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Site-Specific & Re-bridging Conjugation Services

Precision-engineered conjugation for antibodies and nanobodies using cysteine re-bridging, enzymatic ligation, and glycan or click chemistries. Achieve homogeneous conjugates, controlled DAR, and LC-MS verified quality under ISO-certified systems.

ISO 9001/13485
LC-MS/HIC/SEC-MALS QC
Bench → Preclinical
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Overview

Bio-Synthesis conjugation services provide advanced site-specific platform enables homogeneous antibody-drug conjugates (ADCs) and nanobody-fluorophore conjugates through bioorthogonal click and enzymatic Sortase A labeling. We combine bis-maleimide re-bridging, enzymatic ligation, glycan-directed oxime/hydrazone, and click chemistry (DBCO↔Azide, TCO↔Tetrazine) to build homogeneous conjugates for ADC prototypes, imaging probes, and nanobody-drug conjugates.

Our linker portfolio (pyridazinedione, dibromomaleimide, Sortase A, TGase, FGE) is verified by LC-MS, HIC, and SEC-MALS under ISO 9001/13485 workflows—improving stability, pharmacokinetics, and reproducibility from discovery to preclinical scale.

Learn more about our antibody conjugation expertise or payload and label conjugation capabilities.

Engineered Cys Re-bridging (DAR≈2) Enzymatic (Sortase/TGase/FGE) Glycan (Oxime/Hydrazone) Click (DBCO / TCO)
Site-specific antibody conjugation via maleimide–thiol linking: engineered antibody (–SH) to payload

Core Conjugation Capabilities

Strategy Linker / Chemistry Applications QC Focus
Engineered Cysteine (IgG / Thiomab) Maleimide, vinylsulfone, pyridazinedione, click (DBCO–Azide / TCO–Tetrazine) ADC prototypes, precise fluorophore labeling LC–MS, HIC, SEC–MALS
Disulfide Re-bridging Bis-maleimide / dibromomaleimide, thioether re-bridging Homogeneous DAR≈2, stability improvement LC–MS subunit, DAR, SEC–MALS
Glycan-Directed NaIO₄ oxidation → oxime/hydrazone (aminooxy/hydrazide) Uniform Fc labeling with minimal CDR impact ELISA/SPR, LC–MS
Enzymatic Ligation Sortase A (LPXTG), Transglutaminase (Q-tag), FGE (formylglycine) N-/C-terminal precision Intact MS, activity assays
Nanobody (VHH/sdAb) C-terminal Cys-tag, Sortase A, DBCO–Azide or TCO–Tetrazine Imaging probes, nanobody-drug/oligo conjugates LC–MS, SEC, binding retention
Technical Notes & Sample Submission
  • Amount: ≥ 1 mg antibody (≥ 1 mg/mL); ≥ 2 mg if optimizing DAR or dual payloads.
  • Buffer: PBS/HEPES pH 7.0–7.5; avoid Tris/glycine (amines) & DTT/TCEP (reducing agents).
  • Nanobody Samples: 0.3–0.8 mg at ≥ 0.5 mg/mL; handles: C-terminal Cys-tag, azide/alkyne, or LPXTG for Sortase A.
  • Linkers Supported: Bis-maleimide, pyridazinedione, DBCO/azide, TCO/tetrazine, aminooxy/hydrazide.
  • Docs: Antibody/nanobody name, isotype/scaffold, clone/lot, concentration, buffer, desired chemistry & target DAR/DoL.
  • QC Package: LC–MS (intact/subunit), HIC (DAR), SEC–MALS (aggregation), ELISA/SPR/BLI (binding).
  • Shipping: 2–8 °C (cold pack) for liquid; dry ice for frozen; avoid weekend arrivals.
  • Return Format: PBS pH 7.4 (default) or user buffer; lyophilized on request.
  • Re-bridging Tip: Mild partial reduction (TCEP ≤ 1 mM, 5–10 min) before bis-maleimide quench.
Re-bridging: DAR ≈ 2 + restore disulfide Sortase A: terminal precision TCO/Tz + DBCO/Azide: orthogonal dual labels Glycan (Oxime/Hydrazone): uniform Fc Maleimide / Pyridazinedione: thiol-selective, stable
Linker Compatibility Table

