Analysis of several factors affecting the quality of fetal bovine serum

There are many kinds of fetal bovine serum on the market, and many researchers, especially those who have just contacted cell culture, can hardly distinguish the quality of serum. Based on my experience in serum production and sales for more than ten years, I have summarized the following:

First, the appearance

When you get the serum, the first thing you are exposed to is the appearance of the serum. For those who lack experience in cell culture, the judgment of appearance is especially important.

1, color

According to the different hemoglobin content, fetal bovine serum can show yellow or red. The serum standard for cell culture in China is no more than 20mg/dl. In fact, the level of hemoglobin has no direct effect on serum. The significance of this indicator is It can reflect the rigorous standardization of the blood collection process, and good operation can reduce the hemolysis of serum.

The blood collection points of domestic serum are very scattered, and most of them are collected by the butcher immediately after blood collection, so there is very little hemolysis, showing a bright waxy yellow. Of course, domestic serum rarely has fetal calf serum in the standard sense.

Imported fetal bovine serum is more or less hemolyzed, because the true fetal bovine serum has poor coagulation function and red blood cells are easily broken.

In general, domestically produced serum exhibits sallow. Imported serum, the best quality is yellow, reddish, such as Gibco 16000, almost orange-red or bright red. Of course, heat-inactivated serum or improperly preserved serum, due to the destruction of hemoglobin, will appear dark red or even brown.

2, precipitation

Many serum customers will find that the imported serum has a precipitate, which is suspected of the quality of the serum, which is unfounded.

The precipitation in serum is produced by the aggregation of fibrin, which has no effect on the serum quality. There are many reasons for the precipitation, which is closely related to the processing and production methods of the manufacturers.

Domestically produced serum, mostly from the north, due to low prices, the preservation environment is not good, from blood collection, freezing, transportation to production will undergo multiple freeze-thaw cycles, each freeze-thaw process will precipitate part of fibrin precipitation, so serum After the finished product is filtered, it looks more "clean" and there is very little precipitation.

Imported fetal bovine serum is rarely frozen and thawed before filtration. The finished product is also clear, but over time, a large amount of fibrin in the serum will precipitate and form a precipitate. Of course, the imported newborn bovine serum is generally about 2 weeks old, and the various protein contents in the serum are obviously high. After the production, the serum may be cloudy or even precipitated.

Of course, the serum that is purchased is frozen, and needs to be melted when used. The melting process is preferably carried out slowly at a lower temperature, otherwise the precipitation is relatively more, although the precipitation does not directly affect the quality of the serum, but the cells Microscopic observation has certain obstacles.

3. Clarity

Imported fetal bovine serum is characterized by low levels of protein and lipids, which are thin and light, while domestically produced serum, because most of it is newborn calf serum, is relatively more viscous and slightly darker, which is preliminary for serum exposure. It is difficult for people to judge, but comparing the two can be easily distinguished.

Second, the main technical indicators

At present, the quality standard of domestic serum is the 2005 edition of the Pharmacopoeia of the People's Republic of China. The main indicators are as follows:

1, endotoxin

The standard is no higher than 5 EU/ml. Endotoxin is a component of the cell wall after bacterial disruption, so the level of endotoxin can indicate the aseptic operation in a series of processes from blood collection to production. At present, domestically produced serum can basically meet this requirement. Many imported fetal bovine serum endotoxin levels are higher, such as Gibco 26140, which only requires no more than 50 EU/ml, which is 10 times higher than our national standard, even 16000. There was no effect on serum quality at 10 EU/ml. It can be seen that the high endotoxin content does not affect the quality, unless the content is extremely high, indicating that it is already contaminated.

2, total protein content

The fetal bovine serum is generally in the range of 30-40 mg/ml, and the value is high, indicating that the cattle of the blood collection is too large, not the fetal calf, and the value is low, indicating that the serum may be mixed with water.

3, hemoglobin

The standard is no higher than 20mg/dl, the redder the color, the higher the value, and vice versa, the lower the value.

4, pH

Domestically produced serum, mostly above 7.5, imported fetal bovine serum, mostly below 7.5, the specific reasons are unknown, may be related to the age of cattle, which can also be used to initially identify the source of serum.

5, microorganisms

Including bacteria, mold, mycoplasma, phage, various pathogenic viruses. With the improvement of the production conditions of domestic serum manufacturers, "large" microorganisms such as bacteria and mold can be controlled by 100%, and most of the mycoplasma can be removed after 0.1um filtration. The contamination of E. coli phage is still relatively serious, mainly brought into the process of production environment, and can not be filtered, it is difficult to completely remove, but has little effect on serum quality. Pathogenic viruses, especially BVDV, exist in almost 90% of domestic serum. These microorganisms are one of the important factors affecting the quality of domestic serum, and the imported fetal bovine serum is basically well controlled.

6, immunoglobulin

The domestic serum is only qualitatively tested, and the results are also very inaccurate. Most of the imported fetal bovine serum is quantitatively detected. The value of immunoglobulin can fully reflect the age of cattle at the time of blood collection. Domestically produced serum is basically newborn cattle. IgM is easily produced in serum, and the content of IgG is also high. Imported fetal bovine serum does not contain IgM or IgG. The content is also low.

7, other

Whether domestic or imported serum, antibiotics are not tested (except for tetracycline-free fetal bovine serum). In foreign countries, the use of antibiotics is very strict and the dosage is very small. The products of each cow including serum can be traced. Therefore, the fetal bovine serum can be free of antibiotics or the content is extremely low. Domestically, the abuse of antibiotics has become common. Phenomenon, high residual in serum, is extremely unfavorable for cell culture, which is the root cause of poor quality of domestically produced serum.

Third, the blood source

Serum blood sources in the market are mainly divided into China, North America, South America and Australia.

1. The quality of domestically produced serum is poor. This is recognized. The main reason is not the responsibility of the manufacturer, but the poor natural environment and the extensive use of antibiotics. The domestic environment is seriously polluted, and the antibiotics are extremely abused during the breeding process. The toxic and harmful substances will remain in the serum in large quantities, which is not conducive to the growth of the cells.

2, South American serum, a lot of sources, such as Bioind's Panama, Gibco's Uruguay, Brazil, etc., these serum due to uncontrollable blood collection, quality is uneven, of course, compared to domestic serum is much better. In addition, domestically sold South American sera are mostly bright red, such as Bioind, Gibco, Hylene and other brands, but Argentina's serum is exceptional, which may be related to blood collection and production processes in various countries.

3, North American serum, mainly from the United States and Canada, such as Hclone's SH30396, SH30070, SH30071, Gibco's 16000-044, 26140-079 and so on. This type of serum, the higher the grade, the lighter the color, the light yellow with a little reddish, SH30070 and SH30396 contrast is very obvious, the special fetal bovine serum can basically carry out stem cell culture. Another notable feature of North American serum is that each bottle of serum is traceable, which is especially important for some large vaccine plants and pharmaceutical companies.

4, Australian serum, the source is mainly New Zealand and Australia, which entered the Chinese market after the North American serum embargo, generally does not have traceability function, due to production, transportation and other reasons, the price is relatively expensive. Compared with Gibco's 10099 and 16000, the latter has a higher quality grade, a lighter color and a higher cost performance.

The above information resources are compiled and released by Nanjing Huike Experimental Equipment Co., Ltd., for reference only.

Nanjing Huike Experimental Equipment Co., Ltd. is the agent of imported brands Gibco and Hyclone fetal bovine serum and other brand serum, complete product range, long-term quality assurance, providing comprehensive pre-sales and after-sales service, welcome new and old customers to patronize!