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Published on: March 13, 2013
Development of fluorescence change-based, reagent-less optic immunosensor
1Department of Applied Physics, Seikei University, 3-3-1, Kichijoji-kitamachi, Musashino-shi, Tokyo 180-8633, Japan.
Insights
A novel optic immunosensor detects immunoglobulin G (IgG) without reagents. This portable device uses fluorescently labeled protein A and optic fibers, showing decreased fluorescence intensity with increasing IgG concentration.
Area of Science:
- Biomedical Engineering
- Biosensing Technology
- Immunotechnology
Background:
- Development of sensitive and specific diagnostic tools is crucial for disease detection.
- Existing immunosensors often require reagents or lack portability, limiting their practical application.
- Protein A's specific binding to immunoglobulin G (IgG) offers a basis for immunoassay development.
Purpose of the Study:
- To develop a reagent-less, regenerable, and portable optic immunosensor for detecting immunoglobulin G (IgG).
- To investigate the sensor's performance based on fluorescence intensity changes upon protein-protein interactions.
- To evaluate both steady-state and transient fluorescence responses for IgG quantification.
Main Methods:
- Fabrication of an optic immunosensor using a glass plate immobilized with Qdot-labeled protein A.
- Integration of the immobilized plate with optic fibers for excitation and fluorescence emission.
- Measurement of fluorescence intensity changes in response to varying concentrations of IgG in a phosphate-buffered saline solution.
Main Results:
- The optic immunosensor demonstrated a decrease in fluorescence intensity upon binding of IgG to Qdot-labeled protein A.
- The fluorescence decrease correlated with IgG concentration in both steady-state and transient phases.
- The system proved to be reagent-less, regenerable, and portable, suitable for on-site detection.
Conclusions:
- The developed optic immunosensor is a viable tool for sensitive and specific IgG detection.
- The reagent-less and portable nature of the sensor enhances its potential for clinical diagnostics and field applications.
- Fluorescence intensity changes serve as a reliable indicator for IgG quantification in real-time.
Abstract:
A reagent-less, regenerable and portable optic immunosensor was developed. A model sample, immunoglobulin G (IgG), was detected with this system based on changes in fluorescent intensity of fluorescent labeled protein A with specific reactivity to IgG depending on a reaction between the proteins. A glass plate immobilized with Qdot-labeled protein A was placed on the top of optic fibers designed for both excitation and fluorescence emission. The optic fibers with the Qdot-labeled protein A-immobilized glass plate were inserted into a solution of pH 7.4 phosphate buffered saline. After stabilization of the fluorescence intensity, IgG was added and the time-course of the fluorescence intensity was measured on a fluorometer connected with the optic fibers. Furthermore, the fluorescence response of a transient state was evaluated with the same system. When the Qdot-labeled protein A bound to IgG, fluorescence intensity decreased because of the inhibition by IgG. The degree of fluorescence decrease depends on the IgG concentration at a steady state and also in a transient state.
