Surface-Functionalized Nanofibers via Green Electrospinning: A Sustainable Platform for Enzyme Immobilization

In this work, we present a sustainable and efficient approach for the fabrication of surface-functionalized nanofibers via green electrospinning, an aqueous-based technique that employs polymer latexes and eliminates the need for organic solvents. Three carboxylic acid and one epoxy-functionalized latexes were synthesized through seeded semibatch emulsion polymerization using acrylic acid and glycidyl methacrylate as functional comonomers, alongside methyl methacrylate and butyl acrylate as the main monomers. The resulting latexes were blended with polyvinyl alcohol (PVA) as a sacrificial template polymer and electrospun into continuous nanofibers. The obtained nanofibers were thermally annealed at 80 °C to promote particle coalescence, followed by water treatment to remove the PVA, yielding homogeneous nanofibers with accessible surface functional groups. The accessibility and reactivity of the surface functional groups were demonstrated through the covalent immobilization of cutinase via NHS-ester and epoxy-amine coupling reactions, yielding stable and catalytically active biocatalytic nanofibers. Carboxylic acid-functionalized nanofibers showed immobilization yields of 10-18% and specific activities of 100-200 µmol min-1 mg-1. In contrast, epoxy-functionalized nanofibers exhibited a lower immobilization yield of approximately 5% but a substantially higher specific activity of approximately 330 µmol min-1 mg-1. This lower enzyme loading may favor a less densely packed immobilization, reducing steric constraints and improving enzyme accessibility and catalytic efficiency. Moreover, the epoxy-functionalized nanofiber mats exhibited enhanced operational and storage stability, significantly extending the lifetime of the immobilized biocatalyst. This approach provides a straightforward and environmentally friendly route to produce functional nanofibers without the use of organic solvents or post-spinning chemical modification steps, offering significant potential for applications in biosensing, biocatalysis, biomedical engineering, and environmental remediation.