Cyanine 3 Tyramide (Cy3 Tyramide): Principles, Applications, and Experimental Selection Guide for Tyramide Signal Amplification (TSA)
Cyanine 3 Tyramide (Cy3 Tyramide): Principles, Applications, and Experimental Selection Guide for Tyramide Signal Amplification (TSA)
Overview of Cyanine 3 Tyramide – Key Information
Item | Information |
English name | Cyanine 3 Tyramide |
Common abbreviations | Cy3 Tyramide; Tyramide-Cy3; Cy3TSA, etc. |
CAS No. | 174961-75-2 |
Molecular formula | C₃₉H₄₇N₃O₈S₂ |
Molecular weight | Approx. 749.94 g/mol |
Chemical nature / structural features | A small-molecule fluorescent substrate in which a Cy3 fluorophore is conjugated to tyramide, used as a tyramide substrate for HRP-catalyzed signal amplification. |
Fluorescence type | Orange fluorescent cyanine dye (Cy3 family), compatible with imaging in the “Cy3/TRITC channel”. |
Excitation maximum (Ex) | ~550 nm (measured maximum in Cy3-tyramide TSA systems) |
Emission maximum (Em) | ~570 nm (orange to orange-red fluorescence) |
Appearance | Brown to black solid powder |
Solubility | Soluble in DMSO at approx. 16 mM and readily miscible; also soluble in most organic solvents (e.g., DMF, THF). Poorly soluble in water; typically prepared first as a stock solution in DMSO and then diluted into an aqueous buffer. |
Recommended storage conditions | Store dry and protected from light; –20 °C is the commonly recommended storage temperature (some literature/manufacturers suggest –80 °C for long-term storage). Avoid repeated freeze–thaw cycles. |
Main applications | Used as a fluorescent tyramide substrate in HRP-catalyzed tyramide signal amplification (TSA) to enhance signals in immunohistochemistry (IHC), immunocytochemistry (ICC), in situ hybridization (ISH/FISH), and other high-sensitivity immunoassays. |
Mechanism (brief) | In the presence of low concentrations of H₂O₂, HRP catalyzes the oxidation of Cy3-tyramide to generate reactive radicals. These radicals covalently couple to tyrosine and other residues on proteins surrounding the target, depositing large numbers of Cy3 fluorophores near the target and achieving roughly 10–100-fold signal amplification. |
Typical platforms | High-sensitivity IHC/ICC, ISH/FISH, multiplex fluorescence imaging, multiplex IHC, and high-sensitivity assays for pathogens or low-abundance proteins. |
Intended use | For research use only; not intended for diagnostic or therapeutic applications. |
Mechanism: Why Does It Amplify the Signal?
Cy3 Tyramide is particularly important because it is used in a technique known as Tyramide Signal Amplification (TSA).
1. Core concept of TSA
TSA is an enzyme-based signal amplification method:
1. HRP (horseradish peroxidase) is conjugated to an antibody or probe in the system.
2. A working solution containing a tyramide–fluorophore conjugate (e.g., Cy3 Tyramide) and hydrogen peroxide (H₂O₂) is added.
3. HRP catalyzes oxidation of the tyramide moiety, generating highly reactive intermediates.
4. These intermediates covalently bind to tyrosine and other residues on proteins in the immediate vicinity of HRP, thereby “depositing” a large number of Cy3 fluorophores around the target.
As a result:
- A site that originally had only one antibody carrying a limited number of fluorophores is effectively converted into “one antibody + a cloud of deposited Cy3 fluorescence”, and the signal is amplified by several-fold up to orders of magnitude.
- According to the literature and manufacturers’ data, TSA can increase the sensitivity of certain immunoassays by approximately 10–100 fold or more, markedly lowering the minimum detectable level of the target.
2. How does it differ from a conventional fluorescent secondary antibody?
Conventional immunofluorescence:
- (a) Each target epitope is bound by several secondary antibodies, and each secondary antibody carries only a fixed number of fluorophores → the total signal is limited.
TSA (using Cy3 Tyramide as an example):
- (b) Each HRP site can catalyze the deposition of multiple Cy3 Tyramide molecules, forming a high-density, covalently bound fluorescent layer around the target. The signal is greatly amplified and, because the label is covalently attached, it is more resistant to washing and photobleaching.
