The biopolymer ulvan from Ulva fasciata: Extraction towards nanofibers fabrication

As a biocompatible polymer, ulvan has applications in countless fields. Therefore, the following study intends to extract ulvan from Ulva fasciata, emphasizing its use for biomedical and industrial applications in the manufacture of nanofibrous webs. The extracted ulvan was characterized using FT-IR, DSC, XRD, GPC, and NMR. The extracted ulvan's FT-IR spectra confirmed that it is a sulfated polysaccharide. The HPLC analysis showed that the extracted ulvan is composed of rhamnose, xylose, glucose and glucuronic acid. NMR showed that the proton chemical shifts at 1.3 are due to methyl protons of rhamnose 3-sulfate in the ulvan samples. The X-ray diffractograms suggested that the extracted ulvan is semi-crystalline polymer with major crystalline reflection at 2θ of 29.4°. Deionized water has been successfully used to produce ulvan/polyvinyl alcohol (ulvan/PVA) nanofibers as an eco-friendly solvent. It was found that the ulvan-to-PVA (1:2) ratio results in nanofiber that is well handled and smooth. In addition to pretreated ones, the ulvan extracted without organic solvent pretreatment showed bead free nanofibers. It is concluded that pretreatment with organic solvent in ulvan extraction, particularly in the manufacture of nanofibers, is not recommended. In addition, the resulting nanofibrous mat has sufficient mechanical properties for various applications to be incorporated.