Electrospinning of hair keratin with polycaprolactone

Abstract

Keratin has been blended with many polymer types particularly in the field of tissue engineering. However, the choice of solvent is still unclear on which is able to fully utilise keratin’s bioactivity. In this study, a comparison was done with different solvents as well as the exploring of new techniques such as Simultaneous Hybrid Electrospinning to identify the best method to retain keratin properties. Keratin was blended with polycaprolactone (PCL) in various solvent to examine its “electrospinnability” as well as its keratin characteristics. Keratin blended in PCL was electrospun onto a random orientation to determine its characteristics such as its morphology, mechanical strength, wettability and its chemical composition. When keratin comes into contact with an acidic solvent, protein precipitation was observed and that would change its chemical structure. In order to retain its original structure while attaining good structural integrity, a change in electrospinning technique was needed since there is no known solvent that could dissolve both keratin and PCL without adverse effects. Amongst all of the solvent used, Hexafluoro-2-propanol (HFIP) emerged as the more ideal solvent as attributes of keratin found in the blend with PCL were more prominent after material analysis. To explore on Simultaneous Hybrid Electrospinning, we would require highly concentrated keratin nanofibers and PCL nanofibers. Past studies indicated its possibility of electrospinning clear keratin solution using an alkaline solution of sodium sulfide (Na2S) with a keratin polyethylene oxide (PEO) composition of 60:1. As there was restriction in the purchase of high purity Na2S, a lower purity Na2S was used instead. The lower purity Na2S was unable to replicate the results which leads to the use of sodium sulfide nonahydrate (Na2S.9H2O). The solution was clear without any trace of precipitation but electrospraying was observed. Electrospraying occurs when the conditions of electrospinning is not met but is able to form partial nanofibers that is accompanied with unevaporated solvents. The purpose of spinning high concentration keratin nanofibers was to create a nanofiber mat that would contain a uniformed mixture of PCL and high concentration keratin nanofibers. However, as the high concentration keratin nanofiber mat was unable to be electrospun, Simultaneous Hybrid Electrospinning technique was not carried out. After exploring the use of different solvents and potential techniques, the ideal method of producing PCL blend with keratin would be to use HFIP as its solvent.