Fabrication of biodegradable polyurethane microspheres by a facile and green process

Abstract

Two different compositions of water-based biodegradable polyurethane (PU) in the form of homogeneous nanoparticles (NPs) were synthesized using biodegradable polyesters as the soft segment. The first PU (PU01) was based on poly(ε-caprolactone) (PCL) diol and the second PU (PU02) was based on 40% PCL diol and 60% polyethylene butylene adipate diol. The PU NP dispersions with different solid contents were sprayed into liquid nitrogen and resuspended in water to generate elastic microspheres (50-60 µm) with different nanoporosities. In vitro degradation analysis revealed that microspheres of PU02 (i.e., PU02 MS) degraded faster than those of PU01 (PU01 MS). Methylene blue was encapsulated during microsphere formation and the release was investigated. Microspheres made from a lower content (10%) of PU02 dispersion (i.e., PU02 MS_10) showed a greater burst release of methylene blue in 6 h, whereas those made from a higher content (30%) of PU01 dispersion (i.e., PU01 MS_30) revealed a prolonged release with a significantly lower burst release. Biocompatibility evaluation using L929 fibroblasts demonstrated that cells were attached and proliferated on microspheres after 24 h. On the other hand, microspheres may further self-assemble into films and scaffolds. Surface modification of microspheres by chitosan may modify the self-assembly behavior of microspheres. Microspheres could be stacked to form scaffolds with different macroporosities. Fibroblasts were successfully seeded and grown in the microsphere-stacked scaffolds. We concluded that the biodegradable and elastic microspheres may be facilely produced from a green and sustainable process with potential applications in drug release and three-dimensional cell culture.

Preparation and Properties of Hydrophilic Rosin-Based Aromatic Polyurethane Microspheres

“…At the same time, the larger specific surface area provides storage places for target molecules, which could be used in biomedical applications. 7 For example, Budriene et al 8 synthesized PU microspheres with a good thermal stability and narrow particle size distribution, using 4,4′-diphenyl-methane diisocyanate and poly(tetrahydrofuran) as raw materials, and the fixation rate of maltogenase reached 97.5%. Liu et al 9 successfully prepared two kinds of PU microspheres with a shape memory function using polycarbonate and isophorone diisocyanate or hexamethylene diisocyanate as raw materials for vascular embolization, respectively.…”

“…As a new type of organic polymer material, PU microspheres contain many polar chemical groups, such as −NHCOO, which exhibit high adsorption, chelation, and ion exchange, as well as good stability in an aqueous solution. At the same time, the larger specific surface area provides storage places for target molecules, which could be used in biomedical applications . For example, Budriene et al synthesized PU microspheres with a good thermal stability and narrow particle size distribution, using 4,4′-diphenyl-methane diisocyanate and poly­(tetrahydrofuran) as raw materials, and the fixation rate of maltogenase reached 97.5%.…”

Preparation of hollow polyurethane microspheres with tunable surface structures via electrospraying technology

“…Among all the morphologies studied, PU microspheres which have attracted wide attention for their merits of excellent mechanical properties, high adsorption, good blood compatibility and stability, are of great potential as adsorbents, drug carriers, coatings and paints. [4][5][6] Several different structural PU microspheres have been prepared to expand its application, including solid microspheres, 7 nanoparticle coated microspheres 8 and porous/hollow microspheres. 6,9,10 During the last decade, polymer microspheres with hollow interiors displayed diverse applications, including encapsulation of drug compounds, protection of sensitive agents and adsorption of pollutants.…”