Porous Polymers from High Internal Phase Emulsions as Scaffolds for Biological Applications

Abstract

High internal phase emulsions (HIPEs), with densely packed droplets of internal phase and monomers dispersed in the continuous phase, are now an established medium for porous polymer preparation (polyHIPEs). The ability to influence the pore size and interconnectivity, together with the process scalability and a wide spectrum of possible chemistries are important advantages of polyHIPEs. In this review, the focus on the biomedical applications of polyHIPEs is emphasised, in particular the applications of polyHIPEs as scaffolds/supports for biological cell growth, proliferation and tissue (re)generation. An overview of the polyHIPE preparation methodology is given and possibilities of morphology tuning are outlined. In the continuation, polyHIPEs with different chemistries and their interaction with biological systems are described. A further focus is given to combined techniques and advanced applications.

Keywords: biodegradable polymers; cell culturing; emulsion templating; polyHIPE; porous polymers; tissue engineering.

Figure 1

Schematic representation of the formation of a polyHIPE.

Figure 2

Typical polyHIPE morphology consisting of cavities and interconnecting pores.

Figure 3

SEM images of polyHIPEs prepared with radical polymerisation and different nominal porosities: (A,C) 90%; (B,D) 92%. Samples (C,D) were prepared with 0.01 M NaCl and 1% v/v DMSO. Used with permission from reference [111].

Figure 4

SEM image of: (a) interconnecting pores of the primary pores (hard sphere templating); (b) secondary pores (HIPE). Used with permission from reference [83].

Figure 5

(a) printing of the scaffold; (b–d) photos of the dried scaffold; (e) SEM image of the printed scaffold; (f) photo of the composite scaffold (constructed from different precursor HIPEs). Used with permission from reference [99].

Figure 6

Injectable double barrel system to enable long storage and fast curing upon injection [57]. (Used with permission from ACS Publications. Further permissions related to the material excerpted should be directed to the ACS).