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Biotinylation
CellMosaic® offers a comprehensive portfolio of biotinylation kits, reagents, and custom bioconjugation services based on our proprietary AqT® (AqueaTether®) technology, available with either stable or releasable biotin linkages. Our product line supports multiple labeling strategies, including surface amine labeling, site-specific reduced thiol labeling, engineered Cys, N-glycan, and other specialized conjugation approaches for antibodies, proteins, and antibody-drug conjugates (ADCs).
Why Choose CellMosaic®?
CellMosaic combines proprietary AqT® linker technology with multiple site-specific biotinylation strategies to produce highly water-soluble, stable, and reproducible biotin conjugates while preserving biomolecular function.
| Feature | CellMosaic AqT® Biotinylation | Conventional Biotinylation |
|---|---|---|
| Water solubility | High | Low |
| Organic solvent required | Minimal or none | Usually required |
| Maximum biotin loading | Higher biotin loading | Limited |
| Heterogeneity and aggregation | Improved homogeneity and reduced aggregation | Greater heterogeneity and aggregation |
| Labeling options | Surface amines, reduced thiols, glycans, and engineered cysteines | Primarily surface amines |
| Antibody activity | Better preserved with site-specific labeling | May be affected |
AqT® Linkers: Water-Soluble Biotin for Better Bioconjugates
Biotin is highly hydrophobic and only sparingly soluble in water (0.19 mg/mL in a saturated aqueous solution measured at CellMosaic). Most conventional biotinylation reagents require significant amounts of organic solvent, which can promote protein aggregation, precipitation, and loss of activity during labeling.
CellMosaic's proprietary AqT® linker transforms biotin into a highly water-soluble reagent that enables biotinylation with minimal or no organic solvent. The increased hydrophilicity of AqT® biotin is demonstrated by C18 reversed-phase HPLC compared with commercially available biotinylation reagents. Click the figure links below to view the experimental results.
Figure 1. Overlay of C18 HPLC Chromatograms of AqT® Biotin Acid, Biotin, and Biotin-PEG4 Acid
Figure 2. Overlay of C18 HPLC Chromatograms of AqT® Biotin Maleimide, Biotin-PEG2 Maleimide, and Biotin-BMCC
The hydrophilic AqT® spacer creates a protective hydration shell around adjacent biotin molecules, rreducing hydrophobic interactions among neighboring biotin molecules and minimizing aggregation. As a result, antibodies and proteins can often be labeled with substantially higher biotin densities while maintaining excellent solubility, stability, and biological activity. Higher biotin loading can significantly enhance signal amplification in many detection and capture assays.
Site-Specific Labeling Technologies
Conventional NHS ester chemistry randomly labels surface lysine residues. CellMosaic also offers several site-specific biotinylation technologies, including reduced thiol labeling (Cat#: CM86141), engineered cysteine labeling, and glycan labeling. Site-specific conjugation provides more uniform biotin placement, preserves antigen-binding activity, improves reagent reproducibility, and can increase assay sensitivity by positioning biotin away from functional binding sites
Dual Labeling Technologies with AqT® Biotin
Cell-based binding and internalization assays, such as flow cytometry (FACS), often require biotinylated antibody–drug conjugates (ADCs) for detection. Because conventionally linked ADCs are already highly hydrophobic and close to theiir aggregation limit, additional biotin labeling is generally avoided.
CellMosaic's AqT® Biotin ADC Labeling Kit (Surface Amines) (Cat#: CM86145) enables direct dual labeling of ADCs, producing conjugates with a typical drug-to-antibody ratio (DAR) of 3–5 and 2–4 biotin molecules per antibody for reliable assay detection.
Performance Comparison
The performance of AqT® biotin technologies has been evaluated against commercially available biotinylation reagents using HIC-HPLC and SEC-HPLC. The results show reduced hydrophobicity and heterogeneity, minimal aggregation, improved stability, and higher achievable biotin loading. Click the figure links below to view the experimental results.
Figure 3. Comparison of HIC-HPLC Profiles of Antibodies Labeled with Various AqT® Biotin Loadings and Conventional Biotin Linkers (PEG2 and BMCC) via Reduced Thiol Labeling
Figure 4. Comparison of HIC-HPLC Profiles of Antibodies Labeled with Various AqT® Biotin Loadings and Native Biotin (No Spacer Linker) via Surface Amine Labeling
These advantages result from two complementary technologies: CellMosaic's proprietary AqT® linker, which minimizes hydrophobicity, and versatile labeling chemistries that enable both conventional and site-specific biotinylation.