About Us

We are a premier bioconjugation service provider with over 15 years of specialized expertise in Custom Antibody Labeling. As an integral part of our comprehensive antibody services portfolio, our dedicated conjugation laboratory focuses on one critical mission: transforming your precious antibodies into highly functional, application-ready detection tools. Our team of PhD-level chemists and protein scientists has successfully executed thousands of labeling projects, mastering the delicate balance between preserving antibody affinity and achieving optimal label incorporation. We serve academic researchers, diagnostic developers, and pharmaceutical companies globally, providing reliable, high-quality conjugation services for a vast array of antibody formats (monoclonal, polyclonal, recombinant fragments) and label types. We understand that a successful conjugate is the cornerstone of sensitive and specific assays, and we are committed to delivering products that meet the highest standards of performance and consistency.

☞Antibody Labeling Process

Our labeling process is a rigorous, multi-step workflow built on robust chemistry and stringent quality control to ensure the conjugate's functionality and stability.

 Phase 1: Antibody Pre-QC & Buffer Exchange 

• Input Analysis: We begin by analyzing your provided antibody. We assess its concentration (A280), purity (SDS-PAGE), and aggregation state (optional SEC-HPLC) to ensure it is suitable for labeling.

• Buffer Optimization: Antibodies are typically transferred into a conjugation-optimal buffer (e.g., carbonate/bicarbonate, PBS, or borate buffer at pH 8.5-9.5) via dialysis or gel filtration to remove interfering amines (e.g., Tris, azide) and to achieve the ideal pH for reaction.

 Phase 2: Conjugation Chemistry & Reaction 

We select and execute the most appropriate chemistry based on the label and the desired application:

 Phase 3: Purification & Removal of Unconjugated Label 

• Size-Exclusion Chromatography (SEC): The primary purification method. Using columns like PD-10 or HPLC SEC, we separate the high-molecular-weight antibody-conjugate from unreacted small-molecule dyes, biotin, or enzymes.

• Additional Purification: For enzyme conjugates, affinity chromatography may be used. For demanding applications, further purification via ion-exchange or hydrophobic interaction chromatography can be performed to remove aggregates or over-labeled species.

Phase 4: Characterization & Quality Control

Every conjugate undergoes comprehensive QC before release:

• Degree of Labeling (DOL) Calculation: Precisely measured by spectrophotometry, calculating the ratio of label absorbance to antibody absorbance (e.g., A280 for antibody, A495 for FITC, A280/A650 for Alexa Fluor 647).

• Concentration Determination: Final antibody concentration is measured and reported.

• Functionality Validation (Critical):

  ELISA: Testing to confirm the conjugate retains its ability to bind the target antigen.

  Specific Activity (for enzyme conjugates): Measurement of enzyme activity per mg of antibody.

  F/P Ratio Verification (for fluorescent conjugates): Confirmation of the fluorescein-to-protein (F/P) or dye-to-protein ratio.

• Purity & Aggregation Analysis: SDS-PAGE (stained for both protein and fluorescence, if applicable) and/or SEC-HPLC to confirm purity and the absence of high-molecular-weight aggregates.

Phase 5: Formulation & Storage

The final conjugate is formulated into a stabilizing buffer (often containing BSA or gelatin as a carrier protein and a preservative like sodium azide or ProClin™), sterile-filtered (0.22 µm), aliquoted to prevent freeze-thaw cycles, and shipped under appropriate conditions.

Figure1.Two site-specific labelling strategies for the conjugation of the macrocyclic chelating agent, DOTA, to the anti-Leucine Rich Repeat Containing 15 (LRRC15) mAb DUNP19 were studied.

☞Why Choose Our Labeling Service?

Labeling an antibody is a critical, often irreversible step that can make or break an assay. Partnering with us minimizes risk and maximizes success.

• Expertise in Delicate Protein Chemistry: Our chemists specialize in the nuanced chemistry of antibodies. We expertly navigate the trade-offs between label density and antibody activity, employing strategies to maximize signal while preserving immunoreactivity—a balance that is difficult to achieve without deep experience.

• Preservation of Antibody Activity is Paramount: We treat your antibody's affinity and specificity as our top priority. Our process optimization and QC are designed first and foremost to ensure the labeled antibody remains fully functional. Our validation includes a mandatory antigen-binding check.

• Wide Range of Labels & Custom Chemistries: We offer conjugation to an extensive catalog of labels, from common dyes and enzymes to rare or custom probes. We can also advise on and execute novel or specialized conjugation strategies to meet unique project needs.

