- Cart 0
- English
Donkey Serum: An Essential Technical Tool in Immunological Experiments
June 12, 2026
Clicks：78
Behind the faint fluorescent signals in the laboratory lies a critical experimental step — selecting an appropriate blocking serum.
In immunohistochemistry experiments, a researcher once encountered a troublesome issue: excessive background noise and blurred fluorescent signals of target proteins. The problem was effectively resolved after adopting donkey serum as the blocking solution, yielding clear and distinguishable experimental results.
As a common reagent in life science research, donkey serum is featured with low cross-reactivity and high blocking efficiency, making it an indispensable product in numerous laboratories.
01 What is Donkey Serum?
Simply put, donkey serum is a pale yellow transparent liquid isolated from the blood of healthy donkeys after a series of treatments. When blood coagulates naturally without anticoagulants, serum is separated out.
The most distinct difference between serum and plasma is that serum contains no fibrinogen. Meanwhile, a variety of substances released by platelets and coagulation factors are altered during the coagulation process.
In terms of classification, donkey serum is divided into general donkey serum and normal donkey serum specially formulated for immunological assays. Normal donkey serum refers to the serum collected from healthy donkeys without specific antigen immunization.
It does not contain high levels of antibodies against specific antigens, but consists of conventional complements and various immunoglobulins naturally present in healthy donkeys.
In production, donkey serum is manufactured via aseptic blood collection from healthy donkeys, followed by coagulation, centrifugation and microporous filtration. Some products are further processed by lipid extraction for higher clarity, desalting and dialysis, and finally preserved in liquid or lyophilized powder form.
02 Functions of Donkey Serum
Donkey serum exerts multiple vital functions in cell culture and immunological experiments, which are summarized into six categories as follows:
Nutritional Support: Donkey serum provides hormones essential for exponential cell growth, as well as nutrients that are deficient or absent in basic culture media.
It serves as a major source of low-molecular-weight nutrients and builds a favorable microenvironment for cell proliferation.
Binding and Transport: Serum contains diverse binding proteins that recognize vitamins, lipids, metal ions and hormones. These proteins can bind substances and modulate their biological activities, playing a key role in cellular metabolism.
Protection and Detoxification: Under certain conditions, binding proteins combine with toxic metals and pyrogens to achieve detoxification. This function protects cells from harmful substances and maintains normal cell growth.
Cell Adhesion Promotion: Donkey serum supplies adhesion factors required for cells to attach and spread on plastic culture substrates, which is critical for adherent cells.
Buffering Regulation: Serum acts as a pH buffer solution to stabilize the pH of culture environment and create optimal living conditions for cells.
Enzyme Inhibition: Donkey serum contains protease inhibitors, which inactivate residual trypsin during cell passaging and prevent cells from trypsin-induced damage.
03 Application Scenarios of Donkey Serum
As a fundamental laboratory reagent, donkey serum is widely applied in various research fields, especially in immunological assays.
Immunohistochemistry & Immunofluorescence
In these assays, donkey serum is mainly used as a blocking agent to block non-specific protein binding sites and endogenous Fc fragment binding sites on samples.
This operation blocks the binding between antibodies and Fc receptors on specimens, thereby reducing background signals and false-positive results.
In routine protocols, 5-10% normal donkey serum (diluted at 1:10 to 1:20) is applied for blocking at room temperature for 5-10 minutes. It is unnecessary to wash the sample after blocking, and the diluted primary antibody can be added directly.
This blocking procedure effectively improves the signal-to-noise ratio and enables clear and accurate localization of target proteins.
ELISA
In Enzyme-Linked Immunosorbent Assay (ELISA), donkey serum also plays an important role. Generally, dilute donkey serum with PBS at a ratio of 1:100 and incubate at 37°C for 1 hour.
By blocking non-specific binding sites on ELISA plates, donkey serum lowers experimental background and enhances detection sensitivity and accuracy.
Cell Culture
Donkey serum shows unique advantages in the in vitro culture of specific cell types. Researches have proven that supplementing with donkey autologous serum at appropriate concentrations can promote proliferation and migration of donkey granulosa cells.
Compared with fetal bovine serum, donkey serum provides a more compatible combination of growth factors for culturing homologous cells.
Western Blot
In Western Blot assays, donkey serum acts as a blocking agent to occupy non-specific protein binding sites on blotting membranes.
It minimizes non-specific antibody binding, so as to obtain distinct target protein bands and improve the reliability of experimental results.
04 Standard Operating Procedures for Donkey Serum
Proper usage and storage methods are essential to guarantee the performance of donkey serum.
Storage Conditions: Store donkey serum at below -20°C and avoid repeated freeze-thaw cycles. The remaining serum after opening can be stored at 4°C for no more than one month.
For lyophilized donkey serum, aliquot and store at -20°C or lower after reconstitution if not for immediate use.
Thawing Method: Take the serum out of the freezer, thaw gradually at 2~8°C first, then warm to room temperature completely. Shake gently and uniformly during thawing to ensure homogeneous components.
Note that long-term storage at 2~8°C may cause aggregation of proteins and lipoproteins, resulting in precipitation or turbidity. The sediment can be removed by centrifugation at 3500 rpm for 10 minutes under aseptic conditions.
Application Tips:
- Dilution: Dilute donkey serum to target concentration with 0.01mol/L PBS (pH 7.2-7.4). 5% working concentration (1:20 dilution) is the commonly used starting concentration for most blocking experiments.
- Blocking Time: The routine blocking duration is 5-30 minutes at room temperature, which can be adjusted according to different experimental requirements.
- Control Setting: Normal donkey serum is frequently used as a negative control in immunological assays to evaluate assay specificity.
05 Future Application Prospects
Apart from conventional immunological experiments, donkey serum also presents great potential in cutting-edge research fields.
Recent studies have demonstrated that donkey serum albumin (DSA) extracted from Colla Corii Asini possesses excellent antioxidant activity. At the concentration of 10.0 mg/mL, the scavenging rates against superoxide anion radicals, ABTS⁺ radicals, DPPH radicals and hydroxyl radicals reach 73.39%, 83.61%, 71.24% and 83.79% respectively.
This finding opens up new possibilities for developing donkey serum into functional foods and natural antioxidants.
In veterinary diagnostics, donkey serum has been applied to establish detection methods for Mycoplasma bovis which causes calf pneumonia and arthritis. As a blocking agent, it enables accurate pathogen detection in immunoenzymatic histochemistry.
With technological advancement, the application scope of donkey serum keeps expanding in immunoassays, cell culture and biotechnology. Its low cross-reactivity makes it an ideal choice for complex experiments such as multi-color immunolabeling and multiplex detection.
As technology evolves, this classic laboratory reagent continues to gain new vitality. In the future, donkey serum is expected to be further applied in tissue engineering, vaccine development and high-sensitivity diagnostic techniques.
Regardless of the expanding application scenarios, its core value always lies in assisting researchers to explore the unknown territory of life sciences and uncover the mysteries in the microscopic world.
Absin Donkey Serum Recommendation
| Catalog No. | Product Name | Specification |
|---|---|---|
| abs935 | Donkey Serum | 100mL |
Contact Absin
Absin provides antibodies, proteins, ELISA kits, cell culture, detection kits, and other research reagents. If you have any product needs, please contact us.
| Absin Bioscience Inc. worldwide@absin.cn |
 Follow us on Facebook: Absin Bio |