Structure and Morphology Changes during in Vitro Degradation of Electrospun Poly(glycolide-co-lactide) Nanofiber Membrane

Abstract

Electrospun poly(glycolide-co-lactide) (PLA10GA90, LA/GA ratio 10/90) biodegradable nanofiber membranes possessed very high surface area to volume ratios and were completely noncrystalline with a relatively lowered glass transition temperature. These characteristics led to very different structure, morphology, and property changes during in vitro degradation, which were examined systematically. A shrinkage study showed that the electrospun crystallizable but amorphous PLA10GA90 membranes exhibited a very small shrinkage percentage when compared with the electrospun membranes of noncrystallizable poly(lactide-co-glycolide) (PLA75GA25, LA/GA 75/25) and poly(d,l-lactide). Although the weight loss of electrospun PLA10GA90 membranes exhibited a similar degradation behavior as cast thin films, detailed studies showed that the structure and morphology changes in electrospun membranes followed different pathways during the hydrolytic degradation. After 1 day of degradation in buffer solution at 37 degrees C, electrospun PLA10GA90 membranes exhibited a sudden increase in crystallinity and glass transition temperature, due to the fast thermally induced crystallization process. The continuous increase in crystallinity and apparent crystal size, as well as the decrease in long period and lamellae thickness, indicated that the thermally induced crystallization was followed by a chain cleavage induced crystallization process. The mass loss rate was accelerated after 6 days of degradation. The increase in glass transition temperature during this period further confirmed that the degradation of PLA10GA90 nanofibers was initiated from the amorphous region within the lamellar superstructures. A mechanism of structure and morphology changes during in vitro degradation of electrospun PLA10GA90 nanofibers is proposed.

Porous Polymeric Bioresorbable Scaffolds for Tissue Engineering

“…For such applications PLA e PLAGA copolymers with different compositions have been successfully foamed either as plain materials [117,125,129] or in combination with inorganic substances [87,130]. Moreover, scCO 2 foaming is a powerful technology for the production of scaffolds loaded with biomolecules such as growth factors [131][132][133][134][135] and DNA [134,135] that, once released, have been shown to maintain their activity. …”

“…In ES scaffolds, the macroscopic shrinkage and the change of fibre morphology has been attributed to changes of molecular conformation due to chain relaxation occurring when macromolecules in the amorphous state acquire mobility [134]. Indeed, when the fibre is generated during the ES process, …”

“…Moreover, when patterned mats or mats made of aligned fibres are placed in EtOH they loose completely their original fibre orientation. These changes of scaffold dimension and of fibre morphology introduce obvious limitations in the use of those ES materials that undergo strong shrinkage during their sterilization and some authors have even excluded the use of such polymers for TE applications [87,134,135].…”

Three-dimensional electrospun ECM-based hybrid scaffolds for cardiovascular tissue engineering

“…This high porosity allows the efficient exchange of nutrients and metabolic waste between the scaffold and its environment, and provides a high surface area for local and sustained delivery of biochemical signals to the seeded cells [11][12][13][14][15][16]. On the other hand, the small pore size of reported electrospun scaffolds has thus far shown to be difficult for ingrowth and migration of seeded cells.…”

Luminescent polyvinylpyrrolidone/ZnO hybrid nanofibers membrane prepared by electrospinning

“…Electrospinning was first reported in 1934 and has been receiving much attention due to its simplicity and effectivity to produce ultrafine fibers with diameter in the range of nanometer to micrometer. Up to now, the electrospun fibers have been finding a broad range of applications in membrane technology [20], tissue engineering [21], optical and biosensors [22,23], superhydrophobic surface [24,25] and drug delivery [26]. When a strong electrostatic force is applied to the capillary containing a polymer solution, it is ejected from the capillary and deposited as a nonwoven fibrous mat on a template serving as the ground for the electric charges.…”