Concentrated Polymer Brush-Modified Magnetic Particles for a Diagnostic Immunoassay.
Gabriel Tai Huynh1, Jun Qiu2, Edith van den Bosch2
1Research Center for Macromolecules and Biomaterials, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
Langmuir : the ACS Journal of Surfaces and Colloids
|November 25, 2025
Summary
Biofouling in diagnostic assays was reduced using concentrated polymer brushes on magnetic particles. This enhanced antibody immobilization and improved detection sensitivity for human serum albumin.
Area of Science:
- Biomaterials Science
- Nanotechnology
- Analytical Chemistry
Background:
- Nonspecific protein absorption (biofouling) hinders the sensitivity of magnetic particle (MP)-based diagnostic assays.
- This biofouling reduces the limit of detection and overall performance of diagnostic devices.
- Developing bioinert surfaces is crucial for improving MP-based assay sensitivity.
Purpose of the Study:
- To develop a biofouling-resistant surface for magnetic particles using concentrated polymer brushes (CPBs).
- To immobilize antibodies onto CPB-coated MPs for use as an immunoassay platform.
- To evaluate the sensitivity and selectivity of the developed immunoassay platform for human serum albumin (HSA) detection.
Main Methods:
- Coating magnetic particles with poly[poly(ethylene oxide) methyl ether methacrylate] (PPEGMA) to form CPBs.
- Immobilizing anti-human serum albumin antibodies onto the PPEGMA brush layer via click chemistry.
- Quantifying antibody grafting efficiency using BCA assay.
- Assessing HSA capture efficacy using colorimetric analysis and liquid chromatography/mass spectrometry.
- Determining the limit of detection for HSA using the antibody-conjugated MPs.
Main Results:
- High antibody grafting efficiency (∼0.80 antibody per chain) was achieved on the CPB-coated MPs.
- The CPB-coated MPs demonstrated high selectivity for HSA in buffered solutions and human serum.
- The developed immunoassay platform detected HSA down to 6.4 ng mL⁻¹, showing a 30% increase in sensitivity compared to unmodified MPs.
- Colorimetric analysis and LC/MS confirmed the capture efficacy and selectivity of the antibody-conjugated MPs.
Conclusions:
- Concentrated polymer brushes effectively reduce biofouling on magnetic particle surfaces.
- CPB-coated MPs provide a sensitive and selective platform for immunoassay development.
- The enhanced sensitivity and selectivity of these MPs have significant implications for improving diagnostic assay performance.
- This CPB-based approach is adaptable for various immunoassay applications by altering polymer and biofunctional groups.
