Influence of natural deep eutectic solvents on stability and structure of cellulase

•Seven NADESs significantly prolonged half-life time of cellulase at 50 °C.•Bet/1,4-Bu outperformed others with 80% cellulase activity remaining (50 °C, 72 h).•Half-life time of cellulase in the presence of Bet/1,4-Bu was increased by 11 folds.•HBDs promoted stability more evidently than HBAs, among which polyols were the best.•Cellulase in NADESs enhancing its stability exhibited higher spectrum intensity.