Abstract: Articles which are composite structure are prepared which comprise a fibrillated polytetrafluoroethylene (PTFE) matrix containing enmeshed and immobilized therein viable cells capable of their usual and continuous biochemical and biological performances. The viable cells cells can be animal, bacterial, fungal or yeast. Almost all cells entrapped within said matrix are separated from each other and are unbound within said matrix such that when said matrix is cut the cells of the cut edge are free to escape from the matrix.

Abstract: A polytetrafluoroethylene (PTFE) fibril matrix is prepared containing entrapped viable cells such as animal, bacterial, fungal or yeast cells. Cells are blended with surfactant and soap-free PTFE in aqueous dispersion to form a damp paste. Water is added to the paste and a resultant stiff dough is biaxially calendered between calendering rolls to cause fibrillation and form the PTFE fibril matrix. Calendering is preferably carried out at a temperature of 5.degree. to 70.degree. C. and a pressure of 1000 to 3000 MPa. The fibril matrix may be dried.