Fluorescent Dye Labeling
Fluorescent Probesg

Fluorescent Labeling Probes

Labels, tags and probes containing small compounds such as florescence, visible chromogenic character can be used to label proteins and nucleic acids. Bio-affinity towards other molecules (biotin, digoxygenin), enzymatic (AP, HRP) or chemiluminescent (esters or acridine) can be used as well. Bio-Synthesis has unique and unrivalled expertise in research and development, offering you the best quality fluorescent probes and multiple labels within the same molecule. Each labeled probe service is meticulously monitored according to our stringent quality assurance and quality control standards for an optimized label to biomolecule ratio.

Fluorescent Dyes:

  • Fluorescein Derivatives
  • Rhodamine Derivatives
  • Coumarin Derivatives
  • BODIPY Derivatives
  • Cascade Blue Derivatives
  • Lucifer Yellow Derivatives
  • Phycobiliprotein Derivatives
  • Enzyme
  • Organometalic Compound

Bio-Synthesis Custom Reporter Molecule Labeling Services includes experimental design, development of protocols and procedure for the preparation of conjugates to be used in various detection and assay system. For the last two decades, we have accumulated a portfolio of reporter conjugates. To obtain further information regarding custom bioconjugation, contact our Technical Service Center at 800.220.0627 or contact us online with your detail project specifications. A project manager will be assigned to help you with design and develop an appropriate synthetic method

Custom Biopolymer Labeling

There are multiple ways to label biopolymers. The choice is determined by the technique you are going to use in your experiment. Detection of probes or labels usually takes one of three general forms: spectrophotometric, radiosensitive detectors or indirectly through another labeled substance. Spectral probes can be of two types, chromogenic or fluorescent. Chromogenic labels typically are reserved for non-covalent staining of gross structural features within cells and tissues, as these are present at relatively high concentration. The sensitivity of visible wavelength dye is not often good enough to provide detectability for low-concentration antigens or low-copy proteins. Even if a protein is covalently modified with a chromogen, the number of associated dye molecules needed to detect it just through its absorbance properties could be prohibitively large to make it visible.

Fluorescent molecules, by contrast, can provide tremendous sensitivity due to their property of discrete emission of light upon excitation. Protein, nucleic acids and other molecules can be labeled with fluorescent probes to provide highly receptive reagents for numerous in vitro assay procedures. For instance, fluorescently tagged antibodies can be used to probe cells and tissues for the presence of particular antigens and detected through the use of fluorescence microscopy techniques. Since each probe has its own fluorescence emission character, more than one labeled molecule-each tagged with a different fluorophore can be used at the same time to detect two or more target molecules.

Fluorescent labeling is the process of covalently attaching a fluorophore to another molecule, such as a protein or nucleic acid. This is generally accomplished using a reactive derivative of the fluorophore that selectively binds to a functional group present in the target molecule. The most commonly labeled molecules are antibodies,which are then used as specific probes for the detection of a particular target.Fluorescent labeling can be applied to a wide variety of detection systems and allows sensitive and quantitative measurement.

Whether you are labeling proteins and antibodies for immunofluorescence, nucleic acids for in situ hybridization or lipids for membrane studies, Bio-Synthesis will help you find the right conjugation product.

Custom Biomolecule Labeling Services

Service Portfolios

  • Oligonucleotide Labeling
  • Peptide Labeling
  • Antibody Enzyme Labeling
  • Antibody Fluorescent Dye Labeling
  • Half antibody Labeling through Thiol
  • Protein Labeling
  • Enzyme l\Labeling
  • Oligo redox Labeling
  • Organometalic Compounds
  • Antibody Gold Labeling
  • Oligo qDot Labeling

Sample Submission Requirement

Biomolecules supplied by customers should be sufficiently pure. Please provide 1-3 mgs of starting material with the necessary data for purity assessment. Commercially available biopolymers can be supplied by customers or synthesized and ordered through Bio-Synthesis.


Price varies based on the project specifications. Our service includes materials and labor for conjugation only! Price does not include the cost of biopolymer synthesis or Bio-Synthesis orders from commercial vendors and, if deemed necessary, biopolymer modifications to introduce additional functional groups, extra linkers and spacers. Please contact us for a quote.


Coupling of preactivated labels and biomolecules with chemical reactive groups such as amine, acid, aldehyde, hydrazine, hydroxyamine, maleimide/alkyl halide and sulfhydryl functional group.