Overview of Key Applications of Cy3 Tyramide (TSA)
Application type | Typical samples / targets | Advantages of using Cy3 Tyramide–based TSA |
Immunohistochemistry (IHC) | FFPE or frozen tissue sections; low-abundance signaling proteins (e.g., Notch pathway components, nuclear receptors, transcription factors) | Substantially enhances staining intensity for weakly expressed proteins, allowing nuclear and intracellular targets that were previously “barely visible” to be clearly visualized, while preserving subcellular localization. |
Immunocytochemistry (ICC) | Adherent or suspension cells; low-abundance receptors, transcription factors, signaling molecules, etc. | Delivers strong fluorescence signals even at relatively low primary antibody concentrations, thereby reducing cell/sample consumption; well suited for high-resolution confocal imaging. |
In situ hybridization (ISH/FISH) | DNA/RNA probe detection in tissues or cells: low-copy genes, lowly expressed mRNAs, viral genomes, etc. | Using HRP-labeled probes or anti-DIG/anti-biotin antibodies, Cy3-tyramide is deposited at hybridization sites, dramatically boosting low-copy nucleic acid signals and enabling multicolor FISH. |
Multiplex immunofluorescence / multiplex IHC / spatial tissue imaging | Multiple rounds of staining for different immune markers on the same FFPE or frozen section (e.g., tumor immune microenvironment analysis, multi-marker diagnostic panels). | After TSA staining, fluorescence is covalently fixed in the tissue, allowing subsequent antibody stripping and additional staining rounds. In combination with tyramides of different colors (including Cy3), 5–7 or more markers can be detected, making it highly suitable for high-plex mIHC/mIF. |
High-sensitivity immunoassays & pathogen detection | Pathogens, toxins, or low-level proteins in food, environmental, or biological samples (e.g., detection of E. coli O157:H7). | When combined with immunomagnetic separation and other enrichment methods, TSA can greatly lower the limit of detection, enabling rapid detection even at low contamination levels; suitable for building high-sensitivity ELISA and other immunoassay platforms. |
Neuroanatomy and challenging receptor localization | Low-abundance receptors in brain tissue (e.g., AR, ER), neural pathway tracing, and weak signals in complex tissue structures. | TSA markedly enhances immunostaining of lowly expressed nuclear receptors and other markers, allowing reliable visualization of regions (such as AR in the prefrontal cortex) that are difficult to detect with conventional methods. |
Experimental Tips and Important Considerations
1. Signal amplification ≠ the stronger, the better
1. TSA has very high amplification potential. If the primary antibody concentration is too high and the TSA incubation time is too long, you may see:
(a) Non-specific staining and high background fluorescence;
(b) “Overexposed” regions with loss of fine structural detail.
2. Recommendations:
(a) First optimize the primary antibody dilution (usually more dilute than in conventional immunofluorescence);
(b) Perform a time-course for the TSA reaction to identify the optimal balance between signal intensity and background.
2. Interference from endogenous HRP/peroxidase
1. Many tissues have inherent peroxidase activity (e.g., blood cells and certain tissue types). If endogenous activity is not adequately blocked, non-specific tyramide deposition can occur.
2. Therefore, thorough blocking with H₂O₂ is a critical step in TSA experiments.
3. Designing the sequence for multiplex staining
1. In multiplex protocols, the weakest targets are usually assigned to the earlier TSA rounds to take full advantage of signal amplification.
2. When performing multiple rounds of TSA, consider:
(a) Spectral overlap between different fluorophores (Cy3 is similar to TRITC in spectrum);
(b) Whether antigen retrieval or high-temperature steps will affect previously deposited fluorescence or damage tissue morphology.
4. Use caution when performing quantitative analysis
1. TSA is inherently a nonlinear amplification method: deposition efficiency is influenced by HRP activity, substrate concentration, reaction time, and other factors.
2. When making quantitative comparisons (e.g., expression levels between samples), you must ensure that:
(a) All samples within a batch are processed under strictly identical staining conditions;
(b) Appropriate positive and negative controls are included;
(c) TSA is used primarily for semi-quantitative analysis and localization, rather than for precise absolute quantification.
