After the preparation of immune colloidal gold, it needs to be diluted to a certain concentration and adsorbed in special inert media to make the product. In general, special media are commonly used as glass fiber or non-woven fabrics. Glass fiber and non-woven fabric themselves are generally hydrophobic, and the colloidal gold industry generally uses surfactant pretreated glass fiber or non-woven fabric, usually the formula is 1%Tween20 + moderate PVA. After media treatment, the compatibility of immune colloidal gold dilution is the most critical. The present summary principles are summarized as follows:

1. Suitable ion species and strength

After all, immune colloidal gold contains bioactive molecules, and it also faces many different samples when applied. In principle, it needs to be diluted in a buffer with suitable PH. The empirical value is 6-9. The optional buffers in this range are mainly Tris and PB, and they do not exclude other kinds of buffers. When the buffer ion strength used is too large more than 0.2M, it may cause poor release, poor chromatography, or abnormal detection results. The variety of ions also has many limitations due to the different biomolecules of immune colloidal gold, such as calmodulin may be related to Ca 2 + ions. The halogen ion strength seems to have a special destructive effect on the colloidal gold stability, such as the textbook optimal labeling conditions for NaCl debugging.

2. Macromolecular material acts as evenly dispersed skeletons of dried colloidal gold

This is actually the theoretical basis of the freeze-drying process, which is suitable for the colloidal gold drying process. Those who have studied freeze drying should feel very small about this process. Vacuum is a thermodynamic endothermic process. Expershow that vacuum drying of colloidal gold is a process of freezing and then sublimation, which is very similar to lyophilization. Due to the fast drying process, non-woven materials use most of the drying process, but the skeleton action of macromolecules is still of great help to the release speed and ratio of the product. Commonly used macromolecular substances such as PEG4000, PEG20000, PVP, etc., it is recommended to choose one as far as possible.

3. Small molecular material for protection against protein activity

Glycerol, sucrose, trehalose, and various oligosaccharides commonly used in protein storage are helpful to the storage stability of products. Ignoring the addition of these substances may limit the production and market of products from the laboratory. These substances are also commonly used by frozen stem cells.

4. Inert protein

The functions of such substances are even more complex. First of all, it protects the activity of the target protein and maintains the colloidal stability of colloidal gold. They eliminate non-specific closed substances and also play the skeleton role of dispersed colloidal gold particles. Often used BSA, OVA, Casein, and other cheap protein seems to be not easy to find, skim milk powder personal advice, the quality is too difficult to control, of course, if you have been using it and the effect is good, there is no need to worry too much.

5. Surface active agent

This thing is absolutely indispensable in this industry, but the adsorption material has been pretreated with surface activity, or can not be added to the immunocolloid gold diluent. Under normal circumstances, Tween20 is ok, in fact, protein regulation commonly used non-ionic surfactants can try, a period of time ago a high person said TritonX-100 may interfere with the N end of the protein is not used, I listened not very understand, here please give advice.

6. Other

Product species differ, the above five types of material, legend and some can "improve product sensitivity", "improve product detection linear range", "forced conversion * * detection best cut-off range", "HAMA effect inhibition" and "line time depth change end" such as mysterious addition, theoretically does not rule out the possibility, but often a "god" effective range is very narrow, that is to say, a "god" may only apply to a company an antibody of a product, another environment is invalid. The job looking for god is often the senior technical personnel of a large company with research and development type, and the control of the gods is often like the enterprise secret.