Cellulase catalyzes the hydrolysis of cellulose to glucose and is of great interest for biofuel production. Cellulase fibers with diameters ranging from 100 to 500 nm were fabricated for the first time by core-shell electrospinning. The enzymes in the core were cross-linked using glutaraldehyde and the PEO outer shell washed away using water and methanol to produce a free standing nonwoven enzyme fiber mat. The activity of the cross-linked protein fibers was determined to be 24% that of the free enzyme for hydrolysis of an insoluble paper substrate. Also, the cellulase was complexed with Ca(2+) and electrospun for EDX analysis. Elemental mapping of Ca(2+) showed fibers that cross-linked cellulase fibers maintained the fibrous morphology after washing away the PEO shell. (C) 2011 Elsevier B.V. All rights reserved.