the bottle

First: is the conjugate alkaline phosphatase, or is the target a phospho-epitope? If either is yes, take the Tris base — TBS or TBST. Second: do you want the detergent supplied, or would you rather add it yourself and keep control of the concentration? That is the difference between the T and non-T versions, and nothing else in the formulation changes.[2,4,5]

3 %
BSA, all four formulations
7.4
pH, all four formulations
Filtration Architecture

Four membrane passes, two of them sub-0.1 µm

The source specifies one sterility process for all four 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.

  1. 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.

  2. 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 — including the protein aggregate range that lands on a blot as speckle.

  3. 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.

  4. 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 blocker in particular benefits from the polish

A blocking buffer is a concentrated protein solution applied across the whole membrane or the whole plate, so any aggregate suspended in it is deposited over the entire detection surface rather than in one lane. Particulate in a blocker reads as background everywhere — which is precisely the noise the blocking step exists to remove.

0.1 µm
membrane passes × 2
0.04 µm
membrane passes × 2
Quadruple-stage filtration architecture used for Diagnocine BSA Based Blocking Buffers: 0.1 micron pre-filtration, 0.04 micron pre-filtration, 0.1 micron sterile filtration, and a final 0.04 micron sterile polishing pass for low-background Western blot, ELISA, and immunohistochemistry blocking buffers in PBS, PBST, TBS, and TBST.
Figure 1. The four-pass filtration sequence applied to all four formulations in this family — 0.1 µm twice and 0.04 µm twice, in a sterile environment. © Diagnocine® — BSA Based Blocking Buffers
Formulation Reference

Four bottles, two decisions

The catalog is a two-by-two grid: phosphate or Tris base, crossed with detergent absent or present. BSA concentration, pH, filtration, and storage are constant across all four.

Formulation Saline base Detergent Catalog numbers
BSA (3%) with PBS Phosphate-buffered saline cancel Not indicated by the name DCP-BSAPBS3X_500 ml
DCP-BSAPBS3X_1000 ml
BSA (3%) with PBST Phosphate-buffered saline check_circle Indicated by the name[2] DCP-BSAPBST3X_500 ml
DCP-BSAPBST3X_1000 ml
BSA (3%) with TBS Tris-buffered saline cancel Not indicated by the name DCP-BSATBS3X_500 ml
DCP-BSATBS3X_1000 ml
BSA (3%) with TBST Tris-buffered saline check_circle Indicated by the name[2] DCP-BSATBST3X_500 ml
DCP-BSATBST3X_1000 ml

Phosphate base or Tris base — what turns on the choice

Downstream condition PBS / PBST TBS / TBST
HRP-conjugated detection check_circle Both bases are in common use[2] check_circle Both bases are in common use[2]
Alkaline phosphatase (AP) conjugates cancel PBS interferes with the AP signal[2,4] check_circle Preferred base for AP-labelled antibodies[2,4]
Phospho-specific primary antibodies cancel Not recommended — the antibody can bind buffer phosphate as well as the target[5] check_circle Tris base removes the phosphate competition[5]
Biotin–avidin detection check_circle BSA is a single purified protein devoid of endogenous biotin[1] check_circle BSA is a single purified protein devoid of endogenous biotin[1]
Anti-bovine, anti-goat, anti-horse or anti-sheep secondaries Use with care — trace bovine IgG in BSA can be a target regardless of base[5] Use with care — trace bovine IgG in BSA can be a target regardless of base[5]
BSA concentration · pH · storage 3 % · 7.4 · −20 °C 3 % · 7.4 · −20 °C
Two things the source does not state, and that are not guessed here. First, the detergent identity and concentration in the PBST and TBST formulations: the name indicates a detergent is present, but no value is published in this description. Second, the exact salt composition of each base. Request the Certificate of Analysis for both at support@diagnocine.com before matching a formulation to a validated protocol.
Applications by Assay

The three immunoassay formats named by the source

Western blotting, ELISA, and immunohistochemistry are the three applications the source names. Notes that go beyond the source are footnoted to their external authority.

Membranes · all four formulations
  • Minimizing non-specific binding on membranes, to enhance the sensitivity and specificity of the blot.
  • 3 % sits inside the 3–5 % BSA range in common use for membrane blocking.[2,3]
  • BSA blocking solutions are preferred with biotin labels, AP labels, and anti-phosphoprotein antibodies.[2]
  • Choose TBS or TBST when the secondary antibody is alkaline phosphatase conjugated, or when the target is a phospho-epitope.[2,4,5]
  • The PBST and TBST formulations arrive with the detergent already present, so blocking and washing chemistry match without a separate addition.[2]
Microplates · all four formulations
  • Saturating excess protein-binding sites on microplates, which is what reduces non-specific binding in the assay.
  • BSA blocking buffer is used specifically for saturating excess protein-binding sites on membranes and microplates in immunoassays.[1]
  • Inadequate blocker leaves excess background; excessive blocker can mask the antibody–antigen interaction or inhibit the marker enzyme — the concentration is worth titrating.[4]
  • For AP-based colorimetric read-outs such as pNPP, use the TBS or TBST formulation.[2,4]
Tissue sections · all four formulations
  • Minimizing non-specific antibody binding in immunohistochemistry, one of the three formats the source names.
  • Purified BSA solutions are supplied for blocking across Western blotting, ELISA, IHC, and nucleic acid detection methods.[1]
  • For AP-based chromogens, use a Tris-based formulation: phosphate inhibits alkaline phosphatase.[4]
  • Check the secondary antibody host first — anti-bovine, anti-goat, anti-horse, and anti-sheep conjugates can react with trace bovine IgG in BSA.[5]
Shared Specifications

Identical across all four formulations

Only the buffer the albumin is made up in changes between the four catalog lines. Everything below is common to all eight catalog numbers.

