To study the biocompatibility of alginate oligosaccharides with different degree of lysis and effect on wound healing.

Depending on the difference of molecular weight, the alginate oligosaccharides with different degree of lysis were separated by dialysis method. The molecular weight was <1000, 1000-5000, 5000-10000 and >10000 respectively, and the non-cleaved alginate was used as control. Observed the film formation ability of alginate oligosaccharides with different molecular weight, detected the bacteria resistance and moisture retention after film formation ability, and detected the cytotoxicity, sensitization and intradermal stimulation according to the requirements of GB/T 16886 to verify the biocompatibility. A full-thickness wound defect model with a diameter of 3 cm was prepared on the back of SD rats. Alginate oligosaccharide solution with different degrees of lysis was used for dressing change, which was divided into experimental group 1-4, alginate solution as the positive control group, and physiological saline as the negative control group. The dressing was changed daily. The wound healing rate was calculated on the 7th and 14th days.The wound tissue was taken for HE staining to observe the tissue changes, and sirius red picric acid staining was used to observe the collagen secretion.

When the molecular weight was less than 1000, no film formation was observed, and there was no obvious bacteria resistance and moisture retention. With the increase of molecular weight, the film formation ability, bacteria resistance and moisture retention were enhanced. At the concentration of 0.02%, the alginate oligosaccharides with different molecular weight and non-cleaved alginate had no obvious cytotoxicity and sensitization, but when the molecular weight was less than 1 000, it had slight intradermal stimulation. On the 7th and 14th day after modeling, except for experimental group 2, the wound healing rate of each group in the experimental group and the positive control group was significantly higher than that of the negative control group(F=0.018, 0.097, 0.016, 0.055; t=3.737, 3.853, 3.861, 3.525; P<0.05; F=0.562, 0.111, 1.162, 0.206; t=3.484, -1.557, -0.319, 3.851; P<0.05). HE and sirius red picric acid staining showed that when the molecular weight was above 5 000, the granulation tissue proliferation and collagen content increased significantly.

The algal oligosaccharides with low degree of lysis has the ability of film formation, bacteria inhibition and moisture retention, and can provide a moist environment suitable for wound healing.