The optimization of hydrophilicity of PVA scaffold due to citric acid addition and heat treatment

Abstract

Materials developed for wound healing have to meet several criteria, such as being non-cytotoxic, biocompatible, biodegradable,
having good mechanical properties, and acting selectively with osteoblasts. The aim of this study was, using
an electrospinning method, to prepare a polymer scaffold to get a stable, adequate, hydrophilic structure, which will enhance
wound healing during bone regeneration. To achieve that, a cross-linked polyvinyl alcohol fibre net was prepared
by heat treatment and applied to the water-based polymer in presence of a citric acid solution. The viscosity of the initial
polymer was determined from the flow curve measurements. The surface properties of the fibre nets were monitored by
the low-vacuum scanning electron microscopy and the contact angle measurements. It was found that the addition of a
citric acid as a cross-linker in a concentration exceeding 2m/m% increased the diameter of the polyvinyl alcohol fibres.
When adding 8m/m% citric acid, an initial diameter of 224 ± 52 nm has increased to 269 ± 109 nm. Furthermore, the distribution
also became wider due to the development of bonding points for ester bonds. This process was enhanced by a
two-hour heating at 120 °C; thus, resulting in modification of the OH groups on the surface. The decrease of hydrophilicity
was proved by the increase in contact angles. In addition, it was demonstrated that the scaffold structure prepared
with this method does not degrade during the 24–120 h long water treatment.