Attribute Specification, as stated by the source
Blocking agentBovine Serum Albumin (BSA), the primary blocking agent, at 3 %
Nature of the agentA single purified protein with a high affinity for proteins
MechanismSaturates excess protein-binding sites, reducing non-specific binding
Surfaces blockedMembranes and microplates
Named applicationsWestern blotting, ELISA, immunohistochemistry
Fill sizes500 ml and 1000 ml
pH7.4
Storage−20 °C
SterilityFiltered 0.1 µm twice and 0.04 µm twice, in a sterile environment
CustomizationOther concentrations; additions of chemicals, compounds, proteins, or supplements; different pH; further modifications — on inquiry
Intended useResearch Use Only (RUO)
CUSTOMIZATION: Please INQUIRE if other concentrations, additions of chemicals/compounds/proteins/supplements, different pH, and modifications are needed — support@diagnocine.com.
FAQ

Questions this catalog gets asked

It is a specialized reagent for immunoassays such as Western blotting, ELISA, and immunohistochemistry. It minimizes non-specific binding, which enhances the sensitivity and specificity of the assay. Bovine serum albumin is the primary blocking agent, and it works by saturating excess protein-binding sites on membranes and microplates.
BSA is a single purified protein with a high affinity for proteins, rather than a protein mixture. In practice that matters most for three detection systems: BSA blocking solutions are preferred with biotin labels, alkaline phosphatase labels, and anti-phosphoprotein antibodies, because milk carries casein — itself a phosphoprotein — and endogenous biotin.[1,2]
Both bases are in common use for blocking, but two conditions push you to Tris. If the detection conjugate is alkaline phosphatase, take TBS or TBST: PBS interferes with the AP signal.[2,4] If the blot targets phosphorylated proteins, PBS is also not recommended, because the primary antibody can bind phosphate in the buffer as well as the target protein.[5]
The detergent. A small amount of Tween-20 is commonly added to blocking and washing solutions to reduce background staining, and the resulting buffers are written PBST and TBST.[2] The PBST and TBST catalog lines arrive with the detergent already present; the PBS and TBS lines do not indicate one. The source does not publish the detergent identity or its concentration for this family, so no value is stated here — request the Certificate of Analysis at support@diagnocine.com.
One case is worth checking before you start. Most commercial BSA preparations, including high-purity grades, contain trace contaminating bovine IgG. That IgG can become an antigen for cross-reacting secondary antibodies — particularly anti-bovine, anti-goat, anti-horse, and anti-sheep — which may raise background or reduce antibody titer.[5] If your secondary has one of those specificities, discuss an alternative blocker at support@diagnocine.com.
Each formulation is supplied in 500 ml and 1000 ml fills, at pH 7.4. All four are filtered 0.1 µm twice and 0.04 µm twice in a sterile environment — a four-pass architecture whose last two passes are sub-0.1 µm polishing steps. Storage is at −20 °C.
Yes. Other concentrations, additions of chemicals, compounds, proteins or supplements, a different pH, and other modifications are available — please inquire at support@diagnocine.com.
Scientific References

Primary literature and cited sources

The source description carries no citation or reference list. The entries below are supporting literature for the 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

  1. 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.
  2. 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 format in which microplate blocking became necessary.

Footnoted Technical Sources

  1. Thermo Fisher Scientific. Blocker BSA product record — a purified BSA solution for saturating excess protein-binding sites on membranes and microplates in immunoassays, and for blocking in Western blotting, ELISA, IHC, and nucleic acid detection; a single purified protein devoid of endogenous biotin. thermofisher.com
  2. Bio-Rad. Western Blotting: Immunodetection — Blocking and Antibody Incubation; 3–5 % BSA in PBS or TBS, Tween-20 added to give PBST or TBST, TBS/TBST preferred with AP-labelled antibodies, and BSA preferred with biotin and AP labels and anti-phosphoprotein antibodies. bio-rad-antibodies.com
  3. Boster Bio. Blocking Buffer Optimization for Western Blot — 3–5 % BSA in PBS or TBS as the common blocking solution, with Tween-20 added to blocking and washing solutions. bosterbio.com
  4. Thermo Fisher Scientific. Blocking Buffers for Western Blot and ELISA — blocker concentration effects, and the recommendation to select a TBS-based blocking buffer with alkaline phosphatase conjugates because PBS interferes with AP activity. thermofisher.com
  5. Jackson ImmunoResearch. Western blotting guide, membrane blocking, and the Bovine Serum Albumin technical note — PBS not recommended when phosphorylated proteins are the focus, and trace contaminating bovine IgG in commercial BSA as an antigen for anti-bovine, anti-goat, anti-horse, and anti-sheep secondaries. jacksonimmuno.com
Blocker selection support. For help matching a blocking buffer to a detection system, or for documentation requests including the Certificate of Analysis, contact support@diagnocine.com. Ready to order? Back to the BSA Based Blocking Buffers catalog.

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