• Rigorous, Data-Driven Quality Control: We provide full transparency. Every conjugate comes with a detailed Certificate of Analysis (CoA) that includes the critical DOL/F/P ratio, concentration, purity data (gel images), and proof of functionality. You know exactly what you are receiving.

• Efficient & Reliable Turnaround: We have optimized our workflows for efficiency. You receive your high-quality conjugate in a predictable timeframe, accelerating your research or product development schedule.

• One-Stop Solution & Expert Consultation: From buffer exchange and labeling to purification and validation, we handle it all. Our team is available for technical consultation to help you select the best label and chemistry for your specific application (e.g., flow cytometry, IHC, Western blot, ELISA).

☞Our Service Workflow

Our streamlined, client-focused workflow ensures a smooth, transparent, and collaborative experience.

 Step 1: Project Inquiry & Consultation 

Contact us with details about your antibody and desired label/application. We provide a recommendation on the optimal conjugation strategy and a formal quote.

 Step 2: Project Initiation & Sample Submission 

Upon approval, you ship your purified antibody (>100 µg recommended) to our facility. We provide a sample submission form to capture all necessary specifications.

 Step 3: Antibody QC & Pre-Treatment 

We perform initial quality checks and buffer exchange if required. We contact you if any issues with the starting material are identified.

 Step 4: Conjugation Reaction & Purification 

Our chemists execute the conjugation under optimized conditions, followed by thorough purification to remove unconjugated label and aggregates.

Step 5: Characterization, QC & Client Report 

The conjugate undergoes full characterization. We send you a pre-shipment QC report with key data (DOL, concentration, SDS-PAGE) for your review.

 Step 6: Final Formulation & Delivery 

Upon your confirmation, we formulate, aliquot, and ship the final conjugate on dry ice or with cold packs, along with the comprehensive Certificate of Analysis.

 Our Service Process Flowchart: 

☞Common Tags Used in Antibody Labeling

We offer conjugation services for a comprehensive range of tags and labels to suit every application need.

A. Fluorescent Dyes (for Imaging & Flow Cytometry):

• Alexa Fluor® Series (488, 555, 568, 594, 647, 680, 750): Bright, photostable, and pH-insensitive dyes. The industry standard for most fluorescence applications.

• DyLight® Fluors (350, 405, 488, 550, 594, 633, 650, 680, 755): Comparable to Alexa Fluor dyes, offering excellent brightness and stability.

• FITC (Fluorescein Isothiocyanate): A classic green fluorescent dye, cost-effective but prone to photobleaching.

• PE (Phycoerythrin) & APC (Allophycocyanin): Large, extremely bright phycobiliproteins used primarily in flow cytometry. Require specialized conjugation.

• Tandem Dyes (e.g., PE-Cy5, PE-Cy7, APC-Cy7): Conjugates where energy is transferred from a donor fluorophore (PE/APC) to an acceptor dye, enabling multicolor panels.

• ATTO & Cy® Dyes (Cy3, Cy5, Cy5.5, Cy7): Well-established, high-performance organic dyes.

B. Enzymes (for Chromogenic & Chemiluminescent Detection):

• HRP (Horseradish Peroxidase): The most common enzyme for ELISA and Western blotting. Catalyzes reactions with substrates like TMB (colorimetric) or luminol (chemiluminescent).

• AP (Alkaline Phosphatase): Another popular enzyme, used with substrates like BCIP/NBT (colorimetric) or CDP-Star (chemiluminescent). Stable and effective.

C. Non-Fluorescent Tags & Haptens:

• Biotin: A small vitamin tag that binds with extremely high affinity to streptavidin/avidin. Enables powerful signal amplification in multiple assay formats.

• DNP (Dinitrophenol) / Digoxigenin (DIG): Small hapten tags used in specialized applications like in situ hybridization and some ELISA formats.

D. Specialty & Functional Tags:

• Biotinylation (Site-Specific): Using cleavable biotin or enzymatic biotinylation (BirA enzyme) for highly controlled labeling.

• Crosslinkers & Photoactivatable Groups: For creating antibody-oligonucleotide conjugates (for imaging mass cytometry) or other advanced constructs.

Let our experts handle the critical conjugation step. Contact us today to discuss your Custom Antibody Labeling project and obtain a high-performance, ready-to-use conjugate that ensures the success of your most important assays.