The purity of PureCol^® collagen is determined by SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis in conjunction with bacterial collagenase sensitivity and silver staining techniques with a method sensitivity of 99.9%. It was found that PureCol® collagen is 95 to 98% Type I collagen and the remainder being comprised of Type III collagen.

SDS polyacrylamide gel electrophoresis demonstrates the presence of alpha, beta and gamma components in an appropriate ratio of approximately 40:30:30, respectively. PureCol^® collagen is a native collagen as judged by polarimetry and trypsin sensitivity although the product does contain a low percentage of collagen fragments or shortened helices.

Conclusion: With the test method sensitivity of 99.9% (SDS-PAGE gel electrophoresis in conjunction with bacterial collagenase sensitivity and silver staining techniques) and no other proteins present in the preparation, it can be concluded that the purity of the PureCol^® collagen is 99.9%.

The viscosity of PureCol^® is ~32 cp.

PureCol^® product has an isoelectric zone instead of isoelectric point. The isoelectric zone is pH 7 to 8. In addition, the collagen molecules in the PureCol® product will come out of solution starting at a pH above 5.5 and reach its plateau at pH 7 to 8 then gradually tapering off at pH 8 to 9.5.

Reduction of a commercially available, pepsin-solubilized, bovine dermal collagen (Vitrogen 100) (PureCol’s old product name) with sodium [3H]borohydride provided radiolabeled collagen preparations with specific activities ranging from 7.1-12.0 muCi/mg collagen. These specific activities were 2-3 times greater than those obtained by reduction of intact rat tail tendon collagen under similar conditions.

The alpha, beta, and higher aggregate components of type I collagen were radiolabeled as well as the alpha component of a small amount of type III collagen present in the samples. Fractionation of cyanogen bromide peptides showed that alpha 1(I)CB7, alpha 1(I)CB8, and alpha 2(I)CB3,5 were the predominant peptides labeled by this procedure. Amino acid analysis indicated that the majority of the radioactivity was in reducible cross-links, precursors of these cross-links, and in hexosyllysine residues.

Reconstitution experiments comparing this radiolabeled collagen with nonlabeled collagen showed them to be indistinguishable. Bacterial collagenase digestion of this reconstituted fibrillar collagen in both a lightly cross-linked (glutaraldehyde 0.0075%) and noncross-linked form provided evidence that digestion of labeled and nonlabeled collagens proceeded at similar rates. Thus, labeling did not change the properties of the collagen. Cross-linking made the preparation refractory to proteolytic degradation. Injection of fibrillar collagen preparations, spiked with radiolabeled collagen, into the guinea pig dermis followed by quantitation of the amount of radioactivity recovered from implant sites as a function of time, indicated that the lightly cross-linked samples also were more resistant to degradation in vivo than the noncross-linked preparation.

The half-life of noncross-linked collagen was about 4 days while that of the cross-linked collagen was about 25 days. These degradation rates were much faster than observed for similar, nonlabeled samples injected into the dermis of humans, presumably due to a higher metabolic activity in the guinea pig dermis.

Since the collagen in PureCol collagen contains approximately 95% Type I bovine collagen and 5% Type III bovine collagen, an anti-bovine collagen Type I antibody for your study can be used.

There is no difference. Vitrogen was the old tradename, and PureCol^® is the new tradename.

Please review our collagen hydrogel whitepapers found here: https://advancedbiomatrix.com/3d-collagen-hydrogel-stiffness.html

Please visit our collagen gelation diagnosis page: https://advancedbiomatrix.com/collagen-gelation-diagnosis.html

Please view our white paper here:
https://advancedbiomatrix.com/recommended-volumes-for-coatings-and-hydrogels.html 

We completed a study to show that DNA is completely destroyed at pH 2, and demonstrated that our collagen products do not contain DNA.

The collagen is fully hydrolyzed. The amino acid analysis is done using the Waters AccQ-Tag derivatization method. During the acid hydrolysis step, asparagine (N) is converted to aspartic acid (D) and glutamine (Q) is converted to glutamic acid (E). Tryptophan (W), if present, is destroyed during acid hydrolysis. Experimentally, one can determine the picomoles (pmol) of each amino acid per injected detected using amino acid standards.For the concentration determination, the total number of pmol of each amino acid is summed to get the total pmol of the 18 amino acids detected. The total pmol amino acids is divided by the theoretical number of amino acid residues in collagen based on the published sequence. The result is the pmol of collagen injected. The result is then multiplied by the dilution and 300,000 is used as the collagen molecular weight to get to mg/mL. The molecular weight of collagen is not well agreed upon.

