Development of Insoluble PVA Electrospun Nanofibers Incorporating R-Limonene or β-Cyclodextrin/R-Limonene Inclusion Complexes

Abstract

Electrospinning of water-soluble polymers is considered a green process for encapsulating active compounds in polymeric nanofibers, but generally the obtained materials remain water-soluble so applications are limited. In this paper, water-insoluble poly(vinyl alcohol) (PVA) nanofibers incorporating R-limonene (a highly volatile antimicrobial) were developed. In order to avoid R-limonene loses during fabrication, β-cyclodextrin was added to the formulation. A proper heat treatment of the materials led to water-insolubilization by means of citric acid crosslinking. Nanofibers diameters were increased by the presence of β-cyclodextrin/R-limonene as a consequence of new crystalline structure. Also, encapsulation efficiency of R-limonene was improved from (19 ± 1)% to (70 ± 1)% when β-cyclodextrin was present in the formulation. Antimicrobial activity resulted low; even so, nanofibers incorporating R-limonene inhibited Escherichia coli growth. Biodegradation rate of PVA nanofibers decreased significantly when incorporating R-limonene, but it was unaffected when the active principle was also encapsulated in β-cyclodextrin. The results of this research showed that an additional encapsulation of volatile compounds with cyclodextrins could be useful to improve encapsulation efficiency in heat-treatment crosslinked materials while maintaining both the antimicrobial activity and biodegradable character of the material.