Oxyalkylation modification as a promising method for preparing low-melting-point agarose.

In this study, agarose was chemically modified with ethylene oxide, 1,2-epoxypropane and 1,2-epoxybutane, to prepare hydroxyethyl agarose (HEAG), hydroxypropyl agarose (HPAG), and hydroxybutyl agarose (HBAG). The structures and properties of the products were characterized by Fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy, X-ray diffractometry (XRD), rheology measurement and gel electrophoresis. The results showed that the gelling temperature (Tg) of HEAG, HPAG, and HBAG were decreased to 28.3 °C, 29.0 °C and 28.7 °C respectively, with the melting temperature (Tm) simultaneously declined to 64.2 °C, 63.8 °C and 63.0 °C, respectively. Meanwhile, the gel strength of HBAG, HEAG, and HPAG were dramatically reduced to 194 g/cm2, 312 g/cm2 and 279 g/cm2, respectively. Furthermore, HEAG and HPAG showed excellent separation efficiency which is in accordance with commercialized low-melting-point (LMP) agarose (Amersco 0815). These results indicated that oxyalkylation is a promising and economical method for the preparation of LMP agarose.