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Human Serum Anti-aquaporin-4 Immunoglobulin G Detection by Cell-based Assay
Published on: April 5, 2019
A multipurpose capacitive biosensor for assay and quality control of human immunoglobulin G
Mahmoud Labib1, Martin Hedström, Magdy Amin
1Department of Biotechnology, Lund University, Box 124, 22100 Lund, Sweden.
Insights
A new capacitive biosensor system enables sensitive, label-free detection of human immunoglobulin G (hIgG) and its aggregates. This assay offers rapid quality control for biopharmaceuticals, improving upon existing methods.
Area of Science:
- Biosensor Technology
- Analytical Chemistry
- Biopharmaceutical Quality Control
Background:
- Human immunoglobulin G (hIgG) is a critical therapeutic protein requiring rigorous quality control.
- Existing methods like Size-Exclusion Chromatography-UV (SEC-UV) have limitations in detecting low-level aggregates.
- Development of sensitive and rapid assays is crucial for in-process monitoring.
Purpose of the Study:
- To develop and validate a flow-injection biosensor system for the sensitive detection and quantification of hIgG.
- To assess the biosensor's capability for detecting hIgG aggregates.
- To establish the biosensor as a potential tool for post-SEC-UV binding assays in biopharmaceutical quality control.
Main Methods:
- Utilized a capacitive transducer-based biosensor system employing self-assembled monolayers (SAMs) with covalently attached concanavalin A.
- Assessed electrochemical characteristics using cyclic voltammetry with potassium ferricyanide.
- Performed label-free assays for hIgG and its aggregates in a flow-injection system.
Main Results:
- Achieved a sensitive label-free assay for hIgG with a detection limit of 1.0 µg/mL.
- Demonstrated a linear capacitance response to hIgG concentration (5.0–100 µg/mL) on a logarithmic plot.
- Successfully detected hIgG aggregates at concentrations as low as 0.01% of total hIgG content.
- Performed up to 18 successive assays on a single electrode within 15 minutes without significant sensitivity loss.
Conclusions:
- The developed flow-injection biosensor system provides a sensitive and rapid method for hIgG quantification and aggregate detection.
- This biosensor represents a valuable potential post-SEC-UV binding assay for in-process quality control of hIgG.
- The system enhances the ability to monitor product quality beyond the limitations of conventional SEC-UV methods.
Abstract:
We report a flow-injection biosensor system with a capacitive transducer for assay and quality control of human immunoglobulin G (hIgG). The sensing platform is based on self-assembled monolayers (SAMs) of carboxylic acid terminated alkyl-thiols with covalently attached concanavalin A. The electrochemical characteristics of the sensor surface were assessed by cyclic voltammetry using a permeable redox couple (potassium ferricyanide). The developed biosensor proved capable of performing a sensitive label-free assay of hIgG with a detection limit of 1.0 microg mL(-1). The capacitance response depended linearly on hIgG concentration over the range from 5.0 to 100 microg mL(-1), in a logarithmic plot. Typical measurements were performed in 15 min and up to 18 successive assays were achieved without significant loss of sensitivity using a single electrode. In addition, the biosensor can detect hIgG aggregates with concentrations as low as 0.01% of the total hIgG content (5.0 microg mL(-1)). Hence, it represents a potential post-size-exclusion chromatography-UV (post-SEC-UV) binding assay for in-process quality control of hIgG, which cannot be detected by SEC-UV singly at concentrations below 0.3% of the total hIgG content.
