1. Degradation Profile of Electrospun PLGA Matrix
Dana Dolev1, Oded Nissan2
1 – Bio Medical Engineering Department, Tel Aviv University; 2 – Optonol Ltd.
Introduction
Electro spun fibers are used in various applications as scaffolds for tissue engineering; carriers for drug delivery system and wound dressing materials.
Electrospinning is a polymer processing technique in which a stream of a polymer solution is subjected to a high electric field, resulting in formation of nano-micro dimension fibers.
Polylactide (PLA), polyglycolide (PGA), and their copolymer polylactide-co-glycolide (PLGA) find wide applications in the pharmaceutical and medicine industries owing to their excellent biodegradation, biocompatibility and nontoxic degradation products.
The degradation profile of each of these materials has great influence on their function in the medical application. The degradation is affected by many parameters.
Objectives
Finding raw materials for electrospun matrices that provide different degradation rates (hence fit different medical applications).
Studying the effect of fiber size on the degradation of a fibrous matrix.
Determining the quantitative connection between the in vitro real time and in vitro accelerated tests
Understanding the quantitative connection between in vivo and in vitro degradation.
Materials
1. Poly (lactide-co-glycolide acid) 75:25 ['material A']
2. Poly (D-L-lactide-co-L-lactide acid) 50:50 ['material B']
3. Poly (D-lactide-Glycolic acid) 60:40 ['material C']
4.50:50 mixture of material A and material B ['material D']
5.50:50 mixture of material A and material C ['material E']
Preparation of electrospun fiber matrix
A syringe full of polymer solution was placed in the electrospinning machine. The machine was set
to a voltage of 20-30kV and the elctrospun fibers were collected on a metal collector.
Method #1 – In-Vitro study
Performed both in a 37ºc (‘real time’) and 48ºc (accelerated) environments
The samples are kept in pH controlled environment
The samples are tested periodically for various parameters
Method #2 – In-Vivo study
Carried out on rodents’ eyes
The implants are histopathologicaly evaluated periodically.
Results
Comparing degradation profiles
of the various materials
Effect of fiber size on matrix degradation profile (material ‘A’)
Comparing 'real time' and 'accelerated' tests (material ‘A’)
11µm
13µm
15µm
In-Vivo Study Results-
Histopathological
Sections
3 months – no degradation months – degradation begins months – full degradation
Conclusions
The studied materials have different degradation rates; material B has the lowest rate while material E has the highest.
The fiber diameter (at the studied range) does not significantly affect the degradation profile of the matrix.
The ‘acceleration factor’ obtained from this study was approx. 4 (=the degradation is 4 times faster in 48ºc than in 37ºc).
The in vivo and in vitro degradation profiles of the matrix performed strong connection; The in vivo degradation is apparently slightly slower that the in vitro degradation.