Enrichment of cellulose acetate nanofibre assemblies for therapeutic delivery of l-tryptophan

The essential amino acid l-tryptophan is naturally present in the body, and is also available as a water soluble dietary supplement. The feasibility of preparing enriched cellulose acetate (CA)-based fibres as a vehicle for therapeutic delivery of such biomolecules was investigated. A new ternary solvent system consisting of acetone: N,N-dimethylacetamide: methanol (2:1:2) has been demonstrated to permit the solution blending of CA with the water soluble l-tryptophan. Nanofibrous webs substantially free of structural defects were continuously produced with mean fibre diameters in the range of 520-1010 nm, dependent on process parameters. Morphology and diameter of fibres were influenced by concentration of CA spinning solution, applied voltage and flow rates. The kinetic release profile of l-tryptophan from electrospun CA nanofibres was described by the pseudo-second order kinetic model. Fibres with mean diameter of 720 nm provide both the highest initial desorption rate and rate constant, which was partially attributed to the low fibre diameter and high relative surface area, but also the fact that the 720 nm fibres produced were the most bead-free, providing diffusion advantages over the fibres with lowest mean diameter (520 nm). The feasibility of combining l-tryptophan within fibres provides a promising route for manufacture of transdermal delivery devices.