Aladdin – Related Products
Aladdin Catalog No. | Product name | Grade / Purity | CAS No. |
Cyanine 3 tyramide (Tyramide-Cy3) | ≥95% (HPLC) | 174961-75-2 | |
Lactoperoxidase from milk | EnzymoPure™, ≥35 units/mg dry weight | 9003-99-0 | |
Horseradish peroxidase (HRP) | EnzymoPure™, ≥250 U/mg, Rz ≥ 3 | 9003-99-0 | |
Horseradish peroxidase (HRP) | EnzymoPure™, >100 U/mg (pyrogallol), Rz > 1 | 9003-99-0 | |
Horseradish peroxidase (HRP) | EnzymoPure™, ≥150 U/mg powder, Rz ≥ 1.5 | 9003-99-0 | |
Horseradish peroxidase (HRP) | EnzymoPure™, >200 U/mg, Rz 2–4 | 9003-99-0 | |
Horseradish peroxidase (HRP) | EnzymoPure™, >150 U/mg, Rz > 2 | 9003-99-0 | |
Peroxidase from horseradish | Type I, essentially salt-free, lyophilized powder, ≥50 units/mg solid (pyrogallol assay) | 9003-99-0 | |
Peroxidase from horseradish | Type X, ammonium sulfate suspension | 9003-99-0 | |
Peroxidase from horseradish (EIA grade, purified) | EnzymoPure™, Rz 2.9, ≥500 units/mg protein | 9003-99-0 | |
Peroxidase from horseradish (HRP) | EnzymoPure™, ≥180 U/mg powder, Rz ≥ 2.0 | 9003-99-0 | |
H112515 | Hydrogen peroxide solution (H₂O₂) | AR, 30 wt.% in H₂O | 7722-84-1 |
H112517 | Hydrogen peroxide solution (H₂O₂) | GR, 30 wt.% in H₂O | 7722-84-1 |
H112519 | Hydrogen peroxide solution (H₂O₂) | ACS, 30 wt.% in H₂O, contains stabilizer | 7722-84-1 |
H433856 | Hydrogen peroxide solution (H₂O₂) | Moligand™, with inhibitor, 30 wt.% in H₂O, meets USP testing specifications | 7722-84-1 |
H755825 | Hydrogen peroxide solution (H₂O₂) | For microbiology, 3% | 7722-84-1 |
C1505233 | Hydrogen peroxide solution (H₂O₂) | Moligand™, main component: 3–3.5% hydrogen peroxide | 7722-84-1 |
Dimethyl sulfoxide (DMSO) | UltraBio™ molecular biology grade, ≥99.5% (GC) | 67-68-5 | |
Dimethyl sulfoxide (DMSO) | Molecular biology grade, ≥99.9% | 67-68-5 | |
N433313 | N,N-Dimethylformamide (DMF) | Suitable for peptide synthesis | 68-12-2 |
N,N-Dimethylformamide (DMF) | Molecular biology grade, ≥99.9% | 68-12-2 | |
N,N-Dimethylformamide (DMF) | Anhydrous grade, ≥99.8% | 68-12-2 | |
Tetrahydrofuran (THF) | Ultra-dry grade, ≥99.9%, H₂O ≤ 50 ppm, inhibitor-free | 109-99-9 | |
Tetrahydrofuran (THF) | Anhydrous grade, ≥99.9%, inhibitor-free | 109-99-9 |
References
1. Tocris Bioscience. Cyanine 3 Tyramide – product information.
2. MedChemExpress (MCE). Cyanine 3 Tyramide (Tyramide-Cy3) – datasheet.
3. Yeasen Biotechnology. Cyanine 3 Tyramide – product manual.
4. Biotium. Tyramide Signal Amplification (TSA) – Technical Note.
5. Tocris Bioscience. Tyramide Signal Amplification (TSA) overview.
6. Bobrow MN, Harris TD, Shaughnessy KJ, Litt GJ. Catalyzed reporter deposition, a novel method of signal amplification. J Immunol Methods. 1989;125:279–285.
7. Bobrow MN, Shaughnessy KJ, Litt GJ. Catalyzed reporter deposition, a novel method of signal amplification. II. Application to membrane immunoassays. J Immunol Methods. 1991;137:103–112.
8. Sanno N, Osamura RY. Catalyzed reporter deposition method for amplifying endocrine products. Endocr Pathol. 1998;9:195–199.
9. von Gijlswijk RP, et al. Fluorochrome-labeled tyramides: use in immunohistochemistry and fluorescence in situ hybridization. J Histochem Cytochem. 1997;45:375–382.
10. Tyramide Amplification in Immunohistochemistry. In: Methods in Molecular Biology (Springer Protocols).
11. Stack EC, Wang C, Roman KA, et al. Multiplexed immunohistochemistry, imaging, and quantitation: a review, with an assessment of Tyramide Signal Amplification, multispectral imaging and multiplex analysis. Methods. 2014;70(1):46–58.
12. Gerdes MJ, et al. Fully automated 5-plex fluorescent immunohistochemistry with tyramide signal amplification. J Immunol Methods.
13. Akoya Biosciences. Opal Multiplex IHC Assay Development Guide.
14. Beyotime Biotechnology. Endogenous Peroxidase Blocking Buffer – instruction manual.
15. IHC WORLD. Blocking Endogenous Peroxidase. (Summary of common practice using 3% or 0.3% H₂O₂ for blocking endogenous peroxidase in IHC.)
Aladdin: https://www.aladdinsci.com/