Solid dispersions in the form of electrospun core-sheath nanofibers

Abstract

Background: The objective of this investigation was to develop a new type of solid dispersion in the form of core-sheath nanofibers using coaxial electrospinning for poorly water-soluble drugs. Different functional ingredients can be placed in various parts of core-sheath nanofibers to improve synergistically the dissolution and permeation properties of encapsulated drugs and to enable drugs to exert their actions.

Methods: Using acyclovir as a model drug, polyvinylpyrrolidone as the hydrophilic filament-forming polymer matrix, sodium dodecyl sulfate as a transmembrane enhancer, and sucralose as a sweetener, core-sheath nanofibers were successfully prepared, with the sheath part consisting of polyvinylpyrrolidone, sodium dodecyl sulfate, and sucralose, and the core part composed of polyvinylpyrrolidone and acyclovir.

Results: The core-sheath nanofibers had an average diameter of 410 ± 94 nm with a uniform structure and smooth surface. Differential scanning calorimetry and x-ray diffraction results demonstrated that acyclovir, sodium dodecyl sulfate, and sucralose were well distributed in the polyvinylpyrrolidone matrix in an amorphous state due to favoring of second-order interactions. In vitro dissolution and permeation studies showed that the core-sheath nanofiber solid dispersions could rapidly release acyclovir within one minute, with an over six-fold increased permeation rate across the sublingual mucosa compared with that of crude acyclovir particles.

Conclusion: The study reported here provides an example of the systematic design, preparation, characterization, and application of a novel type of solid dispersion consisting of multiple components and structural characteristics.

Keywords: coaxial electrospinning; core-sheath nanofibers; dissolution; permeation; poorly water-soluble drug; solid dispersion.

Figure 1

Schematic diagram of the coaxial electrospinning process (A) and digital pictures of the process (B).

Figure 2

Characterization of the electrospun core-sheath nanofibers. (A) FESEM images of nanofiber surfaces; (B) FESEM images of nanofiber cross-sections; (C) distribution of nanofiber diameters; (D) TEM images of the fiber core-sheath structure. Abbreviations: FESEM, field emission scanning electron microscope; TEM, transmission electron microscopy.

Figure 3

Differential scanning calorimetry thermograms of the components (acyclovir, PVP, SDS, and sucralose) and their core-sheath nanofibers under a heating rate of 10°C per minute and a nitrogen gas flow rate of 40 mL/minute. Abbreviations: PVP, polyvinylpyrrolidone; SDS, sodium dodecyl sulfate.

Figure 4

X-ray diffraction patterns of the components (acyclovir, PVP, SDS, and sucralose) and their core-sheath nanofibers with CuKα radiation at 40 mV and 300 mA. Abbreviations: PVP, polyvinylpyrrolidone; SDS, sodium dodecyl sulfate.

Figure 5

Molecular structures of the components (A) and hydrogen bonding between acyclovir molecules and between acyclovir and PVP molecules (B). Abbreviation: PVP, polyvinylpyrrolidone.

Figure 6

ATR-FTIR spectra of the components (acyclovir, PVP, SDS, and sucralose) and their core-sheath nanofibers at 500–4000 cm⁻¹ and a resolution of 2 cm⁻¹. Abbreviations: PVP, polyvinylpyrrolidone; SDS, sodium dodecyl sulfate; ATR-FTIR, attenuated total reflectance Fourier transform infrared.

Figure 7

In vitro dissolution profiles of the acyclovir powders and core-sheath nanofiber solid dispersions.

Figure 8

In vitro permeation profiles of the acyclovir powders and core-sheath nanofiber solid dispersions.