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Formation of hydroxyapatite-polyphosphazene polymer composites at physiologic temperature.
Y E Greish1, J D Bender, S Lakshmi
1Intercollege Materials Research Laboratory, 136 Materials Research Laboratory Building, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Journal of Biomedical Materials Research. Part A
|February 17, 2006
Summary
Bone analog composites form at body temperature using hydroxyapatite (HAp) and a biocompatible polymer. This process involves calcium ions crosslinking the polymer as HAp forms, enabling in vivo applications.
Area of Science:
- Biomaterials Science
- Materials Chemistry
- Biomineralization
Background:
- Developing bone graft substitutes requires materials that mimic natural bone structure and composition.
- In situ formation of bone analogs under physiological conditions is highly desirable for minimally invasive applications.
- Hydroxyapatite (HAp) is a key component of natural bone, making it a target for synthetic bone analogs.
Purpose of the Study:
- To investigate the formation of bone analog composites composed of hydroxyapatite and a biocompatible polymer at 37°C.
- To understand the mechanism of composite formation under conditions mimicking the in vivo environment.
- To evaluate the effect of polymer content on the kinetics of hydroxyapatite formation.
Main Methods:
- Utilized poly[bis(carboxylatophenoxy)phosphazene] (acid-PCPP) as the biocompatible polymer.
- Employed tetracalcium phosphate (TetCP) and anhydrous dicalcium phosphate (DCPA) as precursors for HAp formation.
- Analyzed the compositional evolution of calcium phosphates using X-ray diffraction and infrared spectroscopy.
Main Results:
- HAp formation occurred via a dissolution-precipitation mechanism, creating a mildly alkaline environment.
- Calcium ions liberated during HAp formation effectively crosslinked the acidic polymer (acid-PCPP).
- The proportion of polymer (5, 10, or 15 wt %) influenced the kinetics of HAp formation.
Conclusions:
- True composite formation, integrating HAp and the crosslinked polymer, was achieved at physiological temperature (37°C).
- The described method allows for in situ formation of bone analog composites.
- This approach holds promise for developing advanced biomaterials for bone regeneration.