Microsphere markers play an important role in biomedical research, clinical diagnosis, and other fields. They are often used in techniques such as immune testing and molecular diagnostics, achieving accurate detection of target substances by binding to specific biomolecules. However, during the storage process of microsphere markers, unstable storage often occurs, among which signal attenuation is one of the more common problems. Many people often believe that buffer solution is the main cause of unstable storage of microsphere markers, but in reality, this phenomenon involves multiple complex factors.

hepes powder

Reasons for signal attenuation

1. Microsphere aggregation: When the ion strength of the buffer solution is too high, it can cause charge shielding, weakening the electrostatic repulsion between originally mutually repulsive microspheres, leading to microsphere aggregation. In some detection experiments, if the ionic strength of the buffer solution exceeds the appropriate range, microspheres will gradually aggregate together, forming larger aggregates. These aggregates not only alter the particle size distribution of microspheres, but also affect their binding ability with target biomolecules, leading to signal attenuation in detection. The lack of surfactants is also an important reason for microsphere aggregation.

2. Antibody inactivation or detachment: The coupling stability between antibodies and microspheres is one of the key factors affecting the preservation of microsphere markers. If the coupling chemical bond is unstable, the antibody may gradually detach from the surface of the microsphere during storage, causing the microsphere to lose its labeling function and the signal to weaken.

3. Degradation of fluorescent substances: The signal of fluorescent microsphere markers mainly depends on the luminescence of fluorescent substances. However, fluorescent dyes are easily affected by photobleaching. If no light avoidance measures are taken during storage, the fluorescent dye molecules will undergo irreversible structural changes after absorbing photons, resulting in a gradual decrease in their luminescence intensity. Oxidation or hydrolysis reactions may also disrupt the structure of fluorescent groups, causing them to lose their luminescent ability. In some environments containing oxygen or water, fluorescent dye molecules may react with oxygen or water molecules, leading to the degradation of fluorescent groups and causing signal attenuation of microsphere markers.

4. Unstable components in the buffer: The lack of stabilizers such as proteins, sugars, etc. in the buffer can result in a lack of protection for antibodies and microspheres during storage. Proteins and carbohydrates can form a protective film by interacting with groups on the surface of antibodies or microspheres, reducing non-specific adsorption and interference from external factors.

Optimization suggestions

1. Optimization of buffer formula: Choose a suitable buffer system, PBS or HEPES buffer systems with pH 7.2-7.4 are commonly used. This pH range is close to the physiological pH of most biomolecules and can maintain the stability of antibodies. Adding stabilizers is an important measure to optimize the buffer formula. 0.5-1% BSA or fetal bovine serum can reduce non-specific adsorption, protect antibodies and microspheres. Carbohydrates, such as 1-5% trehalose or sucrose, protect protein structure through the "water substitution" effect. Surfactants such as 0.01-0.1% Tween-20 or Triton X-100 can inhibit microsphere aggregation. Antioxidants, such as 0.1% ascorbic acid or 0.05% EDTA, can prevent oxidative damage and protect the activity of fluorescent substances and antibodies.

2. Coupling process improvement: Adopting more stable coupling chemical methods can improve the coupling stability between antibodies and microspheres. The streptavidin biotin system or click chemistry coupling methods have high specificity and stability, which can form strong chemical bonds and reduce the risk of antibody detachment. Blocking the unbound sites on the surface of microspheres after coupling can reduce non-specific adsorption and improve the specificity and stability of microsphere markers. Common sealing agents include ethanolamine or glycine.

3. Optimization of storage conditions: Generally speaking, 4 ℃ and light avoidance storage are ideal conditions, which can slow down the degradation rate of microsphere markers. Avoid repeated freezing and thawing, as ice crystals may form during the freezing and thawing process, which may damage the structure of microspheres and antibodies. If freezing is required, 10% glycerol can be added. Choosing the appropriate preservative is also crucial. Using ProClin 300 (0.05%) instead of sodium azide can avoid interference with antibody activity and inhibit microbial growth.

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Recommended formula for basic preservation solution

The basic buffer can be selected from 10 mM PBS (pH 7.4) or 10 mM HEPES buffer (pH 7.2). PBS has good buffering capacity and biocompatibility, which can provide a stable acid-base environment for microsphere markers. HEPES performs well in some experiments that require high buffering performance, with a relatively stable buffering range that can maintain the activity of microsphere markers.

The unstable storage of microsphere markers is a complex issue, and although buffer solution is an important factor, it is not the determining factor. As a manufacturer of biological buffering agents, Hubei Xindesheng has excellent buffering effect and can stably maintain the pH of the system. Xindesheng has become a trusted partner for numerous research institutions and enterprises. If you are interested, please feel free to contact us!