Related Experiment Video
Updated: Mar 21, 2026
10:09
Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers
Published on: June 30, 2018
8.7K
Effect of Assembly pH on Polyelectrolyte Multilayer Surface Properties and BMP-2 Release
Claire Salvi1, Xuejian Lyu1, Amy M Peterson1
1Departments of †Chemical Engineering, ‡Mechanical Engineering, and §Biomedical Engineering, Worcester Polytechnic Institute , 100 Institute Road, Worcester, Massachusetts 01609, United States.
Biomacromolecules
|May 18, 2016
Summary
Polyelectrolyte multilayer coatings assembled at pH 6-7 enhance bone morphogenetic protein 2 (BMP-2) stability and release for orthopedic implants. These pH-controlled coatings preserve BMP-2 bioactivity and structure, crucial for implant success.
Area of Science:
- Biomaterials Science
- Surface Chemistry
- Orthopedic Engineering
Background:
- Orthopedic implant success relies on osteoconductive factors like bone morphogenetic protein 2 (BMP-2).
- Layer-by-layer assembly of polyelectrolyte multilayers (PEM) offers controlled drug delivery for implants.
- Optimizing PEM assembly conditions is critical for sustained release and bioactivity.
Purpose of the Study:
- To investigate the impact of solution pH during PEM assembly on BMP-2 release and coating properties.
- To evaluate the stability and bioactivity of BMP-2 released from PEM coatings.
- To determine the influence of assembly pH on surface properties like roughness and surface energy.
Main Methods:
- Adsorption of BMP-2 onto anodized titanium surfaces.
- Layer-by-layer assembly of poly-l-histidine and poly(methacrylic acid) PEM coatings at varying pH.
- Quantification of BMP-2 release profiles over time.
- Assessment of BMP-2 bioactivity and structural integrity post-release.
- Measurement of surface roughness and surface energy.
Main Results:
- PEM coatings assembled at pH 6-7 demonstrated enhanced stability and sustained BMP-2 release over several months.
- Initial BMP-2 adsorption was approximately 2 μg/cm(2), with pH-dependent release kinetics observed.
- Three distinct release phases were identified: burst, sustained, and depletion.
- Released BMP-2 retained its bioactivity and structural integrity.
- Surface energy decreased at more basic assembly pH, while surface roughness remained unchanged.
Conclusions:
- Solution pH is a critical parameter for controlling PEM coating stability and BMP-2 release kinetics.
- Optimal assembly pH (6-7) ensures sustained release and preserves BMP-2 bioactivity, vital for orthopedic applications.
- The initial BMP-2 layer influences PEM surface structure but not exposed functional groups.
