Characterization and evaluation of thermoresponsive Ecovio®/PNIPAAm electrospun fibers

ABSTRACT In this work were obtained electrospun fibers from Ecovio® and poly (N-isopropylacrylamide) high molar mass (Ecovio®/PNIPAAm AMM) and low molar mass (Ecovio®/PNIPAAm BMM) blends. Ecovio®/PNIPAAm AMM blend fibers were obtained from solutions with a concentration of 10% and in the mass ratios of 100/0, 85/15, 70/30, 50/50 and 0/100. Ecovio®/PNIPAAm BMM fibers were obtained from 20% Ecovio® solutions with 1%, 2%, 3% or 10% addition of PNIPAAM BMM. The electrospun fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy using attenuated reflectance enhancement (FTIR-ATR) and fiber surface wettability measurements. The addition of PNIPAAm AMM to the solutions of Ecovio®/PNIPAAm blends favored the electrospinning of the solutions, since the fibers obtained showed spherical morphology and absence of beads, mainly from the 30% mass ratio of PNIPAAm AMM. In addition, the presence of PNIPAAm AMM made Ecovio®/PNIPAAm fibers thermosensitive. This result was observed from water drop contact angle measurements as a function of temperature, which showed that the wettability of these fibers increased at temperatures below 32 ºC and at temperatures above 32 ºC decreased. This was due to the hydrophilic-hydrophobic transition characteristic of PNIPAAm in the 32-35 °C range. On the other hand, the same behavior was not observed for the Ecovio®/PNIPAAm BMM fibers, which had an improvement in wettability with the addition of PNIPAAm BMM, but did not exhibit the thermosensitivity behavior, probably due to the smaller size of the PNIPAAm BMM chains, which did not favor the hydrophilic-hydrophobic transition. Thus, it is likely that only the electrospun Ecovio®/PNIPAAm AMM fibers could have potential application in the area of cell growth/detachment.