✓ Compatible  |  △ Conditional (buffer or sequence dependent)  |  ✗ Avoid

Linker / Chemistry Cys (–SH) Amine (–NH2) Glycan (–CHO) Azide / Alkyne TCO / Tetrazine Notes
Maleimide / Vinylsulfone ✓ ✗ ✗ ✗ ✗ Thiol selective; pH 6.5–7.0; quench excess linker.
Bis-maleimide / Dibromomaleimide (Re-bridging) ✓ ✗ ✗ ✗ ✗ Disulfide re-bridging (DAR≈2) after partial reduction.
NHS / Sulfo-NHS Esters ✗ ✓ ✗ ✗ ✗ Amine coupling; avoid Tris/glycine during reaction.
Oxime / Hydrazone ✗ ✗ ✓ ✗ ✗ Glycan oxidation to –CHO; mild aqueous conditions.
Click: DBCO ↔ Azide (SPAAC) △ △ △ ✓ ✗ Copper-free; orthogonal to thiols/amines.
Click: TCO ↔ Tetrazine (IEDDA) △ △ △ ✗ ✓ Ultra-fast bioorthogonal coupling; great for dual payloads.
Pyridazinedione (Thiol-selective) ✓ ✗ ✗ △ △ Stable thio-conjugates; can combine with orthogonal click.
Enzymatic (Sortase / TGase / FGE) △ △ ✗ △ △ Depends on engineered tags and acceptor handles.

FAQ

Do you support nanobodies (VHH/sdAb)?
Yes—C-terminal Cys-tags (maleimide), Sortase LPXTG, or click handles (DBCO/azide or TCO/tetrazine) are supported. We deliver site-specific, homogeneous nanobody conjugates for imaging or payload delivery.
What information speeds up a quote?
Antibody/nanobody identity, buffer & concentration, desired chemistry (re-bridging/enzymatic/glycan/click), target DAR/DoL, QC requirements, and return buffer/format.
How do I choose between re-bridging, enzymatic, or glycan routes?
Choose re-bridging for DAR≈2 and restored disulfides; choose Sortase/TGase for terminal precision; choose glycan-directed when you need uniform Fc labeling away from CDRs. Click routes enable orthogonal dual payloads.
What’s a typical QC package?
Intact/subunit LC-MS, HIC for DAR distribution, SEC-MALS for aggregation, and binding (ELISA/SPR/BLI). Optional: release testing for cleavable linkers.
More FAQ'sAll FAQ's

Speak to a Scientist

Tell us about your biomolecule, desired label/payload, and intended use. We’ll recommend chemistry, linker design, and release testing to meet your goals.

Full Name *
Email *
Company / Institution *
Phone *
Project Type *Pick the primary route; we’ll advise if a hybrid strategy is better.
Desired ScaleWe support bench through preclinical quantities.
Preferred Linker / Notes
Payload(s)We also support dual payloads via orthogonal click.
Project Summary
Attach Spec / Sequence (optional)Include sequence or tag info (LPXTG, Q-tag, Cys-tag) if available.

By submitting, you agree to be contacted regarding your request.

972-420-8505 (USA) 800-227-0627 (INTL.) info@biosyn.com Contact Us

References

  1. Bio-Synthesis Inc. Custom Antibody Conjugation Services. www.biosyn.com
  2. Hermanson GT. Bioconjugate Techniques, 3rd ed. Academic Press, 2013.
  3. Chari RVJ et al. Antibody–Drug Conjugates. Angew Chem Int Ed. 2014;53(15):3796-3827.
  4. Glen Research — Labels & Modifiers Catalog. glenresearch.com

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