Water stable nanofibrous tubes from hyaluronan derivative and nanocrystalline cellulose

The field of nanotechnology has undergone unprecedented development in the recent decades and nanofibrous structures are still in the focus of attention. One of the current topics in this field is a preparation of the vascular... [ view full abstract ]

The field of nanotechnology has undergone unprecedented development in the recent decades and nanofibrous structures are still in the focus of attention. One of the current topics in this field is a preparation of the vascular grafts by the electrospinning method. This method enables easy preparation of grafts with diameter smaller than 6 mm, which could be used e.g. as coronary arteries grafts. In most cases, electrospun grafts are made of a synthetic polymer (PCL, PLA) as it provides sufficient mechanical properties, but their slow degradation rates limit cell infiltration. Synthetic polymers are thus often combined with a natural polymer (e.g. chitosan), which are hydrophilic and have faster degradation rates, but suffer from insufficient mechanical properties. 

This work aims to describe preparation and characterization of nanofibrous tubes made of a natural polymer - a hyaluronic acid, respectively its 3-(2-furyl)acrylic acid derivative (HA-FU). Using the classic process of electrospinning we were able to prepare nanofibrous tubes, from water solutions only, with a diameter of 5 mm and length up to 15 cm. The UV-crosslinkable hyaluronan enabled us to prepare water stable nanofibrous tubes (Fig.1 left) that could be used e.g. as a top layer of the synthetic grafts and thus enhance its bio properties. To enhance mechanical properties of the HA-FU tubes and made them more durable, a non-toxic, natural and biocompatible nanocrystalline cellulose (NCC) was used as an additive. The presence of NCC in tube structure after 7-day water immersion was confirmed by the confocal microscopy (Fig.2). Mechanical tests showed significant enhancement when 5% of NCC was added (Fig.3). The viability of 3T3 fibroblast was determined to show a non-toxic behaviour of prepared tubes. The viability was not significantly affected by the samples. Based on these results we do not suppose any cytotoxic effect of the HA-FU and HA-FU+NCC nanofibers. The NCC addition does not affect material toxicity. To demonstrate it possible application within a nanofibrous graft from a synthetic polymer, a composite tube made of PCL:HA-FU tube was prepared. The tube kept its shape after immersion and formed a gel HA-FU layer on its top (Fig.1 right).