IN-VITRO FORMATION BY REVERSE DIALYSIS OF COLLAGEN GELS CONTAINING HIGHLY ORIENTED ARRAYS OF FIBRILS

Acid extracts of rat tail tendon were subjected to reverse dialysis ag ainst 0.5% PEG at 4 degrees C in an attempt to induce liquid crystalli zation. After 48 h, gel and fibril formation were initiated by continu ing dialysis at 20 degrees C against the same PEG solution adjusted to pH 7.4. The inclusion of calcium- or magnesium chloride (final concen tration 0.3-33 mM) in the collagen solution before dialysis resulted i n strongly birefringent gels that showed a progressive rotation of the slow axis of birefringence with increasing distance from the lateral margin of the gel. The gels contained fibers running predominantly in the plane of the flattened gel and crossing at angles of between 55 de grees and 90 degrees. We suggest that liquid crystallization is respon sible for this phenomenon and that it might be possible to exploit thi s to produce materials for tissue engineering. (C) 1998 John Wiley & S ons, Inc.