To investigate the biocompatibility and degradation rate of crosslinking sodium hyaluronate gel with different ratio of molecular weight, so as to choose the effective, safe and totally degraded hyaluronate gel for aesthetic injection.

①Compound colloid was formed by cross-linking the divinyl sulphone and sodium hyaluronate with different molecular weight (4×10^5, 8×10^5, 10×10^5, 12×10⁵). ②Healthy level KM mice was randomly divided into two groups to receive hyaluronic acid gel or liquid injection. Each group was subdivided into three subgroup to receive hyaluronic acid with different molecular weight. The biocompatibility and degradation rate, of hyaluronate were observed at 7, 90, 180 days after injection. At the same time, different molecular weight of sodium hyaluronate gel is sealed or exposed respectively under the low temperature preservation to observe its natural degradation rate. ③The most stable colloid was selected as aesthetic injector for volunteers to observe the aesthetic effect.

The sodium hyaluronate gel with molecular of 4×10⁵ was completely degraded 90 days later. The sodium hyaluronate gel with molecular of 8×10⁵ was completely degraded 180 days later. The sodium hyaluronate gel with molecular of 10×10⁵ was degraded to 90.0% after 180 days. The sodium hyaluronate liquid can be degraded completely within 7 days. The colloid could be kept for at least 12 months when sealed under low temperature, but was totally degraded when exposed for 1d. Sodium hyaluronate gel with molecular 10×10⁵ was confirmed to be kept for at least 6 months in animal experiment and clinical trials.

Under the same condition of material ratio, the higher the molecular weight is, the lower the degradation rate is. But the liquidity of gel is not good for injection when molecular weight is too large. It suggests that Sodium hyaluronate gel with molecular 10×10⁵ maybe the best choice in cosmetic injections.

Hyaluronic acid; Divinyl sulphone; Materials testing