Applications brief: Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems

Key points


  • AFM-IR revealed the formation of chitosan salts in polycaprolactone/chitosan fibres in multiple solvent systems
  • This study compared the spinnability of biomedically important fibre blends in different solvents


Key words

AFM-IR | Chitosan | Electrospinning | PCL/chitosan fibres | Solvent system | Chitosan salts

Authors

O. Urbanek, P. Sajkiewicz, F. Pierini, M. Czerkies, D. Kołbuk

Abstract

Electrospinning of chitosan blends is a reasonable idea to prepare fibre mats for biomedical applications. Synthetic and natural components provide, for example, appropriate mechanical strength and biocompatibility, respectively. However, solvent characteristics and the polyelectrolyte nature of chitosan influence the spinnability of these blends. In order to compare the effect of solvent on polycaprolactone/chitosan fibres, two types of the most commonly used solvent systems were chosen, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and acetic acid (AA)/formic acid (FA). Results obtained by various experimental methods clearly indicated the effect of the solvent system on the structure and properties of electrospun polycaprolactone/chitosan fibres. Viscosity measurements confirmed different polymer–solvent interactions. Various molecular interactions resulting in different macromolecular conformations of chitosan influenced its spinnability and properties. HFIP enabled fibres to be obtained whose average diameter was less than 250 nmwhile maintaining the brittle and hydrophilic character of the nonwoven, typical for the chitosan component. Spectroscopy studies revealed the formation of chitosan salts in the case of the AA/FA solvent system. Chitosan salts visibly influenced the structure and properties of the prepared fibre mats. The use of AA/FA caused a reduction of Young’s modulus and wettability of the proposed blends. It was confirmed that wettability, mechanical properties and the antibacterial effect of polycaprolactone/chitosan fibres may be tailored by selecting an appropriate solvent system. TheMTTcell proliferation assay revealed an increase of cytotoxicity to mouse fibroblasts in the case of 25%w/wof chitosan in electrospun nonwovens.

Topographic images of a single electrospun fibre (a) and a casted film produced using the same fibre starting solution (b). IR nanoscopy characterization: AFM-IR maps of the chitosan N–H bending absorption at 1645 cm−1 recorded analysing the single fibre and the polymer blend film.
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