Terahertz spectroscopy: an investigation of the structural dynamics of freeze-dried poly lactic-co-glycolic acid microspheres
Author(s)
Shmool, Talia A
Hooper, Philippa J
Schierle, Gabriele S Kaminski
van der Walle, Christopher E
Zeitler, J Axel
Type
Journal Article
Abstract
Biodegradable poly lactic-co-glycolic acid (PLGA) microspheres can be used to encapsulate peptide and offer a promising drug-delivery vehicle. In this work we investigate the dynamics of PLGA microspheres prepared by freeze-drying and the molecular mobility at lower temperatures leading to the glass transition temperature, using temperature-variable terahertz time-domain spectroscopy (THz-TDS) experiments. The microspheres were prepared using a water-in-oil-in-water (w/o/w) double-emulsion technique and subsequent freeze-drying of the samples. Physical characterization was performed by morphology measurements, scanning electron microscopy, and helium pycnometry. The THz-TDS data show two distinct transition processes, 𝑇g,𝛽
in the range of 167–219 K, associated with local motions, and 𝑇g,𝛼
in the range of 313–330 K, associated with large-scale motions, for the microspheres examined. Using Fourier transform infrared spectroscopy measurements in the mid-infrared, we were able to characterize the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined 𝑇g,𝛽
and 𝑇g,𝛼
and free volume and microsphere dynamics.
in the range of 167–219 K, associated with local motions, and 𝑇g,𝛼
in the range of 313–330 K, associated with large-scale motions, for the microspheres examined. Using Fourier transform infrared spectroscopy measurements in the mid-infrared, we were able to characterize the interactions between a model polypeptide, exendin-4, and the PLGA copolymer. We observe a relationship between the experimentally determined 𝑇g,𝛽
and 𝑇g,𝛼
and free volume and microsphere dynamics.
Date Issued
2019-06
Date Acceptance
2019-06-11
Citation
Pharmaceutics, 2019, 11 (6)
ISSN
1999-4923
Publisher
MDPI AG
Journal / Book Title
Pharmaceutics
Volume
11
Issue
6
Copyright Statement
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
License URL
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000475330500043&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=a2bf6146997ec60c407a63945d4e92bb
Subjects
BETA-RELAXATION
CAGED MOLECULE-DYNAMICS
CONFORMATION
drug delivery
formulation development
GLASS-TRANSITION
Life Sciences & Biomedicine
MICROPARTICLES
microspheres
molecular mobility
Pharmacology & Pharmacy
PLGA
PROTEIN
Science & Technology
STABILITY
STATE
TEMPERATURE
terahertz spectroscopy
VISCOUS-LIQUIDS
Publication Status
Published
Article Number
291
Date Publish Online
2019-06-20