Nonaqueous Synthesis of Macroporous Nanocomposites Using High Internal Phase Emulsion Stabilized by Nanohydroxyapatite

Nonaqueous high internal phase emulsions (HIPEs) stabilized by nanohydroxyapatite (NHA)/surfactant hybrids are used as template to prepare interconnected porous monoliths. The use of a sustainable deep eutectic solvent (DES) comprised of urea and choline chloride (UChCl), as the internal phase, enables an efficient interaction of NHA/surfactant at the HIPE interface, which in turn allows for a bottom-up approach to selective interfacial functionalization of poly(HIPE's) voids surface after polymerization of methyl methacrylate continuous phase. UChCl DES is a suitable internal phase for HIPE polymerization thanks to its polarity and viscosity that provides further stabilization of the emulsion precursor. This simple synthetic method produces well-defined functional poly(methyl methacrylate) (pMMA) scaffolds with tunable mechanical properties and exposed NHA at the inner surface. Based upon a preliminary biocompatibility in vivo test, poly(HIPEs) show enhanced biocompatibility in comparison with sterile gauze. Interestingly, pMMA NHA nanocomposite scaffold remains in the tissue after 90 d allowing little ingrowth of cells while causing a normal foreign-body reaction in the rats' muscle tissue. Interfacial functionalization of well-defined interconnected porous monoliths with nanomaterials via DES-based HIPEs approach is a promising method that encourages further investigation for the synthesis of biodegradable and biocompatible scaffolds nanocomposites for tissue engineering purposes.