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Updated: Nov 21, 2025
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
An SPR imaging immunosensor for leptin determination in blood plasma
Anna Sankiewicz1, Adam Hermanowicz, Artur Grycz
1Faculty of Chemistry, Bioanalysis Laboratory, University of Bialystok, Bialystok, Poland. ania@uwb.edu.pl.
Insights
A novel Surface Plasmon Resonance imaging (SPRi) immunosensor was developed for sensitive leptin detection in blood plasma. This SPRi method offers a faster, simpler alternative to ELISA for determining leptin levels.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Immunosensing
Background:
- Leptin is a crucial hormone regulating feeding behavior and energy balance.
- Accurate leptin determination is vital for understanding metabolic disorders.
- Existing methods like ELISA can be time-consuming and complex.
Purpose of the Study:
- To develop and validate a specific SPRi immunosensor for quantifying leptin in human blood plasma.
- To establish the analytical performance characteristics of the developed immunosensor.
- To compare the SPRi method with ELISA for leptin determination.
Main Methods:
- Immobilization of rabbit anti-leptin antibodies on a gold chip using a cysteamine linker and EDC/NHS protocol.
- Utilizing non-fluidic array Surface Plasmon Resonance imaging (SPRi) for signal detection.
- Optimization of assay conditions to achieve desired sensitivity and linearity.
Main Results:
- The SPRi immunosensor demonstrated a linear response range from 0.23 to 5 ng mL-1.
- Achieved a Limit of Detection (LOD) of 0.07 ng mL-1 and a Limit of Quantitation (LOQ) of 0.23 ng mL-1.
- Validation studies showed high correlation (Pearson's r=0.991) with ELISA and accurate recovery rates (97-110%).
Conclusions:
- The developed SPRi immunosensor provides a direct, rapid, and simplified method for leptin analysis in plasma.
- This technology holds promise as a valuable tool for clinical diagnostics and research, particularly in studies of malnutrition.
- The SPRi method significantly outperforms ELISA in terms of speed and simplicity.
Abstract:
Leptin is a hormone that has a fundamental role in the regulation of feeding and energy balance. A developed specific SPRi immunosensor for leptin may be a new tool for leptin determination in blood plasma. The immunosensor consists of rabbit anti-leptin antibody immobilized on a gold chip via cysteamine linker, using the EDC/NHS protocol. Non-fluidic array SPRi is used for analytical signal formation. Under optimized conditions, the linear response range of the immunosensor covers concentrations from 0.23 to 5 ng mL-1. The LOD of the immunosensor is 0.07 ng mL-1, and the LOQ is 0.23 ng mL-1. The precision of measurement depends on leptin concentration, and is between 9.1% and 2.2%. Recoveries of the leptin spike are between 97% and 110%. The immunosensor and related analytical method were validated by parallel determination of leptin in series of plasma from children suffering from malnutrition and a control group, using Enzyme-Linked Immunosorbent Assay (ELISA) and SPRi. Pearson's correlation coefficient was equal to 0.991. The developed immunosensor and related method are more direct, faster and much simpler than ELISA.