Service Specification: Our reporter labeling services are prepared by techniques that can allow site specific conjugation. Labeling ratio can be optimized at client's request. After standard desalting or purification, a small percent of heterogeneous products containing single or multi-site conjugate per molecule may exist.


Biomolecules we use to label with various dyes, tags or probes are:

  • Protein: Enzyme, antibodies, antigens, cell adhesion molecules
  • Peptides: Synthetic polypeptides
  • Saccharides: Sugars, oligosaccharides and polysaccharides
  • Lipids: Fatty acids, phospholipids, glycolipids and any fat-like substances.
  • Ligands: Hormone receptors, cell surface receptors, avidin and biotin, small molecules
  • Labels: Fluorescent dyes, infrared-absorbing and UV-Vis absorption chromophores, nonradioactive labels
  • Nucleic acids and nucleotides: DNA, RNA, PNA, nucleic acid analogs and genomic DNA
  • Synthetic polymers: PEG, Nanoparticles, gold particles, dendrimers, dendron, PAMAM
  • Others: Conjugated or mixtures of any the above
  • Solid Supports: agarose, glass plates, membrane, beads


After labeling, final conjugates must first be isolated from excess or unreacted reagent by gel filtration or dialysis. In many cases, simple dialysis may suffice to remove unreacted reagent from the reaction solution. Final concentration and labeling ratio determination (if applicable).

Optional services such as gel filtration chromatography may also be used to either remove excess reagent or isolate and characterized the cross-linked product. For reagents (mostly protein and other biological molecules) that are similar in size or larger than the antibody, one must resort to other purification techniques such as affinity chromatography, ion-exchange chromatography, and hydrophobic interaction chromatography.

Cross-linked target molecule may then be further characterized by biochemical or biophysical techniques. Once the product has been purified, it may be subject to many different types of studies including spectroscopic (MALDI-TOF, ESI, LC-MS Fluorescence),electrophoresis, immunochemical biochemical, enzymatical analysis. QC (quality control)and QA (quality assurance) procedures are also followed independently to offer you double guarantee for the highest quality possible of every delivered conjugates.Moreover, our dedicated technical account managers will guide your project through every step of the process and constantly keep you informed of the latest project progress.

Ordering and Submitting Requests for Bioconjugation Services

For us to better understand your customized project, please complete our Bioconjugation Service Questionnaire. The more our chemists understand your project’s needs, the more accurate your provided feedback will be. Providing us with your project’s details enables us to recommend the best reagents to use for your project. The most useful and readily available tools for bioconjugation projects are cross-linking reagents. A large number of cross-linkers, also known as bifunctional reagents, have been developed. There are several ways to classify the cross-linkers, such as the type of reactive group, hydrophobicity or hydrophilicity and the length of the spacer between reactive groups. Other factors to consider are whether the two reactive groups are the same or different (i.e. heterobifunctional or homobifunctional reagents), spacer is cleavable and if reagents are membrane permeable or impermeable. The most accessible and abundant reactive groups in proteins are the ϵ-amino groups of lysine. Therefore, a large number of the most common cross-linkers are amino selective reagents, such as imidoesters, sulfo-N-hydroxysuccinimide esters and N-hydroxysuccinimide esters. Due to the high reactivity of the thiol group with N-ethylmaleimide, iodoacetate and a-halocarbonyl compounds, new cross-linkers have been developed containing maleimide and a-carbonyl moieties. Usually, N-alkylmaleimides are more stable than their N-aryl counterparts.

In addition to the reactive groups on the cross-linkers, a wide variety of connectors and spacer arms have also been developed. The nature and length of the spacer arm play an important role in the functionality. Longer spacer arms are generally more effective when coupling large proteins or those with sterically protected reactive side-chains. Other important considerations are the hydrophobicity, hydrophilicity and the conformational flexibility. Long aliphatic chains generally fold on themselves when in an aqueous environment, making the actual distance spanned by such linker arms less than expected. Instead, spacers containing more rigid structures (for example, aromatic groups or cycloalkanes) should be used. These structures, however, tend to be very hydrophobic which could significantly decrease the solubility of the modified molecules or even modify some of their properties. In such cases, it is recommended to choose a spacer that contains an alkyl ether (PEO) chain. Bio-Synthesis offers several cross-linkers with PEO chains, such as thiol-binding homobifunctional reagents, heterobifunctional bases and their derivatives.

Within 3-5 days upon receiving your project scope, we will provide you an appropriate quotation. An order can be placed with PO (Purchase Order) or major credit cards ( ). Your credit card will be billed under Bio-Synthesis, Inc.