Physical characterization of blends of poly(D-lactide) and LHRH (a leuprolide decapeptide analog).
Stereocomplexes between poly(D-lactide) (PDLA) and poly(L-lactide) (PLLA) have been extensively studied, including, in recent years, several reports on the stereocomplexation of PDLA with small molecules such as peptides. Here, the possible complexation between PDLA and luteinizing hormone releasing hormone (LHRH), a l-configured decapeptide, is considered for which several observations were made: (1) in calorimetry an additional endothermic peak appears at a lower temperature than the melting temperature of pure PDLA; (2) in Raman analyses a band splitting of the C=O stretching mode (not present in pure PDLA) shows up; (3) in X-ray diffraction, however, no change is observed after mixing the two species, indicating no crystal structure modification (and the absence of any stereocomplex crystal structure). The calorimetric double melting peak is merely explained by the presence of two distinct morphological forms of PDLA, whereas the spectroscopic band splitting can be due to simple differences of crystallinity. From these observations it is concluded that the LHRH modifies the crystallization of PDLA without, however, the formation of a stereocomplex.
Fraschini
Carole
C
Département de Chimie, Université de Montréal, C.P.6128, Succursale Centre-Ville, Montréal, Québec, Canada, H3C 3J7.
Jalabert
Matthieu
M
Prud'homme
Robert E
RE
D001672:Biocompatible Materials / Q000737:chemistry*; D001704:Biopolymers / Q000737:chemistry; D002151:Calorimetry; D002152:Calorimetry, Differential Scanning; D002244:Carbon / Q000737:chemistry; D002845:Chromatography; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D004337:Drug Carriers / Q000737:chemistry; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry*; D006358:Hot Temperature; D016729:Leuprolide / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011208:Powders; D011485:Protein Binding; D011487:Protein Conformation; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D001672:Biocompatible Materials; D001704:Biopolymers; D004337:Drug Carriers; D046911:Macromolecular Substances; D010455:Peptides; D011091:Polyesters; D011108:Polymers; D011208:Powders; D014867:Water; D007987:Gonadotropin-Releasing Hormone; C033616:poly(lactide); D002244:Carbon; D016729:Leuprolide; D010100:Oxygen