Electrospinning and Electrospun Fibrous Structures for Tissue Engineering and Controlled Release Applications

Abstract

Scientific publications on electrospinning and electrospun fibrous structures have been increasing exponentially since late 1990s, which testifies the worldwide interest in this “new” technology. It has been demonstrated over the past two decades that electrospun micro- and nanofibers can have diverse applications such as filtration, sensors, cosmetics, etc. There has been a huge interest in electrospun fibrous structures for biomedical applications, which stems primarily from the distinctive advantages of using fibrous structures in tissue engineering and controlled release. With advances in electrospinning technologies and associated disciplines, electrospinning will find increasingly wider applications in the biomedical field. The principle of electrospinning is simple, and the parameters for basic electrospinning are not many. But with innovative modifications of the basic electrospinning technology, new fiber collecting techniques, and developments of techniques such as emulsion electrospinning, possibilities for creating fibrous structures with distinctive and desirable properties appear to be boundless. Our research has investigated the effects of polymer solution properties and electrospinning parameters on fiber formation using a number of biopolymers and their composites. Negative voltage electrospinning (NVES) is rarely reported. Our studies pioneered NVES of tissue engineering scaffolds and have provided insights into electrospinning which can help to overcome some major technological problems in scaffold fabrication. Furthermore, our results showed that negative residual charges in scaffolds could significantly influence the cellular response. For making scaffolds with highly aligned fibers, we used a rotating-drum fiber collector together with arrayed electrodes. Not every polymer can be made into nanofibers via conventional electrospinning. We investigated using co-axial electrospinning to form nanofibers for several biopolymers. Developing bioceramic-polymer composite scaffolds for bone tissue engineering is a major area in our research and we investigated electrospinning of nanocomposite scaffolds. In vitro biological studies showed that composite fibers elicited enhanced response of osteoblastic cells. For the controlled release of biomolecules such as bone morphogenetic proteins, emulsion electrospinning was employed to form fibrous delivery systems. The emulsion composition was shown to be important for forming core-shell structured nanofibers, which affected the release behaviour of biomolecules. For the controlled, simultaneous or sequential release of two growth factors, we have developed new electrospinning technologies and fabricated bi- or tricomponent fibrous delivery vehicles. Biological assessments have affirmed the synergistic effects of dual delivery and controlled release of growth factors from novel scaffolds.