Thermal properties and physicochemical behavior in aqueous solution of pyrene-labeled poly(ethylene glycol)-polylactide conjugate.
A fluorescence-labeled bioresorbable polymer was prepared by a coupling reaction of poly(ethylene glycol)-polylactide (PEG-PLA) with carboxyl pyrene, using N,N'-diisopropylcarbodiimide/1-hydroxy-7-azabenzotriazole (DIC/HOAt) as a coupling agent and 4-dimethylaminopyridine (DMAP) as a catalyst. The obtained copolymer, termed PEG-PLA-pyrene, was characterized using various analytical techniques, such as gel permeation chromatography (GPC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), proton nuclear magnetic resonance ((1)H-NMR), infrared spectroscopy (IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), to identify the molecular structure and to monitor the thermal property changes before and after the reaction. The presence of a pyrene moiety at the end of polylactide (PLA) did not alter the crystallization ability of the poly(ethylene glycol) (PEG) blocks, indicating that the conjugate preserved the inherent thermal properties of PEG-PLA. However, the presence of PEG-PLA blocks strongly reduced the melting of pyrene, indicating that the thermal characteristics were sensitive to PEG-PLA incorporation. Regarding the physicochemical behavior in aqueous solution, a higher concentration of PEG-PLA-pyrene resulted in a higher ultraviolet-visible (UV-vis) absorbance and fluorescence emission intensity. This is of great interest for the use of this conjugate as a fluorescence probe to study the in vivo distribution as well as the internalization and intracellular localization of polymeric micelles.
National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan ; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
Wei-Lin
WL
Chen
National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan ; PhD Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, Taiwan.
Yun-Fen
YF
Peng
National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan.
Sheng-Kuo
SK
Chiang
National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan ; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan ; PhD Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, Taiwan.
Ming-Hsi
MH
Huang
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D015394:Molecular Structure; D011091:Polyesters / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
D008823:Micelles; D011091:Polyesters; D011108:Polymers; D011721:Pyrenes; D014867:Water; D011092:Polyethylene Glycols; C083464:poly(ethyleneglycol-lactide); C030984:pyrene
PEG-PLA; bioresorbable polymer; fluorescence probe; poly (ethylene glycol)-polylactide; polymeric micelles; pyrene