A facile technique to prepare biodegradable coaxial electrospun nanofibers for controlled release of bioactive agents

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Abstract

A one-step, mild procedure based on coaxial electrospinning was developed for incorporation and controlled release of two model proteins, BSA and lysozyme, from biodegradable core-shell nanofibers with PCL as shell and protein-containing PEG as core. The thickness of the core and shell could be adjusted by the feed rate of the inner dope, which in turn affected the release profiles of the incorporated proteins. It was revealed that the released lysozyme maintained its structure and bioactivity. The current method may find wide applications for controlled release of proteins and tissue engineering.

Introduction

The interconnected, three dimensional porous structures and enormous surface areas [1] of electrospun scaffolds prepared from biodegradable polymers have great potentials in tissue engineering, drug delivery, and gene therapy, etc. Due to their biodegradability, biocompatibility and fiber-forming properties [1], [2], aliphatic polyesters were the most studied materials amongst all biodegradable polymers. Agents soluble in common organic solvents can be conveniently incorporated into polyester nanofibers by direct electrospinning and sustained release could be achieved [3]. However, entrapment and sustained release of water-soluble bioactive agents by conventional electrospinning techniques remains challenging [1], [4]. Very recently, a spinneret composed of two coaxial capillaries was developed for simultaneously electrospinning two different polymer solutions into core-shell structured nanofibers [5]. In this communication, we demonstrated for the first time the capabilities of this technique for incorporation of water-soluble bioactive agents into biodegradable non-woven polymer meshes; and their subsequent controlled release. Compared with other methods widely used for encapsulation of proteins, growth factors and DNA [6], the current technique has the advantages of being facile, high loading efficiency/capacity, mild preparation condition and relatively steady release characteristics.

Section snippets

Materials

Poly(ɛ-caprolactone) (PCL, Mn 42,500) was purchased from Aldrich (Milwaukee, MI). Poly(ethylene glycol) (PEG, Mn 35,000) was obtained from Fluka (Buchs, Switzerland). BSA (fraction V) and lysozyme (from chicken egg white, approx. 50,000 units/mg) were supplied by Sigma (St. Louis, MO).

Characterization

The 1H NMR spectra of the composite scaffolds were obtained by a Bruker DMX-500 NMR spectrometer at room temperature using CDCl3 as a solvent. Surface morphology of the electrospun scaffolds was observed on a JEOL

Results and discussion

The configuration of the coaxial spinneret we used for electrospinning was modified from the design reported by Sun (Fig. 1) [5]. Two immiscible liquids were fed through two concentrically arranged needles, with their sharp ends blunted to facilitate formation of a stable jet. The inner diameters of the needles were 0.9 and 0.57 mm, respectively. The flow of solution through the inner needle was controlled by a syringe pump, whereas the outer polymer solution was pressurized by nitrogen to

Conclusions

Coaxial electrospinning is a versatile method for incorporation of water-soluble macromolecules and they could be released steadily from the nanofibrous scaffolds produced. The implication is that bioactive agents such as growth factors and DNA could readily be integrated into the nanofibrous scaffolds using the method we described, and they could be utilized in gene therapy and tissue engineering.

Acknowledgements

The research is supported by National Natural Science Foundation of China under Project 20304013.

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