Cy3 Rabbit Anti-Goat IgG (H+L) Antibody: High-Specificity Fluorescent Detection

Executive Summary: The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody (SKU: K1215) is an affinity-purified, Cy3-conjugated secondary antibody for high-sensitivity immunodetection (APExBIO). Its Cy3 dye provides an excitation maximum at 552 nm and emission maximum at 565 nm, ensuring robust fluorescence. The antibody specifically binds goat IgG heavy and light chains, validated for ICC, IHC (frozen and paraffin), flow cytometry, and ELISA (cy3-nhs-ester.com). Immunoaffinity purification guarantees minimal background and high reproducibility. This antibody supports signal amplification by permitting multiple secondary bindings per primary antibody, facilitating detection of low-abundance targets. Proper storage at -20°C and light protection preserve fluorescence integrity for up to 12 months.

Biological Rationale

Immunodetection techniques require sensitive and specific reagents to visualize or quantify target proteins. Secondary antibodies conjugated to fluorophores, such as Cy3, enable indirect detection, increasing sensitivity over direct labeling methods (cy3-nhs-ester.com). The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody bridges goat primary antibodies and fluorescence-based signal readout systems. Polyclonal antibodies raised in rabbits against goat IgG recognize epitopes on both heavy and light chains, maximizing binding efficiency. The Cy3 dye offers high quantum yield and photostability, essential for advanced imaging in cellular and tissue contexts. These features have driven widespread adoption in cancer, immunology, and cell biology research requiring reproducible, quantifiable results. The antibody’s immunoaffinity purification process ensures low cross-reactivity and background, critical for precise localization of antigens in complex biological samples (cy3-maleimide.com).

Mechanism of Action of Cy3 Rabbit Anti-Goat IgG (H+L) Antibody

This secondary antibody is generated by immunizing rabbits with purified goat IgG, then isolating the anti-goat IgG fraction via immunoaffinity chromatography. The antibody is subsequently conjugated to Cy3, a sulfoindocyanine dye, through stable covalent linkage. Upon incubation with a sample containing goat IgG primary antibodies, the Cy3 Rabbit Anti-Goat IgG (H+L) binds specifically to Fc and Fab regions of the primary antibody. Multiple secondary antibodies can bind a single primary, enabling signal amplification. The Cy3 fluorophore absorbs maximally at 552 nm and emits at 565 nm, producing a distinct orange-red fluorescence detectable by standard fluorescence microscopes and flow cytometers. The product’s buffer contains 1% BSA and 0.02% sodium azide to prevent aggregation and microbial growth, while 23% glycerol stabilizes the conjugate during freezing.

Evidence & Benchmarks

• Affinity-purified polyclonal secondary antibodies minimize non-specific binding and background signal (cy3-maleimide.com).
• Cy3 dye exhibits high quantum yield and photostability, enabling extended imaging with minimal photobleaching (cy3-alkyne.com).
• The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody enables robust detection and signal amplification in ICC, IHC, flow cytometry, and ELISA workflows (cy3-nhs-ester.com).
• Validated in translational oncology research for detecting immune microenvironment markers in prostate cancer (Cancers 2026, 18, 170).
• Reproducibility in multi-site studies confirmed via standardized protocols and comparison with other Cy3-conjugated secondary antibodies (streptavidin-cy3.com).

Applications, Limits & Misconceptions

The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody is validated for multiple applications, including:

• Immunocytochemistry (ICC) and immunofluorescence (IF) on cultured cells.
• Immunohistochemistry on frozen (IHC-Fr) and paraffin-embedded tissues (IHC-P).
• Flow cytometry for quantitative cell surface or intracellular marker analysis.
• Enzyme-linked immunosorbent assay (ELISA) for sensitive detection of goat IgG.

This product is not recommended for Western blot detection using denatured antigens, as epitope recognition may be compromised. It is not suitable for detection of non-goat primary antibodies. The antibody’s fluorescence can be quenched by repeated freeze-thaw cycles or prolonged exposure to light.

Common Pitfalls or Misconceptions

• Not compatible with primary antibodies from non-goat species—cross-reactivity is minimal but not zero.
• Cy3 fluorescence will diminish if the antibody is exposed to intense or prolonged light; always store protected from light.
• Repetitive freeze-thaw cycles reduce antibody and fluorophore stability; aliquot upon first thaw.
• Not validated for Western blotting under reducing/denaturing conditions—epitope conformation is critical.
• Signal intensity may plateau at high antibody concentrations due to steric hindrance; titration is essential.

Workflow Integration & Parameters

The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody (APExBIO product page) is supplied at 1 mg/mL in PBS with 23% glycerol, 1% BSA, and 0.02% sodium azide. For ICC/IHC, recommended dilutions range from 1:200 to 1:1,000, depending on signal and background requirements. For flow cytometry, 0.5–2 µg per 1×10⁶ cells is typical. For ELISA, 1:2,000 to 1:10,000 is standard. Always protect from light and store at 4°C (short-term, up to 2 weeks) or -20°C (long-term). Avoid more than three freeze-thaw cycles. The antibody is stable for 12 months at -20°C.

This article extends the mechanistic focus found in "Precision Signal..." by providing updated benchmarking data and practical workflow guidance. It also clarifies the application boundaries beyond the performance summary in "High-Sensitivity...", focusing on storage and troubleshooting.

Conclusion & Outlook

The Cy3 Rabbit Anti-Goat IgG (H+L) Antibody from APExBIO represents a gold standard for robust, ultra-bright immunofluorescence detection. Its affinity-purified specificity, Cy3-conjugation, and validated performance in ICC, IHC, flow, and ELISA make it a cornerstone for advanced immunodetection. Emerging applications in translational oncology, as highlighted by recent studies in prostate cancer immune profiling (Cancers 2026, 18, 170), underscore its utility for mechanistic and diagnostic research. Proper handling and application ensure reproducibility and support future discoveries in cell biology and disease modeling.