We currently offer two groups of products

1. SA-PolyHRP Diluents/Blockers and Stabilizers


2. Antibody/Antigen and General Conjugate Diluents/Blockers and Stabilizers

Click here for a structural scheme giving general product view.

Both groups include ready-to-use products (balanced Diluents/Blockers and
Stabilizers) and Casein Buffer Concentrates (CBC), intermediate products, that can be
further processed into customer-tailored reagent having desired functionality.

further processed into customer-tailored reagent having desired functionalitys.
that had been developed for using in the capacity of auxiliary liquid reagents with SA-
PolyHRP conjugates.

Casein Buffer 20X-4X Concentrate 1 #CBC1

is a concentrated stable liquid filterable formulation of universal Casein Colloid Buffer,
true biotin free, made in proprietary manufacturing process.

Recommended use includes

(I) Blocking of the solid phase (immunoplates, blotting membranes, other porous and
non-porous materials) after coating with capture reagent (e.g. binding antibody or
antigen) made with the sense of occupying free vacant sites onto immunosorbent
surface. As a rule adsorbed inert blocker also supports immobilized specific capture
reagent improving that way long-term stability of prepared immunosorbent, especially
after drying.

(II) Application of CBC as constituent part of diverse Diluent formulations with both
specimen/calibrator and detector reagents/conjugates. Casein will eliminate adverse
matrix effects with different complex specimens and block non specific binding (NSB)
of detecting conjugates to immunosorbent in absence of analyte.

1 volume of CBC mixed with 3-to-19 volumes of your own diluent or simple PBS will
yield 4-to-20 volumes of Casein Diluent/Blocker depending on desired working (NSB-
eliminating) strength.

CBC will effectively eliminate NSB/backgrounds in ELISA, blotting, ICT and IHC
applications. Notice, that casein will block protein-to-protein binding of truly non-
specific origin. CBC will not prevent specific interactions associated with e.g.
heterophilic antibodies, HAMA, rheumatoid factors and other essentially specific
interfering substances that may also cause false positive reactions in certain assay

(In order to eliminate above adverse, primarily human blood serum/plasma matrix
effects add your Specimen/Sample diluent with Universal Blocker of heterophilic
antibodies, rheumatoid factors, HAMA and complement #UB or HAMA Blocker

CBC1 is absolutely biotin-free and therefore is ideally compatible with enhanced
biotin-streptavidin detection systems showing no drop in detection activity with
streptavidin conjugates. Moreover, diluents made of CBC boost positive signals in
systems with Streptavidin-PolyHRP conjugates which, along with lowering
backgrounds, significantly improves signal-to-noise ratios.

Each batch of produced CBC1 passes rigorous control providing evidence of complete
endogenous biotin removal. SA-PolyHRP80 conjugate diluted 1/20.000 (50 ng/ml total
conjugate, approx.
10 ng/ml conjugated Streptavidin) in 1/2 CBC1, after longer overnight exposition in
diluted state, is applied in our standard ELISA QC release use test. Batch is released
for sale if it does not show in above functional test quantitatively trustworthy inhibition
effect in direct comparison with internal gold standard CBC1 reference
(exhaustively biotin-depleted) material.

Notice, that equimolar (free, 244.3 Da) biotin concentration that theoretically shall
cause 100% inhibition in described situation (assuming streptavidin size 60 kDa and 4
active biotin-binding sites) is 162,86 pg/ml. This almost exactly corresponds to
standard certification of vitamin-free caseins given typically 0,05 µg D-biotin per 1 g
dry material.

CBC used as a component of liquid ready-to-use formulations features stabilizing
effect with detecting streptavidin & antibody conjugates and controls. CBC is
especially useful in stabilizing larger PolyHRP conjugates.

CBC is stable at +4°C at least 2 years from the date of manufacture.

CBC1 is essentially 5.5% (w/v) 0.45µm/0.2µm-filterable colloidal solution of true biotin-
free casein in 0,15M salt buffer base pH 7,3. It contains non-mercury safe wide-
spectrum anti-microbial preservative/biocide
5-Bromo-5-Nitro-1,3-dioxane at 0,1%.

CBC is filtered through 0.45µm at the end of manufacture process.

Casein Buffer 20X-4X Concentrate 1
5,5% (w/v) biotin-free 

Universal Casein Diluent/Blocker #UCDB

is ready-to-use reagent applicable for blocking ELISA plates and blotting membranes,
diluting complex specimens and diverse detection reagents/conjugates including high
performance and ultrasensitive biotin-streptavidin systems. Effectively eliminates NSB
in ELISA, blotting, ICT and IHC applications.

UCDB is essentially a liquid formulation of 1,375 (w/v) biotin-free casein in neutral
NaCl/Phosphate Buffer preserved with
5-Bromo-5-Nitro-1,3-Dioxane at 625 ppm, 0.45µm-filtered.

UCDB is stable at +4°C over 2 years from the date of release.

Universal (SA-PolyHRP) Casein Diluent/Blocker
biotin-free, ready-to-use, #UCDB

2. A second group, General Antibody/AntigenConjugate Diluents/Blockers and
Stabilizers, consists of similarly designed casein and casein-based products with
matching to first group functional background-eliminating and stabilizing activities. The
only essential difference is presence of biotin which makes these products
incompatible with SA-PolyHRP conjugates. Better to say not directly compatible"
since non biotin free blocking and stabilizing buffers can still be unrestrictedly used
with other components of diverse assay systems utilizing SA-PolyHRP where their
functional performance will basically be well compared to performance of respective
products of the first, biotin-free group.

In sense of corresponding performance, by ruling out immediate use with SA-PolyHRP
(as e.g. diluent or stabilizer),

Casein Buffer 20X-4X Concentrate 2 #CBC2
is essentially equal to
Casein Buffer 20X-4X Concentrate 1 #CBC1;

Antibody/Antigen/(PolyHRP) ConjugateDiluent/Blocker #AADB
is essentially equal to
Universal (SA-PolyHRP) Casein Diluent/Blocker #UCDB;

Antibody/Antigen (PolyHRP) Conjugate Stabilizer #AA1
is essentially equal to
Streptavidin-PolyHRP Conjugate Stabilizer #SA1 and

High Temperature Antibody/Antigen (PolyHRP) Conjugate
Stabilizer HT #AA3-RHT is essentially equal to
High Temperature Streptavidin-PolyHRP Conjugate Stabilizer HT

Therefore actually all said above about specialty biotin-free items equally applies to
second group products, at least in what concerns basic composition and functional
performance characteristics (with natural reservation concerning incompatibility with
SA-PolyHRP conjugates) and overall stability in respective storage conditions.

Casein Buffer 20X-4X Concentrate 2
5,5% (w/v)

Antibody/Antigen/(PolyHRP) Conjugate Diluent/Blocker

Refer to PolyHRP Users Guide for learning in more details how can you benefit from
better using our Diluents/Blockers and Stabilizers.