In vitro regulation of single collagen fibril length by buffer compositions and temperature.

An understanding of collagen ultrastructure is very important for designing biopolymers mimicking collagen functions in tissue engineering, or for diagnosing abnormal collagen structure in clinical study. The present study examined formation of a large population of type I collagen single fibrils under different buffer compositions and temperatures. Fibril structures were investigated by dark-field microscopy and atomic force microscopy (AFM). In the phosphate buffered saline (PBS) buffer, the average lengths of single fibrils were 4.8+/-2.2, 5.0+/-1.9 and 9.2+/-5.0 microm for 37 degrees C, 33 degrees C and 29 degrees C, respectively. The differences were significant (P < 0.05) between 37 degrees C and 29 degrees C and between 33 degrees C and 29 degrees C. In the sodium phosphate (SP) buffer, the average lengths of single fibrils were 10.6+/-5.4, 11.1+/-4.5 and 19.6+/-11.7 microm for 37 degrees C, 33 degrees C and 29 degrees C, respectively. Similarly, the differences were significant (P < 0.05) between 37 degrees C and 29 degrees C and between 33 degrees C and 29 degrees C. While at the same temperature, the average lengths of single fibrils differed significantly (P < 0.05) between PBS and SP buffers. Single fibrils formed in SP buffer were found to have greater average length than those formed in PBS buffer.