Biotin-Avidin System

Biotin is a small-molecule vitamin compound that is naturally available. Avidins (such as streptavidin) are tetramer proteins that can bind closely to biotin. Their combination is the most secure non-covalent interaction in nature, with an unusually slow off rate and strong affinity, and can withstand extreme pH and ionic strength washing. Biotin-avidin system is mostly used in molecular biology and bio-nanotechnology, where it amplifies signals through strong specificity and affinity, performing quantitative detection and sample purification.

Fig.1 Biotin-avidin system in clinical immunoassays. (John, et al., 2020)

Biotinylated Oligonucleotides

Biotin-modified oligonucleotides can be tightly bound to streptavidin by a biotin-avidin system, which can be labeled with fluorescent dyes and enzymes or attached to solid surfaces as required to achieve the experimental or diagnostic goals. Biotin is usually added to the 5' end or 3' end of the oligonucleotide by a C6 or triethylene glycol (TEG) spacer. Biotin deoxythymidine (Biotin-dT) is used to link biotin to the interior of the oligonucleotide, which does not disrupt the nucleotide spacing. Photocleavable biotin modifications have been made possible by adding a spacer between biotin and oligonucleotide that is cleaved under exposure to 300-350 nm UV light.

Fig.2 Chemical structure of biotin phosphoramidite used in 5'-labeled primers for PCR amplification. (CD BioGlyco)

Biotin-based Oligonucleotide Modification Service at CD BioGlyco

Biotin labeling is the most popular attachment chemistry for oligonucleotide modification. CD BioGlyco launches a variety of biotinylated oligonucleotide synthesis services to ensure your safe use in different experiments and diagnostics.

• 5'-biotin linkers: By adding a 5'-biotinylated primer to the PCR amplification reaction, the products can be attached to biotin and separated from the unlabeled DNA strands. The separated strands can be sequenced, cut, cloned, or hybridized and probed by complementary oligonucleotides. Biotin-C6 linker and biotin-TEG linker are commonly used. The spacer with larger atom numbers reduces the steric hindrance, allowing the biotin portion to bind to streptavidin more easily. In addition, according to your needs, we customize dual-biotin-modified or even multi-biotin-modified oligonucleotides to improve the target binding affinity, signal strength, and sensitivity of detection.
• 3'-biotin linkers: It is consistent with the 5'-biotin linker modification strategy. 3'-biotinylated Oligonucleotides can be purified by streptavidin affinity columns. In addition, in PCR amplification, the biotin tag at the 3'-end can be used to prevent the digestion of 3'-exonuclease as well as the 3'-extension.
• Internal biotin linkers: The internal biotin label is connected by the addition of biotin-dT, and the longer spacer will allow the nucleotide interval to remain.

Fig.3 Some biotin linkers. (CD BioGlyco)

Applications

• Non-radioactive immunoassay detection.
• Nucleic acid isolation (PCR product isolation).
• Detection of specific DNA/RNA sequences.
• Molecular diagnosis: nucleic acid detection, genetic diagnosis, pathogenic microorganism detection, early screening of tumors.
• Development of nucleic acid drug.

Highlights

• Mature technology for oligo biotin modification.
• Various biotin labels (3'/5'-biotin linkers, internal biotin linkers, spacers with different lengths).
• Personalized and customized service.
• Professional expert team.
• End-to-end guidance.

CD BioGlyco has a dedication to innovation, the highest standard of quality, and expertise in Sugar-nucleotides Synthesis. The backroom team at CD BioGlyco has always been committed to pushing science forward and providing unparalleled service. Please feel free to contact us if you are interested in our services.