[Preparation and degradation characteristics of bone repair composite--PDLLA/HA/DBM].
OBJECTIVE
To explore a new method of preparing the composite of DL-polylactic acid (PDLLA), hydroxyapatite(HA), decalcium bone matrix (DBM), and to observe the degradation characteristics of PDLLA/HA/DBM in vitro.


METHODS
An emulsion blend method was developed to prepare the composite of PDLLA/HA/DBM based on the weight rate of PDLLA:HA:DBM = 1.5-2:1-1.5:1. The characteristics of the particles was observed by scanning electron microscope. In vitro, PDLLA/HA/DBM and PDLLA were put into PBS(pH7.4) respectively; the pH value, weight and biomechanics of them were determined during the degradation.


RESULTS
Without heating, the emulsion blend method could be developed to prepare PDLLA/HA/DBM. Scanning electron microscope showed that the gap diameter in the compound material was 100 to 400 microns, and the porosity was 71.3%; During degradation, the pH value of PDLLA decreased little within 2 weeks, then decreased obviously and decreased to 4.0 at the end of the 4th week; while the pH value of PDLLA/HA/DBM kept quite steady and was 6.4 at the end of the 12th week. The weight of PDLLA decreased little within 4 weeks, then decreased obviously and remained 50% of its prime weight at the end of the 12th week; while the weight of PDLLA/HA/DBM decreased little within 5 weeks, then decreased obviously and remained 60% of the prime at the end of the 12th week. The prime biomechanical strength was 1.33 MPa in PDLLA and 1.71 MPa in PDLLA/HA/DBM. There was significant difference between them (P < 0.05). The strength of PDLLA decreased little within 3 weeks, then decrease obviously and was 0.11 MPa at the end of the 12th week; the strength of PDLLA/HA/DBM decreased little within 4 weeks, then decrease obviously and was 0.21 MPa at the end of the 12th week.


CONCLUSIONS
The emulsion blend method is a new method to prepare bone repair materials. As a new bone repair material, PDLLA/HA/DBM is suitable for bone tissue engineering for its good characteristics of porosity and degeneration.
Zhao
Jian-hua
JH
Institute of Field Surgery, Daping Hospital, Third Military Medical University, Chongqing, P. R. China 400042.
Liao
Wei-hong
WH
Wang
Yuan-liang
YL
D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D001857:Bone Matrix / Q000648:ultrastructure; D001861:Bone Regeneration; D018786:Bone Substitutes / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods
D001672:Biocompatible Materials; D018786:Bone Substitutes; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D017886:Durapatite