Preparation and characterization of poly(D,L-lactide) and its porous biomaterials

Abstract

Poly(D,L-lactide) was synthesized by indirect method from D,L-lactic acid and characterized by infrared spectrum and proton nuclear magnetic resonance. The influences of monomer purity, initiator concentration, polymerization temperature and polymerization time on the relative molecular mass of poly(D, L-lactide) were investigated. The polylactide was made into porous materials by using solvent-casting particulate-leaching method. Under the optimized conditions, polylactides with a viscosity average molecular mass up to 1.82 × 10⁵ are obtained and the results are fairly reproducible. Scanning electron microscope observation indicates that the sample is highly porous and well-distributed with good interconnections between pores and the pore size of porous materials is in the range from 200 µm to 500 µm and it can be used as scaffold for bone tissue engineering.

Keywords

lactide / polylactic acid / tissue engineering / scaffold

References

[1] KricheldorfH R. Syntheses and application of polylactides[J]. Chemosphere, 2001, 43: 49-54

[2] LuntJ. Large-scale production, properties and commercial applications of polylactic acid polymer [J]. Polymer Degradation and Stability, 1998, 59: 145-152

[3] GriffithL G. Polymertic biomaterials[J]. Acta Mater, 2000, 48: 263-277

[4] KumarN, MajetiN V, DombA J. Biodegradable block copolymers [J]. Advance Drug Delivery Reviews, 2001, 53: 23-44

[5] ZhangGuo-dong, YangJi-yuan, FengXin-de. Research progress of polylactides [J]. Chemistry Advances, 2000, 12(1): 89-93(in Chinese)

[6] HyonS H, JamshidiK, IkadaY. Synthesis of polylactides with different molecular weight[J]. Biomaterials, 1997, 18: 1503-1508

[7] JacobsenS, FritzH G, DegeeP, et al.. New developments on the ring opening polymerization of polylactide [J]. Industrial Crops and Products, 2000, 11: 265-275

[8] AjiokaM, EnomotoK, SuzukiK, et al.. Basic properties of polylactic acid produced by the direct condensation polymerization of lactic acid[J]. Bull Chem Soc Jpn, 1995, 68(8): 2125-2131

[9] MoonS I, LeeC W, MiymotoM, et al.. Melt polycondensation of L-lactic acid with Sn catalysts activated by various proton acid: a direct manufacturing route to high molecular weight poly (L-lactic acid) [J]. J Polym Sci: Part A: Polym Chem, 2000, 38(9): 1673-1679

[10] MoonS I, LeeC W, TaniguchiI, et al.. Melt/solid polycondensation of L-lactic acid: a alternative route to poly(l-lactic acid) with high molecular weight[J]. Polymer, 2001, 42: 5059-5062

[11] XuK, KozlucaS, DenkbasE B, et al.. Synthesis of PDLLA homopolymers with different molecular weight[J]. J Appl Polym Sci, 1996, 59: 561-563

[12] BurgJ L, PorterS, KellamJ F. Biomaterials developments for bone tissue engineering[J]. Biomaterials, 2000, 21: 2347-2359

[13] TsurugaE, TakitaH, WakisakaY, et al.. Pore size of porous hydroxyaptite as the cell-substrtum controls BMP indycede osteogenesis [J]. J Biochem, 1997, 121: 317-24

[14] HomesR E. Bone generation within a coralline hydroxyapatite implant [J]. Plast Reconstr Surg, 1979, 63: 626-633

[15] RuanJian-mingBiocompatability Evaluation of Biomaterials in Vitro[D], 1998, Glasgow, Glasgow Strathclycle University, England: 37-76

[16] LiYa-jun, RuanJian-ming. Study on the biodegradation of poly(D,L-lactide)/hydroxyapatite porous composite[J]. Journal of Central South University of Technology, 2002, 33(3): 262-265(in Chinese)