Fluorescence immunoassay (FIA) is a simple, rapid, and sensitive technique that is used to measure many compounds including drugs, hormones, and proteins. This method has been widely applied in the in vitro diagnostics (IVD) industry. As an expert in IVD assay development, Creative Biolabs is committed to offering a reliable and sensitive FIA-based testing service to accelerate the application of FIA technique in the IVD field.

Introduction of FIA

Immunoassay is a highly selective bioanalytical method that measures the presence or concentration of analytes including macromolecules and small molecules in a solution through the use of an antibody or an antigen as a biorecognition agent. This method is based on the specificity of antibodies to their antigen. Fluorescent probes, as detectable signals, have been widely used in immunoassay. Fluorescent probes have many advantages as detectable signals including high sensitivity and a variety of measurable properties such as emission intensity, orientation, waveform, and lifetime. In a classical FIA, fluorescent dyes that illuminate in UV light are used to detect the specific binding of an antigen and antibody. The fluorescent dyes, fluorescein isothiocyanate and lissamine rhodamine emit blue-green and orange-red fluorescence, respectively under UV rays in the fluorescence microscope. The advantages of an FIA method include higher sensitivity detection of the analyte, simplified reagents, and simpler assay designs.

With the development of fluorescent labeling technologies and instrumental technologies, a variety of FIA-related technologies have been developed, including:

1) Fluorescent excitation transfer immunoassay

2) Fluorescence polarization immunoassay (FPIA)

3) Time-Resolved Fluorescence Immunoassays (TRFIA)

4) Fluorescence Energy Transfer Immunoassays

5) Phase-Modulation Fluorescence Spectroscopy

6) Phase-Resolved Fluoroimmunoassays

7) Phase Fluorescence and Fluorescence Lifetime Immunoassays

8) Liposome Fluoroimmunoassays

TRFIA-based Diagnosis of Hepatocellular Carcinoma

Hepatocellular carcinoma is the sixth most common malignant neoplasms and affects 626,000 people annually. It is necessary to develop a sensitive method to diagnose this disease as early as possible. Chen et al. (2016) designed and developed an effective, sensitive, and reliable TRFIA-GPC3 kit for diagnosing hepatocellular carcinoma. In the study, a sandwich TRFIA was used to detect serum GPC3 which is a potential novel marker for hepatocellular carcinoma, with the lowest detectable concentration of 38.74 pg /mL.

Schematic of the TRFIA.Fig.1 Schematic of the TRFIA. (Chen, 2016)

Our Capabilities

Equipped with the sensitive FIA technology and rich expertise in IVD assay development, Creative Biolabs is confident in offering a flexible FIA-based detection development service. Besides, we also customize a personalized FIA-based testing solution according to your project's requirements. If you are interested in our services, please contact us to discuss your project and achieve more details.


  1. Chen, J.J.; et al. Development of a time-resolved fluorescence immunoassay for the diagnosis of hepatocellular carcinoma based on the detection of glypican-3. Journal of Fluorescence. 2017, 27(4): 1479-1485

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