Microstructural control of modular peptide release from microporous biphasic calcium phosphate

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Drug Delivery

Background:

• Controlling drug release from tissue scaffolds is crucial for therapeutic efficacy.
• Current methods involve coatings, carriers, and binding affinity modulation.
• Synthetic peptide delivery requires precise control over scaffold microstructure.

Purpose of the Study:

• To investigate the role of interconnected microporosity in biphasic calcium phosphate (BCP) scaffolds for modulating synthetic peptide incorporation and release.
• To identify key microstructural characteristics influencing peptide release kinetics.
• To develop a model for predicting relative diffusivity based on scaffold microstructure.

Main Methods:

• Comparison of three modular peptides for incorporation and release, selecting one for further study.
• Evaluation of peptide incorporation and release from four BCP substrate types: non-microporous (NMP) and three microporous (MP) variations (50/5, 60/5, 50/50).
• Experimental analysis combined with a relative diffusivity model to correlate microstructure with release characteristics.

Main Results:

• Microporous (MP) substrates showed significantly higher peptide incorporation than non-microporous (NMP) substrates.
• NMP substrates exhibited a lower release rate but higher initial burst release compared to MP substrates.
• The pore interconnection to pore size ratio was the dominant factor influencing relative diffusivity, as indicated by the model.
• Significant differences in release were observed when both pore size and pore fraction were altered.

Conclusions:

• Scaffold microstructure, particularly interconnected microporosity, can effectively modulate synthetic peptide release.
• The ratio of pore interconnection to pore size is critical for controlling drug diffusivity.
• Rational design of BCP scaffolds requires careful consideration of both pore size and pore fraction for optimized drug delivery.