Diluting with 1X PBS (rather than water or 0.01 N HCl) would have an effect for coating purposes.   It would change the pH of the diluted collagen solution from acid to neutral pH. The pH change will transform the collagen molecules from a molecular form to a fibrillar form; and then the nature of coating surface will be changed from a monomeric coating to a fibrillar coating.

We use the following antibodies from SouthernBiotech:

1. 1310-02 – Goat Anti-Type I Collagen-FITC

2. 1310-08 – Goat Anti-Type I Collagen-BIOT

3. 7100-05 – Streptavidin-HRP

The major collagen molecular species in our Type I collagen products are monomers (approx. 70%), but there are dimers, trimers and a few percentages of oligomers too (approx. 30%) with some minor amounts of collagen fragments. The collagen monomer is a rod shaped molecule with 300 nm in length and 1.5 nm in diameter. The dimer, trimer and oligomer are 600 nm, 900nm and even longer in length respectively. According to the coating procedures, the collagen molecules are attached to the charged polystyrene surface randomly by charge or affinity in acid conditions during the 1-2 hrs incubation period at 37°C, and any unattached materials are removed by aspiration and rinsing. Therefore, the coated surface is a single layer of collagen monomer, dimer, trimer and oligomer mixtures. The thickness of the mono-molecular layer is dependent on how those molecules are attached on the surface. The coating density thickness would generally be characterized as a 1 molecule thickness which could be ranging from a few nanometers to a few hundred nanometers with the whole surface being covered by collagen.

The net charge of Type I collagen products’ (PureCol^®, Bovine Collagen and VitroCol®, Human Collagen) molecule is directly related to the pH.  At an acidic pH, the amino acids (zwitterions) along the collagen molecule are positively charged, making the entire collagen molecule positive. At the isoelectric point (or zone) of collagen, around pH 7-8, the amino acids along the collagen molecule are positively and negatively charged, making the net charge of the collagen molecule close to zero. At a basic pH, the amino acids along the collagen molecule were negatively charged, making the entire collagen molecule negative.

Further, the nature of the charge of the collagen coating surface will be dependent on the type of coating applied. For a monomeric collagen coatings when the collagen is applied under an acidic pH condition, the surface is positively charged. If the surface is rinsed with pH neutral buffer or media then it will change the charge of the collagen surface net charge close to zero. For a 3D gel coating, the collagen prepared under neutral pH; the net charge of the collagen surface is close to zero.

Using rotary shadowing technique under transmission electron microscopy, it was found that our collagen, on average, consists of approximately 80% monomers, 13% dimers, trimers, and oligomers with the remaining 7% collagen fragments.

Yes. The collagen molecule in PureCol, Nutragen, VitroCol, and all of our other Atelo collagen products were prepared from native collagen matrix by pepsin treatment under controlled conditions to remove the non-helical portion, telo-peptides, only and the helical portion is intact. In this case, the enzymatic active sites for MMP (Matrix Metalloproteinase), such as for Mammalian Collagenase Matrix Metalloproteinase 8 (MMP-8), on the molecule was preserved.

These pepsin treated collagen products should behave as native intact collagen.

TGF beta would have been digested with the pepsin enzymatic digestion step. It was undetectable by SDS PAGE silver stain as well. We didn’t do any specific measurements by ELISA however but presences of TGF beta is not anticipated.

We primarily use the Biuret method, but we also use BCA, AAA, and hydroxyl-proline assays.

- Collagen solutions that are frozen tend to have issues forming 3D hydrogels, and will likely not work. The solutions should still be good for 2D coatings. 

- Collagen solutions that are left out at room temperature for extended periods of time may show signs of degradation, which will affect the formation of 3D hydrogels. It is likely still fine for 2D coatings. 

Our recommendation is this: If you are using the product directly for a publication, we highly suggest buying a new bottle if the one you have was compromised. 

In the publication "Fibroblast Promotes Head and Neck Squamous Cell Carcinoma Cells Invasion through Mechanical Barriers in 3D Collagen Microenvironments," they reported the porosity of FibriCol^® type I atelocollagen hydrogels prepared at various concentrations, as reported below:

1 mg/ml = 5.7 + 2.3 μm

2 mg/ml = 3.7 + 1.5 μm

4 mg/ml = 1.3 + 0.7 μm

8 mg/ml = 0.8 + 0.4 μm

We can say that our coating saturates the available culture surface with a dense layer of collagen that is stable and cannot be washed off.

The “coating density” is represented by an array of molecules packaged at maximum, area-filling density, in a mono-molecular layer onto the surface.

The absolute mass of coated collagen per surface area depends on the Stoke’s radius and shape of the specific ECM being coated, yielding coating densities in the range of  0.2 – 0.4 micrograms of protein per square centimeter of available surface.