Microsphere-Based Scaffolds in Regenerative Engineering

Abstract

Microspheres have long been used in drug delivery applications because of their controlled release capabilities. They have increasingly served as the fundamental building block for fabricating scaffolds for regenerative engineering because of their ability to provide a porous network, offer high-resolution control over spatial organization, and deliver growth factors/drugs and/or nanophase materials. Because they provide physicochemical gradients via spatiotemporal release of bioactive factors and nanophase ceramics, microspheres are a desirable tool for engineering complex tissues and biological interfaces. In this review we describe various methods for microsphere fabrication and sintering, and elucidate how these methods influence both micro- and macroscopic scaffold properties, with a special focus on the nature of sintering. Furthermore, we review key applications of microsphere-based scaffolds in regenerating various tissues. We hope to inspire researchers to join a growing community of investigators using microspheres as tissue engineering scaffolds so that their full potential in regenerative engineering may be realized.

Keywords: microsphere fabrication; microsphere incorporating scaffolds; microsphere sintering; microsphere-based scaffolds; microspheres.

Figure 1

Microsphere fabrication via (a) emulsion-solvent extraction and (b) precision particle fabrication (PPF) methods. (a) The major steps in an emulsion-solvent extraction method along with its several variations: (i) single emulsion, (ii) double emulsion, and (iii) cryopreparation. (b) Schematic of a PPF setup consisting of a custom-designed dual nozzle (expanded view shown on the right) and an acoustic excitation device.

Figure 2

Design strategies for fabricating microsphere-based scaffolds.